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1、BRITISH STANDARD BS EN 725-6:1996 Advanced technical ceramics Methods of test for ceramic powders Part 6: Determination of the specific surface area The European Standard EN 725-6:1996 has the status of a British Standard ICS 81.060.10 BS EN 725-6:1996 This British Standard, having been prepared und
2、er the direction of the Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 September 1996 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference RPI/13 Draft for comment 92/49116 DC
3、 ISBN 0 580 25842 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee RPI/13, Advanced technical ceramics, upon which the following bodies were represented: AEA Technology Aluminium Federation British Ceramic Research Ltd.
4、British Industrial Ceramic Manufacturers Association Department of Trade and Industry (National Physical Laboratory) Flat Glass Manufacturers Association GAMBICA (BEAMA Ltd.) Institute of Refractories Engineers Ministry of Defence Refractories Association of Great Britain Society of British Aerospac
5、e Companies Ltd. University of Manchester Amendments issued since publication Amd. No.DateComments BS EN 725-6:1996 BSI 07-1999i Contents Page Committees responsibleInside front cover National forewordii Foreword2 Text of EN 725-63 BS EN 725-6:1996 ii BSI 07-1999 National foreword This British Stand
6、ard has been prepared by Technical Committee RPI/13 and is the English language version of EN 725-6:1996 Advanced technical ceramics Methods of test for ceramic powders Part 6: Determination of the specific surface area published by the European Committee for Standardization (CEN). EN 725-6:1996 was
7、 produced as a result of international discussions in which the UK took an active part. NOTEInternational and European Standards as well as overseas standards, are available from Customer Services, BSI, 389 Chiswick High Road, London, W4 4AL. A British Standard does not purport to include all the ne
8、cessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the
9、 EN title page, pages 2 to 13 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 725-6 January 1996 ICS 81.060.10
10、 Descriptors: Ceramics, powdery materials, tests, determination, specific area, absorption, nitrogen English version Advanced technical ceramics Methods of test for ceramic powders Part 6: Determination of the specific surface area Cramiques techniques avances Mthodes dessai pour les poudres cramiqu
11、es Partie 6: Dtermination de la surface spcifique Hochleistungskeramik Prfverfahren fr keramische Pulver Teil 6: Bestimmung der spezifischen Oberflche This European Standard was approved by CEN on 1995-11-02. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate t
12、he conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists i
13、n three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies
14、of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretar
15、iat: rue de Stassart 36, B-1050 Brussels 1996 All rights of reproduction and communication in any form and by any means reserved in all countries to CEN and its members. Ref. No. EN 725-6:1996 E EN 725-6:1996 BSI 07-1999 2 Foreword This European Standard was prepared by CEN/TC184, Advanced technical
16、 ceramics, the Secretariat of which is held by BSI. This European Standard shall be given the status of a national standard or by endorsement, at the latest by July 1996, and conflicting national standards shall be withdrawn at the latest by July 1996. The method given is closely based on ISO 8008:1
17、987 Aluminium oxide primarily used for the production of aluminium Determination of specific surface area by nitrogen absorption (single point method), published by the International Organization for Standardization (ISO). EN 725 Advanced technical ceramics Methods of test for ceramic powders, consi
18、sts of eleven Parts: Part 1: Determination of impurities in alumina; Part 2: Determination of impurities in barium titanate (ENV); Part 3: Determination of oxygen content of non-oxides by thermal extraction; Part 4: Determination of oxygen content of non-oxides by XRF analysis (ENV); Part 5: Determi
19、nation of particle size distribution; Part 6: Determination of specific surface area; Part 7: Determination of absolute density; Part 8: Determination of tapped density; Part 9: Determination of untamped bulk density; Part 10: Determination of compaction properties; Part 11: Determination of the den
20、sification on natural sintering (ENV). In accordance with the Common CEN/CENELEC Rules, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Swede
