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ASTM C1368-01

(Test Method)

Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Ambient Temperature

Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Ambient Temperature

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1.1 This test method covers the determination of slow crack growth (SCG) parameters of advanced ceramics by using constant stress-rate flexural testing in which flexural 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 (Refs (1-3)) 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 Definitions E1150, 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 Definitions E1150).
1.2 Values expressed in this test method are in accordance with the International System of Units (SI) and Practice E380.
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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

Status
Historical
Publication Date
09-Jun-2001
ICS
81.060.30 - Advanced ceramics
Technical Committee
C28 - Advanced Ceramics
Drafting Committee
C28.01 - Mechanical Properties and Performance
Current Stage
Ref Project

Relations

Replaces
ASTM C1368-00 - Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Ambient Temperature
Effective Date
10-Jun-2001
Replaced By
ASTM C1368-06 - Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Ambient Temperature
Effective Date
01-Jan-2006
Referred By
ASTM C1323-22 - Standard Test Method for Ultimate Strength of Advanced Ceramics with Diametrally Compressed C-Ring Specimens at Ambient Temperature
Effective Date
10-Jun-2001
Referred By
ASTM C1161-18(2023) - Standard Test Method for Flexural Strength of Advanced Ceramics at Ambient Temperature
Effective Date
10-Jun-2001
Referred By
ASTM C1211-18(2023) - Standard Test Method for Flexural Strength of Advanced Ceramics at Elevated Temperatures
Effective Date
10-Jun-2001
Referred By
ASTM C1834-16 - Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress Flexural Testing (Stress Rupture) at Elevated Temperatures
Effective Date
10-Jun-2001
Referred By
ASTM C1576-05(2017) - Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress Flexural Testing (Stress Rupture) at Ambient Temperature
Effective Date
10-Jun-2001
Referred By
ASTM C1465-08(2019) - Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Elevated Temperatures
Effective Date
10-Jun-2001
Referred By
ASTM C1674-23 - Standard Test Method for Flexural Strength of Advanced Ceramics with Engineered Porosity (Honeycomb Cellular Channels) at Ambient Temperatures
Effective Date
10-Jun-2001
Referred By
ASTM C1014-17 - Standard Specification for Spray-Applied Mineral Fiber Thermal and Sound Absorbing Insulation
Effective Date
10-Jun-2001
Referred By
ASTM C1684-18(2023) - Standard Test Method for Flexural Strength of Advanced Ceramics at Ambient Temperature—Cylindrical Rod Strength
Effective Date
10-Jun-2001

