1、Designation: B 915 01 (Reapproved 2007)Standard Test Method forMeasuring Static Heat Resistance of Self-Cleaning OvenCoating1This standard is issued under the fixed designation B 915; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the 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 the procedure for the qualitativeand quantitative evaluation of static heat effe
3、cts on porcelainenamel coatings.1.2 This test method is adaptable to various temperaturesand times, since the requirements in the porcelain enamelingindustry differ between manufacturers.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is t
4、heresponsibility 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:2D 523 Test Method for Specular Gloss3. Terminology3.1 Definitions of Terms Specific t
5、o This Standard:3.1.1 blistering, na defect caused by gas evolution con-sisting of a bubble that protrudes on the surface of the glass.3.1.2 color and gloss change, nthis is determined by thecolor and gloss delta values calculated between each heat testcycle.3.1.3 copper heads/stickers, nprotrusions
6、 of iron oxidecrystals permeated from the steel substrate or conglomeratedmetal components in the enamel.3.1.4 crazing, na defect appearing as one or more finecracks in the porcelain enamel from thermal contraction andexpansion in the glass.3.1.5 edge burn off, nthis may occur in the first 24 to 72h
7、 and appears as a thin dull discolored gray line around theentire edge of the test plate.3.1.6 enamel breakdown, nthe point at which the glasscomposite has disintegrated. Microscopic examination willshow loss of enamel bubble structure and devitrification of theenamel. This stage reveals metallic ty
8、pe elements derived fromthe glass composition and the iron oxide from the steelsubstrate that has completely permeated the glass.3.1.7 hazy appearance/scumming, adjthe glass will de-velop an opaque film that exhibits low gloss on the surface ofthe porcelain enamel.3.1.8 metalizing, nenamel on test p
9、lates will have areflective copper color from condensed metals in the enamelthat may increase with the deterioration of the glass during theheat test cycle.4. Significance and Use4.1 This test method is intended for testing the porcelainenamel finish on oven parts of self-cleaning ranges.4.2 The num
10、erical values and visual evaluation derived bythis test method are used to measure differences in heatresistant characteristics between enamel formulas intended tomeet oven manufacturer specifications.5. Apparatus5.1 Furnace, capable of holding a constant temperature of920F (493C) minimum.5.2 Standi
11、ng Bracket, approximately 10 by 10 by 6 in. (25.4by 25.4 by 15.24 cm). Dimensions may vary according to testplate size.5.3 Two Heavy-Gauge Steel Rods, approximately 12 in.(30.48 cm) long and18 in. (0.32 cm) in diameter.5.4 Standard Size38 -16 or38 -24 (0.96-cm) Nuts, used forspacers between heat tes
12、t plates.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 approved March 1, 2007. Published March 2007. Originallyappro
13、ved in 2001. Last previous edition approved in 2001 as B 915 01.2For 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 websi
14、te.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.5 Spectrocolorimeter, capable of reading color by reflec-tion of enameled plates on reflectance 45/0 and L*, a*, b*color space.3Equipment available for making color readings isan i
15、nstrument that reads Spectrocolorimeter L, a, b scale4suchas Macbeth Color Eye or a Hunter Lab ColorQUEST.55.6 Gloss Meter, capable of reading 60 ASTM glossmeasurements (see Test Method D 523).66. Procedure6.1 Punched holes are located14 in. (0.63 cm) down fromthe top and12 in. (1.2 cm) from the rig
16、ht and left sides on a538-by538-in. (13.65- by 13.65-cm) uncoated metal plate.6.2 The metal plate is processed in the enamel formula thatis to be subjected to static heat testing.6.3 Before placing the test plate on heat test, initial color (L,a, b) and gloss (60) readings are recorded, dated, andes
17、tablished as 0 h.6.4 The enameled plate should be clean and free of anyfingerprints or smudges. To clean a soiled plate, a lint-freepaper towel dampened with alcohol is rubbed back and forth onthe surface until plate is clean. To prevent further smudging,handle test plates on the edges.6.5 A steel r
18、od is passed through each hole of the test plate.The test plates are suspended across the top of the standingbracket by the steel rods.6.6 If more than one test plate is required, a spacer is placedon the rods between each test plate. This allows a14-in.(0.63-cm) space between each test plate. Appro
19、ximately 26heat test plates can be suspended from the two steel rods.6.7 A cover plate is placed on both ends of each row. Thecover plate should be an enameled plate the same size as theheat test plates (previous heat test plates no longer needed fortesting may be used). Place cover plates on the tw
20、o rods withenamel side towards test plates. The cover plates protect theend heat test plates from being subjected to direct oven wallheat.6.8 The standing bracket containing the heat test plates isplaced in a constant oven temperature of 920F (493C) for360 h.76.9 The test plates are removed from the
