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BRITISH STANDARD Advanced technical ceramics Ð Methods of test for ceramic powders Part 10 Determination of compaction properties The European Standard EN 725-10 : 1997 has the status of a British Standard ICS 81.060.99 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BS EN 725-10 : 1997 BS EN 725-10 : 1997 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 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 Aerospace Companies Ltd University of Manchester This British Standard, having been prepared under 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 July 1997 BSI 1997 Amendments issued since publication Amd No The following BSI references relate to the work on this standard: Committee reference RPI/13 Draft for comment 93/301336 DC ISBN 580 27913 Date Text affected BS EN 725-10 : 1997 Contents Committees responsible National foreword Foreword Text of EN 725-10 BSI 1997 Page Inside front cover ii i BS EN 725-10 : 1997 National foreword This British Standard has been prepared by Technical Committee RPI/13 and is the English language version of EN 725-10 : 1997 Advanced technical ceramics Ð Methods of test for ceramic powders Ð Part 10: Determination of compaction properties, published by the European Committee for Standardization (CEN) EN 725-10 : 1997 was produced as a result of international discussions in which the United Kingdom took an active part EN 725-10 : 1997 has been approved by CEN member bodies under the weighted voting procedures introduced in 1988 to coincide with the introduction of `New Approach' Directives from the Commisssion of the European Community NOTE International and European Standards as well as overseas standards, are available from Customer Services, BSI, 389 Chiswick High Road, London, W4 4AL 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 EN title page, pages to 8, an inside back cover and a back cover ii BSI 1997 EN 725-10 EUROPEAN STANDARD NORME EUROPÊENNE EUROPẰISCHE NORM March 1997 ICS 81.060.99 Descriptors: Ceramics, powdery materials, compression tests, compacting, determination, compressibility, testing conditions English version Advanced technical ceramics Ð Methods of test for ceramic powders Ð Part 10: Determination of compaction properties CeÂramiques techniques avanceÂes Ð MeÂthodes d'essai pour poudres ceÂramiques Ð Partie 10: DeÂtermination des proprieÂteÂs de compaction Hochleistungskeramik Ð PruÈfverfahren fuÈr keramische Pulver Ð Teil 10: Bestimmung der Verdichtungseigenschaften This European Standard was approved by CEN on 1996-12-22 CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the 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 in 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 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 Comite EuropeÂen de Normalisation EuropaÈisches Komitee fuÈr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1997 Copyright reserved to CEN members Ref No EN 725-10 : 1997 E Page EN 725-10 : 1997 Foreword This European Standard has been prepared by Technical Committee CEN/TC184, Advanced technical ceramics, the secretariat of which is held by BSI This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 1997, and conflicting national standards shall be withdrawn at the latest by September 1997 EN 725 consists of 11 parts: Part : Part : Determination of impurities in alumina Determination of impurities in barium titanate (ENV) Part : Determination of oxygen content of non-oxides by thermal extraction Part : Determination of oxygen content of non-oxides by XRF analysis (ENV) Part : Determination of particle size distribution Part : Determination of specific area Part : Determination of absolute density Part : Determination of tapped bulk density Part : Determination of untamped bulk density Part 10 : Determination of compaction properties Part 11 : Determination of reactivity on sintering (ENV) Contents Foreword Scope Normative references Principle Symbols and designation Apparatus Procedure Expression of results Test report Repeatability and reproducibility Annex A (informative) Example of presentation of test report Page 3 3 3 According to the CEN/CENELEC Internal Regulations, the national standards organizations of 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, Sweden, Switzerland and the United Kingdom BSI 1997 Page EN 725-10 : 1997 Scope Apparatus This part of EN 725 describes methods for the determination of the extent to which a ceramic powder is compacted, when subjected to uniaxial compressive loading in a confining die, under specified conditions 5.1 Die, which shall be made from hard material, preferably tungsten carbide The cylindrical die shall contain two punches for producing cylindrical compacts and shall be of the floating type or of the type suspended from a spring The die shall be capable of making compacts of diameter 20 mm to 26 mm with a height to diameter ratio between 0,3 and 0,5, with