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ASTM C1368-01 - Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Ambient TemperatureASTM C1368-01 - Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Ambient Temperature
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ASTM C1368-01 - Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Ambient Temperature
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Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C 1368 – 01
Standard Test Method for
Determination of Slow Crack Growth Parameters of
Advanced Ceramics by Constant Stress-Rate Flexural
1
Testing at Ambient Temperature
This standard is issued under the fixed designation C 1368; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
3
1. Scope Ceramics at Ambient Temperature
C 1239 Practice for Reporting Uniaxial Strength Data and
1.1 This test method covers the determination of slow crack
Estimating Weibull Distribution Parameters for Advanced
growth (SCG) parameters of advanced ceramics by using
3
Ceramics
constant stress-rate flexural testing in which flexural strength is
C 1322 Practice for Fractography and Characterization of
determined as a function of applied stress rate in a given
3
Fracture Origins in Advanced Ceramics
environment at ambient temperature. The strength degradation
4
E 4 Practices for Force Verification of Testing Machines
exhibited with decreasing applied stress rate in a specified
E 6 Terminology Relating to Methods of Mechanical Test-
environment is the basis of this test method which enables the
4
ing
evaluation of slow crack growth parameters of a material.
E 337 Test Method for Measuring Humidity with a Psy-
NOTE 1—This test method is frequently referred to as “dynamic
chrometer (the Measurement of Wet-Bulb and Dry-Bulb
2
fatigue” testing (Refs (1-3) ) in which the term“ fatigue” is used
5
Temperatures)
interchangeably with the term “slow crack growth.” To avoid possible
E 380 Practice for Use of the International System of Units
confusion with the “fatigue” phenomenon of a material which occurs
6
(SI) (The Modernized Metric System)
exclusivelyundercyclicloading,asdefinedinDefinitionsE 1150,thistest
method uses the term “constant stress-rate testing” rather than “dynamic E 1823 Terminology Relating to Fatigue and Fracture Test-
4
fatigue” testing.
ing
NOTE 2—In glass and ceramics technology, static tests of considerable
2.2 Military Handbook:
duration are called “static fatigue” tests, a type of test designated as
MIL-HDBK-790 Fractography and Characterization of
stress-rupture (See Definitions E 1150).
7
Fracture Origins in Advanced Structural Ceramics
1.2 Values expressed in this test method are in accordance
3. Terminology
with the International System of Units (SI) and Practice E 380.
1.3 This standard does not purport to address all of the
3.1 Definitions—The terms described in Terminology
safety concerns, if any, associated with its use. It is the
C 1145, Terminology E 6, Terminology E 616, and Definitions
responsibility of the user of this standard to establish appro-
E 1150 are applicable to this test method. Specific terms
priate safety and health practices and determine the applica-
relevant to this test method are as follows:
bility of regulatory limitations prior to use.
3.1.1 advanced ceramic, n—a highly engineered, high-
performance, predominately nonmetallic, inorganic, ceramic
2. Referenced Documents
material having specific functional attributes. (C 1145)
2.1 ASTM Standards:
3.1.2 constant stress rate,s˙, n—a constant rate of maximum
C 1145 Terminology of Advanced Ceramics
stress applied to a specified beam by using either a constant
C 1161 Test Method for Flexural Strength of Advanced
loading or constant displacement rate of a testing machine.
3.1.3 environment, n—the aggregate of chemical species
and energy that surrounds a test specimen. (E 1150)
1
This test method is under the jurisdiction of ASTM Committee C28 on
3
Advanced Ceramics and is the direct responsibility of Subcommittee C28.01 on Annual Book of ASTM Standards, Vol 15.01.
4
Properties and Performance. Annual Book of ASTM Standards, Vol 03.01.
5
Current edition approved June 10, 2001. Published June 2001. Originally Annual Book of ASTM Standards, Vol 11.03.
6
published as C 1368 – 97. Last previous edition C 1368 – 00. Annual Book of ASTM Standards, Vol 14.02.
2 7
The boldface numbers in parentheses refer to the list of references at the end of Available from Army Research Laboratory—Materials Directorate, Aberdeen
this standard. Proving Ground, MD 21005.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
C 1368
3.1.4 environmental chamber, n—the container of bulk between practical configurations and resulting errors, as dis-
volume surrounding a test specimen. (E 1150) cussed in Refs (4, 5). Only the four-point test configuration is
3.1.5 flexural strength, s , n—a measure of the strength of a used in this test method.
f
s
...

