1、Designation: C368 88 (Reapproved 2016)Standard Test Method forImpact Resistance of Ceramic Tableware1This standard is issued under the fixed designation C368; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. 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 following tests:1.1.1 Impact tests at the center of both flatware and hollowware and at the rim of hol
3、low ware, and1.1.2 Chipping tests at the rim of flatware. Specimens maybe either glazed or unglazed.NOTE 1The impact test at the center of the specimen is used todetermine: (1) the magnitude of a blow that will produce initial fracture,and (2) the amount of energy necessary to produce complete failu
4、re. In thefirst case, the initial fracture shows on the side of the piece opposite fromthat being struck and appears to be a function of the square of thethickness and of the inherent brittleness of the body or body-glazecombination; it is relatively independent of the size or design of thespecimen.
5、 The second factor is more dependent upon design and often issubject to wide variation within a given group of pieces.NOTE 2The impact test at the rim of hollow ware is similar to achipping test, and the type of failure that is obtained is useful in evaluatingthe effect of the shape of the object.NO
6、TE 3In addition to the inherent strength of the body, chipping testresults are greatly affected by contour of rim and to a lesser extent bythickness of rim, inclination of leaf, and fit of glaze.1.2 The values stated in inch-pound units are to be regardedas the standard. The SI (metric) units given
7、in parentheses arefor information purposes only.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 reg
8、ulatory limitations prior to use.2. Referenced Documents2.1 ASTM Adjuncts:2ADJC0368 Machine for Testing Chinaware3. Significance and Use3.1 The purpose of this test method is to predict productresistance to impact breakage in service.4. Apparatus4.1 Impact Tester, Pendulum TypeThe impact test appara
9、-tus (Figs. 1 and 2)2shall consist of a device having thefollowing essential features:4.1.1 A steel tup of specified size and of hardness RockwellC55,4.1.2 Support of a tup by a V-suspension,4.1.3 Provision for a means of release from fixed heights soas to give reproducible results, independent of t
10、he operator, and4.1.4 Provision for holding the test specimen in place byspring clamps against rigid metal supports.4.2 MicrometerFor measuring thickness of testspecimens, a micrometer caliper that can be read to 0.001 in.(0.03 mm) shall be used.5. Test Specimens5.1 Specimens shall be selected so as
11、 to be representative ofthe lot being sampled. In general, impact tests shall be based ona minimum of ten specimens and chipping tests on at least fivespecimens. Specimens shall be inspected for soundness andobvious physical defects before testing.6. Procedure for Impact Testing of Flatware6.1 Mount
12、 the cylindrical tube shown in Fig. 2 (Note 4)onthe backstop, C , Fig. 1, and set at a height such that the threeball bearings mounted in the end of the cylindrical tube are incontact and symmetrical with the central portion of thespecimen, which shall be stood on edge on the base plate. Thespecimen
13、 may be tested with either the face or the back towardthe hammer; in general, a lower failure value is obtained whenthe face is struck. Adjust the backstop so that the sphericalsurface of the tup, D, just touches the surface of the specimenwhen the tup is hanging free (vertically). Tighten the two w
14、ingnuts at the base of the backstop.NOTE 4In this portion of the test, the cylindrical tube replaces theangle clamp, E, shown in position on the backstop, C,inFig. 1.6.2 Adjust the positioning arms, F, held in retracted positionby means of their cotter keys so that the forward edges of thesleeve and
15、 of the clamp coincide. Adjust the clamps on thevertical posts to grip the specimen at the same height that thependulum will strike it; that is, halfway up. Adjust the arms sothat the rubber-covered surface at right angles to its rod willcontact the rim of the sample; remove the cotter keys to permi
16、t1This test method is under the jurisdiction ofASTM Committee C21 on CeramicWhitewares and Related Products and 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 19
17、55. Last previous edition approved in 2011 as C368 88 (2011). DOI:10.1520/C0368-88R16.2Detailed working drawings of the apparatus are available from ASTMHeadquarters. Request Adjunct No. ADJC0368.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Unit
18、ed States1the positioning arms to hold the specimen against the cylindri-cal tube. Adjust the pendulum support bar, B, and lock it inposition by means of the handwheels, A, so that the tup strikesthe center of the specimen.6.3 With the preliminary adjustments completed, subject thespecimen to a sche
19、dule of impacts starting at 0.02 ftlbf (0.027J) and increasing in increments of 0.01 ftlbf (0.014 J) untilinitial fracture, and in increments of 0.02 ftlbf thereafter tofailure.NOTE 5The tests may be performed rapidly by grasping the portion ofthe releasing device that lies below the dial segment fr
