The proposal is motivated by the availability of a novel ceramic sintering process (Spark Plasma Sintering) which enables densification of components in short times, purity, nanoscale grain size and potentially high strength. The process will be applied to pure oxide biomedical ceramics, to develop high strength femoral heads with fine surface finish and to metal cutting inserts with carbide or nitride dispersions in oxide matrices which have high toughness, wear resistance and low reactivity with important alloys. The objective is to develop an economic manufacturing route for oxide components which have large property increments over existing products, to facilitate EU competitiveness and international market penetration.
-A suitable commercial grade of a-alumina was identified for use in the project studies. This, in conjunction with problems associated with fabricating suitable precursor materials within the project, meant that manpower effort could be switched from WP1 to WP3 in order to include rapid firing sintering in the work programme. The production of two types of whisker-reinforced materials was successfully fed into the processing programme. A colloidal precursor of zirconia toughened alumina (ZTA) was produced within the project and compared with commercially available powders.
-PS, HP, sinterHIP and SPS have been carried out over a range of conditions and extensive analysis has been carried out on the samples produced. Cutting insert trials have been used to examine the most promising material / sintering combination. The SPS process demonstrated the expected benefits of nanoscale grain size, faster sintering times and increased mechanical properties. Results of the trails on the SPS processed cutting inserts proved very encouraging, especially with regard to those associated with typical aerospace material trials. Prototype femoral head shapes were produced towards the end of the project and these were provisionally characterised. This proved the capability of SPS to produce much larger and complex shaped parts directly from powder than previously demonstrated. The functional material study was limited to a ferroelectric material based on barium titanate / strontium titanate mixtures and an optically transparent alumina. Both of which demonstrated some very interesting preliminary results. -We were also able to demonstrate that, for the pure alumina, sinterHIPing could also produce nanoscale grain sizes with the associated increase in mechanical properties that were comparable to those of SPS processed parts.