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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.  
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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 consid...
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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 Structures  
1.3 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 Configurations  
L = 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.  
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1.3.2 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.  
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ASTM C1341-13(2023)(Test Method)
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5.1 This test method is used for material development, quality control, and material flexural specifications. Although flexural test methods are commonly used to determine design strengths of monolithic advanced ceramics, the use of flexure test data for determining tensile or compressive properties of CFCC materials is strongly discouraged. The nonuniform stress distributions in the flexure test specimen, the dissimilar mechanical behavior in tension and compression for CFCCs, low shear strengths of CFCCs, and anisotropy in fiber architecture all lead to ambiguity in using flexure results for CFCC material design data (1-4).3 Rather, uniaxial-forced tensile and compressive tests are recommended for developing CFCC material design data based on a uniformly stressed test condition.  
5.2 In this test method, the flexure stress is computed from elastic beam theory with the simplifying assumptions that the material is homogeneous and linearly elastic. This is valid for composites where the principal fiber direction is coincident/transverse with the axis of the beam. These assumptions are necessary to calculate a flexural strength value, but limit the application to comparative type testing such as used for material development, quality control, and flexure specifications. Such comparative testing requires consistent and standardized test conditions, that is, test specimen geometry/thickness, strain rates, and atmospheric/test conditions.  
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1.1.1 Test Geometry I—A three-point loading system utilizing center point force application on a simply supported beam.  
1.1.2 Test Geometry IIA—A four-point loading system utilizing two force application points equally spaced from their adjacent support points, with a distance between force application points of one-half of the support span.  
1.1.3 Test Geometry IIB—A four-point loading system utilizing two force application points equally spaced from their adjacent support points, with a distance between force application points of one-third of the support span.  
1.2 This test method applies primarily to all advanced ceramic matrix composites with continuous fiber reinforcement: unidirectional (1D), bidirectional (2D), tridirectional (3D), and other continuous fiber architectures. In addition, this test method may also be used with glass (amorphous) matrix composites with continuous fiber reinforcement. However, flexural strength cannot be determined for those materials that do not break or fail by tension or compression in the outer fibers. This test method does not directly address discontinuous fiber-reinforced, whisker-reinforced, or particulate-reinforced ceramics. Those types of ceramic matrix composites are better tested in flexure using Test Methods C1161 and C1211.  
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5.1 Open-hole tests of composites are used for material and design development for the engineering application of composite materials (5-11). The presence of an open hole in a composite component reduces the cross-sectional area available to carry an applied force, creates stress concentrations, and creates new edges where delamination may occur. Standardized open-hole tests for composite materials can provide useful information about how a composite material may perform in an open-hole application and how to design the composite for notches and holes.  
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5.2.1 The open-hole (notched) tensile strength (SOHTx) for test specimen with a hole diameter x (mm).  
5.2.2 The net section tensile strength (SNSx) for a test specimen with a hole diameter x (mm).  
5.2.3 The proportional limit stress (σ0) for an OHT specimen with a given hole diameter.  
5.2.4 The stress response of the OHT test specimen, as shown by the stress-time or stress-displacement plot.  
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1.1 This test method covers the determination of the effect of surface grinding on the flexure strength of advanced ceramics. Surface grinding of an advanced ceramic material can introduce microcracks and other changes in the near surface layer, generally referred to as damage (see Fig. 1 and Ref. (1)).2 Such damage can result in a change—most often a decrease—in flexure strength of the material. The degree of change in flexure strength is determined by both the grinding process and the response characteristics of the specific ceramic material. This method compares the flexure strength of an advanced ceramic material after application of a user-specified surface grinding process with the baseline flexure strength of the same material. The baseline flexure strength is obtained after application of a surface grinding process specified in this standard. The baseline flexure strength is expected to approximate closely the inherent strength of the material. The flexure strength is measured by means of ASTM flexure test methods.
FIG. 1 Microcracks Associated with Grinding (Ref. (1))2  
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5.1 For advanced ceramics, Knoop indenters are used to create indentations. The surface projection of the long diagonal is measured with optical microscopes.  
5.2 The Knoop indentation hardness is one of many properties that is used to characterize advanced ceramics. Attempts have been made to relate Knoop indentation hardness to other hardness scales, but no generally accepted methods are available. Such conversions are limited in scope and should be used with caution, except for special cases where a reliable basis for the conversion has been obtained by comparison tests.  
5.3 For advanced ceramics, the Knoop indentation is often preferred to the Vickers indentation since the Knoop long diagonal length is 2.8 times longer than the Vickers diagonal for the same force, and cracking is much less of a problem (1).5 On the other hand, the long slender tip of the Knoop indentation is more difficult to precisely discern, especially in materials with low contrast. The indentation forces chosen in this test method are designed to produce indentations as large as may be possible with conventional microhardness equipment, yet not so large as to cause cracking.  
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1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 Units—When Knoop and Vickers hardness tests were developed, the force levels were specified in units of grams-force (gf) and kilograms-force (kgf). This standard specifies the units of force and length in the International System of Units (SI); that is, force in newtons (N) and length in mm or μm. However, because of the historical precedent and continued common usage, force values in gf and kgf units are occasionally provided for information. This test method specifies that Knoop hardness be reported either in units of GPa or as a dimensionless Knoop hardness number.  
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.  
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ASTM C1684-18(2023)(Test Method)
Standard Test Method for Flexural Strength of Advanced Ceramics at Ambient Temperature—Cylindrical Rod Strength