21、 oven after every 24h, stand at room temperature and evaluated for the amount ofchange in color, gloss, and physical appearance.6.10 The color and gloss readings of test plates are datedand recorded after every 24 h of exposure to heat. Deltas arecalculated by measuring the gloss and color change fr
22、om 0 to24 h as shown in example 1. With the final change from 0 to360 h or at failure, whichever occurs first.Example 1:0 h 9-1-95 Gloss L a bPlate No. 1 90.4 +19.86 0.23 2.6524 h 9-2-95 Gloss L a bPlate No. 1 89.3 +18.48 0.10 1.50Delta at 24 h: D Gloss DL Da Db1.1 1.38 +0.13 +1.156.10.1 The (+) and
23、 () values indicate the direction ofchange, that is, a (+a) change in value would indicate anincrease in redness, while a (a) change in value wouldindicate an increase in green. Similarly, a (+b) change in valuewould indicate an increase in yellowness, while a (b) changein value would indicate an in
24、crease of blueness in the colorvalues of the test plate.6.11 The plates are checked visually for enamel breakdown,such as, metalizing, crazing, blistering, copperheading, hazyappearance, and edge burnoff, color, and gloss change.6.12 Heat test plates that do not display any extremephysical breakdown
25、 are returned to the 920F (493C) oven tocontinue the heat test cycle.6.13 Test plates are removed every 24 h from the oven, setto room temperature, and visually examined. Color and glossreadings are recorded, dated, and the total number of hours ofexposure is recorded.6.14 Test plates that fail beca
26、use of excessive color andgloss change or show extreme enamel breakdown as describedin 6.11 are removed from the test and recorded as to what timefailure has occurred.6.15 Test plates that complete the 360 h are examinedvisually. Deltas of color and gloss readings from 0 to 360 h arerecorded.7. Rati
27、ng Test Specimens7.1 A full heat test life cycle begins when the enameledplate(s) is placed in the preheated furnace and ends after the360-h time frame.7.2 The plate(s) shall be rated for the number of cycles it haspassed without failure. For example, enamel that failed at 168h would be unfavorable
28、compared to enamel that did not failuntil 336 h. Heat test plates are rated by the number of hoursaccumulated in the furnace before failure occurs.7.3 For comparison purposes, sample plates processed instandard enamel would have to be heat tested at the same timeto complete the rating of the test en
29、amel from 0 to 360 h.7.4 Visual examination of an enameled test plate after a360-h heat cycle would be rated according to the calculation oftotal color change. (DE)8, when its value is equal to or less thanthe (DE) calculated for a standard enamel, which might be acurrent production enamel, over the
30、 full 360-h heat cycle.7.5 Change in gloss over full heat cycle must be comparableto the standard enamel.3L*, a*, b* color space: “Auniform-color space using anAdams-Nicherson cuberoot formula, suggested in 1974 for adaptation by the CIE (International Commis-sion on Illumination) in 1976 for use in
31、 the measurement of small color differences.”4Hunter L, a, b scales: “A uniform color scale devised by Hunter in 1958 for usein a color difference meter, based on Herings opponent-colors theory of colorvision.”5Hunter Associates Laboratory, Inc., 11491 Sunset Hills Rd., Reston, VA220925280. Macbeth,
32、 Little Britain Road, P.O. Box 230, Newburgh, NY 12550.660 ASTM gloss measurements: “The 60 optical head reads the angles ofincidence (i) and view (v) are 60 as measured from perpendicular to the specimen.”7The heat test cycle of 920F (493C) for 360 h was established to represent theaverage home use
33、 of running 12 cleaning cycles per year on a 10-year basis = 120cycles, assuming the oven cleaning cycle runs3hatpeak temperature (approxi-mately). Heat test oven temperature and time may be adjusted in accordance to userspecifications.8By definition, DE = (DL)2+ (Da)2+ (Db)2, where DL, Da, and Db a
34、re thetotal color element changes from 0 to 360 h. See ASTM Color AppearanceMeasurements, 3rd Ed., available from ASTM Headquarters.B 915 01 (2007)28. Report8.1 The following is a list of data to be recorded:8.1.1 Number of hours test plate has accumulated in thefurnace.8.1.2 Color readings on the L
35、, a, b scales.8.1.3 Gloss readings on the 60 gloss meter.8.1.4 Changes in gloss, color, and DE values are recorded.8.1.5 Written comments on any visual enamel breakdownduring the test cycle.9. Precision and Bias9.1 No justifiable statements can be made regarding theprecision and bias of this test me
36、thod. This test is subject to awide margin of subjective visual rating and enamel batchformulation. Since base metal composition, fabrication, enamelformulation, and processing will give rise to variables in theheat resistance of porcelain-enameled plates, each test plateshould be considered separat
37、ely.10. Keywords10.1 porcelain enamel coatings; self-cleaning oven coating;static heatASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of t
38、he 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 time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Yo
39、ur comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comment
40、s 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 ASTM 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).B 915 01 (2007)3
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