TIMREXÂ® Graphites and Cokes for Friction Materials - Timcal

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www.timcal.comApplicationproperties ofmodel brakeliningsGraphite and cokein sintermetallicfriction materialsOne reason for the different levels of wearand tear of sinter linings with T and KSgraphites lies in the varying shapes of thegraphite particles. The more flaky T graphiteparticles tend to align vertically to the directionof pressure during the compressionprocess. This leads to lamination of the grainand anisotropic mechanical stability after sintering.Under heavy stress in the frictionprocess, shearing forces can lead to greaterwear and tear of the lining.Coke resultsCokes may be added in a concentrationrange of 5-10% of the powder mixture toregulate the friction coefficient. As the grainsize and concentration of the coke increase,so the friction coefficient is reduced.Abrasion of the lining is reduced whenused in combination with graphite powders.KS graphites do not tend to align themselvesin any particular direction duringthe compression process because their particlesare irregularly shaped, and their texturesare more homogenous after sintering.0,60,50,4Use of less fine-grained graphites alsohelps to reduce wear and tear: Cu particlesare usually enveloped by any fine graphiteparticles present in the mixing process.The graphite-coated Cu surfaces are thenno longer available in the sinter process forthe formation of sinter contacts, leading toa reduction in grain stability and toincreased wear and tear in the frictionprocess.Friction coefficient µ0,30,20,10FC 250 FC 850 FC 250-1500Coke typeFriction coefficientof sintered Cu-C -brakepads with 10% TIMREX® CokeSinterconditions: 850°C, 3 hSinterdensity: 53% of thetheoret. densityLargely isotropic and undisturbed Cu sintertextures are obtained by using KSgraphites with a reduced proportion of finegrains.KS 150-600SP and KS 5-75TT graphitepowders are predestinated for sintered brakelinings based on Cu. KS 75 is particularlysuitable for large surface clutch linings withlow surface compression.
Applicationproperties ofmodel brakeliningsGraphite and cokein organic bondedfriction materialsGraphiteMethodGraphite powders are used as solidlubricants, and should fulfill the followingprinciple functions:Test samplesConcentration (mass%)Formulationof test samplesSet the required friction coefficientin a range from 0.38 to 0.45.Level off the friction curve.Reduce wear and tear on discand lining.AdditiveGraphiteBaryteformul. 1800formul. 24040formul. 32060formul. 41070The suitability of a raw material for aspecific brake lining can only be clearlyestablished in a dynamometer test and byvehicle road tests. However, tests usingmodel linings on friction testbeds canfrequently give an indication of the tribologicalbehaviour of graphites, and canbe an aid to formulation.AluminaPhenolic resinParameter164diameter:height:Naturalgraphite 116414.3 mm4 mmT 800164Naturalgraphite 2164T 200-2000Investigated graphitepowdersAsh (%)5.2 0.11.80.05Particle size (µm)0-300fine flakes0-700500-2000grains200-2000Test equipment:Standard F.A.S.T. MachineSliding speed: 7 m/sSliding time: 90 minProcedure: Heavy duty brake
Page 1 and 2: Graphites and Cokesfor friction mat
Page 3 and 4: Graphite andCoke Powdersfor Brake L
Page 5 and 6: Particle shapeAdvantages and applic
Page 7 and 8: Particle shapeAdvantages and applic
Page 9 and 10: GraphiteProperties:Density and inte
Page 11 and 12: GraphiteProperties:Thermal conducti
Page 13 and 14: Coke Properties:Coke structureThe s
Page 15: Applicationproperties ofmodel brake
Page 19 and 20: Applicationproperties ofmodel brake

TIMREXÂ® Graphites and Cokes for Friction Materials - Timcal

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