定价： 0元 / 折扣价： 0 元 加购物车

定价： 1177元 / 折扣价： 1001 元

定价： 689元 / 折扣价： 586 元

定价： 1177元 / 折扣价： 1001 元 加购物车

4.1 This test method may be used for material development, material comparison, quality assurance, characterization, reliability assessment, and design data generation.4.2 Continuous fiber-reinforced ceramic matrix composites (CFCCs) are generally characterized by fine-grain sized (<50 μm) matrices and ceramic fiber reinforcements. In addition, continuous fiber-reinforced glass (amorphous) matrix composites can also be classified as CFCCs. Uniaxially loaded compressive strength tests provide information on mechanical behavior and strength for a uniformly stressed CFCC.4.3 Generally, ceramic and ceramic matrix composites have greater resistance to compressive forces than tensile forces. Ideally, ceramics should be compressively stressed in use, although engineering applications may frequently introduce tensile stresses in the component. Nonetheless, compressive behavior is an important aspect of mechanical properties and performance. The compressive strength of ceramic and ceramic composites may not be deterministic. Therefore, test a sufficient number of test specimens to gain an insight into strength distributions.4.4 Compression tests provide information on the strength and deformation of materials under uniaxial compressive stresses. Uniform stress states are required to effectively evaluate any nonlinear stress-strain behavior that may develop as the result of cumulative damage processes (for example, matrix cracking, matrix/fiber debonding, fiber fracture, delamination, etc.) that may be influenced by testing mode, testing rate, effects of processing or combination of constituent materials, or environmental influences. Some of these effects may be consequences of stress corrosion or sub-critical (slow) crack growth which can be minimized by testing at sufficiently rapid rates as outlined in this test method.4.5 The results of compression tests of test specimens fabricated to standardized dimensions from a particulate material or selected portions of a part, or both, may not totally represent the strength and deformation properties of the entire, full-size product or its in-service behavior in different environments.4.6 For quality control purposes, results derived from standardized compressive test specimens may be considered indicative of the response of the material from which they were taken for given primary processing conditions and post-processing heat treatments.4.7 The compressive behavior and strength of a CFCC are dependent on, and directly related to, the material. Analysis of fracture surfaces and fractography, though beyond the scope of this test method, are recommended.1.1 This test method covers the determination of compressive strength, including stress-strain behavior, under monotonic uniaxial loading of continuous fiber-reinforced advanced ceramics at ambient temperatures. This test method addresses, but is not restricted to, various suggested test specimen geometries as listed in the appendixes. In addition, test specimen fabrication methods, testing modes (force, displacement, or strain control), testing rates (force rate, stress rate, displacement rate, or strain rate), allowable bending, and data collection and reporting procedures are addressed. Compressive strength, as used in this test method, refers to the compressive strength obtained under monotonic uniaxial loading, where monotonic refers to a continuous nonstop test rate with no reversals from test initiation to final fracture.1.2 This test method applies primarily to advanced ceramic matrix composites with continuous fiber reinforcement: unidirectional (1D), bidirectional (2D), and tridirectional (3D) or other multi-directional reinforcements. In addition, this test method may also be used with glass (amorphous) matrix composites with 1D, 2D, 3D, and other multi-directional continuous fiber reinforcements. This test method does not directly address discontinuous fiber-reinforced, whisker-reinforced, or particulate-reinforced ceramics, although the test methods detailed here may be equally applicable to these composites.1.3 The values stated in SI units are to be regarded as the standard and are in accordance with IEEE/ASTM SI 10.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Refer to Section 7 for specific precautions.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 646元 / 折扣价： 550 元 加购物车

5.1 This test method evaluates the relative sensitivity of materials to mechanical impact in ambient pressure liquid oxygen, pressurized liquid oxygen, and pressurized gaseous oxygen.5.2 Any change or variation in test sample configuration, thickness, preparation, or cleanliness may cause a significant change in impact sensitivity/reaction threshold.5.3 Suggested criteria for discontinuing the tests are: (1) occurrence of two reactions in a maximum of 60 samples or less tested at the maximum energy level of 98 J (72 ft•lbf) or one reaction in a maximum of 20 samples tested at any other energy level for a material that fails; (2) no reactions for 20 samples tested at the 98-J (72-ft•lbf) energy level; or (3) a maximum of one reaction in 60 samples tested at the maximum energy level.1.1 This test method2 describes test equipment and techniques to determine the impact sensitivity of materials in oxygen under two different conditions: (1) in ambient pressure liquid oxygen (LOX) or (2) under pressure-controlled conditions in LOX or gaseous oxygen (GOX). It is applicable to materials for use in LOX or GOX systems at pressures from ambient to 68.9 MPa (0 to 10 000 psig). The test method described herein addresses testing with pure oxygen environments; however, other oxygen-enriched fluids may be substituted throughout this document.1.2 This test method provides a means for ranking nonmetallic materials as defined in Guide G63 for use in liquid and gaseous oxygen systems and may not be directly applicable to the determination of the sensitivity of the materials in an end-use configuration. This test method may be used to provide batch-to batch acceptance data. This test method may provide a means for evaluating metallic materials in oxygen-enriched atmospheres also; however, Guide G94 should be consulted for preferred testing methods.1.3 Values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. See also Section 9.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 1011元 / 折扣价： 860 元 加购物车

