Metselaar, H.S.C.

English

University of Twente Research Information

Second Engineering Mechanics-Symposiurm, Nov. 1999 23Thermally Induced Wear of CeramicsH.S.C. MetselaarUniversity of Twente,Twente Institute of MechanicsP.O. Box 217, 7500 AE Enschede, The Netherlandsphone +31-(0)53-4892476, email h.metselaar@wb.utwente.nlIntroductionCeramics have a high strength and are chemically stable materials, however they are often not usedbecause extreme wear is feared due to their brittle nature. Therefore a model has been derived,predicting the transition of mild to severe wear due to thermally induced stresses (Metselaar et al.1999): The temperature rise due to frictional heating in a tribological contact induces thermal stressesin the material. When this stress exceeds a threshold value, fracture will occur. The severity of thecontact can be described as:seff TaKfWVTS∆=in which sT∆  is the thermal shock resistance, proportional with ( )dEKIcπαν−1  and ++= 111212 4.0667.2 KcVaKKKeff ρ .Severe wear will occur when TS exceeds a certainthreshold value that is to be determined. The validation of this model will be described here, as well asthe determination of the threshold value.ValidationIn order to validate this model, wear measurements have been performed on a pin-on-disc tribometer.As disc material a zirconia was used because of its low thermal conductivity, allowing high TS-valuesat moderate loads and speeds. As pin materials several other ceramics were used, viz. alumina,silicon carbide, silicon nitride and zirconia. For each experiment the TS-value was calculated from theexperimental conditions and the resulting coefficient of friction. These TS can be plotted against theresulting specific wear rate (in mm3/Nm), to obtain the following graph.Figure 1: Overview of results of all present experiments.ConclusionSimple pin-on-disc experiments using different materials were performed to validate a modeldescribing the onset of severe wear in ceramic tribosystems. From these experiments also a thresholdvalue could be determined.ReferencesMetselaar, H. S. C., Winnubst, A. J. A. & Schipper, D. J. (1999), ‘Thermally induced wear of ceramics’, Wear225–229, 857–861.

Thermally Induced Wear of Ceramics

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