Shuya Nakao

Influence of powder characteristics of alumina in a glass-alumina mixed layer upon constrained sintering of the sandwich substrate with an inner-self-constraining layer

Abstract Constrained sintering of substrates with a laminate structure that have an inner-self-constraining alumina layer laminated between two glass-alumina mixed layers has been studied. The influence of the particle size of alumina in the glass-alumina mixed layers upon firing shrinkage was investigated. Sintering shrinkage in the x-y direction of the substrate decreased with increasing the particle size of alumina in glass-alumina mixed layers. Penetration length of glass to the inner-self-constraining alumina layer increased with increasing particle size of alumina in glass-alumina mixed layers. It was considered that sintering shrinkage in the x-y direction of the substrate and penetration length of a glass into alumina layer will be dependent on the coverage of alumina particles on surface of glass particles. As for the particle size of alumina in glass-alumina mixed layers, it is desirable for it to be the same as the particle size of glass and the coverage of the surface of glass particle with alumina particles should be less than 17.5% in the case of constrained sintering of substrates with an inner-self-constraining alumina layer. Sintering shrinkage in the x-y direction was less than 0.2%.

Influence of agglomeration upon dewaxing properties of greenware for low pressure molding

This paper presents the influence of agglomeration upon the flow property of the slurry and dewaxing properties of the greenware for low pressure molding. (Zr, Sn)TiO4 powder agglomerate was pulverized by a high speed mixer. The agglomeration state was evaluated by tapping density and residual of #350 sieving. The flow property was measured by viscosity and grindmeter scratch. The dewaxing properties were evaluated by pore size distribution, the fraction of residual binder after dewaxing and rejection ratio of greenware due to crack. Pulverization of the agglomerate reduces the thixotoropy of the slurry, contributing to uniform pore size and residual binder distributions. They all contribute to reduce cracks in greenware.