1、BSI Standards PublicationBS ISO 18591:2015Fine ceramics (advancedceramics, advanced technicalceramics) Determinationof compressive strength ofceramic granulesBS ISO 18591:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 18591:2015.The UK participation in it
2、s preparation was entrusted to TechnicalCommittee RPI/13, Advanced technical ceramics.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its
3、 correctapplication. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 82469 2ICS 81.060.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Str
4、ategy Committee on 31 December 2015.Amendments/correction issued since publicationDate T e x t a f f e c t e dBS ISO 18591:2015 ISO 2015Fine ceramics (advanced ceramics, advanced technical ceramics) Determination of compressive strength of ceramic granulesCramiques fines (cramiques avances, cramique
5、s techniques avances) Dtermination de la force de compression des granules de cramiqueINTERNATIONAL STANDARDISO18591First edition2015-12-01Reference numberISO 18591:2015(E)BS ISO 18591:2015ISO 18591:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in Switzerland
6、All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested
7、 from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 18591:2015ISO 18591:2015(E)Foreword iv1 Scope . 12 No
8、rmative references 13 Principle 14 Symbols and designation . 15 Apparatus . 16 Sampling 27 Procedure. 27.1 Quantity . 27.2 Cleaning of the die and the punches . 27.3 Powder testing conditions 27.4 Lubrication . 37.5 Compaction and ejection 38 Expression of results 48.1 Load-displacement curve. 48.2
9、Pressure-density curve 48.3 Compressive strength of ceramic granules. 49 Test report . 4Bibliography 8 ISO 2015 All rights reserved iiiContents PageBS ISO 18591:2015ISO 18591:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodie
10、s (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations,
11、 governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further ma
12、intenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).At
13、tention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduct
14、ion and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to confor
15、mity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information.The committee responsible for this document is ISO/TC 206, Fine ceramics.iv ISO 2015 All rights reservedBS ISO 18591
16、:2015INTERNATIONAL STANDARD ISO 18591:2015(E)Fine ceramics (advanced ceramics, advanced technical ceramics) Determination of compressive strength of ceramic granules1 ScopeThis International Standard specifies the testing method to determine the compressive strength of ceramic granules, when subject
17、ed to uniaxial compressive loading in a confining die, under specified conditions.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undat
18、ed references, the latest edition of the referenced document (including any amendments) applies.ISO 7500-1, Metallic materials Calibration and verification of static uniaxial testing machines Part 1: Tension/compression testing machines Calibration and verification of the force-measuring systemISO/I
19、EC 17025, General requirements for the competence of testing and calibration laboratories3 PrincipleIn general, a ceramic powder compact is made of ceramic granules. When ceramic granules are compacted uniaxially in a confining die by pressing, first they are rearranged during compaction. However, w
20、hen a pressure higher than the critical pressure is applied to ceramic granules, the deformation and the fracture of granulated powder also occur. The final density of powder compact depends on the compressive strength (critical pressure) of ceramic granules. When ceramic granules are pressed in a d
21、ie by using a universal testing machine (UTM), a load-displacement (or load-strain) curve can be obtained. Load-displacement curve can be converted into pressure-density curve by using the dimensions and density of a powder compact ejected from the die. The compressive strength can be determined fro
22、m the slope change in the pressure-density curve.4 Symbols and designationSymbol Designation UnitpGreen density of powder compact g/cm3m Mass of powder compact gV Volume of powder compact cm3A Area of powder compact cm2h Height of powder compact cml Displacement of powder compact cmlfFinal displacem
23、ent of powder compact cm5 Apparatus5.1 Cylindrical die, which shall be made from a hard material, preferably hardened steel or tungsten carbide. The die for producing cylindrical compacts shall contain two punches and shall be of a floating type ISO 2015 All rights reserved 1BS ISO 18591:2015ISO 185
24、91:2015(E)or of type suspended from a spring. The die shall be capable of making powder compacts with a diameter in the range of 10 mm to 25 mm and a height to diameter ratio between 0,3 and 0,5, as indicated in Figure 1. The upper part of the die shall be preferably designed to avoid damage to the
25、powder compact during ejection due to the spring-back phenomenon. An ejection cone of height about 5 mm, allowing a gentle increase of the diameter at the top of the die of approximately 1 %, as shown in Figure 1, should be used.5.2 Universal Testing Machine (UTM), which can apply pressure at consta
26、nt velocity to the ceramic granules. The accuracy of the test machine shall be in accordance with ISO 7500-1, Grade 1 (accuracy 1 % indicated load). The UTM shall be capable of simultaneously measuring compressive displacement and applied load and recording the load-displacement curve during the mea
27、surement.5.3 Balance, capable of weighing a mass of at least 10 g with a precision of 0,001 g.5.4 Micrometer, or other suitable measuring device for measuring the dimensions of the powder compacts with a precision of 0,01 mm or better.6 Sampling6.1 In general, the ceramic granules should be tested i
28、n the as-received condition. In certain instances, the granules may be dried. If the granules are required to be dried, they should be dried at 110 C 5 C for at least 24 h and cooled to room temperature in a desiccator before the test is performed. If the granules contain organic additives or volati
29、le substances, they should not be dried. During drying, the granule layer shall have a maximum thickness of 5 mm.6.2 Should there be any treatment (e.g. drying) of the ceramic granule before the test, this shall be recorded in the test report.6.3 The test shall be carried out on three different test
