1、Designation: C1525 04 (Reapproved 2013)C1525 18Standard Test Method forDetermination of Thermal Shock Resistance for AdvancedCeramics by Water Quenching1This standard is issued under the fixed designation C1525; the number immediately following the designation indicates the year oforiginal adoption
2、or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes the determination of the resistance of advanced ce
3、ramics to thermal shock by water quenching.The method builds on the experimental principle of rapid quenching of a test specimen at an elevated temperature in a water bathat room temperature. The effect of the thermal shock is assessed by measuring the reduction in flexural strength produced by rapi
4、dquenching of test specimens heated across a range of temperatures. For a quantitative measurement of thermal shock resistance,a critical temperature interval is determined by a reduction in the mean flexural strength of at least 30 %. The test method doesnot determine thermal stresses developed as
5、a result of a steady state steady-state temperature differencesdifference within aceramic body or of thermal expansion mismatch between joined bodies. The test method is not intended to determine the resistanceof a ceramic material to repeated shocks. Since the determination of the thermal shock res
6、istance is performed by evaluatingretained strength, the method is not suitable for ceramic components; however, test specimens cut from components may be used.1.2 The test method is intended primarily for dense monolithic ceramics, but may also be applicable to certain composites suchas whisker- or
7、 particulate-reinforced ceramic matrix composites that are macroscopically homogeneous.1.3 Values expressed in this standard test method are in accordance with the International System of Units (SI) and StandardIEEE/ASTM SI 10.1.4 This standard does not purport to address all of the safety concerns,
8、 if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance w
9、ith internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards
10、:2C373 Test Methods for Determination of Water Absorption and Associated Properties by Vacuum Method for Pressed CeramicTiles and Glass Tiles and Boil Method for Extruded Ceramic Tiles and Non-tile Fired Ceramic Whiteware ProductsC1145 Terminology of Advanced CeramicsC1161 Test Method for Flexural S
11、trength of Advanced Ceramics at Ambient TemperatureC1239 Practice for Reporting Uniaxial Strength Data and Estimating Weibull Distribution Parameters for Advanced CeramicsC1322 Practice for Fractography and Characterization of Fracture Origins in Advanced CeramicsE4 Practices for Force Verification
12、of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE616 Terminology Relating to Fracture Testing (Discontinued 1996) (Withdrawn 1996)3IEEE/ASTM SI 10 Standard for Use of the International System of Units (SI): The Modern Metric SystemAmerican NationalStandard for Metric Pract
13、ice1 This test method is under the jurisdiction of ASTM Committee C28 on Advanced Ceramics and is the direct responsibility of Subcommittee C28.01 on MechanicalProperties and Performance.Current edition approved Aug. 1, 2013July 1, 2018. Published September 2013July 2018. Originally approved in 2002
14、. Last previous edition approved in 20092013 asC1525 04 (2009).(2013). DOI: 10.1520/C1525-04R13.10.1520/C1525-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the
15、standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous ve
16、rsion. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM Internati
17、onal, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.2 European Standard:4EN 820-3 Advanced Technical CeramicsMonolithic CeramicsThermomechanical PropertiesPart 3: Determination ofResistance to Thermal Shock by Water Quenching3. Terminology3.1 Definitions:3.1.1
18、 The terms described in Terminologies C1145, E6, and E616 are applicable to this standard test method. Specific termsrelevant to this test method are as follows:3.1.2 advanced ceramic, na highly engineered, high performance, predominately non-metallic, inorganic, ceramic materialhaving specific func
19、tional attributes. C11453.1.3 critical temperature difference, Tc, , ntemperature difference between the furnace and the ambient temperaturewater bath that will cause a 30 % drop in the average flexural strength.3.1.4 flexural strength, f, FL2, na measure of the ultimate strength of a specified beam
20、 specimen in bending, determinedat a given stress rate in a particular environment.3.1.5 fracture toughness, na generic term for measures of resistance to extension of a crack. E6163.1.6 slow crack growth (SCG), nsubcritical crack growth (extension) which may result from, but is not restricted to, s
