1、Designation: C285 10Standard Test Methods forSieve Analysis of Wet-Milled and Dry-Milled PorcelainEnamel1This standard is issued under the fixed designation C285; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThese test methods provide a rapid means of determining the fineness of glass frit in wet- ordry-milled porcelain enamel coati
3、ng materials by sieve analysis. Fineness is a key predicator offusibility, tearing, gloss, opacity, suspension in the slip, and ease of spraying because of the directrelationship to surface area.1. Scope1.1 These test methods cover the determination of thefineness of frit in wet- or dry-milled porce
4、lain enamels andother ceramic coatings for metals by means of the No. 200(75-m) or No. 325 (45-m) sieve.1.2 The two methods appear as follows:SectionsMethod AReferee MethodMethod BRoutine Method4to910 to 141.3 Method A is intended for use where a referee method ofhigher accuracy is required, while M
5、ethod B is intended tomeet the needs of normal enamel plant production controloperations where a rapid, simplified method of sieve testing isrequired. The accuracy of the simplified method has proved tobe entirely adequate for this use. The simplified test, however,is not recommended where high accu
6、racy is required.1.4 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 us
7、e.2. Referenced Documents2.1 ASTM Standards:2E11 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Significance and Use3.1 The fineness of the frit has a direct bearing on many ofits properties, such as fusibility, tearing, gloss, opacity, suspen-sion in the slip, and ease of spraying.M
8、ETHOD AREFEREE METHOD4. Apparatus4.1 BalanceThe balance or scale shall be of at least 500-gcapacity, and accurate to 0.1 g.4.2 SievesThe sieves shall conform to Specification E11.They shall include the No. 40 (425-m) sieve and also the No.200 (75-m) or the No. 325 (45-m) sieve (Note 1), or both. ANo
9、. 325 sieve shall be used when the fineness is such that, froma sample containing 100 g of dry solids, less than2gisretained on a No. 200 sieve. An 8-in. (203-mm) full-heightsieve is recommended. This height is preferred because there isless tendency to flood or splash, and also because it fitscomme
10、rcial automatic tapping and shaking machines. Allsieves used for testing shall be standardized initially and afterevery 50 tests against a reference sieve tested by the NationalBureau of Standards and bearing its precision seal. Thecorrection for the sieve used in this test shall be determined bysie
11、ving tests made in conformity with the procedure of this testmethod. Identical samples shall be sieved through the referencesieve and the test sieve. Test materials shall be chosen so that5 to 10 % of the material will be retained on the referencesieve. The difference between the percentage residue
12、on thereference sieve and that on the test sieve is the amount ofcorrection which shall be algebraically added to, or subtractedfrom, the correction for the reference sieve to obtain the finalcorrection (Note 2). The No. 40 sieve need not be calibrated.1These test methods are under the jurisdiction
13、of ASTM Committee B08 onMetallic and Inorganic Coatings and are the direct responsibility of SubcommitteeB08.12 on Materials for Porcelain Enamel and Ceramic-Metal Systems.Current edition approved April 1, 2010. Published May 2010. Originallyapproved in 1951. Last previous edition approved in 2005 a
14、s C285 88 (2005).DOI: 10.1520/C0285-10.2For 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.1Copyright ASTM Intern
15、ational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 1Tyler Standard Sieves of 35, 200, and 325 mesh correspond,respectively, to ASTM sieves No. 40, 200, and 325 (U.S. Standard SieveSeries numbers).NOTE 2For example, when comparing the reference sieve wit
16、h a testsieve, should 8.5 g be retained on the reference sieve and 7.5 g on the testsieve, the total correction for the test sieve would then be 8.5 7.5,or + 1.0.4.3 DryerA suitable means for drying the sieves and slipsample, without exceeding a temperature of 250F (122C),shall be provided. No dryer
17、 is needed for sieve tests ofdry-milled enamel.4.4 Mechanically Operated Sieve Shaker The mechanicalshaking device shall be such as to produce a lateral and verticalmotion of the sieve, accompanied by a jarring action so as tokeep the sample moving continuously over the surface of thesieve. If a mac
18、hine shaker is to be used, the thoroughness ofsieving shall be tested by comparing and calibrating with thehand method of sieving, as described in Section 6.5. Sample5.1 Wet-Milled EnamelSelect a sample of slip represen-tative of the material to be tested. Protect samples fromevaporation. Determine
19、the water content of the slip by dryinga representative 100-g sample of slip to constant weight at atemperature not exceeding 250F (122C). Pass the samplethrough a No. 40 sieve before weighing, and discard thematerial retained on the sieve. Sample the slip after stirring byweighing out to the neares
20、t 0.1 g, a quantity calculated tocontain 100 g of dry solids.5.2 Dry-Milled EnamelSelect a sample representative ofthe material to be tested and containing 100 g of dry solids,weighed to the nearest 0.1 g.6. Procedure for Wet-Milled Enamel6.1 Wet SievingTransfer the weighed sample to the No.200 or N
21、o. 325 sieve. Wash the sample through the sieve witha gentle flow of water from a rubber hose until the waterpassing through the sieve appears clear and free of cloudiness.This usually requires 2 min. Exercise care to prevent any lossof sample because of splashing or overflowing. Dry the sievewith i
22、ts residue until the residue easily moves about as a drypowder when the sieve is shaken. Complete the sieving andweighing operation in accordance with 6.2 or 6.3. Make tests induplicate.6.2 Hand SievingHold the sieve, with pan and coverattached, in one hand at an angle of about 20 from thehorizontal
23、. Move the sieve up and down in the plane ofinclination at a rate of about 150 times per minute, and strikeagainst the palm of the other hand at the top of each stroke.After every 25 strokes, turn the sieve about one sixth of arevolution in the same direction. Continue the operation untilnot more th
