1、Designation: C 773 88 (Reapproved 2006)Standard Test Method forCompressive (Crushing) Strength of Fired WhitewareMaterials1This standard is issued under the fixed designation C 773; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers two test procedures (A and B)for the determination of the compressive strength of
3、firedwhiteware materials.1.2 Procedure A is generally applicable to whiteware prod-ucts of low- to moderately high-strength levels (up to 150 000psi or 1030 MPa).1.3 Procedure B is specifically devised for testing of high-strength ceramics (over 100 000 psi or 690 MPa).1.4 This standard does not pur
4、port to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E4
5、 Practices for Force Verification of Testing MachinesE 6 Terminology Relating to Methods of Mechanical Test-ingE 165 Test Method for Liquid Penetrant Examination3. Significance and Use3.1 Resistance to compression is the measure of the greateststrength of a ceramic material. Ideally, ceramics should
6、 bestressed this way in use. This test is a measure of the potentialload-bearing usefulness of a ceramic.PROCEDURE A4. Apparatus4.1 Testing MachineAny testing machine conforming toPractices E4 and to the requirements for speed of testingprescribed in Sections 5 and 12 of this test method, may beused
7、.4.2 Spherical Bearing BlockIn vertical testing machines,the spherical bearing block shall be spring suspended from theupper head of the machine in such a manner that the upperplaten of the machine (lower face of the spherical bearingblock) remains in a central position (spherical surfaces in fullco
8、ntact) when not loaded. The spherical surfaces shall be welllubricated, and the center of curvature shall lie on the lowerface of the platen. The diagonal or diameter of the platen shallbe only slightly greater than the diagonal of the 112-in.(38.1-mm) square contact blocks to facilitate accurate ce
9、nter-ing of the specimens.4.3 Contact BlocksCold-rolled steel contact blocks shallbe used between the test specimen and the platens of themachine. These blocks shall be 112 in. (38.1 mm) square by58to34 in. (15.9 to 19.1 mm) thick, and the contact faces shall besurface ground until plane and paralle
10、l. The contact blocksshall be resurfaced, if necessary, after each strength test, andmay be reused only so long as the thickness remains over12 in.(12.7 mm). If the contact block is cracked during testing, itshall be replaced.4.4 Cushion PadsCushion pads shall be used between thetest specimens and t
11、he contact blocks to aid in distributing theload. New cushion pads shall be used for each specimen.Suitable materials for cushion pads, selected in accordancewith the compressive strength range of the material beingtested, are shown in the following table:Compressive Strength Range, psi (MPa) Cushio
12、n Pad5000 to 50 000 incl (34.5 to 345) blotting paper,164 in. (0.4 mm) thickOver 50 000 to 150 000 incl (345 to1030.0)mild steel,132 in. (0.8 mm) thick (65HRB max)1This test method is under the jurisdiction ofASTM Committee C21 on CeramicWhitewares and Related Products and is the direct responsibili
13、ty of SubcommitteeC21.03 on Methods for Whitewares and Environmental Concerns.Current edition approved Feb. 15, 2006. Published February 2006. Originallyapproved in 1974 to replace C 407 and C 528. Last previous edition approved in1999 as C 773 88 (1999).2For referenced ASTM standards, visit the AST
14、M website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, Unite
15、d States.5. Procedure5.1 Dye-check specimens in accordance with Test MethodE 165 before testing. Discard any pieces exhibiting cracks orflaws visible to the unaided eye.5.2 Clean the test specimens with a suitable solvent aftergrinding and immerse in an ultrasonic bath filled with hotdetergent solut
16、ion. Then rinse specimens in hot water, dry at110 6 2C (230 6 4F) for 2 h and cool to room temperaturein a desiccator.5.3 Carefully center the specimen in the machine betweenthe contact blocks. Place an appropriate guard around thespecimen to contain flying fragments at failure; eye protectionshould