tolerances as indicated in figure The upper part of the die shall be (preferably) designed to avoid damage to the compact during the ejection phase due to springback phenomenon An ejection cone of height mm, allowing an increase of the diameter at the top of the die of approximately %, as shown in figure 1, should be used The die may be fitted with a venting valve NOTE An example of the reporting of results is shown in annex A Normative references This European Standard incorporates by dated or undated reference, provisions from other publications These normative references are cited at the appropriate places in the text and in the publications listed hereafter For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision For undated references the latest edition of the publication referred to applies ISO 3611 Micrometer callipers for external measurement Principle The powder is compacted uniaxially in a confining die by double-action pressing Samples of the powder may be pressed either at a single specified pressure or at a series of specified pressures After ejection from the die, the apparent density of the compact is determined The density obtained in the former case represents the compaction properties of the powder at the specified pressure The densities obtained in the latter case are utilized for drawing the compaction curve of the powder, which is a plot of the density as a function of the compacting pressure Symbols and designation Table Symbol Designation Unit Apparent density kg/m3 m Mass of the compact g V Volume of the compact cm3 If the apparent density is measured at one specified pressure only, for example 200 MPa, the symbol becomes (200) BSI 1997 5.2 Press, capable of applying sufficient force with an accuracy of ± % 5.3 Balance, capable of weighing at least 10 g with an accuracy of ± 0,005 g 5.4 Micrometer, (see ISO 3611), or other suitable measuring device for measuring the dimensions of the compacts with an accuracy of ± 0,01 mm Procedure 6.1 Drying NOTE Powders containing organic additives should not be dried Dry the powder at 110 ÊC ± ÊC for at least 24 h and until constant mass is attained Store in a desiccator until the test is performed During drying the powder layer shall have a maximum thickness of mm 6.2 Quantity The quantity of the test sample shall be chosen to give the required number of compacts (see clause 8), with dimensions as specified in 5.1 Three compacts shall be used for each pressure used in the determination If necessary, preliminary tests should be made in order to establish the quantity of powder which is needed for fulfilling this requirement 6.3 Cleaning of the die and punches Wipe the die cavity and the punches with a soft, clean paper towel soaked with an appropriate solvent such as acetone Allow the solvent to evaporate Page EN 725-10 : 1997 6.4 Powder testing conditions 6.4.1 Powders which not contain a lubricant shall be compacted either: a) in a dry die; NOTE Seizure and excessive die wear may occur, particularly at high compacting pressures b) in a die with lubricated walls (see 6.5); c) in a dry die, after mixing a lubricant with the powder (see 6.4.2) 6.4.2 Powders which contain a lubricant shall be compacted in a dry die 6.5 Lubrication 6.5.1 Lubrication of the die walls or of the powder is likely to modify the compaction results Similarly, depending on the type and quantity of lubricant added to the powder, the results may vary within wide ranges The test report (see clause 8) shall therefore mention whether or not lubrication had taken place, and if the lubrication was carried out on the walls of the die or on the powder Use one of the following two methods (see 6.5.2 and 6.5.3) if lubrication is applied 6.5.2 To lubricate the die wall, apply a mixture or a solution of a lubricant in the volatile organic liquid, for example 20 g of stearic acid in 980 g of acetone After any excess liquid has drained away, allow the solution adhering to the walls to evaporate leaving a thin layer of lubricant Alternatively, press in the die, before testing, inert spheres (polyurethane spheres for instance) coated with lubricant After removal of the pressed disc of inert material, a thin layer of lubricant remains on the walls of the die 6.5.3 Lubricate the powder to be tested by thoroughly mixing it with a quantity (0,5 % to 1,5 %) of a suitable solid lubricant (for example zinc stearate or stearic acid) 6.6 Compacting and ejection 6.6.1 Position the die using spacers between the die and the foot of the lower punch, in order to leave a free volume in the die large enough to contain the bulk powder (see figure 2) 6.6.2 A known weight of powder, which shall be the same for each compact in a series, sufficient to almost fill the die cavity is poured into the die 6.6.3 Wipe the wall of the die remaining free, to remove any powder that may have adhered to it during the filling of the mould 6.6.5 Position the die with its punches between the plate ends of the