Cutting performance improvement of Si3N4 ceramic cutting tools by adding boride.

Cutting performances of silicon nitride (Si3N4) ceramic cutting tools with and without boride additive (2.5 vol% ZrB2 or TiB2) prepared by hot‐pressing at 1500°C were investigated. Due to the α‐ to β‐Si3N4 phase transformation and low densification temperature, boride‐containing Si3N4 ceramics with high hardness and high toughness were obtained. The turning tests showed that the effective cutting lengths of the Si3N4–2.5 vol% TiB2 ceramic (∼2480 m) and Si3N4–2.5 vol% ZrB2 ceramic (∼2200 m) were higher than the monolithic Si3N4 ceramic (∼1780 m). As the toughness was improved while maintaining relative high hardness, the cutting performances of the boride‐containing Si3N4‐based inserts were improved by adding 2.5 vol% ZrB2 or TiB2. The improved cutting performance indicated that the boride‐containing Si3N4 ceramics are expected to be used in the field of ceramic cutting tools. [ABSTRACT FROM AUTHOR]