21、n, Switzerland, United Kingdom. Contents Page Foreword2 1Scope3 2Principle3 3Apparatus3 4Procedure6 5Expression of results8 6Test report13 Figure 1 Adsorption apparatus4 Figure 2 Thermostat for the heating of the adsorption bottles in the desorption procedure4 Figure 3 Additional device for degassin
22、g under vacuum6 Figure 4 Nomogram12 Table 1 Recommended masses of sample7 Table 2 B1, B2 = f(Tz)10 Table 3 Quantities and symbols11 EN 725-6:1996 BSI 07-19993 1 Scope This Part of EN 725 specifies a method for the determination of the specific surface area of powders used for technical ceramics, by
23、a nitrogen adsorption, single-point method. The method is limited to the measurement of surface areas of over 1 m2/g. 2 Principle The method is based on the property of the solids to adsorb gas molecules at their surface. In the range between 0,05 to 0,3 times the saturation vapour pressure of the m
24、easuring gas, the multilayer adsorption begins. The formation of the first monolayer of adsorbed molecules can be detected from the behaviour of the adsorption isotherm in this range; this is the only process relevant to the present method. Nitrogen is introduced at ambient temperature and at atmosp
25、heric pressure into two bottles of equal volume, one of which contains the test portion while the other is empty. The connected bottles are immersed in a refrigerant bath of liquid nitrogen. Since some nitrogen is adsorbed by the sample, a differential pressure occurs between the two bottles and is
26、measured by means of a differential manometer. From this difference, the number of molecules adsorbed on the surface is calculated. This number is multiplied by the known area occupied by a single adsorbed molecule so that the total surface area is obtained. The area occupied by an adsorbed nitrogen
27、 molecule is taken as 16,2 1020m2. 3 Apparatus 3.1 Adsorption apparatus (see Figure 1) The apparatus consists of a reference bottle (7) and a sample adsorption bottle (8) which are moved on to the two connecting pieces, with sealing rings in between to make the joint gas-tight. At each connecting pi
28、ece, there is a valve (1 and 2), by which the bottles can be connected to the atmosphere. The measuring gas is admitted to the bottle through the capillaries inside the connecting pieces. The bottles, made of shock-resisting glass, have a volume of about 100 cm3. The difference between the volume of
29、 the two bottles shall not exceed 0,1 %. The necks of the bottles consist of calibrated glass tubes with an internal diameter of 9 mm 0,02 mm. Each tube has an upper and lower mark. In this way, several bottles can be used as either sample or reference bottles without compensating the volumes for ea
30、ch combination of bottles. A differential manometer containing dibutyl phthalate is arranged between the two bottles. The legs of the differential manometer are connected to the two inlet capillaries of the adsorption bottles. By means of the valve 4, the two bottles, i.e. the two inlet capillaries,
31、 can be separated from or connected to each other. By means of the valve 5, the liquid in the two legs of the differential manometer can be separated or connected. The legs of the differential manometer consist of calibrated glass tubes with an internal diameter of 5 mm 0,02 min. This ensures that t
32、he change in volume during the adsorption measurement can be calculated with sufficient accuracy. The inlet capillary of the sample bottle, being the shorter of the two, is connected to a compensating volume (10), which is adjusted during preparation of the apparatus. The measuring gas is admitted t
33、o the apparatus via the valve 3. If the valves 1, 2 and 4 are open, the measuring gas is passed through both bottles. If the valves 1 and 4 are closed, the reference bottle is shut off and only the sample bottle is purged with the measuring gas. During measurement, only a part of the gas volume, whi
34、ch is downstream of the valve 3 and upstream of the valves 1 and 2, is cooled by liquid nitrogen to the measuring temperature. The gas volume remaining at room temperature shall be limited to 10 % of the total volume at maximum. For this reason, the connections to the adsorption bottles are capillar
35、ies, which occupy most of the necks of the bottles in order to keep the portion remaining at room temperature as small as possible. The adsorption bottle has calibrated volume of 100 cm3. To facilitate weighing of the sample as well as the cleaning of the adsorption bottle, two-piece bottles are app