press Apply and release a preliminary pressure The pressure shall be lower than the lower pressure used in the test Remove the spacers supporting the die If the die is supported by springs, or by some similar system, it is unnecessary to apply this preliminary pressure Apply the selected test pressure and maintain for NOTE.Taking into account the different press technology, it is difficult to specify a rate of increase of the force as well as the displacement speed of the punch 6.6.6 Perform decompression slowly (for example 10 mm/min) to avoid breaking the compact 6.6.7 Eject the compact by using a relative movement between the die and the lower punch Transfer the compact to a desiccator for h to allow a possible expansion due to springback Remove from the desiccator, weigh to the nearest 0,005 g and measure to the nearest 0,01 mm, the dimensions (both height and diameter) in three different places, and take the average 6.7 Compacting pressures For plotting the compaction curve of a powder at different pressures, the pressures applied shall be 25 MPa, 50 MPa, 100 MPa and 200 MPa If compaction properties are to be determined at a single pressure only, this pressure shall be one of the pressures given above Expression of results 7.1 Calculation The apparent density of the compact is given by the formula: m = V where: m V is the mass of the compact, in grams; is the volume of the compact, in cubic centimetres Calculate the density in grams per cubic centimetre and then convert the answer to kilograms per cubic metre, expressed to the nearest 20 kg/m3 Express the compaction properties for a given compacting pressure as the average of the three density figures, calculated to the nearest 20 kg/m3, obtained at the specified pressure 6.6.4 Insert the upper punch into the die BSI 1997 Page EN 725-10 : 1997 Figure A.1 Example of tooling to produce a cylindrical compact BSI 1997 Page EN 725-10 : 1997 Figure A.2 Diagram of powder compacting operations BSI 1997 Page EN 725-10 : 1997 7.2 Compaction curve Draw the compaction curve of a powder through points representing the average of determinations of at each of the specified pressures Test report The test report shall include the following information (see example of presentation in annex A): a) the name of the testing establishment; b) date of the test, report identification and number, operator, signatory; c) a reference to this standard, i.e determined in accordance with EN 725-10; d) a description of the powder (material manufacturer, batch or code number); e) the dimensions of the compacts; f) the type, nature and amount of lubricant and any other organic additives used in the test, including: ± lubrication of the die walls, or no lubrication; ± lubrication of the powder, or no lubrication (state how the lubricant has been added); ± other organic additives; g) the compacting pressures; h) the result obtained including the compaction curve; i) comments about the test or test results Repeatability and reproducibility The experience of three laboratories indicates that the method is capable, for an alumina powder of apparent density 140 kg/m3 (lubricated with % to 1,5 % zinc stearate or stearic acid and pressed in a non-lubricated mould), of achieving: a) a standard deviation of repeatability of kg/m3 ; b) a standard deviation of reproducibility of kg/m3 BSI 1997 Page EN 725-10 : 1997 Annex A (informative) Example of presentation of test report Determination of the compaction properties of an alumina powder A.1 Details of test house, and other requirements of clause A.2 The compaction properties of an alumina powder are determined according to EN 725-10 A.3 This sample is an alumina powder Mass on receipt: Dried for : Mass loss : 75,9523 g 24 h in oven at 110 ÊC 89,3 mg (1176 ppm) A.4 Test conditions Lubrication Lubrication of the powder by the addition of 1,5 % stearic acid in powder form Mix for 10 Press Sechmy single-acting 200 kN hydraulic press, equipped with a floating spring cradle Compaction apparatus Die (tungsten carbide) : Upper punch (tungsten carbide) : Lower punch (tungsten carbide) : 20,000 mm in diameter 19,993 mm in diameter 19,995 mm in diameter Compaction procedure Insertion of the powder according to the procedure Loading with uniform increase of load # 0,6 kN/s achieved by progressive throttling of a needle valve for return to the oil supply tank of the cylinder Holding for 60 s at the nominal compacting pressure (25, 50, 100, 150, or 200 MPa) Slow decompression, according to a cycle identical to the one used for loading Ejection Determination of the density of the compacts Weighing of compact (Type of balance) Measurement of diameter (Type of micrometer) e.g., on base with sliding mobile key mm in diameter Measurement of height (same instrument) Calculation of density BSI 1997 blank BSI 389 Chiswick High Road London W4 4AL | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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