4.1 This practice may be used for material development, material comparison, quality assurance, characterization, reliability assessment, and design data generation.4.2 Continuous fiber-reinforced ceramic matrix composites are generally characterized by crystalline matrices and ceramic fiber reinforcements. These materials are candidate materials for structural applications requiring high degrees of wear and corrosion resistance, and high-temperature inherent damage tolerance (that is, toughness). In addition, continuous fiber-reinforced glass matrix composites are candidate materials for similar but possibly less demanding applications. Although flexural test methods are commonly used to evaluate the mechanical behavior of monolithic advanced ceramics, the nonuniform stress distribution in a flexural test specimen in addition to dissimilar mechanical behavior in tension and compression for CFCCs leads to ambiguity of interpretation of test results obtained in flexure for CFCCs. Uniaxially loaded tensile tests provide information on mechanical behavior for a uniformly stressed material.4.3 The cyclic fatigue behavior of CFCCs can have appreciable nonlinear effects (for example, sliding of fibers within the matrix) which may be related to the heat transfer of the specimen to the surroundings. Changes in test temperature, frequency, and heat removal can affect test results. It may be desirable to measure the effects of these variables to more closely simulate end-use conditions for some specific application.4.4 Cyclic fatigue by its nature is a probabilistic phenomenon as discussed in STP 91A (1) and STP 588 (2).4 In addition, the strengths of the brittle matrices and fibers of CFCCs are probabilistic in nature. Therefore, a sufficient number of test specimens at each testing condition is required for statistical analysis and design, with guidelines for sufficient numbers provided in STP 91A (1), STP 588 (2), and Practice E739. Studies to determine the influence of test specimen volume or surface area on cyclic fatigue strength distributions for CFCCs have not been completed. The many different tensile test specimen geometries available for cyclic fatigue testing may result in variations in the measured cyclic fatigue behavior of a particular material due to differences in the volume of material in the gage section of the test specimens.4.5 Tensile cyclic fatigue tests provide information on the material response under fluctuating uniaxial tensile stresses. Uniform stress states are required to effectively evaluate any nonlinear stress-strain behavior which may develop as the result of cumulative damage processes (for example, matrix microcracking, fiber/matrix debonding, delamination, cyclic fatigue crack growth, etc.)4.6 Cumulative damage due to cyclic fatigue may be influenced by testing mode, testing rate (related to frequency), differences between maximum and minimum force (R or Α), effects of processing or combinations of constituent materials, environmental influences (including test environment and pre-test conditioning), or combinations thereof. Some of these effects may be consequences of stress corrosion or subcritical (slow) crack growth which can be difficult to quantify. Other factors which may influence cyclic fatigue behavior are: matrix or fiber material, void or porosity content, methods of test specimen preparation or fabrication, volume percent of the reinforcement, orientation and stacking of the reinforcement, test specimen conditioning, test environment, force or strain limits during cycling, wave shapes (that is, sinusoidal, trapezoidal, etc.), and failure mode of the CFCC.4.7 The results of cyclic fatigue tests of test specimens fabricated to standardized dimensions from a particular material or selected portions of a part, or both, may not totally represent the cyclic fatigue behavior of the entire, full-size end product or its in-service behavior in different environments.4.8 However, for quality control purposes, results derived from standardized tensile test specimens may be considered indicative of the response of the material from which they were taken for given primary processing conditions and post-processing heat treatments.4.9 The cyclic fatigue behavior of a CFCC is dependent on its inherent resistance to fracture, the presence of flaws, or damage accumulation processes, or both. There can be significant damage in the CFCC test specimen without any visual evidence such as the occurrence of a macroscopic crack. This can result in a loss of stiffness and retained strength. Depending on the purpose for which the test is being conducted, rather than final fracture, a specific loss in stiffness or retained strength may constitute failure. In cases where fracture occurs, analysis of fracture surfaces and fractography, though beyond the scope of this practice, is recommended.1.1 This practice covers the determination of constant-amplitude, axial tension-tension cyclic fatigue behavior and performance of continuous fiber-reinforced advanced ceramic composites (CFCCs) at ambient temperatures. This practice builds on experience and existing standards in tensile testing CFCCs at ambient temperatures and addresses various suggested test specimen geometries, specimen fabrication methods, testing modes (force, displacement, or strain control), testing rates and frequencies, allowable bending, and procedures for data collection and reporting. This practice does not apply to axial cyclic fatigue tests of components or parts (that is, machine elements with nonuniform or multiaxial stress states).1.2 This practice applies primarily to advanced ceramic matrix composites with continuous fiber reinforcement: uni-directional (1-D), bi-directional (2-D), and tri-directional (3-D) or other multi-directional reinforcements. In addition, this practice may also be used with glass (amorphous) matrix composites with 1-D, 2-D, 3-D, and other multi-directional continuous fiber reinforcements. This practice does not directly address discontinuous fiber-reinforced, whisker-reinforced or particulate-reinforced ceramics, although the methods detailed here may be equally applicable to these composites.1.3 The values stated in SI units are to be regarded as the standard and are in accordance with IEEE/ASTM SI 10.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Refer to Section 7 for specific precautions.

