1、Designation:C38558(Reapproved 2014)Standard Test Method forThermal Shock Resistance of Porcelain-Enameled Utensils1This standard is issued under the fixed designation C385;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of l
2、ast 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 of porcelain-enameled utensils to thermal shock.Thistest method
3、 is adaptable to any porcelain-enamel utensil thatcan be filled with water to a depth of 1 in.(25 mm).1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not cons
4、idered standard.1.3 This standard does not purport 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.
5、Apparatus2.1 Hot Plate,capable of maintaining over its entire surfacea uniform temperature,that is,less than 20F(6.7C)varia-tion over the entire surface.Surface temperature of the hotplate shall be capable of being adjusted from 475 to825 6 10F(245 to 440 6 5.5C).The surface temperature ofthe hot pl
6、ate,determined by any suitable surface temperaturemeasuring device,may be varied by changing the wattageinput to the hot plate.If the hot plate surface temperature becalibrated to wattage input,the desired temperature may thenbe set by adjusting wattage input.The wattage input or similarcalibration
7、shall be made for each surface temperature(see 6.2and 6.3).2.2 Timing Device,a clock or similar instrument having asweep second hand and an integrating minute hand.2.3 Container,suitable for holding approximately 4 gal ofwater.2.4 Container,for pouring water into utensil.2.5 Sponge,for wiping utensi
8、l dry.3.Quenching Water3.1 Either tap or distilled water shall be used.NOTE1In areas where tap water is extremely hard,distilled water isrecommended.4.Test Specimens4.1 The test specimens shall consist of five identical uten-sils.NOTE2“Identical utensils”signifies utensils of the same size,shape,and
9、 finish.5.Preparations for Test5.1 Level the hot plate.Switch on the hot plate and adjustthe surface temperature to 475 6 10F(245 6 5.5C).Allowthe hot plate to preheat at this temperature for at least 1 h toobtain a uniform temperature over the entire heating surface.5.2 Place the quenching water in
10、 a large container.Adjustthe temperature of the water to 70 6 2F(21 6 1C).Measureout the amount of water required to fill a test utensil to a depthof 1 in.(25 mm);this amount of water shall be used forquenching.NOTE3The test utensils must be at room temperature at the start ofthe test.6.Procedure6.1
11、 Center a dry utensil directly on the preheated hot plate.After 3 min remove the utensil from the hot plate andimmediately fill the utensil to a depth of 1 in.(25 mm)withquenching water.After 10 s pour out the quenching water andwipe the inside of the utensil with a wrung-out damp sponge.After a tot
12、al nonheating period of 20 s replace the utensil on thehot plate.6.2 Immediately after centering the utensil on the hot plate,adjust the input to the hot plate so that the hot plate surfacetemperature will reach 500 6 10F(260 6 5.5C).Allow theutensil to heat dry for 8 min with the hot plate adjusted
13、 so thatthis new surface temperature will be reached.NOTE4Do not remove the utensil for surface temperature measure-ments during the test.The surface temperature of the hot plate should becalibrated against wattage input before the test is started.The surfacetemperature of the hot plate is the maxim
14、um temperature to be reachedduring the 8-min heating period(see 2.1).1This test method is under the jurisdiction ofASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 onMaterials for Porcelain Enamel and Ceramic-Metal Systems.Current edition a
15、pproved May 1,2014.Published May 2014.Originallyapproved in 1956.Last previous edition approved in 2009 as C385 58(2009).DOI:10.1520/C0385-58R14.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.3 After the 8-min heating period,remove the
16、 utensil andquench as before.Repeat this procedure according to theschedule given in Table 1.Continue the test until the utensilfails or has withstood quenching after the 825F(440C)heating period.NOTE5A failure is the removal of the enamel from the utensil,generally accompanied by a cracking noise,during the heating period.Fish-scaling and crazing are not considered thermal-shock failures.7.Rating Test Specimens7.1 A cycle begins when the utensil is placed on the hotplate and ends after the quen