20、om beneath with thetip of the middle finger of the right hand and moving it back to the correctnotch for the next blow immediately after the tup has been released. CatchFIG. 1 Impact Test ApparatusFIG. 2 Tube to Support Flatware SpecimenC368 88 (2016)2the pendulum on the rebound with the left hand,
21、reseat the tip of the tupinto the jaws of the releasing clamp controlled by the thumb of the righthand, and repeat the above sequence of operations until failure of thespecimen occurs.7. Procedure for Impact Testing of Hollow Ware atCenter7.1 Follow the same procedure as described for flatware inSec
22、tion 6, except remove the cylindrical tube (Fig. 2) and thetwo triangular castings, G, forming the V to permit the rim ofthe specimen to be in contact with the surface of the backstop.Strike specimens at the center of the back, and allow thepositioning arms to contact the specimen at the foot rather
23、 thanat the rim.8. Procedure for Impact Testing of Hollow Ware at Rim8.1 Place the test specimen in the apparatus so that it rests inthe V formed by the two triangular prisms bolted to thebackstop and is held by means of the angle clamp, E, restinglightly on the rim and by the two positioning arms a
24、djusted sothat their lines of pressure are exerted radially and also so thatthey exert no appreciable downward pressure on the rim. Withtups, the handle should be kept out of contact with theapparatus. Adust the backstop so that the eventual point ofcontact on the rim is in the same vertical plane a
25、s the sphericalstriking surface of the tup; tighten the wingnuts.8.2 Adjust the height of the pendulum support bar so thatthe contact between the rim of the specimen and the end of thetup is at the center of the spherical surface of the tup.8.3 With the preliminary adjustments completed, subject the
26、specimen to a series of impacts starting at 0.02 ftlbf (0.027 J)and increasing in increments of 0.01 ftlbf (0.014 J). A straightcrack or a symmetrical bow crack will ordinarily result if thistest is performed properly.9. Procedure for Chipping Test39.1 Place the test specimen in the apparatus as des
27、cribed in8.1, except use the cylindrical end of the tup as the strikingsurface and move the sleeves of the positioning arms forwardin their clamps so that the back edges of each sleeve and itsclamp coincide.9.2 Adjust the pendulum support bar and lock it in positionby means of the handwheels so that
28、 the center of the tupsurface contacts the edge of the specimen.9.2.1 Repeatedly strike rolled-edge specimens on the edgewith the cylindrical end of the hammer with blows of increas-ing force until failure occurs, beginning with an initial blow of0.10 ftlbf (0.136 J) and increasing the force of each
29、 succeedingblow in the increments of 0.02 ftlbf (0.027 J).9.2.2 Test plain-edge specimens as described in 9.2.1, ex-cept that the initial blow shall be 0.02 ftlbf (0.027 J) with anincrement of 0.01 ftlbf (0.014 J).10. Calculation10.1 Calculate the strength factor for flatware tested forimpact, as fo
30、llows:S 5 12I/t2(1)where:S = strength factor, psi;I = average impact to produce initial fracture, ftlbf; andt = average thickness of specimens at point of impact, in.11. Report11.1 Report the following information:11.1.1 Designation of the material tested, including infor-mation on type, shape, and
31、whether glazed or unglazed,11.1.2 Method of selection of specimens,11.1.3 Identification of type of apparatus used, and11.1.4 Data sheet showing:11.1.4.1 Form and essential dimensions of a representativetest specimen,11.1.4.2 Test schedule used, that is, initial impact energyand subsequent increment
32、s,11.1.4.3 Individual and average impact energies to produceinitial fracture,11.1.4.4 Thicknesses of specimens at points of impact andan average thereof,11.1.4.5 For flatware, strength factor calculated from aver-age impact energies and thicknesses of specimens (Section 10),11.1.4.6 Individual and a
33、verage impact energies to producefailure and descriptions of types of failure,11.1.4.7 Chipping failure values and type of chip from eachlocation of each specimen and average of all failure values, and11.1.4.8 Representative rim thickness.11.2 The report may also include:11.2.1 Brief statement of ob
34、served differences, if any,among specimens of unusual characteristics.11.2.2 Inspectors opinion as to whether ware has passed orfailed in respective tests.12. Precision and Bias12.1 No justifiable statements can be made either on theprecision or bias of this test method since the test result merelys
35、tates whether there is conformance to the criteria for accep-tance specified in this test method.13. Keywords13.1 ceramic tableware; impact resistance3See Federal Specification M-C.-301, China Tableware, available from Stan-dardization Documents Order Desk, Bldg. 4 Section D, 700 Robbins Ave.,Philad
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39、u 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
40、 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 Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 88 (2016)4
