Densification of titanium diboride by hot isostatic pressing and production of near-net-shape components

Abstract

Hot isostatic pressing (HIP) was applied to the production of titanium diboride (TiB2) parts. Cylinders were first produced to select the best starting powder (of two possible choices) and the processing conditions. Transverse strength, hardness, and toughness measurements were carried out on the densified products. Results were equivalent or better than data published in the literature, showing that HIP is an efficient method of processing ceramic powders. Constitutive equations representing the rheology of porous materials are presented and applied to the selected titanium diboride powder. Hot pressing and sinter forging tests were carried out to obtain the parameters of the constitutive equations. These equations were used in a finite-element program to simulate the forming of TiB2 crucibles by HIP. These parts were actually processed using graphite or titanium inserts to produce a hollow, cylindrical part with a closed end. Observed and calculated final shapes were compared, showing good agreement. In addition, the finite-element program allowed the calculation of residual stresses after processing, of eventual remaining porosity. It then became possible to optimize processing routes, can, and insert geometries.