定价： 590元 / 折扣价： 502 元 加购物车

4.1 This practice may be used for material development, material comparison, quality assurance, characterization, reliability assessment, and design data generation.4.2 High-strength, monolithic advanced ceramic materials are generally characterized by small grain sizes (<50 μm) and bulk densities near the theoretical density. These materials are candidates for load-bearing structural applications requiring high degrees of wear and corrosion resistance, and high-temperature strength. Although flexural test methods are commonly used to evaluate strength of advanced ceramics, the nonuniform stress distribution in a flexure specimen limits the volume of material subjected to the maximum applied stress at fracture. Uniaxially loaded tensile strength tests may provide information on strength-limiting flaws from a greater volume of uniformly stressed material.4.3 Cyclic fatigue by its nature is a probabilistic phenomenon as discussed in STP 91A and STP 588 (1, 2).4 In addition, the strengths of advanced ceramics are probabilistic in nature. Therefore, a sufficient number of test specimens at each testing condition is required for statistical analysis and design, with guidelines for sufficient numbers provided in STP 91A (1), STP 588 (2), and Practice E739. The many different tensile specimen geometries available for cyclic fatigue testing may result in variations in the measured cyclic fatigue behavior of a particular material due to differences in the volume or surface area of material in the gage section of the test specimens.4.4 Tensile cyclic fatigue tests provide information on the material response under fluctuating uniaxial tensile stresses. Uniform stress states are required to effectively evaluate any nonlinear stress-strain behavior which may develop as the result of cumulative damage processes (for example, microcracking, cyclic fatigue crack growth, etc.).4.5 Cumulative damage processes due to cyclic fatigue may be influenced by testing mode, testing rate (related to frequency), differences between maximum and minimum force (R or Α), effects of processing or combinations of constituent materials, or environmental influences, or both. Other factors that influence cyclic fatigue behavior are: void or porosity content, methods of test specimen preparation or fabrication,test specimen conditioning, test environment, force or strain limits during cycling, wave shapes (that is, sinusoidal, trapezoidal, etc.), and failure mode. Some of these effects may be consequences of stress corrosion or sub-critical (slow) crack growth which can be difficult to quantify. In addition, surface or near-surface flaws introduced by the test specimen fabrication process (machining) may or may not be quantifiable by conventional measurements of surface texture. Therefore, surface effects (for example, as reflected in cyclic fatigue reduction factors as classified by Marin (3)) must be inferred from the results of numerous cyclic fatigue tests performed with test specimens having identical fabrication histories.4.6 The results of cyclic fatigue tests of specimens fabricated to standardized dimensions from a particular material or selected portions of a part, or both, may not totally represent the cyclic fatigue behavior of the entire full-size end product or its in-service behavior in different environments.4.7 However, for quality control purposes, results derived from standardized tensile test specimens may be considered indicative of the response of the material from which they were taken for given primary processing conditions and post-processing heat treatments.4.8 The cyclic fatigue behavior of an advanced ceramic is dependent on its inherent resistance to fracture, the presence of flaws, or damage accumulation processes, or both. There can be significant damage in the test specimen without any visual evidence such as the occurrence of a macroscopic crack. This can result in a specific loss of stiffness and retained strength. Depending on the purpose for which the test is being conducted, rather than final fracture, a specific loss in stiffness or retained strength may constitute failure. In cases where fracture occurs, analysis of fracture surfaces and fractography, though beyond the scope of this practice, are recommended.1.1 This practice covers the determination of constant-amplitude, axial, tension-tension cyclic fatigue behavior and performance of advanced ceramics at ambient temperatures to establish “baseline” cyclic fatigue performance. This practice builds on experience and existing standards in tensile testing advanced ceramics at ambient temperatures and addresses various suggested test specimen geometries, test specimen fabrication methods, testing modes (force, displacement, or strain control), testing rates and frequencies, allowable bending, and procedures for data collection and reporting. This practice does not apply to axial cyclic fatigue tests of components or parts (that is, machine elements with nonuniform or multiaxial stress states).1.2 This practice applies primarily to advanced ceramics that macroscopically exhibit isotropic, homogeneous, continuous behavior. While this practice applies primarily to monolithic advanced ceramics, certain whisker- or particle-reinforced composite ceramics, as well as certain discontinuous fibre-reinforced composite ceramics, may also meet these macroscopic behavior assumptions. Generally, continuous fibre-reinforced ceramic composites (CFCCs) do not macroscopically exhibit isotropic, homogeneous, continuous behavior and application of this practice to these materials is not recommended.1.3 The values stated in SI units are to be regarded as the standard and are in accordance with IEEE/ASTM SI 10.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Refer to Section 7 for specific precautions.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

5.1 Most oxides of nitrogen are formed during high-temperature combustion. The U.S. Environmental Protection Agency (EPA) has set primary and secondary air quality standards for NO2 that are designed to protect the public health and the public welfare (40 CFR, Part 50).5.2 Oxides of nitrogen are generated by many industrial processes that can result in employee exposures. These are regulated by the Occupational Safety and Health Administration (OSHA), which has promulgated exposure limits for the industrial working environment (29 CFR, Part 1910).5.3 These test methods have been found to be satisfactory for measuring oxides of nitrogen in ambient and workplace atmospheres over the ranges shown in 1.1.1.1 These test methods cover procedures for the continuous determination of total nitrogen dioxide (NO2) and nitric oxide (NO) as NOx, or nitric oxide (NO) alone or nitrogen dioxide (NO2) alone, in the ranges shown in the following table:  Approximate Range of Concentration(25°C and 101.3 kPa (1 atm))     Gas Ambient Atmosphere Workplace Atmosphere  μg/m3 (ppm) mg/m3 (ppm)     NO 10 to 600 (0.01 to 0.5) 0.6 to 30 (0.5 to 25)(NO + NO2) = NOx 20 to 1000 (0.01 to 0.05) 1 to 50 (0.5 to 25) NO2 20 to 1000 (0.01 to 0.5) 1 to 50 (0.5 to 25) 1.2 The test methods are based on the chemiluminescent reaction between nitric oxide and ozone.1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 9.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 646元 / 折扣价： 550 元 加购物车

