1、 Reference number ISO 22215:2006(E) ISO 2006INTERNATIONAL STANDARD ISO 22215 First edition 2006-01-15 Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for tensile creep of monolithic ceramics Cramiques techniques Mthodes dessai pour le fluage en traction des cramiques monol
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5、address given below. ISO 2006 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
6、ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2006 All rights reservedISO 22215:2006(E) ISO 2006 All rights reserved iii Con
7、tents Page Foreword iv 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle. 2 5 Apparatus 2 6 Test specimen . 3 7 Procedures 4 8 Determination of the results 5 9 Test report . 5 Bibliography . 7 ISO 22215:2006(E) iv ISO 2006 All rights reservedForeword ISO (the Internationa
8、l Organization for Standardization) is a worldwide federation of national standards bodies (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 es
9、tablished has the right to be represented on that committee. International organizations, 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 standardi
10、zation. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for vot
11、ing. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention 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 suc
12、h patent rights. ISO 22215 was prepared by Technical Committee ISO/TC 206, Fine ceramics. INTERNATIONAL STANDARD ISO 22215:2006(E) ISO 2006 All rights reserved 1 Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for tensile creep of monolithic ceramics 1 Scope This Internati
13、onal Standard specifies the test method for determining the tensile-creep strain and creep rupture time under uniaxial constant force of monolithic fine ceramics and whisker or particulate-reinforced ceramic composites at high temperatures. This test method may be used for material development, mate
14、rial comparison, quality assurance, characterization and design data generation. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the r
15、eferenced document (including any amendments) applies. ISO 3611, Micrometer callipers for external measurement ISO 4287, Geometrical Product Specifications (GPS) Surface texture: Profile method Terms, definitions and surface texture parameters ISO 7500-2, Metallic materials Verification of static un
16、iaxial testing machines Part 2: Tension creep testing machines Verification of the force applied ISO 9513, Metallic materials Calibration of extensometers used in uniaxial testing ISO 15490:2000, Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for tensile strength of monol
17、ithic ceramics at room temperature 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 applied stress value of tensile force applied to a test specimen divided by the original cross-sectional area of the gauge section 3.2 bending strain component
18、 difference between strain at surface and average of strain measured on diametrically opposed sides and equally distant from the axis 3.3 creep rupture time time required for a test specimen to fracture under constant force as a result of tensile creep ISO 22215:2006(E) 2 ISO 2006 All rights reserve
19、d3.4 creep strain time-dependent fractional increase in the gauge length after applying a uniaxial tensile force NOTE Value of the elongation divided by the gauge length. 3.5 elongation increase of the gauge length at any moment during the test 3.6 gauge section parallel portion having the same cros
20、s-section at the middle of a test specimen whose elongation is used for determining creep strain 3.7 gauge length original length of the gauge section determined at room temperature before the test 3.8 gripped section end section of a test specimen that is held by the gripping device of a tensile-cr
21、eep testing apparatus 3.9 gripping device device to hold a test specimen and to transfer a uniaxial tensile force to a test specimen during the test 3.10 tensile creep time-dependent deformation of a test specimen subjected to a uniaxial tensile force 4 Principle The test consists of applying a cons
22、tant uniaxial tensile force to a test specimen for the purpose of determining the tensile-creep strain and creep rupture time. 5 Apparatus 5.1 Tensile-creep testing machine The testing machine shall be such that the constant force can be applied along the axis of the test specimen without fluctuatio
23、n during a tensile-creep test, while keeping to a minimum the inadvertent bending or torsion of the test specimen. The force shall be applied to the test specimen without shock (see 7.2). It is recommended that the machine be isolated from external vibration and shock. The machine shall be verified
24、and shall meet the requirements of class 1 in ISO 7500-2. 5.2 Heating apparatus A heating furnace provided with a temperature-control device shall be used for heating the specimen. The specimen temperature shall be maintained constant with time at 2 K during a tensile-creep test. The maximum deviati
25、on of the temperature over the gauge section shall be less than or equal to 5 K during a tensile-creep test. ISO 22215:2006(E) ISO 2006 All rights reserved 3 5.3 Temperature measuring apparatus 5.3.1 The temperature readout device shall have a resolution of 1 K or less. 5.3.2 When temperature is mea
26、sured by a thermocouple, the measurement shall be accurate to 5 K, including the error inherent to a thermocouple, and any error in the measuring instruments. After assuring no chemical reactivity between the test material and thermocouple material, the thermocouple junctions shall be placed no more
27、 than 2 mm from the surface of the test specimen and shall be suitably screened from direct radiation from the furnace wall. The remaining portions of the wires within the furnace shall be thermally shielded and electrically insulated by suitable covering. 5.3.3 When a thermometer other than a therm
28、ocouple, such as a pyrometer, is used, it shall have an accuracy equivalent or superior to the above-specified one. 5.4 Gripping devices Various types of gripping devices may be used to ensure that test specimens are held in such a way that the force is applied as axially as possible. NOTE The gripp