36、lied. The two pieces are connected by ground joints and fixed by hooks and springs. 3.2 Thermostat, for heating the adsorption bottles in the desorption procedure (see 4.3 and Figure 2). 3.3 Device, for degassing under vacuum (see Figure 3). 3.4 Cooling bath, containing boiling nitrogen. 3.5 Water b
37、ath, capable of being controlled at 22 C 3 C or at approximately 40 C, as required. EN 725-6:1996 4 BSI 07-1999 Figure 1 Adsorption apparatus EN 725-6:1996 BSI 07-19995 Figure 2 Thermostat for the heating of the adsorption bottles in the desorption procedure EN 725-6:1996 6 BSI 07-1999 4 Procedure 4
38、.1 Test portion Choose the mass of sample to be used depending on the supposed specific surface area. Recommended values are given in Table 1. Figure 3 Additional device for degassing under vacuum EN 725-6:1996 BSI 07-19997 Table 1 Recommended masses of sample 4.2 Preparation of apparatus 4.2.1 Chec
39、king of new apparatus 4.2.1.1 General New apparatus shall be checked to ensure that the compensating volume (10) is adjusted correctly and that the apparatus is gas-tight. 4.2.1.2 Checking the equalization of volumes The valve 4 shall be gas-tight when the equalization of the volumes is checked. Fit
40、 the empty adsorption bottles to the connecting pieces; the upper mark of the bottle neck shall coincide with the lower sealing ring. Purge the apparatus with nitrogen by opening all the valves and allowing the gas to flow at approximately 10 1/h. During purging, the bottles are immersed in the wate
41、r bath (see 3.5), up to the lower mark on the neck, in order to bring them to the set temperature of 22 C 3 C. When the equalization of the temperature can be assumed (after at least 5 min), shut off the apparatus from the atmosphere and shut off the two bottles from each other, by closing the valve
42、s in the sequence 1, 2, 3 and 4. On shutting the valve 4, a small pressure difference can appear. If this pressure difference changes within the next 2 min, a complete temperature equalization has not been reached in the adsorption bottles. In this case, open the valves again in the sequence 4, 3, 2
43、 and 1, and purge the apparatus further with nitrogen. After a few minutes, repeat this check. If temperature equalization is achieved, close valve 5. Remove the bottles from the water bath, dry any drops of water adhering to them, and immerse the bottles up to the lower mark in the cooling bath (se
44、e 3.4). When the bottles have attained the temperature of the boiling nitrogen (with empty bottles after about 1 min), open the valve 5 slowly If the volumes of the sample and reference sides have been fully equalized, no pressure difference occurs. In this case, close the valve 5 again and open the
45、 valve 4. Then remove the cooling bath and replace it by the water bath (see 3.5), maintained at approximately 40 C, to thaw out the bottles. Remove the warm water bath as soon as the bottles have reached ambient temperature again. After 2 min, reopen the valves 3, 2 and 1 in that sequence, and purg
46、e the apparatus with nitrogen. During the cooling and heating of the bottles, great pressure differences may occur momentarily so that the measuring liquid in the manometer may be transferred into other parts of the apparatus. For this reason, do not open the valve 5 before temperature equalization.
47、 If the pressure difference should occur during the preparation of the apparatus, change the compensating volume (10) in such a way that the volumes on both sides of the differential manometer are equal. To check the equalization of the volumes, repeat the test described above. 4.2.1.3 Checking of t
48、ightness If, after the slow opening of valve 5, steadily increasing or very great pressure differences occur (more than 400 mm of liquid column), during the equalization of volume at the temperature of boiling nitrogen, then the apparatus will have a leakage to the atmosphere (for instance, caused b
49、y the valves 1, 2, 3). Leakage of valve 4 cannot be recognized by a pressure difference and the following special check shall be carried out. Immerse the bottles in the cooling bath (see 3.4), close the valves 2, 3 and 4, and open the valves 1 and 5. By means of valve 1, create a pressure difference of approximately 300 mm of liquid column. Close the valve 1. Within the next 10 min, the liquid column of the differential manometer shall not sink more than 1 mm. Supposed spe
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