1、STD-BSI BS IS0 728b-ENGL 1777 W Lb24bb7 ObL7bL7 2Lb BRITISH STANDARD Abrasive grains and crude - Chemical analysis of silicon carbide ICs 25.100.70 BS IS0 9286 : 1997 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BS IS0 9286 : 1997 direction of the Engineering Sector Board,
2、was published under the authority of the Standards Board and comes into effect on 15 June 1997 Amd. No. National foreword Date Text affected This British Standard reproduces verbatim IS0 9286 : 1997 and implements it as the UK national standard. The UK participation in its preparation was entrusted
3、to Technical Committee MTE/13, Grinding wheels, abrasive tools, paper and cloths and powders, which has the responsibility to: - aid enquirers to understand the text; - present to the responsible internationaVEuropean committee any enquiries on the interpretation, or proposals for change, and keep t
4、he UK interests informed - monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European public
5、ations referred to in this document may be found in the BSI Standards Catalogue under the section entitled International Standards Correspondence Index, or using the Find facility of the BSI Standards Electronic Catalogue. Compliance with a British Standard does not of itself confer immunity from le
6、gal obligations. Summary of pages This document comprises a front cover, an Mide front cover, the IS0 title page, pages ii and iii, a blank page, pages 1 to 22, an inside back cover and a back cover. O BSI 1997 1 1 ISBN O 580 27568 X STD-BSI BS IS0 9286-ENGL 1777 Lb24bb7 Ob17b21 77q BS IS0 9286 : 19
7、97 I NT E R NAT I O N AL STANDARD IS0 9286 First edition 1997-01 -1 5 Abrasive grains and crude - Chemical analysis of silicon carbide Abrasifs en grains ou en roche - Analyse chimique du carbure de silicium Reference number IS0 9286:1997(E) STD-BSI BS IS0 728b-ENGL 1977 rlbZ,bb7 Obl7b22 BOO BS IS0
8、9286 : 1997 Contents . 1 Scope . 2 Normative reference . 3 Analysis of surface impuriti 3.1 Sampling _ ,. 3.2 Preparation o ple - 3.3 Determination of surface silicon (Sisud) 3.4 Determination of surface carbon (Cs,d) 3.5 Determination of loss on acid treatment (LAT) 3.6 Determination of surface sil
9、icon dioxyde ( 3.7 Calculation of the content of residual silicon carbide (si m is the weight of test portion according to 3.3.4, in grams; 0,000 627 is the conversion factor of the volume of hydrogen gas, in millilitres, to the weight of silicon, in grams; f is the correction factor for reducing th
10、e hydrogen gas volume to normal conditions of temperature and pressure: O OC and 1 O1 3 hPa. f can be obtained by reference to correction tables applicable to gases, taking into account the indicated temperature and the steam pressure above the sealing liquid. 3.4 Determination of surface carbon (Cs
11、ud) 3.4.1 Principle Gravimetric or coulometric determination of carbon dioxide obtained by the heating of the surface carbon in a stream of oxygen inside a combustion furnace. 3.4.2 Test methods 3.4.2.1 Gravimetric method 3.4.2.1.1 Apparatus 3.4.2.1.1.1 Combustion apparatus, as shown in figure 2. 3.