21、uchmechanisms as environmentally-assisted environmentally assisted stress corrosion or diffusive crack growth. C11453.1.7 thermal shock, na large and rapid temperature change, resulting in large temperature differences within or across a body.C11453.1.8 thermal shock resistance, nthe capability of m
22、aterial to retain its mechanical properties after exposure to one or morethermal shocks.4. Summary of Test Method4.1 This test method indicates the ability of an advanced ceramic product to withstand the stress generated by sudden changesin temperature (thermal shock). The thermal shock resistance i
23、s measured by determining the loss of strength (as compared toas-received specimens) for ceramic test specimens quickly cooled after a thermal exposure. A series of rectangular or cylindricaltest specimen sets areis heated across a range of different temperatures and then quenched rapidly in a water
24、 bath.After quenching,the test specimens are tested in flexure, and the average retained flexural strength is determined for each set of specimens quenchedfrom a given temperature. The “critical temperature difference” for thermal shock is established from the temperature difference(exposure tempera
25、ture minus the water quench temperature) that produces a 30 % reduction in flexural strength compared to theaverage flexural strength of the as-received test specimens.5. Significance and Use5.1 The high temperature capabilities of advanced ceramics are a key performance benefit for many demanding e
26、ngineeringapplications. In many of those applications, advanced ceramics will have to perform across a broad temperature range withexposure to sudden changes in temperature and heat flux. Thermal shock resistance of the ceramic material is a critical factor indetermining the durability of the compon
27、ent under transient thermal conditions.5.2 This test method is useful for material development, quality assurance, characterization, and assessment of durability. It haslimited value for design data generation, because of the limitations of the flexural test geometry in determining fundamental tensi
28、leproperties.5.3 Appendix X1 (following EN 820-3) provides an introduction to thermal stresses, thermal shock, and critical material/geometry factors. The appendix also contains a mathematical analysis of the stresses developed by thermal expansion under steadystate steady-state and transient condit
29、ions, as determined by mechanical properties, thermal characteristics, and heat transfereffects.6. Interferences6.1 Time-dependent phenomena such as stress corrosion or slow crack growth may influence the strength tests. This mightespecially be a problem if the test specimens are not properly dried
30、before strength testing.6.2 Surface preparation of test specimens can introduce machining flaws, which may have a pronounced effect on the measuredflexural strength. The surface preparation may also influence the cracking process due to the thermal shock procedure. It isespecially important to consi
31、der surface conditions in comparing test specimens and components.6.3 The results are given in terms of a temperature difference between furnace and quenching bath (T). However, it isimportant to notice that results may be different for the same T but different absolute temperatures. It is therefore
32、 specified in thistest method to quench to room temperature.4 Available from European Committee for Standardization (CEN), 36 rue de Stassart, B-1050, Brussels, Belgium, http:/www.cenorm.be.C1525 1826.4 The formulae presented in this test method apply strictly only to materials that do not exhibit R
33、R-curve-curve behavior, buthave a single-valued fracture toughness. If the test material exhibits a strong R-curve behavior, that is, increase in fracturetoughness with increasing crack length, caution must be taken in interpreting the results.6.5 Test data for specimens of different geometries are
34、not directly comparable because of the effect of geometry on heat transferand stress gradients. Quantitative comparisons of thermal shock resistance for different ceramic compositions should be done withequivalent test specimen geometries.7. Apparatus7.1 Test Apparatus:7.1.1 The test method requires
35、 a thermal exposure/quenching system (consisting of a furnace, specimen handling equipment,and a quench bath) and a testing apparatus suitable for measuring the flexural strength of the test specimens.7.1.2 The test method requires a furnace capable of heating and maintaining a set of test specimens
