ISO-9385-1990.pdf
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1、INTERNATIONAL STANDARD IS0 9385 First edition 1990-05-01 ,ANSI Ynternat DOC SEW Glass and glass-ceramics - Knoop hardness test Verres et vifroc and the projected area np of the permanent indentation given by numerical value equation (1): HK = 0,102 -$ P = 0,102 cotxtan-2-) 130” 0,102F = 14,229 x d2
2、. where E is the test force, in newtons; AP is the projected area, in square millime- tres, of the permanent indentation; d is the length, in millimetres, of the long indentation diagonal. NOTE 1 The factor 0,102 in numerical value equation (1) became necessary through the introduction of the SI-uni
3、t newton for the test force instead of kilogram-force to avoid changing of the value of the Knoop hardness num- ber. This indentation is regarded as a straight pyramid 490 HK 0,1/20 means the Knoop hardness num- with a base area as shown in figure 1, a long inden- ber 490 HK resulting from an applie
4、d test force tation diagonal d and identical transverse area an- of 0,980 7 N (x 0,102 equals 0,l). This test force gles to those of the indenter (see figure 2). was applied for 20 s. Figure 1 - Base area of the indentation produced by the Knoop indenter 172,S“ 130 Figure 2 - Knoop indenter The symb
5、ol HK is supplemented: a) by a number indicating the test force used, ex- pressed in newtons multiplied by 0,102 and therefore equal to the test force expressed in kilogram-force, and b) by a number indicating the duration of test force application in seconds. EXAMPLE Copyright International Organiz
6、ation for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 04:35:21 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 9385:1990(E) 3 Principle The Knoop indenter is forced vertically into the
7、sur- face of a test specimen of glass or glass-ceramics by different test forces for 20 s. Within a 6 min period after removal of the indenter, the length of the long indentation diagonals, left in the surface, are meas- ured using a microscope. 4 Apparatus 4.1 Hardness tester The hardness tester sh
8、all meet the following re- quirements: 4 b) 4 4 4 the relative error of the test force shall be not greater than 1 %; the design of the loading device shall be such that the indenter is vertically lowered, free from stress and vibration, on to the surface of the test specimen at a rate of (0,20 + 0,
9、05) mm/min; the length of the long indentation diagonal shall be measurable with an uncertainty less than 0,5 v-v the microscope measurement shall be carried out with the effective+Onumeric aperture of the objective used of 0,7 , ; the light used for the measurement shall be yellow-green. NOTE 2 The
10、 effective numerical aperture probably dif- fers with the data on the objective. It is recommended to inquire about this from the manufacturer of the hardness tester. 4.2 Knoop indenter The Knoop indenter consists of a diamond-tipped right pyramid with a rhomboid base as shown in figure 2, whose axi
11、s is coincident with the axis of the test force. The Knoop indenter shall be of a shape so that the factor 0,5 cot y x tan y) = 70,28 x lop3 in numerical value equation (1) has a deviation no greater than 1 %. The faces and edges of the Knoop indenter shall be smooth and free from cracks or other fa
12、ults. It is recommended to use only Knoop indenters which have been certified by a testing authority. 4.3 Verification of apparatus It is recommended to test the function of the hard- ness tester regularly, including the Knoop indenter, by measurements of standardized test plates of known hardness,
13、preferably made of glass. Inspect the Knoop indenter microscopically from time to time to detect any breakages or damage to the edges. 5 Test specimen The test surface of the specimen shall be flat. It shall be fire-polished or optically ground and polished. Immediately before testing, it shall be p
14、olished with water and cerium oxide until dry. The minimum thickness of the specimen shall .be 0,5 mm. 6 Procedure The hardness test shall be carried out at a temper- ature from 18 “C to 28 “C, unless otherwise agreed upon. Place the test specimen on the stage of the hard- ness tester so that the te
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