24、an 0.05 g passes through the sieve in 1 min ofcontinuous sieving. Weigh the portion of the sample retainedon the sieve to the nearest 0.1 g.6.3 Machine SievingIf a mechanically operated sieveshaker is used, vary the time during which the sieve (with panand cover attached) and the sample are shaken,
25、and note thelength of time necessary to operate the sieve shaker in order toget the same result as that obtained with hand sieving.Calibrate the machine-sieving operation in terms of handsieving.7. Procedure for Dry-Milled Enamel7.1 Transfer the sample quantitatively to the No. 200 or 325sieve. Comp
26、lete the sieving and weighing operation in accor-dance with 5.2 or 5.3. Make tests in duplicate.8. Calculation and Report8.1 Using the average of duplicate runs, report the finenessof the frit in percentage by mass (to the nearest 0.1 %) of thedry solids content of the sample retained on the No. 200
27、 or 325sieve. The weight in grams is equivalent to weight percentage.9. Precision and Bias9.1 PrecisionIt is generally accepted within the porcelainenamel industry that duplicate tests run by the same operator inthe same laboratory should show a precision of 60.5 or less.Failure to duplicate determi
28、nations within this limit indicatesthe necessity for repetition of the test. The precision ofduplicate tests is negatively influenced by variations in opera-tor technique, sieve binding and wear, and, when it is used, thecondition of mechanical sieving equipment. It is also influ-enced by changing c
29、onditions in the test sample which occurover time and which result in particle agglomeration due tochemical reactions.9.2 BiasNo justifiable statement on bias can be madesince the true value of sieve analysis cannot be established byan acceptable standard sample.METHOD BROUTINE METHOD10. Apparatus10
30、.1 BalanceThe balance or scale shall be at least 200-gcapacity, and accurate to 0.1 g.10.2 SievesThe sieves shall conform to Specification E11and shall include the No. 40 (425-m) and the No. 200 (75-m)sieves. An 8-in. (203-mm) full-height sieve is recommended.This height is preferred because there i
31、s less tendency to floodor splash, and also because it fits commercial automatictapping and shaking machines. A sieve properly cared for willhave 500 tests. It should, however, be compared from time totime with a master standard or reference sieve. It is recom-mended that an extra sieve be purchased
32、 and preserved as amaster standard against which all sieves in use or subsequentlypurchased can be standardized.NOTE 3Tyler Standard Sieves of 35 and 200 mesh correspond,respectively, to ASTM sieves No. 40 and 200 (U.S. Standard Sieve Seriesnumbers).10.3 ContainerA container suitable for weighing a
33、100-gsample.10.4 DryerSee 4.310.5 Mechanically Operated Sieve ShakerSee 4.4.11. Sample11.1 Select a sample of slip from the mill before unloadingand pass it through a No. 40 sieve before weighing. Discard theC285 102material retained on the sieve. The sample shall consist of 100g of slip for wet-mil
34、led porcelain enamel or 100 g of groundfrit for dry-milled porcelain enamel.12. Procedure12.1 Wet-Milled Porcelain EnamelTransfer the 100-gsample of slip to the No. 200 sieve. Wash the sample throughthe sieve with a stream of gently running water, care beingexercised to prevent splashing or overflow
35、ing of the sieve.Continue washing until the water passing through the sieveappears clear and free from cloudiness. This usually requires atleast 2 min. Dry the sieve with its residue until the residueeasily moves about as a dry powder when the sieve is shaken(Note 4). Shake the sieve in an automatic
36、 shaking and tappingmachine, or by hand, until no further material passes throughthe meshes. This usually requires from 5 to 7 min. Transfer theresidue remaining on the sieve to the balance and weigh to thenearest 0.1 g.NOTE 4It is recommended that, at this point, the residue be trans-ferred to anot
37、her sieve for shaking. The use of a second sieve minimizesthe error caused by the clogging when both washing and shaking areaccomplished with the same sieve.12.2 Dry-Milled Porcelain EnamelPlace the 100-gsample of frit powder in a No. 200 sieve and shake in anautomatic shaking and tapping machine, o
38、r by hand, until nofurther material passes through the meshes (Note 5). Thisusually requires from 5 to 7 min. Transfer the residue remain-ing on the sieve to the balance and weigh to the nearest 0.1 g.NOTE 5The end point is usually taken as the time at which not morethan 0.1 g of material passes thr
39、ough the sieve with 1 min shaking.Alittleexperience will indicate to the operator when the shaking operation iscomplete.13. Calculation and Report13.1 Report the weight in grams of the residue on thescreen as equivalent to weight percentage of the original slip,or frit powder, specimen.14. Precision
40、 and Bias14.1 PrecisionIt is generally accepted within the porce-lain enamel industry that duplicate tests run by the sameoperator in the same laboratory should show a precision of60.5 or less. Failure to duplicate determinations within thislimit indicates the necessity for repetition of the test. T
41、heprecision of duplicate tests is negatively influenced by varia-tions in operator technique, sieve binding and wear, and, whenit is used, the condition of mechanical sieving equipment. It isalso influenced by changing conditions in the test samplewhich occur over time and which result in particle a
42、gglomera-tion due to chemical reactions.14.2 BiasNo justifiable statement on bias can be madesince the true value of sieve analysis cannot be established byan acceptable standard sample.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any
43、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 time by the responsible technical c
44、ommittee 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 will receive careful consideration at
45、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 ASTM International, 100 Barr Harbor Dr
46、ive, 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C285 103
