1、NF EN 993-11avril 2008Ce document est usage exclusif et non collectif des clients Saga Web.Toute mise en rseau, reproduction et rediffusion, sous quelque forme que ce soit,mme partielle, sont strictement interdites.This document is intended for the exclusive and non collective use of Saga Web custom
2、ers.All network exploitation, reproduction and re-dissemination,even partial, whatever the form (hardcopy or other media), is strictly prohibited.Saga Web Pour SHANGHAI INTERNAT SCIENCE heating/cooling conditions; material properties. Thermal shock tests are usually intended to test material propert
3、ies. This is done by standardizing brick dimensions and heating conditions through which a relative order of the quality of different types of bricks can be established. However, in case of thermal shock, this can lead to complications in the field of engineering. The major complication is that, dep
4、ending on the type of heating conditions, various material properties are involved. This can be best illustrated on the basis of thermal stress parameters, which are a measure for critical crack initiation. Table 1 Type of heating condition Hot face condition Stress parameter Example sudden temperat
5、ure jump / filling of metallurgical vessels constant heat flow into brick . / Furnace preheating constant heating rate /( . cp ) . / Controlled preheating where maximum allowable deformation; coefficient of expansion; thermal conductivity; bulk density;cp specific heat. EN 993-11:2007 (E) 61 Scope T
6、his European Standard describes two alternative methods for determining the resistance to thermal shock of dense shaped refractory materials by an air quenching method, which proved to give the most reliable results when compared with the behaviour of refractories in furnace linings. Method B can al
7、so be applied to unshaped refractory materials. 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 referenced document (including any
8、 amendments) applies. EN 993-6, 6Methods of test for dense shaped refractory products - Part : Determination of modulus of rupture at ambient temperature 3 Terms and definitions For the purposes of this European Standard, the following terms and definitions apply. 3.1thermal-shock resistance resista
9、nce of refractory shapes to damage caused by sudden temperature changes between 950 C and room temperature caused by air blowing 3.2measure of thermal-shock resistance for method A the number of quench cycles withstood under the test conditions, and for method B the residual cold modulus of rupture
10、(MOR) and residual sonic velocity after 5 quench cycles under the conditions of the test 4 Principle 4.1 Method A The test piece is homogeneously heated to 950 C in an electric furnace then removed, placed on a steel plate and exposed to blowing air. After quenching, the test piece is subjected to a
11、 stress of 0,3 MPa in a bending machine. This cycle is repeated until failure of the test piece occurs. The resistance to thermal shock is defined by the number of cycles withstood by the test piece before breaking. 4.2 Method B The test piece is homogeneously heated to 950 C in an electric furnace
12、then removed, placed on a steel plate and exposed to blowing air. After quenching this is repeated 4 times. After cooling down, the residual cold MOR and the residual sonic velocity are determined. The resistance to thermal shock is defined by the percentage residual MOR and residual sonic velocity
13、related to the MOR and sonic velocity of non-quenched test pieces. EN 993-11:2007 (E) 7NOTE Sonic resonance frequency can also be measured but can give different results. For both method A and method B, other quenching temperatures may be agreed upon by the parties concerned and shall be noted in th
14、e test report. 5 Apparatus 5.1 Electrically heated furnace, capable of maintaining a temperature of 950 C 25 C.5.2 Thermocouple, for use at temperatures in excess of 1 000 C.5.3 Drying oven.5.4 Heating cabinet, for preheating at 250 C to 300 C.5.5 Blowing device, with a 8 mm diameter nozzle of 5 mm
15、length. 5.6 Equipment for measuring the cold MOR in accordance with EN 993-6. 5.7 Steel plate, 400 mm x 250 mm x 20 mm, with pins to locate the test piece under the air-blast; depending on the dimensions of the test-piece, the pins are located in such a manner that the air jet blows at the intersect
16、ion of the diagonals of the test-piece on cooling. 5.8 Equipment for measuring the sonic velocity NOTE Equipment for measuring the sonic velocity in refractories is commercially available and should be used in accordance with the manufacturers instructions. 5.9 Insulated iron tongs for handling the
17、test piece after heating 6 Test pieces 6.1 Number of test pieces 6.1.1 Method A Unless a different number of test pieces has been agreed upon, one test piece shall be taken from each item. 6.1.2 Method B Unless a different number of test pieces has been agreed upon, four test pieces shall be used. T
18、wo test pieces are used for the determination of the cold MOR before testing, MORn. The other two test pieces are used for the thermal shock test. For all four test pieces, determine the sonic velocity, SVn, axially in length of the test pieces before testing. 6.2 Preparation of test pieces 6.2.1 Sh
19、ape For method A the test pieces shall have the dimensions of a quarter-standard brick, i.e. 114 mm x 64 mm x 64 mm. For method B the test pieces shall have the dimensions of a half-standard brick, i.e. 230 mm x 64 mm x 54 mm. EN 993-11:2007 (E) 8They shall be sawn or ground from bricks.NOTE The use
