1、Designation:C55493(Reapproved 2016)Standard Test Method forCrazing Resistance of Fired Glazed Ceramic Whitewares bya Thermal Shock Method1This standard is issued under the fixed designation C554;the number immediately following the designation indicates the year oforiginal adoption or,in the case of
2、 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 covers the determination of the resis-tance to crazing of fired,glazed,ceramic white
3、wares whenstresses residual after glost firing may cause a tendency tocraze,such stresses being induced by factors other thanmoisture expansion.1.2 This test is not intended to induce moisture expansion,which fact should be kept in mind if the materials to beevaluated may exhibit moisture expansion.
4、NOTE1Test Method C424 covers a method for determining resistanceto crazing induced by moisture expansion.Its use is generally confined totesting nonvitreous and semivitreous ceramic whitewares because theseproducts may be subject to such expansion.For whitewares with negli-gible moisture expansion(s
5、uch as vitreous and impervious ware),thethermal shock method described herein is generally to be preferred.1.3 The values stated in inch-pound units are to be regardedas the standard.The values in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety conc
6、erns,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.For a specifichazard statement,see Warning in 6.3.2.Referenced Documents2.1 ASTM Stan
7、dards:2C424 Test Method for Crazing Resistance of Fired GlazedWhitewares by Autoclave Treatment3.Significance and Use3.1 Unless there is a proper match between the expansionsof the glaze and the body,all glazed whitewares may containresidual stresses from the firing that bonded the glaze to thebody.
8、In addition,whitewares are increasingly subjected tothermal stresses in service.Hence,an important use criterionfor a glazed whiteware is adequate resistance to repeatedabrupt thermal changes.In most cases,the result of inadequateresistance to thermal shock is the appearance of a craze patternin the
9、 glaze.This craze pattern is visible by inspection withoblique lighting and application of a suitable ink or dye.3.2 This test method is applicable to vitreous whitewaresthat have negligible crazing as a result of moisture expansion.For nonvitreous and semivitreous bodies,refer to Test MethodC424.4.
10、Apparatus4.1 OvenAn oven suitable to operate in the range 250 to450F(121 to 232C)while holding the required temperatureswithin 65F(63C)and being capable of recovering tempera-ture within 20 min after being loaded with the desired numberof specimen(s).4.2 Water ContainersContainers to hold water at 6
11、8 65F(20 6 3C)before quenching;the capacity of the contain-ers shall be large enough so that the water temperature does notexceed 85F(29C)after quenching a single specimen.Two ormore specimens may be quenched simultaneously in a singlecontainer provided they do not overlap on the bottom of thecontai
12、ner and provided that the water temperature does notexceed 85F(29C)after quenching.As a general rule,it willbe found that 10 cm3of water/g of ware,or 1 gal of water/lbof ware will be adequate to keep the temperature within therequired limits.There shall be enough containers to quench allthe specimen
13、s loaded in the oven.The containers shall be deepenough so that at least12in.(13 mm)of water will cover thequenched specimen(s).5.Test Specimens5.1 The specimen(s)shall preferably be whole pieces ofware;cut or broken specimen(s)shall be used only when wholepieces are impractical or impossible to tes
14、t.If the specimen(s)are cut or broken from whole ware,they shall be selected so asto be representative of the item to be tested.In cutting orbreaking specimen(s),cracks may be induced,therefore,bro-ken or cut specimens shall be inspected for cracks by oblique1This test method is under the jurisdicti
15、on ofASTM Committee C21 on CeramicWhitewares and Related Productsand is the direct responsibility of SubcommitteeC21.03 on Methods for Whitewares and Environmental Concerns.Current edition approved July 1,2016.Published July 2016.Originally approvedin 1964.Last previous edition approved in 2011 as C
16、554 93(2011).DOI:10.1520/C0554-93R16.2For referenced ASTM standards,visit the ASTM 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 lighting and application of a suitable ink or dye before the test.Only broken or cut specimen(s)free from cracks shall