29、ing devices that have been used when measuring tensile creep of monolithic ceramics and their advantages/disadvantages are shown in ASTM C1291 3 . 5.5 Elongation measuring device The elongation shall be measured using an extensometer which meets the requirements of at least class 1 in ISO 9513, or b
30、y other means which ensure the same accuracy without interruption of the test. 6 Test specimen 6.1 Shape and dimensions The shape and dimensions of the test specimens depend on several factors, including the purpose of the tensile test itself, the gripping devices and the shape and dimensions of the
31、 ceramic products whose tensile creep is to be determined. Therefore, various shapes and dimensions may be used. The shapes and dimensions, however, shall be determined so that the tensile stress is applied uniformly in the gauge section (see 7.2). Also, care shall be taken so that stress concentrat
32、ions that could lead to undesired fractures are as small as possible. In addition, the cross-section of the gauge section shall be uniform with a dimensional variation smaller than 0,5 %. The test specimens that have been applied to measuring tensile strength of monolithic ceramics are shown in ISO
33、15490:2000, Annex A. 6.2 Test specimen preparation Surface finishes in the gauge section of the order of average roughness 0,2 mRa to 0,4 mRa, as defined in ISO 4287 (measured in the longitudinal direction) are recommended in order to avoid surface roughness- related fracture. It is highly recommend
34、ed that the final grinding operation in the gauge section be performed along the longitudinal direction of the test specimen in order to ensure that grinding marks are parallel to the applied tensile stress. Care shall be taken in the storage and handling of finished test specimens to avoid the intr
35、oduction of random and severe flaws. NOTE In some cases, the final surface finish may not be as important as the subsurface damage produced during the grinding process. This damage is not readily observed or measured. ISO 22215:2006(E) 4 ISO 2006 All rights reserved7 Procedures 7.1 Test specimen dim
36、ensions The diameter or thickness and width of the gauge section of each test specimen shall be determined to within 0,02 mm beforehand, by using the micrometer in accordance with ISO 3611, or by using equipment that is equivalent or superior. Measurements on at least three different cross-sections
37、in the gauge section shall be made. The average of the multiple measurements shall be used in calculating the cross-sectional area. The length of the gauge section shall be determined by points of attachment of the extensometer. 7.2 Axial alignment The testing system shall be verified using the foll
38、owing procedures at room temperature before the test. On a “dummy” test specimen that has exactly the same shape as that of a test specimen to be tested, three or four strain gauges shall be equally spaced around the circumferences on two cross-sectional planes. The strain-gauge planes shall be symm
39、etrically located about the longitudinal midpoint of the gauge section, and shall be separated by at least 3/4 of the length of the gauge section. Care shall be taken to avoid placing the strain gauges too near geometric transitions in the gauge section, which can cause strain concentration and inac
40、curate measurements of the strain in the uniform gauge section. When the gauge section is not long enough to have two strain-gauge planes, one plane may be used. In this case, the location shall be the longitudinal midpoint of the gauge section. When axial strain gauges are mounted, the gauge axis s
41、hall be aligned with the stress axis so that the deviation is less than 0,035 rad (2). Mount the “dummy” specimen in the gripping device and apply a force so as to give one-half of the stress to be applied in the test. Evaluate the bending strain components using the following equation. The bending
42、strain components verified hereby shall not exceed five. 1/ 2 22 13 24 1234 ()() 2 100 B + = +for four gauges and 222 1 / 2 1232 12 33 1 123 () 21 0 0 B + = +for three gauges, where B is the bending strain component, and 1 , 2 , 3and 4are strain readings for strain gauges. NOTE It is preferable that
43、 the “dummy” specimen be of the same material as that to be tested. 7.3 Heating procedure A specimen shall be heated to a test temperature at such a rate that the specimen and gripping device are free from thermal shock fractures, and shall be soaked to obtain a thermal equilibrium before the test s
44、tarts. Regardless of whether a furnace/test specimen are heated from room temperature to the test temperature, or a test specimen is inserted into a furnace already at the test temperature, the soak time for the entire system to reach equilibrium shall be determined experimentally. The final tempera
45、ture adjustment shall be conducted during this time. 7.4 Loading procedure An initial force, which is the minimum one required for maintaining the axial alignment, may be applied to a specimen while heating the specimen. The initial force shall be less than 10 % of the test force. After soaking the
46、specimen at the test temperature, the force shall be applied along the test axis in such a manner as to minimize bending and torsion of the test specimen, without shock. ISO 22215:2006(E) ISO 2006 All rights reserved 5 7.5 Recording of temperature and of elongation Throughout the test, it is importa
47、nt that sufficient readings be taken of the temperature of the test specimen, in order to demonstrate that the temperature conditions comply with the requirements of 5.3. Either a continuous record or a sufficient number of readings of the elongation shall be made throughout the test so that the cre
48、ep-time curve can be traced. 8 Determination of the results The test results are determined from the preceding readings using the definitions given in Clause 3. 9 Test report 9.1 The following items shall be reported: a) material of a specimen; b) geometry and dimensions of a specimen; c) surface ro
49、ughness of a gauge section; d) test condition: 1) test temperature, and its reading intervals, 2) heating rate and soak time, 3) applied stress, 4) atmosphere; e) test results: 1) time-strain curve, 2) time-strain rate relation, 3) rupture time, fracture strain, and fracture location, when the test was conducted until fracture. 9.2 The following items shall preferably be appended: a) specimen: 1) manufacturer, 2) product type or code, 3) chemical composition, 4) ma