4.1 For many structural ceramic components in service, their use is often limited by lifetimes that are controlled by a process of SCG. This test method provides the empirical parameters for appraising the relative SCG susceptibility of ceramic materials under specified environments. Furthermore, this test method may establish the influences of processing variables and composition on SCG as well as on strength behavior of newly developed or existing materials, thus allowing tailoring and optimizing material processing for further modification. In summary, this test method may be used for material development, quality control, characterization, and limited design data generation purposes. The conventional analysis of constant stress rate testing is based on a number of critical assumptions, the most important of which are listed in the next paragraphs.4.2 The flexural stress computation for the rectangular beam test specimens or the equibiaxial disk flexure test specimens is based on simple beam theory, with the assumptions that the material is isotropic and homogeneous, the moduli of elasticity in tension and compression are identical, and the material is linearly elastic. The average grain size should be no greater than one-fiftieth of the beam thickness.4.3 The test specimen sizes and fixtures for rectangular beam test specimens should be in accordance with Test Method C1161, which provides a balance between practical configurations and resulting errors, as discussed in Refs (4, 5). Only four-point test configuration is allowed in this test method for rectangular beam specimens. Three-point test configurations are not permitted. The test specimen sizes and fixtures for disk test specimens tested in ring-on-ring flexure should be chosen in accordance with Test Method C1499. The test specimens for direct tension strength testing should be chosen in accordance with Test Method C1273.4.4 The SCG parameters (n and D) are determined by fitting the measured experimental data to a mathematical relationship between strength and applied stress rate, log σf = 1/(n+1) log σ˙ + log D. The basic underlying assumption on the derivation of this relationship is that SCG is governed by an empirical power-law crack velocity, v = A[KI/KIC]n (see Appendix X1).NOTE 3: There are various other forms of crack velocity laws which are usually more complex or less convenient mathematically, or both, but may be physically more realistic (6). It is generally accepted that actual data cannot reliably distinguish between the various formulations. Therefore, the mathematical analysis in this test method does not cover such alternative crack velocity formulations.4.5 The mathematical relationship between strength and stress rate was derived based on the assumption that the slow crack growth parameter is at least n ≥ 5 (1, 7, 8). Therefore, if a material exhibits a very high susceptibility to SCG, that is, n < 5, special care should be taken when interpreting the results.4.6 The mathematical analysis of test results in accordance with the method in 4.4 assumes that the material displays no rising R-curve behavior. It should be noted that the existence of such behavior cannot be determined from this test method.4.7 Slow crack growth behavior of ceramic materials exposed to stress-corrosive gases or liquid environments can vary as a function of mechanical, material, and electrochemical variables. Therefore, it is essential that test results accurately reflect the effects of specific variables under study. Only then can data be compared from one investigation to another on a valid basis or serve as a valid basis for characterizing materials and assessing structural behavior.4.8 The strength of advanced ceramics is probabilistic in nature. Therefore, SCG that is determined from the strengths of a ceramic material is also a probabilistic phenomenon. Hence, a proper range and number of applied stress rates in conjunction with an appropriate number of specimens at each applied stress rate are required for statistical reproducibility and design (2). Guidelines are provided in this test method.NOTE 4: For a given ceramic material/environment system, the SCG parameter n is constant regardless of specimen size although its reproducibility is dependent on the variables mentioned in 4.8. By contrast, the SCG parameter D depends significantly on strength and thus on specimen size (see Eq X1.6 in Appendix X1).4.9 The strength of a ceramic material for a given specimen and test fixture configuration is dependent on its inherent resistance to fracture, the presence of flaws, and environmental effects. Analysis of a fracture surface, fractography, though beyond the scope of this test method, is highly recommended for all purposes, especially to verify the mechanism(s) associated with failure (refer to Practice C1322).4.10 The conventional analysis of constant stress rate testing is based on a critical assumption that stress is uniform throughout the test piece. This is most easily achieved in direct tension test specimens. Only test specimens that fracture in the inner gauge section in four-point testing should be used. Three-point flexure shall not be used. Breakages between the outer and inner fixture contact points should be discounted. The same requirement applies to biaxial disk strength testing. Only fractures which occur in the inner loading circle should be used. Furthermore, it is assumed that the fracture origins are near to the tensile surface and do not grow very large relative to the thickness of rectangular beam flexure or disk strength test specimens.4.11 The conventional analysis of constant stress rate testing is also based on a critical assumption that the same type flaw controls strength in all specimens at all loading rates. If the flaw distribution is multimodal, then the conventional analysis in this standard may produce erroneous slow crack growth parameter estimates.1.1 This test method covers the determination of slow crack growth (SCG) parameters of advanced ceramics by using constant stress rate rectangular beam flexural testing, ring-on-ring biaxial disk flexural testing, or direct tensile strength, in which strength is determined as a function of applied stress rate in a given environment at ambient temperature. The strength degradation exhibited with decreasing applied stress rate in a specified environment is the basis of this test method which enables the evaluation of slow crack growth parameters of a material.NOTE 1: This test method is frequently referred to as “dynamic fatigue” testing (1-3)2 in which the term “fatigue” is used interchangeably with the term “slow crack growth.” To avoid possible confusion with the “fatigue” phenomenon of a material which occurs exclusively under cyclic loading, as defined in Terminology E1823, this test method uses the term “constant stress rate testing” rather than “dynamic fatigue” testing.NOTE 2: In glass and ceramics technology, static tests of considerable duration are called “static fatigue” tests, a type of test designated as stress rupture (See Terminology E1823).1.2 Values expressed in this test method are in accordance with the International System of Units (SI) and IEEE/ASTM SI 10.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 646元 / 折扣价： 550 元 加购物车

