ASTM C448-88 (R2021) pdf free download.Standard Test Methods for Abrasion Resistance of Porcelain Enamels.
1.1 These test methods cover determination of the resistance of porcelain enamels to surface abrasion and subsurface abrasion.
1 .2 This standard does 110! purport to address all (f the safety concei-ns, if aiiv, associated with ifs use. It is the responsibility of the user of this standard to establish appropriate sqfetv, health, and environmental practices and dewr— mine (lie applicability of regulatory limitations prior tO USC.
1 .3 This international standard was developed in accordance with inte rnationallv recognized principles on standardiza lion established in the Decision on Principles for the Development of Inter,zational Standards, Guides and Recoinmnendarions issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2. 1 ASTM Standards:
C346 Test Method for 45-deg Specular Gloss of Ceramic Materials
3. Summary of Test Methods
3.1 The first of the tests described herein is intended for the determination of the resistance to surface abrasion of porcelain enamels for which the unabraded 45° specular gloss is more than 30 gloss units. It consists essentially of measuring the specular gloss of the specimens before and after a specified abrasive treatment of the surface, and taking the percentage of the original specular gloss that is retained after treatment as the surface abrasion index.
3.2 The second test is intended for the determination of the resistance to surface abrasion of porcelain enamels for which the unabraded 450 specular gloss is 30 gloss units or less. It consists of determining the weight loss by a specified abrasive treatment and multiplying this weight loss by an adjustment factor associated with each abrasive tester, lot of abrasive, and lot of calibrated plate glass standards used. The adjusted weight loss is taken as an index of resistance to surface abrasion.
3.3 The third test is intended for the determination of the resistance of porcelain enamels to subsurface abrasion. It consists of determining the slope of the linear portion of the abrasion time-weight loss curve and multiplying by an adjustment factor associated with each abrasion tester, lot of abrasive, and lot of calibrated plate glass standards used. The adjusted slope is taken as an index of resistance to subsurface abrasion.
4. Significance and Use
4.1 When a porcelain enamel is first subjected to abrasion of the type involved in these tests, the rate of wear or attrition is relatively low. As the enamel is subjected to continued abrasion, the rate of wear increases until it reaches a steady value. Thereafter, the rate of wear remains almost constant until the enamel is penetrated and the underlying ground coat or metal exposed. The abrasion that occurs during the period of increasing rate-of-weight loss is defined as surface abrasion and results in reduced gloss and cleanability with high-gloss enamels and a modification of color, appearance, or surface texture, or combination thereof with low-gloss enamels. The abrasion that occurs during the period of steady rate-of-weight loss is defined as subsurface abrasion and results in the destruction of the continuity of the coating. ASTM C448-88 pdf download.