Sintering Silicon Nitride to Form Near Net Shape Cutting Tools

点击翻译按钮获取中文摘要

This project deals with the development of a sintered silicon nitride ceramic system having a transverse rupture strength of at least 70,000 psi at 1000oC, densified to 99% of the theoretical density, and formed to near net shape as an indexable cutting tool. The eventual goal is to accomplish sintering to full density with the desired microstructure at one atmosphere of nitrogen pressure. Certain sintering limits restrict the compositional choices. However, optimal properties may be obtained by compositions that can be densified within the microstructure- sintering limits. It is also possible that certain compositions require a two-stage sintering process to achieve 99% theoretical density. Potential benefits from this research would be a fundamental understanding of the sintering mechanism of the silicon nitride ceramic system, and the increased productivity and cost-savings from the use of sintered silicon nitride cutting tools in machining gray cast iron.