17、 be used by the operator.5.4 Apply the load continuously and without impact shockuntil ultimate failure. The rate of loading to be used shalldepend on the compressive strength of the material beingtested, as shown in Table 1.6. Calculation6.1 Calculate the compressive strength of each specimen asfol
18、lows:C 5 P/A (1)where:C = compressive strength of the specimen, psi or MPa;P = total load on the specimen at failure, lbf or N; andA = calculated area of the bearing surface of the specimen,in.2or mm2.7. Report7.1 Report the following information:7.1.1 The procedure used,7.1.2 Type of testing machin
19、e (hydraulic or screw),7.1.3 Material and size of contact blocks or of cushioningmaterials,7.1.4 Description of material being tested (Note 1),7.1.5 Rate of loading,7.1.6 Number of specimens tested,7.1.7 Dimensions and load at failure of each specimen, and7.1.8 Compressive strength of each specimen
20、tested,rounded off to the nearest 100 psi (1.0 MPa), together with theaverage compressive strength of the sample tested and thestandard deviation.NOTE 1It is desirable to include details of the origin of the specimenand subsequent treatment.8. Precision and Bias8.1 Interlaboratory Test DataAn interl
21、aboratory test wasrun in 1979 in which randomly drawn samples of six materialswere tested in each of five laboratories. One operator in eachlaboratory tested ten specimens of each material. The compo-nents of variance for compressive strength results expressed ascoefficients of variation were calcul
22、ated as follows:Single-operator componentBetween-laboratory component1.50 % of the average8.80 % of the average8.2 Critical DifferencesFor the components of variancereported in 8.1, two averages of observed values should beconsidered significantly different at the 95 % probability levelif the differ
23、ence equals or exceeds the following criticaldifferences listed below:Number of Observa-tions in Each AverageCritical Difference, % of Grand AverageASingle-OperatorPrecisionBetween-LaboratoryPrecision10 4.16 24.40AThe critical differences were calculated using t = 1.960 which is based oninfinite deg
24、rees of freedom.8.3 Confidence LimitsFor the components of variancenoted in 8.1, single averages of observed values have thefollowing 95 % confidence limits:Number of Observa-tions in Each AverageWidth of 95 % Confidence Limits, Percent of theGrand AverageASingle-OperatorPrecisionBetween-LaboratoryP
25、recision10 62.94 617.26AThe confidence limits were calculated using t = 1.960 which is based oninfinite degrees of freedom.8.4 BiasNo statement on bias is being made due to lack ofan accepted standard reference material.9. Test Specimens9.1 PreparationThe test specimens shall be right cylin-ders. Th
26、ey may be formed and matured for the purpose ofcompression testing, or they may be cut from matured whitew-are by sawing or coredrilling. The ends of all specimens shallbe ground or lapped to yield plane and parallel faces. Thesefaces shall be perpendicular to the axis of the specimen, andparallel w
27、ithin 15 min of arc (0.044 rad).9.2 SizeThe size of the specimen should be no larger thanto require more than 80 % of the rated capacity of the testingmachine. Examples of specimen size limitations are shown inTable 2.TABLE 1 Typical Loading Rates to Cause Failure in 1 minNOTE 1The loading rate of 1
28、6 000 lbf/min (70 kN/min) shall be usedfor the first three tests of an unknown material to determine the generalstrength classification group. Some specimens crack before ultimatefailure; the load at which the first audible crack occurs shall be noted, butonly the load on the specimen at ultimate fa
29、ilure shall be used forcalculation of compressive strength.Compressive Strength, psi(MPa)Specimen Diameter, in.(mm)Loading Rate, lbf/min (kN/min)10 000(69) 1.00(25.4) 8000(35)50 000(345) 0.64(16.3) 16 000(70)150 000(1034) 0.45(11.5) 24 000(105)TABLE 2 Maximum Specimen Diameter in Inches (Millimetres