5.1 Interlaminar delamination growth can be a critical failure mode in laminated CMC structures. Knowledge of the resistance to interlaminar delamination growth of a laminated CMC is essential for material development and selection, and for CMC component design. (See (1-8)3 which give GIc values of 20 J/m2 to 800 J/m2 for different CMC and carbon-carbon composite systems at ambient temperatures.)5.2 Conducting this test produces multiple values of GIc which are traditionally plotted against the delamination length at which that value was measured (see Fig. 2). The specific data of value to the test requestor will depend on the end use that motivated testing.5.2.1 The first increment of growth, initiated from a pre-implanted insert or machined notch, is sometimes described as the non-precracked (NPC) toughness. NPC toughness may be of interest, as it can represent manufacturing or processing defects, such as foreign object debris in a laminate or an error during machining.5.2.2 The next increment of growth, initiated from the sharp crack tip assumed to be present after the first increment, is sometimes defined as the precracked (PC) toughness. PC toughness may be of interest, as it is more representative of the resistance to delamination growth from a naturally occurring or damage-induced delamination.5.2.3 The remaining increments of growth, collectively forming an R-curve, provide information on how GIc evolves as the delamination advances. In unidirectional tape laminates, the R-curve is often increasing due to bridging of nested fibers across the delamination plane, artificially increasing GIc. For 2-D woven laminates for which there is little interply nesting, the R-curve may be flat.5.2.4 The increments of growth in which the R-curve is flat, and GIc has reached a steady state value defined as GIR, may be of interest and may also useful in design and analysis.5.3 This test method for measurement of GIc of CMC materials can serve the following purposes:5.3.1 To establish quantitatively the effect of CMC material variables (fiber interface coatings, matrix structure and porosity, fiber architecture, processing and environmental variables, conditioning/exposure treatments, etc.) on GIc and the interlaminar crack growth and damage mechanisms of a particular CMC material;5.3.2 To determine if a CMC material shows R-curve behavior where GIc changes with crack extension or reaches a stable value at a given amount of delamination growth. Fig. 2 shows R-curve behavior for a SiC-SiC composite (1);5.3.3 To develop delamination failure criteria and design allowables for CMC damage tolerance, durability or reliability analyses, and life prediction;NOTE 3: Test data can only reliably be used for this purpose if there is confidence that the test is yielding a material property and not a structural, geometry-dependent, property.5.3.4 To compare quantitatively the relative values of GIc for different CMC materials with different constituents and material properties, reinforcement architectures, processing parameters, or environmental exposure conditions; and5.3.5 To compare quantitatively the values of GIc obtained from different batches of a specific CMC material, to perform lot acceptance quality control, to use as a material screening criterion, or to assess batch variability.1.1 This test method describes the experimental methods and procedures for the determination of the critical mode I interlaminar strain energy release rate of continuous fiber- reinforced ceramic matrix composite (CMC) materials in terms of GIc. This property is also sometimes described as the mode I fracture toughness or the mode I fracture resistance.1.2 This test method applies primarily to ceramic matrix composite materials with a 2-D laminate structure, consisting of lay-ups of continuous ceramic fibers, in unidirectional tape or 2-D woven fabric architectures, within a brittle ceramic matrix.1.3 This test method determines the elastic strain energy released per unit of new surface area created as a delamination grows at the interlaminar interface between two lamina or plies. The term delamination is used in this test method to specifically refer to this type of growth, while the term crack is a more general term that can also refer to matrix cracking, intralaminar delamination growth, or fiber fracture.1.4 This test method uses a double cantilever beam (DCB) specimen to determine the critical mode I interlaminar strain energy release rate (GIc). A DCB test method has been standardized for polymer matrix composites (PMCs) under Test Method D5528. This test method addresses a similar procedure, but with modifications to account for the different physical properties, reinforcement architectures, stress-strain response, and failure mechanisms of CMCs compared to PMCs.1.5 This test is written for ambient temperature and atmospheric test conditions, but the test method can also be used for elevated temperature or environmental exposure testing with the use of an appropriate environmental test chamber, measurement equipment for controlling and measuring the chamber temperature, humidity, and atmosphere, high temperature gripping fixtures, and modified equipment for measuring delamination growth.1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6.1 Values expressed in this test method are in accordance with the International System of Units (SI) and IEEE/ASTM SI 10.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 8.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 843元 / 折扣价： 717 元 加购物车

5.1 This test method is used to determine the mechanical properties in flexure of engineered ceramic components with multiple longitudinal hollow channels, commonly described as “honeycomb” channel architectures. The components generally have 30 % or more porosity and the cross-sectional dimensions of the honeycomb channels are on the order of 1 mm or greater.5.2 The experimental data and calculated strength values from this test method are used for material and structural development, product characterization, design data, quality control, and engineering/production specifications.NOTE 1: Flexure testing is the preferred method for determining the nominal “tensile fracture” strength of these components, as compared to a compression (crushing) test. A nominal tensile strength is required, because these materials commonly fail in tension under thermal gradient stresses. A true tensile test is difficult to perform on these honeycomb specimens because of gripping and alignment challenges.5.3 The mechanical properties determined by this test method are both material and architecture dependent, because the mechanical response and strength of the porous test specimens are determined by a combination of inherent material properties and microstructure and the architecture of the channel porosity [porosity fraction/relative density, channel geometry (shape, dimensions, cell wall thickness, etc.), anisotropy and uniformity, etc.] in the specimen. Comparison of test data must consider both differences in material/composition properties as well as differences in channel porosity architecture between individual specimens and differences between and within specimen lots.5.4 Test Method A is a user-defined specimen geometry with a choice of four-point or three-point flexure testing geometries. It is not possible to define a single fixed specimen geometry for flexure testing of honeycombs, because of the wide range of honeycomb architectures and cell sizes and considerations of specimen size, cell shapes, pitch, porosity size, crush strength, and shear strength. As a general rule, the experimenter will have to define a suitable test specimen geometry for the particular honeycomb structure of interest, considering composition, architecture, cell size, mechanical properties, and specimen limitations and using the following guidelines. Details on specimen geometry definition are given in 9.2.5.4.1 Four-point flexure (Test Method A1) is strongly preferred and recommended for testing and characterization purposes. (From Test Method C1161 section 4.5: “The three-point test configuration exposes only a very small portion of the specimen to the maximum stress. Therefore, three-point flexural strengths are likely to be much greater than four-point flexural strengths. Three-point flexure has some advantages. It uses simpler test fixtures, it is easier to adapt to high temperature and fracture toughness testing, and it is sometimes helpful in Weibull statistical studies. However, four-point flexure is preferred and recommended for most characterization purposes.”)5.4.2 The three-point flexure test configuration (Test Method A2) may be used for specimens which are not suitable for 4-point testing, with the clear understanding that 3-point loading exposes only a very small portion of the specimen to the maximum stress, as compared to the much larger maximum stress volume in a 4-point loading configuration. Therefore, 