SIGNIFICANCE AND USE
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. The test method may also be used with glass test specimens, although Test Methods C158 is specifically designed to be used for glasses. This test method may be used with machined, drawn, extruded, and as-fired round specimens. This test method may be used with specimens that have elliptical cross section geometries.  
4.2 The flexure strength 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 rod diameter. The homogeneity and isotropy assumptions 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 (1-3).3 This method includes specific specimen-fixture size combinations, but permits alternative configurations within specified limits. These combinations were chosen to be practical, to minimize experimental error, and permit easy comparison of cylindrical rod strengths with data for other configurations. Equations for the Weibull effective volume and Weibull effective surface are included.  
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 in the material. Flaws in rods may be intrinsically volume-distributed throughout the bulk. Some of these flaws by chance may be located at or near the outer surface. Flaws may alternatively be intrinsically surface-distrib...
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1.1 This test method is for the determination of flexural strength of rod-shaped specimens of advanced ceramic materials at ambient temperature. In many instances it is preferable to test round specimens rather than rectangular bend specimens, especially if the material is fabricated in rod form. This method permits testing of machined, drawn, or as-fired rod-shaped specimens. It allows some latitude in the rod sizes and cross section shape uniformity. Rod diameters between 1.5 and 8 mm and lengths from 25 to 85 mm are recommended, but other sizes are permitted. Four-point-1/4-point as shown in Fig. 1 is the preferred testing configuration. Three-point loading is permitted. This method describes the apparatus, specimen requirements, test procedure, calculations, and reporting requirements. The 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.
FIG. 1 Four-Point-1/4-Point Flexure Loading Configuration  
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.  
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ASTM C1211-18(2023)(Test Method)
Standard Test Method for Flexural Strength of Advanced Ceramics at Elevated Temperatures

SIGNIFICANCE AND USE
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 flexural 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 1/50 of the beam thickness. The homogeneity and isotropy assumptions in the test method rule out the use of it for continuous fiber-reinforced composites for which Test Method C1341 is more appropriate.  
4.3 The flexural strength of a group of test specimens is influenced by several parameters associated with the test procedure. Such factors include the testing rate, test environment, specimen size, specimen preparation, and test fixtures. Specimen and fixture sizes were chosen to provide a balance between the practical configurations and resulting errors as discussed in Test Method C1161, and Refs (1-3).4 Specific fixture and specimen configurations were designated in order to permit the 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 test method, is highly recommended for all purposes, especially if the data will be used for design as discussed in Ref (4) and Practices C1322 and C1239.  
4.5 This method determines the flexural strength at elevated temperature and ambient environmental conditions at a nominal, moderately fast testing rate. The flexural strength under these conditions may or may not necessarily be the...
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1.1 This test method covers determination of the flexural strength of advanced ceramics at elevated temperatures.2 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 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 test method permits testing of machined or as-fired test specimens. Several options for machining preparation are included: application matched machining, customary procedures, or a specified standard procedure. This test 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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ASTM C1323-22(Test Method)
Standard Test Method for Ultimate Strength of Advanced Ceramics with Diametrally Compressed C-Ring Specimens at Ambient Temperature

