Graded machinable Si3N4/h-BN and Al2O3/LaPO4 ceramic composites

This paper provides a new material design method for machinable ceramics within an overall methodology. Examples are provided to illustrate the use of the methodology in specific ceramic materials, and machinability of the materials is characterized with cemented carbide drills instead of diamond tools. This method enables the use of composition compound and structure design combination for the purposes of improving machinability of ceramics while allowing for retaining mechanical properties of the materials. At the same time, this method also provides the basic design principle for the other comparable, but intrinsically different, ceramic systems based on chemical compatibility and thermodynamic properties. Graded machinable Si3N4/h-BN and Al2O3/LaPO4 composites were designed, fabricated and characterized.