3-point flexural strengths are likely to be greater than 4-point flexural strengths, based on statistical flaw distribution factors.5.5 Test Method B (with a specified specimen size and a 4-point-1/4 point flexure loading geometry) is widely used in industry for cordierite and silicon carbide honeycomb structures with small cell size (cell pitch ~2 mm). Test Method B is provided as a standard test geometry that provides a baseline specimen size for honeycomb structures with appropriate properties and cell size with the benefit of experimental repeatability, reproducibility and comparability. (See 9.3 for details on Test Method B.)NOTE 2: Specific fixture and specimen configurations were chosen for Test Method B to provide a balance between practical configurations and linear cell count effect limits and to permit ready comparison of data without the need for Weibull-size scaling.5.6 The calculation of the flexure stress in these porous specimens is based on small deflection elastic beam theory with assumptions that (1) the material properties are isotropic and homogeneous, (2) the moduli of elasticity in tension and compression are identical, and (3) the material is linearly elastic. If the porous material in the walls of the honeycomb is not specifically anisotropic in microstructure, it is also assumed that the microstructure of the wall material is uniform and isotropic. To understand the effects of some of these assumptions, see Baratta et al. (6).NOTE 3: These assumptions may limit the application of the test to comparative type testing such as used for material development, quality control, and flexure specifications. Such comparative testing requires consistent and standardized test conditions both for specimen geometry and porosity architecture, as well as experimental conditions—loading geometries, strain rates, and atmospheric/test conditions.5.7 Three flexure strength values (defined in Section 3 and calculated in Section 11) may be calculated in this test method. They are the nominal beam strength, the wall fracture strength, and the honeycomb structure strength.5.7.1 Nominal Beam Strength—The first approach to calculating a flexure strength is to make the simplifying assumption that the specimen acts as a uniform homogeneous material that reacts as a continuum. Based on these assumptions, a nominal beam strength SNB can be calculated using the standard flexure strength equations with the specimen dimensions and the breaking force. (See Section 11.)5.7.1.1 A linear cell count effect (specimen size-cell count effect) has been noted in research on the flexure strength of ceramic honeycomb test specimens (7, 8). If the cell size is too large with respect to the specimen dimensions and if the linear cell count (the integer number of cells along the shortest cross-sectional dimension) is too low (<15), channel porosity has a geometric effect on the moment of inertia that produces an artificially high value for the nominal beam strength. (See Appendix X1.) With the standard elastic beam equations the strength value is overestimated, because the true moment of inertia of the open cell structure is not accounted for in the calculation.5.7.1.2 This overestimate becomes increasingly larger for specimens with lower linear cell counts. The linear cell count has to be 15 or greater for the calculated nominal beam strength, SNB, to be within a 10 % overestimate of the wall fracture strength SWF.NOTE 4: The study by Webb, Widjaja, and Helfinstine (7) showed that for cells with a square cross section a minimum linear cell count of 15 should be maintained to minimize linear cell count effects on the calculated nominal beam strength. (This study is summarized in Appendix X1.)5.7.1.3 For those smaller test specimens (where the linear cell count is between 2 and 15), equations for wall fracture strength and honeycomb structure strength are given in Section 11. These equations are used to calculate a more accurate value for the flexure strength of the honeycomb, as compared to the calculated nominal beam strength.5.7.2 Wall Fracture Strength, SWF, is calculated using the true moment of inertia of the honeycomb architecture, based on the geometry, dimensions, cell wall thickness, and linear count of the channels in the honeycomb structure. The wall fracture strength is a calculation of the true failure stress in the outer fiber surface of the specimen. (Appendix X1 describes the calculation as cited in the Webb, Widjaja, and Helfinstine (7) report). Section 11 on calculations gives the formula for calculating the moment of inertia for test specimens with square honeycomb channels and uniform cell wall thickness.NOTE 5: The moment of inertia formula given in Section 11 and Appendix X1 is only applicable to square cell geometries. It is not suitable for rectangular, circular, hexagonal, or triangular geometries. Formulas for those geometries have to be developed from geometric analysis and first principles.5.7.3 Honeycomb Structure Strength, SHS, is calculated from the wall fracture strength SWF. This calculation gives a flexure strength value which is independent of specimen-cell size geometry effects. The honeycomb structure strength value can be used for comparison of different specimen geometries with different channel sizes. It also gives a flexure strength value that can be used for stress models that assume continuum strength. (See Appendix X1.) Section 11 on calculations gives the formula for calculating the honeycomb structure strength for test specimens with square honeycomb channels and uniform cell wall thickness.5.7.4 The following recommendations are made for calculating a flexure strength for the ceramic honeycomb test specimens.5.7.4.1 For flexure test specimens where the linear cell count is 15 or greater, the nominal beam strength SNB calculation and the honeycomb structure strength SHS are roughly equivalent in value (within 10 %). The nominal beam strength SNB calculation can be used considering this variability.5.7.4.2 For flexure test specimens where the linear cell count is between 5 and 15, the nominal beam strength SNB calculation may produce a 10 % to 20 % overvalue. The SNB value should be used with caution.5.7.4.3 For flexure test specimens where the linear cell count is less than 5, the nominal beam strength SNB calculation may produce a 20 % to 100 % overvalue. It is recommended that the honeycomb structure strength SHS be calculated and used as a more accurate flexure strength number.5.7.4.4 If specimen availability and test configuration permit, test specimens with a linear cell count of 15 or greater are preferred to reduce the specimen linear cell count effect on nominal beam strength SNB to less than 10 %.5.8 Flexure test data for porous ceramics will have a statistical distribution, which may be analyzed and described by Weibull statistics, per Practice C1239.5.9 This flexure test can be used as a characterization tool to assess the effects of fabrication variables, geometry and microstructure variations, and environmental exposure on the mechanical properties of the honeycombs. The effect of these variables is assessed by flexure testing a specimen set in a baseline condition and then testing a second set of specimens with defined changes in geometry or fabrication methods or after controlled environmental exposure.5.9.1 Geometry and microstructure variations would include variations in cell geometry (shape dimensions, cell wall thickness, and count) and wall porosity (percent, size, shape, morphology, etc.).5.9.2 Fabrication process variations would include forming parameters, drying and binder burn-out conditions, sintering conditions, heat treatments, variations in coatings, etc.5.9.3 Environmental conditioning would include extended exposure at different temperatures and different corrosive atmospheres (including steam).5.10 This