1、INTERNATIONAL STANDARD ISO 20509 First edition 2003-12-01 Reference number ISO 20509:2003(E) ISO 2003 Fine ceramics (advanced ceramics, advanced technical ceramics) Determination of oxidation resistance of non-oxide monolithic ceramics Cramiques techniques Dtermination de la rsistance loxydation des
2、 cramiques monolithiquesISO 20509:2003(E) ii ISO 2003 All rights reserved PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and in
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7、eserved iii Contents Page 1 Scope 1 2 Normative references 1 3 Terms and definitions 1 4 Apparatus . 2 5 Test pieces . 3 6 Test procedure . 3 7 Calculations . 5 8 Test report 7 Annex A (informative) Useful information 8 Annex B (informative) Interlaboratory evaluation of the test method . 9 Bibliogr
8、aphy . 11ISO 20509:2003(E) iv ISO 2003 All rights reserved Foreword ISO (the International 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 committ
9、ees. 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, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the Int
10、ernational Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. 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
11、Standards adopted by the technical committees are circulated to the member bodies for voting. 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 s
12、ubject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 20509 was prepared by Technical Committee ISO/TC 206, Fine ceramics.INTERNATIONAL STANDARD ISO 20509:2003(E) ISO 2003 All rights reserved 1 Fine ceramics (advanced ceramics, advanced technic
13、al ceramics) Determination of oxidation resistance of non-oxide monolithic ceramics 1S c o p e This International Standard describes the method of test for determining the oxidation resistance of non-oxide monolithic ceramics, such as silicon nitride, Sialon 1)and silicon carbide at high temperature
14、s. This International Standard is intended to provide an assessment of the mass and dimensional changes of test pieces following oxidation at high temperature in an oxidizing atmosphere, and to assess whether oxidation has a significant effect on the subsequent strength. This test method may be used
15、 for materials development, quality control, characterization, and design data generation purposes. 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 late
16、st edition of the referenced document (including any amendments) applies. ISO 3611:1978, Micrometer callipers for external measurement ISO 6906:1984, Vernier callipers reading to 0,02 mm ISO 7500-1: 2) , Metallic materials Verification of static uniaxial testing machines Part1: Tension/compression t
17、esting machines Verification and calibration of the force-measuring system ISO 14704:2000, Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for flexural strength of monolithic ceramics at room temperature IEC 60584-1:1995, Thermocouples Part 1: Reference tables IEC 60584-2:
18、1989, Thermocouples Part 2: Tolerances 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 oxidation resistance resistance against oxidation of a non-oxide ceramic material due to reaction with oxygen in the surrounding atmosphere, including any
19、internal reactions as a result of the presence of open porosity or of diffusion of ions to or from the ceramic surface 3.2 flexural strength maximum nominal stress at fracture of a specified elastic beam loaded in bending 1) Sometimes written SiAlON is the acronym for a ceramic that contains silicon
20、, aluminium, oxygen and nitrogen. 2) To be published. (Revision of ISO 7500-1:1999)ISO 20509:2003(E) 2 ISO 2003 All rights reserved 4 Apparatus 4.1 High temperature furnace, e.g. any suitable air atmosphere furnace with a nominal temperature capability of at least . The furnace chamber shall have an
21、 inlet for a sufficient supply of oxidation gas to ensure that the atmosphere does not stagnate and become oxygen deficient. The temperature shall be capable of being raised to that required for testing at a minimum of , of being controlled to better than at all oxidation temperatures, and of being
22、cooled at more than to below . Before commencing oxidation tests, the furnace chamber shall be baked out using the same atmosphere as proposed for testing and at a temperature at least as high as the intended oxidation test temperature for a period of at least in order to remove contaminants. 4.2 Su
23、pport or supporting stand, for oxidation tests. The test pieces shall be supported using techniques that minimize contact area, degree of adhesion and extent of reaction with the test piece (see Figure 1). Preferably this should be done using point or line contact only. Any contact of the supports w
24、ith the regions of the test piece surfaces to be subjected later to loading roller contact in flexural strength testing shall be avoided. Examples of suitable support methods include the use of a block with drilled holes no more than deep such that the test pieces can stand near vertically with a mi
25、nimum of end and edge contact. The samples can also be situated on horizontal supports on rollers of silicon carbide or mullite, on small diameter platinum wires, either suspended or resting on a clean non-reactive ceramic surface, or on semi-rings which can be cut from ceramic tubes (alumina, mulli
26、te, silicon carbide, or silicon nitride). NOTE 1 It may be necessary to perform some preliminary assessments to ensure that the supporting material is sufficiently non-reactive as to not significantly contribute to the mass changes in the sample. NOTE 2 Candidate materials for supporting test pieces
27、 include silicon carbide, mullite, platinum wire and alumina. Silicon carbide and mullite may be the most suitable materials. Alumina may react with test pieces, and platinum is inappropriate for non-oxide ceramics containing free metallic species, such as silicon carbide containing silicon. 4.3 Ove
28、n, capable of maintaining a temperature of to . 4.4 Testing machine for flexural strength, capable of applying a uniform crosshead speed. The testing machine shall be in accordance with ISO 7500-1: Class 1 with an accuracy of of indicated load at fracture. a) b) c) d) a) a refractory block with appr
29、opriate-sized holes in it, suitable for muffle furnace; b) a support system based on tubes and discs with holes, suitable for vertical tube furnace; c) a pair of supported parallel rods spaced near the ends of the test-pieces and with an adequate gap underneath, suitable for a muffle furnace; d) a t
