Use of the combined sintered HIP process in the production of hardmetals and ceramics

The use of the combined sintering/HIP process is gaining increasing importance in the production of hardmetals and ceramics. Initial laboratory and production-scale tests were carried out on varous Al2O3-ZrO2-TiC-base hardmetals and ceramics. Depending on their composition, hardmetals hot-isostatically pressed at pressures of 100 MPa absorb several μg/g of the pressure gas, usually argon. In the combined sintering/HIP technique, which was tested with a maximum pressure of 8 MPa in the case of hardmetal, argon pickup was not observed (detection limit 0,1 μg/g). In terms of porosity and strength properties, the tests revealed no major differences between hot-isostatically pressed samples and those manufactured by the new sintering/HIP technique. Similar results were obtained with Al2O3-ZrO2-base ceramics having various TiC contents. In the case of materials containing 5 mass% TiC, the sintering/HIP process produced a marked improvement in strength. Optimization of the individual process parameters in the production of ceramics by the combined sinter/HIP process is greatly facilitated by an integral dilatometer. (orig.)