flexure test may be used to assess the thermal shock resistance of the honeycomb ceramics, as described in Test Method C1525.5.11 The flexure test is not the preferred method for determining the Young's modulus of these porous structures. (For this reason, the deflection of the flexure test bar is not commonly measured in this test.) Young's modulus measurements by sonic resonance (Test Method C1198) or by impulse excitation (Test Method C1259) give more reliable and repeatable data.5.12 It is beyond the scope of this standard to require fractographic analysis at the present time. Fractographic analysis for critical flaws in porous honeycomb ceramics is extremely difficult and of very uncertain value.1.1 This test method covers the determination of the flexural strength (modulus of rupture in bending) at ambient conditions of advanced ceramic structures with 2-dimensional honeycomb channel architectures.1.2 The test method is focused on engineered ceramic components with longitudinal hollow channels, commonly called “honeycomb” channels (see Fig. 1). The components generally have 30 % or more porosity and the cross-sectional dimensions of the honeycomb channels are on the order of 1 mm or greater. Ceramics with these honeycomb structures are used in a wide range of applications (catalytic conversion supports (1),2 high temperature filters (2, 3), combustion burner plates (4), energy absorption and damping (5), etc.). The honeycomb ceramics can be made in a range of ceramic compositions—alumina, cordierite, zirconia, spinel, mullite, silicon carbide, silicon nitride, graphite, and carbon. The components are produced in a variety of geometries (blocks, plates, cylinders, rods, rings).FIG. 1 General Schematics of Typical Honeycomb Ceramic Structures1.3 The test method describes two test specimen geometries for determining the flexural strength (modulus of rupture) for a porous honeycomb ceramic test specimen (see Fig. 2):FIG. 2 Flexure Loading ConfigurationsL = Outer Span Length (for Test Method A, L = User defined; for Test Method B, L = 90 mm)NOTE 1: 4-Point-1/4 Loading for Test Methods A1 and B.NOTE 2: 3-Point Loading for Test Method A2.1.3.1 Test Method A—A 4-point or 3-point bending test with user-defined specimen geometries, and1.3.2 Test Method B—A 4-point-1/4 point bending test with a defined rectangular specimen geometry (13 mm × 25 mm × > 116 mm) and a 90 mm outer support span geometry suitable for cordierite and silicon carbide honeycombs with small cell sizes.1.4 The test specimens are stressed to failure and the breaking force value, specimen and cell dimensions, and loading geometry data are used to calculate a nominal beam strength, a wall fracture strength, and a honeycomb structure strength.1.5 Test results are used for material and structural development, product characterization, design data, quality control, and engineering/production specifications.1.6 The test method is meant for ceramic materials that are linear-elastic to failure in tension. The test method is not applicable to polymer or metallic porous structures that fail in an elastomeric or an elastic-ductile manner.1.7 The test method is defined for ambient testing temperatures. No directions are provided for testing at elevated or cryogenic temperatures.1.8 The values stated in SI units are to be regarded as standard (IEEE/ASTM SI 10). English units are sparsely used in this standard for product definitions and tool descriptions, per the cited references and common practice in the US automotive industry.1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.10 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 The purpose of this guide is to ensure that a functional system will result when considering the use of prefabricated panel or H-bar insulation systems. Both systems require a varying degree of pre-engineering and prefabrication so that the insulation will produce the specified thermal, mechanical and environmental design requirements Both the prefabricated panels and H-bar systems which can also be used in combination with each other are to be designed to:4.1.1 Limit loss of heat from insulated surface.4.1.2 Limit exposed surface temperatures for burn protection of personnel.4.1.3 Maintain optimum temperatures of the insulated equipment at or above a specified minimum value required for the proper operation of the equipment.4.1.4 Produce a system or assembly that is designed to provide allowance for thermal expansion; is structurally adequate; is of a weathertight construction; and incorporates design features that promote efficient removal for inspection, repair and maintenance where required.1.1 This guide describes design, fabrication, shipping, handling, jobsite storage, and installation of prefabricated panel and H-Bar insulation systems for vessels, ducts, and equipment operating at temperatures above ambient. Typical applications include, but are not limited to, air and gas ducts, steam generating units, air quality control systems, fans, storage tanks, process vessels, and coke drums1.2 The insulation described herein is limited to systems consisting of insulating units specially designed to fit the surfaces to be insulated, and engineered for the service and environmental requirements. The insulation unit may also include special design features which facilitate the removal and replacement for maintenance and inspection.1.3 When prefabricated panels are used, each insulation unit factory preassembled and typically comprised of the insulation, an outer lagging to which the insulation is attached, an inner retaining wire mesh, optional foil lining, and means for mechanically securing multiple units together in an assembly.1.4 H-bar systems represent insulation units that are typically comprised of the insulation, outer lagging and a uniquely configured subgirt design which both supports the insulation and provides a means for mechanically securing multiple units together in an assembly. The design of the subgirt creates an “H” configuration which is fabricated from light gauge sheet metal. The subgirt components consist of: (1) a “J-bar” shape which frames the perimeter edges of the surface to be insulated, holds the insulation in place along the outer edge and provides a screen attachment point for the outer lagging; (2) the “H-bar” shape is placed at defined intervals. The web section of the “H-bar” supports the insulation while the exterior flange allows for the outer lagging to be attached with threaded fasteners.1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.NOTE 1: When prefabricated panel or H-Bar insulation systems are specified, Test Methods C167, C177 and C1061, Material Specifications A36/A36M, A463/A463M, B209, C612, and Terminology C168 should be considered.