Sintering and microstructure of LaPO4 ceramic

To provide preliminary information for design of rare earth phosphate-contained machinable ceramic, sintering and microstructure of LaPO4 were investigated. The results show that LaPO4 can be sintered independently without other components from 1580 to 1620 degrees C, and its grains are ellipsoidal or orbicular in surface but multilayer in the inside. The fracture of LaPO4 ceramic presents transgranular along the larger grains and along-granular for the smaller grains. It is supposed that multi-layer structural LaPO4 may contribute to machinabilities for those LaPO4-contained ceramic duo to its low cleavage energy, which provides a easy path for cracks propagate of material removing, also leads crack deflections, branching and blunting helping to prevent macroscopic fractures from propagation beyond the local machining area.