36、 at the required temperatureto 6 5 K (6 5C). 65 K (65 C). The temperature shall be measured with suitable thermocouples located no more than 2 mm2 mm from the midpoint of the specimen(s) in the furnace. Furnaces will usually have an open atmosphere, because air exposureis common during the transfer
37、to the quench bath.NOTE 1If air exposure is detrimental, a special furnace-quench system can be set up in which both the furnace and the quench unit are containedwithin an inert atmosphere container. A common design for such a system consists of a tube furnace positioned vertically above the quench
38、tank, so thatthe test specimen drops directly into the tank from the furnace.7.1.3 The method requires a test specimen handling equipment designed so that the test specimen can be transferred from thefurnace to the quenching bath within 5 s.7.1.4 A water bath controlled to 293 6 2 K (20C(20 6 2C)2 C
39、) is required. The water bath must have sufficient volume toprevent the temperature in the bath from rising more than 5 K (5C)(5 C) after test specimen quenching. It is recommended thatthe bath be large enough for the test specimens to have cooled sufficiently before reaching the bottom of the bath,
40、 or contain ascreen near the bottom to prevent the test specimens from resting directly on the bottom of the bath.7.1.5 The universal test machine used for strength testing in this test method shall conform to the requirements ofPracticePractices E4. Specimens may be loaded in any suitable test mach
41、ine, provided that uniform test rates, either rates usingeither load-controlled or displacement-controlled mode,mode can be maintained. The loads used in determining flexural strengthshall be accurate to within 61.0 % at any load within the selected load rate and load range of the test machine as de
42、fined inPracticePractices E4.7.1.6 The configuration and mechanical properties of the test fixtures shall be in accordance with Test Method C1161 for usewith the standard four-point flexure specimens. If larger test pieces (sizes(size A or C below) are employed, the test fixture shallbe scaled accor
43、dingly. There are currently no standard fixtures for testing cylindrical rods in flexure; however, the fixtures to beused shall have the appropriate articulation. Test fixtures without appropriate articulation shall not be permitted; the articulationof the fixture shall meet the requirements specifi
44、ed in Test Method C1161.7.1.7 The method requires a 393 K (120C)(120 C) drying oven to remove moisture from test specimens before (if needed)and after quench testing.7.1.8 A micrometer with a resolution of 0.002 mm (or 0.0001 in.) or smaller should be used to measure the test piecedimensions. The mi
45、crometer shall have flat anvil faces. The micrometer shall not have a ball tip or sharp tip, since these mightdamage the test piece if the specimen dimensions are measured prior to fracture.Alternative dimension measuring instruments maybe used, provided that they have a resolution of 0.002 mm (or 0
46、.0001 in.) or finer and do no harm to the specimen.8. Test Specimens8.1 The ceramic test specimens shall be pieces specifically prepared for this purpose from bulk material or cut from components.8.1.1 Specimen SizeThree specimen geometries are defined for use in this test method:8.1.1.1 Type ARods
47、10 6 0.13 mm in diameter, 120 mm long.8.1.1.2 Type BBars 3 6 0.13 mm 4 6 0.13 mm in cross section, minimum 45 mm long with chamfered edges, in accordancewith typeType B in Test Method C1161.8.1.1.3 Type CBars 10 6 0.13 mm 10 6 0.13 mm in cross section, 120 mm long, with chamfered edges.NOTE 2The tes
48、t specimens of Types A and C type are intended to be large enough to produce a materials ranking that is basically independent ofspecimen size and appropriate for larger test specimens (1, 2).5. Test specimens of Type B type may require greater quenching temperature differencesin order to produce st
49、rength reduction. These test specimens may not correctly rank the relative behavior of larger components. Only Type B coincideswith Type B in Test Method C1161.NOTE 3Under some circumstances, the edges of prismatic test specimens or the ends of cylindrical test specimens may be damaged by spallationduring the quench test. These specimens should be discarded from the batch used for strength testing if the damage will interfere with the strength test.In any case, such spallation must be noted in the report. Spallation problems can be allevia