30、 portions.7 Procedure7.1 QuantityThe quantity of the test sample shall be chosen to give the required number of powder compacts (see 8.1), with dimensions as specified in 5.1. If necessary, preliminary tests should be made in order to establish the quantity of powder which is needed for fulfilling t
31、his requirement.7.2 Cleaning of the die and the punchesWipe the die cavity and the punches with a soft clean paper towel soaked with an appropriate solvent, such as acetone. Allow the solvent to evaporate.7.3 Powder testing conditions7.3.1 Ceramic granules which do not contain a lubricant shall be c
32、ompacted in either of the following:a) dry die;NOTE Seizure and excessive die wear can occur, particularly at high compaction pressures.b) die with lubricated walls (see 7.4.1);c) dry die, after mixing a lubricant with the powder (see 7.4.2).2 ISO 2015 All rights reservedBS ISO 18591:2015ISO 18591:2
33、015(E)7.3.2 Ceramic granules which contain a lubricant shall be compacted in a dry die.7.4 Lubrication7.4.1 Lubrication of the die walls or of the ceramic granules is likely to modify the compressive strength results. Similarly, depending on the type and the quantity of lubricant added to the cerami
34、c granules, the results of packing and rearrangement can vary within wide ranges. The test report (see Clause 9) shall therefore mention whether or not lubrication had taken place, if the lubrication was carried out on the walls of the die or on the ceramic granules.Use one of the following two meth
35、ods (see 7.4.2 and 7.4.3) if lubrication is applied.7.4.2 In order to lubricate the die wall, apply a mixture or a solution of a lubricant in the volatile organic liquid, for example, 20 g of stearic acid in 980 g of acetone. After any excess liquid has been drained away, allow the solution adhering
36、 to the walls to evaporate leaving a thin layer of lubricant.Alternatively, press inert spheres (polyurethane spheres for instance) coated with lubricant in the die before testing. After removal of the pressed disc of inert material, a thin layer of lubricant remains on the walls of the die.7.4.3 If
37、 the granules are to be tested in a lubricated condition, lubricate the granules to be tested by thoroughly mixing it with a quantity (0,1 wt% to 3,0 wt%) of a suitable solid lubricant (for example, zinc stearate or stearic acid).7.5 Compaction and ejection7.5.1 Insert the lower punch into the die i
38、n order to leave a free volume in the die large enough to contain the bulk powder see Figure 2 a).7.5.2 Pour the granules into the die and level off to a uniform filling height see Figure 2 a).7.5.3 Wipe the wall of the die, to remove any granule that might have adhered to it during the filling of t
39、he die.7.5.4 Insert the upper punch into the die see Figure 2 b).7.5.5 Position the die with its punches between the platens of UTM. Move the position of platens until the upper and lower parts of die meet the platens.7.5.6 Increase the uniaxial compressive loading to the ceramic granules using a co
40、nstant crosshead speed of 1 mm/min and observe the development of the recorded load-displacement curve that shall be recorded.7.5.7 The slope of load-displacement curve decreases (see Figure 3) and becomes approximately constant as the normal compressive load to the ceramic granules increases. Stop
41、the test and remove the compressive load when the slope of load-displacement curve is constant.7.5.8 Remove the lower punch from the die. Invert the die and, using the UTM, push up the upper punch to eject the powder compaction from the die. Compaction and compact removal steps are indicated in Figu
42、re 2.7.5.9 Record the mass (m) and the size diameter and height (h) of the ejected ceramic powder compact. ISO 2015 All rights reserved 3BS ISO 18591:2015ISO 18591:2015(E)8 Expression of results8.1 Load-displacement curveCompaction of ceramic granules using a UTM allows a load-displacement curve to
43、be recorded as shown in Figure 3. From the load-displacement curve shown in Figure 3, the density of the ceramic powder compact shall be calculated according to Formula (1) (for symbols, see Clause 4):pf=+mVmAhll()(1)Express the compaction properties for a given compressive pressures as the average
44、of the density values determined from three independent measurements.8.2 Pressure-density curveThe load-displacement curve recorded during the measurement by the UTM shall be converted into the pressure (= load/area of powder compact) density curve using Formula (1) given in 8.1 (see Figure 4). The
45、x-axis indicating the compressive pressure shall be expressed on a logarithmic scale. The pressure-density curve should show two distinctive regions with different slopes. At low pressure region, the slope should be small while at pressure region above a certain level, the slope should be higher (se
46、e Figure 4).8.3 Compressive strength of ceramic granulesExtend each straight line from the two regions having approximately constant slopes and determine the intercept point. Take this intersection as the compressive strength of the ceramic granules as shown in Figure 4.9 Test reportThe test report
47、shall be in accordance with the reporting provisions of ISO/IEC 17025 and shall contain at least the following information:a) reference to this International Standard, i.e. ISO 18591;b) name of the testing establishments;c) date of the test, report identification and number, operator, signatory;d) t
48、emperature and relative humidity in the laboratory;e) description of the powder (material manufacturer, batch or code number);f) dimensions of the powder compacts;g) type, nature and amount of lubricant and any other organic additives used in the test, including the following:1) lubrication of the d
49、ie walls or no lubrication;2) lubrication of the powder or no lubrication (state how the lubrication has been added);3) other organic additives;h) compacting pressures;i) result obtained including the pressure-density curve;j) comments about the test or test results.4 ISO 2015 All rights reservedBS ISO 18591:2015ISO 18591:2015(E)1216H= 60 - 80a) DieAAA1,63415152,50,011,6g59725g5970,01l2 45R5b) Upper and lower punchKey1 shrink ring2 hard material3 upper punch, l = H - 104 lower punch, l = H + 35Figure 1 Example o
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