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 This test method may be used for material development, quality control, characterization, and design data generation purposes. This test method is intended to be used with ceramics whose strength is 50 MPa (~7 ksi) or greater.4.2 The flexure stress is computed based on simple beam theory with assumptions that the material is isotropic and homogeneous, the moduli of elasticity in tension and compression are identical, and the material is linearly elastic. The average grain size should be no greater than one-fiftieth of the beam thickness. The homogeneity and isotropy assumption in the standard rule out the use of this test for continuous fiber-reinforced ceramics.4.3 Flexural strength of a group of test specimens is influenced by several parameters associated with the test procedure. Such factors include the loading rate, test environment, specimen size, specimen preparation, and test fixtures. Specimen sizes and fixtures were chosen to provide a balance between practical configurations and resulting errors, as discussed in MIL-STD-1942(MR) and Refs (1, 2).4 Specific fixture and specimen configurations were designated in order to permit ready comparison of data without the need for Weibull-size scaling.4.4 The flexural strength of a ceramic material is dependent on both its inherent resistance to fracture and the size and severity of flaws. Variations in these cause a natural scatter in test results for a sample of test specimens. Fractographic analysis of fracture surfaces, although beyond the scope of this standard, is highly recommended for all purposes, especially if the data will be used for design as discussed in MIL-STD-1942(MR) and Refs (2-5) and Practices C1322 and C1239.4.5 The three-point test configuration exposes only a very small portion of the specimen to the maximum stress. Therefore, three-point flexural strengths are likely to be much greater than four-point flexural strengths. Three-point flexure has some advantages. It uses simpler test fixtures, it is easier to adapt to high temperature and fracture toughness testing, and it is sometimes helpful in Weibull statistical studies. However, four-point flexure is preferred and recommended for most characterization purposes.4.6 This method determines the flexural strength at ambient temperature and environmental conditions. The flexural strength under ambient conditions may or may not necessarily be the inert flexural strength.NOTE 7: time dependent effects may be minimized through the use of inert testing atmosphere such as dry nitrogen gas, oil, or vacuum. Alternatively, testing rates faster than specified in this standard may be used. Oxide ceramics, glasses, and ceramics containing boundary phase glass are susceptible to slow crack growth even at room temperature. Water, either in the form of liquid or as humidity in air, can have a significant effect, even at the rates specified in this standard. On the other hand, many ceramics such as boron carbide, silicon carbide, aluminum nitride, and many silicon nitrides have no sensitivity to slow crack growth at room temperature and the flexural strength in laboratory ambient conditions is the inert flexural strength.1.1 This test method covers the determination of flexural strength of advanced ceramic materials at ambient temperature. Four-point-1/4-point and three-point loadings with prescribed spans are the standard as shown in Fig. 1. Rectangular specimens of prescribed cross-section sizes are used with specified features in prescribed specimen-fixture combinations. Test specimens may be 3 by 4 by 45 to 50 mm in size that are tested on 40-mm outer span four-point or three-point fixtures. Alternatively, test specimens and fixture spans half or twice these sizes may be used. The method permits testing of machined or as-fired test specimens. Several options for machining preparation are included: application matched machining, customary procedure, or a specified standard procedure. This method describes the apparatus, specimen requirements, test procedure, calculations, and reporting requirements. The test method is applicable to monolithic or particulate- or whisker-reinforced ceramics. It may also be used for glasses. It is not applicable to continuous fiber-reinforced ceramic composites.1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 This test method is applicable to the measurement of airborne asbestos in a wide range of ambient air situations and for detailed evaluation of any atmosphere for asbestos structures. Most fibers in ambient atmospheres are not asbestos, and therefore, there is a requirement for fibers to be identified. Most of the airborne asbestos fibers in ambient atmospheres have diameters below the resolution limit of the light microscope. This test method is based on transmission electron microscopy, which has adequate resolution to allow detection of small thin fibers and is currently the only technique capable of unequivocal identification of the majority of individual fibers of asbestos. Asbestos is often found, not as single fibers, but as very complex, aggregated structures, which may or may not also be aggregated with other particles. The fibers found suspended in an ambient atmosphere can often be identified unequivocally if sufficient measurement effort is expended. However, if each fiber were to be identified in this way, the analysis would become prohibitively expensive. Because of instrumental deficiencies or because of the nature of the particulate matter, some fibers cannot be positively identified as asbestos even though the measurements all indicate that they could be asbestos. Therefore, subjective factors contribute to this measurement, and consequently, a very precise definition of the procedure for identification and enumeration of asbestos fibers is required. The method defined in this test method is designed to provide a description of the nature, numerical concentration, and sizes of asbestos-containing particles found in an air sample. The test method is necessarily complex because the structures observed are frequently very complex. The method of data recording specified in the test method is designed to allow reevaluation of the structure-counting data as new applications for measurements are developed. All of the feasible specimen preparation techniques result in some modification of the airborne particulate matter. Even the collection of particles from a three-dimensional airborne dispersion on to a two-dimensional filter surface can be considered a modification of the particulate matter, and some of the particles, in most samples, are modified by the specimen preparation procedures. However, the procedures specified in this test method are designed to minimize the disturbance of the collected particulate material.5.2 This test method applies to analysis of a single filter and describes the precision attributable to measurements for a single filter (see 13.1). Multiple air samples are usually necessary to characterize airborne asbestos concentrations across time and space. The number of samples necessary for this purpose is proportional to the variation in measurement across samples, which may be greater than the variation in a measurement for a single sample.1.1 This test method2 is an analytical procedure using transmission electron microscopy (TEM) for the determination of the concentration of asbestos structures in ambient atmospheres and includes measurement of the dimension of structures and of the asbestos fibers found in the structures from which aspect ratios are calculated.1.1.1 This test method allows determination of the type(s) of asbestos fibers present.1.1.2 This test method cannot always discriminate between individual fibers of the asbestos and non-asbestos analogues of the same amphibole mineral.1.2 This test method is suitable for determination of asbestos in both ambient (outdoor) and building atmospheres.1.2.1 This test method is defined for polycarbonate capillary-pore filters or cellulose ester (either mixed esters of cellulose or cellulose nitrate) filters through which a known volume of air has been drawn and for blank filters.1.3 The upper range of concentrations that can be determined by this test method is 7000 s/mm2. The air concentration represented by this value is a function of the volume of air sampled.1.3.1 There is no lower limit to the dimensions of asbestos fibers that can be detected. In practice, microscopists vary in their ability to detect very small asbestos fibers. Therefore, a minimum length of 0.5 μm has been defined as the shortest fiber to be incorporated in the reported results.1.4 The direct analytical method cannot be used if the general particulate matter loading of the sample collection filter as analyzed exceeds approximately 10 % coverage of the collection filter by particulate matter.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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