SIGNIFICANCE AND USE
4.1 This test method may be used for material development, material comparison, quality assurance, and characterization. Extreme care should be exercised when generating design data.  
4.2 For a C-ring under diametral compression, the maximum tensile stress occurs at the outer surface. Hence, the C-ring specimen loaded in compression will predominately evaluate the strength distribution and flaw population(s) on the external surface of a tubular component in the hoop direction. Accordingly, the condition of the inner surface may be of lesser consequence in specimen preparation and testing.
Note 1: A C-ring in tension or an O-ring in compression may be used to evaluate the internal surface.  
4.2.1 The flexure stress is computed based on simple curved beam theory (1-5).3 It is assumed that the material is isotropic and homogeneous, the moduli of elasticity are identical in compression or tension, and the material is linearly elastic. These homogeneity and isotropy assumptions preclude the use of this standard for continuous fiber reinforced composites. Average grain size(s) should be no greater than one fiftieth (1/50 ) of the C-ring thickness. The curved beam stress solution from engineering mechanics is in good agreement (within 2 %) with an elasticity solution as discussed in (6) for the test specimen geometries recommended for this standard. The curved beam stress equations are simple and straightforward, and therefore it is relatively easy to integrate the equations for calculations for effective area or effective volume for Weibull analyses as discussed in Appendix X1.  
4.2.2 The simple curved beam and theory of elasticity stress solutions both are two-dimensional plane stress solutions. They do not account for stresses in the axial (parallel to b) direction, or variations in the circumferential (hoop, σθ) stresses through the width (b) of the test piece. The variations in the circumferential stresses increase with increases in width (b) and ring thicknes...
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1.1 This test method covers the determination of ultimate strength under monotonic loading of advanced ceramics in tubular form at ambient temperatures. The ultimate strength as used in this test method refers to the strength obtained under monotonic compressive loading of C-ring specimens such as shown in Fig. 1, where monotonic refers to a continuous nonstop test rate with no reversals from test initiation to final fracture. This method permits a range of sizes and shapes since test specimens may be prepared from a variety of tubular structures. The method may be used with microminiature test specimens.
FIG. 1 C-Ring Test Geometry with Defining Geometry and Reference Angle (θ) for the Point of Fracture Initiation on the Circumference  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.2.1 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.

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ASTM C1730-17(2022)(Test Method)
Standard Test Method for Particle Size Distribution of Advanced Ceramics by X-Ray Monitoring of Gravity Sedimentation

