Abstract

Additives out of the systems Al-C, Al-B-C and B-C have been investigated with respect to densification and microstructure development of SiC produced by pressureless sintering and subsequent post-hot isostatically pressing (HIP) treatment. Within the investigated compositional range, the Al-B-C and B-C systems provide sufficient densification to reach pore closure during pressureless sintering and nearly theoretical density during the HIP step of the process. Densification in the IU-B-C system takes place at significantly reduced temperatures, namely similar to 1900 degreesC vs. similar to 2050 degreesC in the Al- free product. Dilatometer experiments and microstructure development indicate the presence of a liquid phase in this system during sintering. Liquid phase sintering in the SiC/(Al-B-C) system vs. solid state sintering in the SiC/(B-C) system will be discussed on the basis of literature data and previous experimental studies of the authors.