20、 of other shapes may be agreed by the parties, but the results will not be directly comparable with those obtained using the test pieces stated above. The test pieces shall be prepared with care so that the brick texture is not damaged. The location within the bricks from which the test pieces are t
21、o be taken shall be agreed upon. 6.2.2 Drying of the test pieces Dry the test pieces at 110 C 5 C to constant mass. Constant mass is obtained when the change in mass after two successive periods of 1 h drying, is not more than 0,1 %. Protect the test pieces from moisture before testing. 7 Procedure
22、7.1 Heating 7.1.1 Place the test pieces on one of their long faces, i.e. for method B on a 230 mm x 64 mm face, into a heating cabinet pre-heated to 250 C and 300 C and keep them at this temperature for at least 4 h. 7.1.2 Put the test pieces into the furnace at 950 C 25 C. The temperature of the fu
23、rnace is measured with a thermocouple positioned over the centre of the basal area of the furnace approximately 20 mm above the test pieces. Immediately after the door of the furnace has been closed, the temperature should not be less than 750 C. Keep the samples in the furnace until they are evenly
24、 heated. 7.2 Cooling Remove a test piece as quickly as possible from the furnace using insulated iron tongs and place its long face on the steel plate, taking care that the nozzle of the air-blowing device and the centre of the upper face are aligned, with the help of the locating pins. The distance
25、 between the nozzle and the test piece shall be 100 mm. Blow compressed air on the test piece for five minutes, ensuring that the pressure immediately before the nozzle is constant and equal to 0,1 MPa 0,01 MPa. Be sure that the compressed air is at room temperature and does not contain moisture lik
26、ely to concentrate in droplets. Always expose the same face of the test piece to the blast. NOTE If conditions remain in accordance with 7.1 and 7.2, more than one test-piece can be simultaneously or successively tested. Should it be necessary to interrupt the test, the test pieces shall be maintain
27、ed in the heating cabinet at 250 C to 300 C after the last quenching. When testing is resumed, the test pieces shall be placed immediately in the furnace at 950 C 25 C. 7.3 Measurement 7.3.1 Method A 7.3.1.1 After quenching, the test piece is submitted to a bending strength of 0,3 MPa 0,05 MPa gradu
28、ally and without shock. 7.3.1.2 The distance between supports shall be 100 mm. The thrust column and the supports shall have a radius of 5 mm. NOTE If the test piece breaks, the test is completed. EN 993-11:2007 (E) 97.3.1.3 If the test piece withstands the bending stress, place it again into the fu
29、rnace at 950 C and start the same cycle. Continue the test until the test piece breaks in the bending test or breaks up into two or more pieces under the cooling blast. The test shall be ended when the test piece has withstood 30 quenchings. 7.3.2 Method B 7.3.2.1 General After 5 quenchings, the fol
30、lowing measurements and determinations have to be applied: 7.3.2.2 After cooling down to ambient temperature, again measure the sonic velocity, SVquenched.NOTE It can be interesting to study the behaviour of the sonic velocity in function of cycles. In this case the test pieces are cooled down to am
31、bient temperatures after each cycle before the measurements. 7.3.2.3 The determination of the cold MOR, MORquenched, has to be made so that the blown face is now the bottom face during the test. 8 Expression of results 8.1 Method A Express the resistance to thermal shock of the product as the number
32、 of quenching cycles withstood by the test piece before failure. 8.2 Method B Express the resistance to thermal shock of the product as the % residual MOR, MORresidual, and % residual Sonic Velocity, SVresidual, using the equations: x100quenchednonquenchedresidual MORMORMOR(1) x100quenchednonquenche
33、dresidual SVSVSV(2) 9 Test report The test report shall include the following information: a) all information necessary for identification of the sample tested, including the designation of the material tested, manufacturer, type and batch number;b) reference to this European Standard, including its
34、 date of publication, i.e. determined in accordance with EN 993-11:2007; c) method used, A or B, including details of: i) number of items tested and the number of test pieces per item; ii) description of the location where the test piece is taken from in the item; and the direction in which the test
35、 pieces are taken, with drawings, if necessary; EN 993-11:2007 (E) 10iii) dimensions of the test pieces; iv) test temperature in cases if or than 950 C; d) result, expressed in accordance with Clause 8: for method A : individual value and, if applicable, mean value of individual values per item; for
36、 method B : mean value of the residual MOR and residual sonic velocity; e) name of the testing establishment; f) any deviations from the procedure; g) any unusual features observed; h) date of the test. EN 993-11:2007 (E) 11Bibliography 1 EN 1402-5, Unshaped refractory products - Part 5: Preparation and treatment of test pieces 2 EN 1402-8, Unshaped refractory products - Part 8: Determination of complementary properties
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