SIGNIFICANCE AND USE
5.1 This test method is useful to both suppliers and users of powders, as outlined in 1.1 and 1.2, in determining particle size distribution for product specifications, manufacturing control, development, and research.  
5.2 Users should be aware that sample concentrations used in this test method may not be what is considered ideal by some authorities, and that the range of this test method extends into the region where Brownian movement could be a factor in conventional sedimentation. Within the range of this test method, neither the sample concentration nor Brownian movement is believed to be significant. Standard reference materials traceable to national standards, of chemical composition specifically covered by this test method, are available from NIST,3 and perhaps other suppliers.  
5.3 Reported particle size measurement is a function of the actual particle dimension and shape factor as well as the particular physical or chemical properties being measured. Caution is required when comparing data from instruments operating on different physical or chemical parameters or with different particle size measurement ranges. Sample acquisition, handling, and preparation can also affect reported particle size results.  
5.4 Suppliers and users of data obtained using this test method need to agree upon the suitability of these data to provide specification for and allow performance prediction of the materials analyzed.
SCOPE
1.1 This test method covers the determination of particle size distribution of advanced ceramic powders. Experience has shown that this test method is satisfactory for the analysis of silicon carbide, silicon nitride, and zirconium oxide in the size range of 0.1 up to 50 µm.  
1.1.1 However, the relationship between size and sedimentation velocity used in this test method assumes that particles sediment within the laminar flow regime. It is generally accepted that particles sedimenting with a Reynolds number of 0.3 or less will do so under conditions of laminar flow with negligible error. Particle size distribution analysis for particles settling with a larger Reynolds number may be incorrect due to turbulent flow. Some materials covered by this test method may settle in water with a Reynolds number greater than 0.3 if large particles are present. The user of this test method should calculate the Reynolds number of the largest particle expected to be present in order to judge the quality of obtained results. Reynolds number (Re) can be calculated using the following equation:
   where:  
  D  =  the diameter of the largest particle expected to be present, in cm,   ρ  =  the particle density, in g/cm3,   ρ0  =  the suspending liquid density, in g/cm3,   g  =  the acceleration due to gravity, 981 cm/sec2, and   η  =  the suspending liquid viscosity, in poise.    
1.1.2 A table of the largest particles that can be analyzed with a suggested maximum Reynolds number of 0.3 or less in water at 35 °C is given for a number of materials in Table 1. A column of the Reynolds number calculated for a 50-µm particle sedimenting in the same liquid system is also given for each material. Larger particles can be analyzed in dispersing media with viscosities greater than that for water. Aqueous solutions of glycerine or sucrose have such higher viscosities.  
1.2 The procedure described in this test method may be applied successfully to other ceramic powders in this general size range, provided that appropriate dispersion procedures are developed. It is the responsibility of the user to determine the applicability of this test method to other materials. Note however that some ceramics, such as boron carbide and boron nitride, may not absorb X-rays sufficiently to be characterized by this analysis method.  
1.3 The values stated in cgs units are to be regarded as the standard, which is the long-standing industry practice. The values given in parentheses are for information onl...

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ASTM C1469-22(Test Method)
Standard Test Method for Shear Strength of Joints of Advanced Ceramics at Ambient Temperature

SIGNIFICANCE AND USE
5.1 Advanced ceramics can be candidate materials for structural applications requiring high degrees of wear and corrosion resistance, often at elevated temperatures.  
5.2 Joints are produced to enhance the performance and applicability of materials. While the joints between similar materials are generally made for manufacturing complex parts and repairing components, those involving dissimilar materials usually are produced to exploit the unique properties of each constituent in the new component. Depending on the joining process, the joint region may be the weakest part of the component. Since under mixed-mode and shear loading the load transfer across the joint requires reasonable shear strength, it is important that the quality and integrity of joint under in-plane shear forces be quantified. Shear strength data are also needed to monitor the development of new and improved joining techniques.  
5.3 Shear tests provide information on the strength and deformation of materials under shear stresses.  
5.4 This test method may be used for material development, material comparison, quality assurance, characterization, and design data generation.  
5.5 For quality control purposes, results derived from standardized shear 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.
SCOPE
1.1 This test method covers the determination of shear strength of joints in advanced ceramics at ambient temperature using asymmetrical four-point flexure. Test specimen geometries, test specimen fabrication methods, testing modes (that is, force or displacement control), testing rates (that is, force or displacement rate), data collection, and reporting procedures are addressed.  
1.2 This test method is used to measure shear strength of ceramic joints in test specimens extracted from larger joined pieces by machining. Test specimens fabricated in this way are not expected to warp due to the relaxation of residual stresses but are expected to be much straighter and more uniform dimensionally than butt-jointed test specimens prepared by joining two halves, which is not recommended. In addition, this test method is intended for joints, which have either low or intermediate strengths with respect to the substrate material to be joined. Joints with high strengths should not be tested by this test method because of the high probability of invalid tests resulting from fractures initiating at the reaction points rather than in the joint. Determination of the shear strength of joints using this test method is appropriate particularly for advanced ceramic matrix composite materials but also may be useful for monolithic advanced ceramic materials.  
1.3 Values expressed in this test method are in accordance with the International System of Units (SI) and 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. Specific precautionary statements are noted in 8.1.  
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.

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