30、est-piece supported by its ends on a ceramic semi-ring. Figure 1 Examples of support systems for flexural strength test pieces 1 500 C 5 C min 1 5 C 5 C min 1 800 C 10 h 3mm 105 C 120 C 1%ISO 20509:2003(E) ISO 2003 All rights reserved 3 4.5 Testing fixture for flexural strength, of three- or four-po
31、int flexure configuration in accordance with 5.2 of ISO 14704:2000. The recommended fixture is fully articulated and of the four-point-1/4 point configuration with the two outer bearings at a distance of . The corresponding total length of test piece is . 4.6 Micrometer, such as shown in ISO 3611:19
32、78 but with a resolution of for measuring the test piece dimensions. The micrometer shall have flat anvil faces such as shown in ISO 3611:1978. The micrometer shall not have a ball tip or sharp tip since these might damage the test piece. Alternative dimension measuring instruments may be used provi
33、ded that they have a resolution of or finer. 4.7 Vernier calliper, with a resolution of or finer for measuring the length of the test piece, in accordance with ISO 6906. Alternative dimension measuring instruments may be used provided that they have a resolution of or finer. 4.8 Balance, capable of
34、weighing up to with a sensitivity of at least . 4.9 Thermocouple, of type R or type S in accordance with IEC 60584-2, permitting the use of the calibration table given in IEC 60584-1. 5 Test pieces If the strength changes are to be determined, flexural strength test pieces in accordance with Clause
35、6 of ISO14704:2000 shall be used. The standard test specimens shall have cross-sectional dimensions ofthickness and width. The length shall be more than fortest fixtures or more than for test fixtures. All the surfaces shall be machined, and edges shall be rounded or chamfered. Any machining procedu
36、re and the surface quality of the test pieces shall be reported. The minimum number of test pieces shall be 10 for each oxidation condition to be tested, plus 10 test pieces as an unoxidized control. Means shall be taken to identify individually, similar test pieces, but shall not be marked or scrib
37、ed in a way that might affect the result of the test. If strength changes are not to be determined, any test piece, in terms of size and shape, may be used. Test pieces shall be clean and free from preparation residues and contamination due to handling which can influence the initial mass measuremen
38、t and/or the oxidation rate. The test-piece cleaning procedure shall be stated in the report. For materials with no significant open porosity and contaminated by handling, and/or by mounting or machining coolant residues, submerge the test-pieces in ethanol in an ultrasonic bath and agitate for at l
39、east . In order to avoid damage, test pieces shall not be allowed to contact either each other or a hard surface during this operation. For materials containing open porosity, internally entrained organic residues can be removed only by heating in air. The maximum temperature to which this should be
40、 done will depend on the material type, but typically a temperature of to for a least is required to oxidize carbonaceous residues. Material with intentionally present free carbon shall be treated at a maximum temperature of to avoid oxidation. 6 Test procedure 6.1 Measurements of dimensions and mas
41、s of specimens For flexural strength test pieces, measure the width, , and thickness, , of each test piece at several places using the micrometer (4.5) with a resolution of . Measure the overall length, , with the vernier callipers (4.6) with a resolution of . For other shapes of test piece, measure
42、 relevant dimensions at several different places (e.g. diameter and thickness of a disc). Wash and degrease the test pieces (see Clause 5). Place in the oven (4.3) and heat to a temperature of to until their mass is constant. Remove and store in a desiccator. When cooled to room temperature, weigh e
43、ach test piece to the nearestusing the balance (4.7). Store in the desiccator until tested. 40 mm 45 mm 0,002 mm 0,002 mm 0,05 mm 0,05 mm 200 g 0,05 mg 3,00 mm 0,20 mm 4,00 mm 0,20 mm 35 mm 30 mm 45 mm 40 mm 10 min 500 C 600 C1 h 350 C bh 0,002 mm L T 0,05 mm 105 C 120 C 0,05 mgISO 20509:2003(E) 4 I
44、SO 2003 All rights reserved 6.2 Baking out in the oxidation furnace Unless used for a similar measurement immediately prior to the test, pre-condition the furnace (4.1) and the test piece support system (4.2) at a temperature similar to or greater than that intended for the oxidation test under the
45、intended flowing gas atmosphere. The maximum temperature shall be maintained for at least . 6.3 Oxidation test 6.3.1 Materials with high oxidation resistance 6.3.1.1 Place the test pieces on their supports (4.2) in the centre of the hot zone of the furnace (4.1) ensuring sufficient space between tes
46、t pieces and their supports for adequate circulation of air. Ensure that contact with supports is minimized (see Figure 1). The contacts shall always be at locations outside the outer span used for the flexural test. The minimum spacing between test pieces as well as that between a test piece and fu
47、rnace furniture shall be . NOTE 1 It is preferred that each batch of a least 10 test pieces per oxidation condition is exposed at the same time in the same facility. Separated exposure at separate times may result in slightly different results. NOTE 2 The minimum spacing between components or test-p
48、ieces under test should be increased with increasing component or test-piece size to ensure unimpeded gas flow between neighbouring oxidizing surfaces. 6.3.1.2 Position a type R or type S thermocouple (4.8) in accordance with IEC 60584-2 adjacent to the test pieces for the purposes of monitoring tes
49、t piece temperature during the oxidation period. Close the furnace. 6.3.1.3 Supply the oxidizing gas at a rate sufficient to provide atmosphere circulation within the furnace cavity and around the test pieces such that stagnation and oxygen depletion is avoided, but not at such a rate that results in inhomogeneous or fluctuating furnace temperature. For testing in normal air, a natural flow of the air through the furnace cavity shall be facilitated. Note that a gas flow rate is recommended of b