12、4.2.1.2 Procedure Prior to starting the measurements, purge the combustion train using a stream of oxygen for 70 min to 15 min. Take from the sample prepared according to 3.2, a test specimen (mo) of 2 g weighed to within Ie 0,000 1 g and place it in a previously calcined and weighed combustion boat
13、. Weigh the absorption tube and insert it in the combustion train. Place the combustion boat containing the sample into the hot zone of the tube furnace at (900 to 915) OC. Pass a stream of oxygen for 30 min at a flow rate of 100 ml/min through the apparatus then remove the absorption tube and weigh
14、 it. The increase in mass corresponds to the weight of carbon dioxide (m$. Finally determine the weight of the residue in the combustion boat (ml1 within I0,OOO 1 g. 3.4.2.1.3 Expression of results The amount of surface carbon expressed as a percentage by mass, is calculated using the equation (0,27
15、2 9 x m2) - (0,375 4 x m3) m0 m1 is the mass of the sample after combustion, in grams; 4 STD-BSI BS IS0 928b-ENGL 1777 = lb24bb9 Obl17b28 229 W BS IS0 9286 : 1997 m2 is the mass of carbon dioxide, in grams; m3 = ml - mg + 0,272 9 m2 The method of determination and calculation compensates for possibl
16、e oxidation of the silicon carbide. Key 1 Oxygen source 2 Flow regulating valve - 3 Flow meter - 4 Column for the absorption of CO2 E 5 Drying column containing anhydrous Mg(C10! absorbent - - - - * * 0-2 Figure 2 - Combustion apparatus for the determination of carbon (resistance furnace) 3.4.2.2 Ge
17、neral coulometric method 3.4.2.2.1 Reagents 3.4.2.2.1.1 Barium perchlorate solution. Dissolve approximately 200 g of barium perchlorate IBa(C104)21 in distilled or deionized water and make up to 1 I. 3.4.2.2.1.2 3.4.2.2.1.3 3.4.2.2.1.4 3.4.2.2.1 -5 3.4.2.2.1.6 3.4.2.2.1.7 Barium carbonate (BaC03). H
18、ydrogen peroxide absorbed on urea H202CO(NH2)21, e.g. perhydrite tablets. 2-propyl alcohol (isopropyl alcohol) iCH3CH(OH)CH31. Granulated soda lime. Buffer solutions for calibrating the pH meter, in accordance with the manufacturers instructions. Oxygen, 99,99 % (VIV). 5 STD-BSI BS IS0 928b-ENGL 177
19、7 Lb24bb9 Ob17b27 Lb5 BS IS0 9286 : 1997 , 3.4.2.2.2 Apparatus Standard laboratory equipment and 3.4.2.2.2.1 Combustion unit, as shown in figure 3. The combustion furnace shall by capable of operating at (1 1 O0 f 30) “C. 3.4.2.2.2.2 Thermocouple, with indicator to measure the furnace temperature. 3
20、.4.2.2.2.3 Flow meter. For assembly and operation refer to the manufacturers instructions. To commission a new apparatus or for occasional checking, carry out several determinations using a reference sample of known surface carbon content in the manner indicated in 3.4.2.2.3 before testing the requi
21、red sample. The carbon content determined must correspond to admissible limits to the carbon content of the reference sample. 3.4.2.2.3 Procedure From the sample prepared according to 3.2 take a 0,2 g test portion (mo) weighed to within f 0,000 1 g and place in a combustion boat which has been previ
22、ously calcined to remove all carbon. Heat the combustion furnace to (850 I20) OC and insert the boat. Record the internal temperature and adjust the furnace temperature correspondingly. It is customary to use gas fractionating which means that only a fraction, (usually one tenth) of the gas to be an
23、alysed is used; except where the surface carbon content is very low, in which case gas fractionating is not used. Adjust the stream of oxygen so as to prevent the surrounding air from being introduced. At the temperature given above, the determination of the surface carbon takes 10 min. Each series
24、of analyses shall be preceded by a blank value determination using a pre-ignited boat (without gas fractionating). Calculate the mean value (I) from three separate determinations. As a general rule, the blank test gives a carbon content which varies between 0,Ol ?O (m/m) and 0,02 YO (rn/m). 3.4.2.2.
25、4 Expression of results The surface carbon content (Csud), expressed as a percentage by mass, is calculated according to the following equation, the result being rounded to the second decimal place. (1 x f) - (I x i) x x w(csurf)= mg 1000 x 100 where I f I J* mg X 1 O00 is the mean value of the numb
26、er of pulses found in the sample; is the gas fractionation coefficient; is the mean value of the number of pulses found in the blank determination according to 3.4.2.2.3; is the gas fractionating coefficient used in the blank tests; is the weight of the test portion (see 3.4.2.2.31, in grams; is the proportionality coefficient, depending on the apparatus which gives the conversion of the number of pulses into milligrams of carbon; is the conversion factor, grams to milligrams. 6