30、) toUse 80 % of Rated Capacity of Testing MachineNOTE 1The ratio of length to diameter of the test specimens may varybetween 1.9 and 2.1. Diameters shall be measured to the nearest 0.001 in.(0.03 mm).Maximum CompressiveStrength, psi (MPa)Testing Machine Capacity, lbf (kN)10 000 (44) 20 000 (89) 30 0
31、00 (134)in. (mm) in. (mm) in. (mm)10 000(69) 1.0(25.4) 1.43(36.3) 1.75(44.4)50 000(345) 0.45(11.5) 0.64(16.3) 0.78(19.8)150 000(1034) 0.26(6.6) 0.37(9.4) 0.45(11.5)C 773 88 (2006)29.3 Number of SpecimensThe number of specimens shallnot be less than ten.PROCEDURE B10. Apparatus10.1 Testing MachineAny
32、 fixed-head testing machineconforming to Practices E4and to the requirements for speedof testing prescribed in 12.3 may be used. A spherical headmust not be used.10.2 Bearing PlatesHardened steel 60 HRC bearingplates shall be used between the contact cylinders and theplatens of the machine. These pl
33、ates shall be approximately 2.5in. (63.5 mm) in diameter by 1 in. (25.4 mm) thick. The contactfaces shall be surface ground until flat and parallel within 0.001in. (0.025 mm) total indicator reading. The bearing plates shallbe resurfaced as necessary to retain their tolerance and toremove any surfac
34、e damage resulting from testing high-strength materials.10.3 Contact CylindersCeramic contact cylinders of thesame material as the specimens to be tested shall be usedbetween the bearing plates and the test specimen to aid indistributing the load and to minimize detrimental “end effects.”These conta
35、ct cylinders shall be12 in. (12.7 mm) high and58in. (15.9 mm) in diameter. The contact faces shall be flat andparallel to within 0.0005 in. (0.013 mm) total indicator reading.Two new contact cylinders should be used for each specimen toprevent a damaged contact cylinder failing prematurely andthereb
36、y giving an erroneous reading. By using contact blocksmade of the same, or similar, material as the test specimenitself there is less deformation and less frictional resistance atthe interfaces.NOTE 2Ceramic contact cylinders of similar composition to that ofthe test specimen may be used so long as
37、the contact cylinders have asimilar elastic modulus and equal or higher tensile strength to that of thetest specimen.11. Test Specimens11.1 PreparationGrind the test specimens to right cylin-ders. Grind the ends of all specimens with a 100-grit or finerdiamond wheel, until parallel and perpendicular
38、 to the axis,within 0.0005 in. (0.013 mm) total indicator reading.11.2 Clean the test specimens with a suitable solvent aftergrinding and follow by immersion in an ultrasonic bath filledwith hot detergent solution. Then rinse the specimens in hotwater, dry at 110 6 2C (230 6 4F) for 2 h and cool to
39、roomtemperature in a desiccator.NOTE 3In the event that water-sensitive specimens, such as MgO, arebeing cleansed, a substitute for water should be used.11.3 SizeSpecimens shall be 0.250 6 0.001 in. (6.350 60.025 mm) in diameter and 0.500 6 0.002 in. (12.70 6 0.05mm) in length.11.4 Number of Specime
40、nsThe number of test specimensshall be not less than ten.12. Procedure12.1 Dye-check specimens and contact cylinders in accor-dance with Test Method E 165 before testing. Discard any partsexhibiting cracks or flaws visible to the unaided eye.12.2 Center the specimen carefully in the machine betweent
41、he bearing plates (Fig. 1) to avoid eccentric loading. Place anappropriate guard around the specimen to contain flyingfragments at failure; eye protection should be used by theoperator.12.3 Apply the load continuously and without impact shockat a rate of 10 000 lbf/min (45 kN/min), within 20 %. Use
42、onlythe load on the specimen at ultimate failure for calculation ofthe compressive strength.13. Keywords13.1 compressive strength; fired whiteware materialsFIG. 1 Apparatus for Testing Compressive StrengthC 773 88 (2006)3ASTM International takes no position respecting the validity of any patent righ
43、ts asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any
44、time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments wil
45、l receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by AST
46、M International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C 773 88 (2006)4
