Thermal and mechanical properties of sintered LaPO4-Al2O3 composites

Mixtures of (1-x)LaPO4 and xAl(2)O(3) (x = 0 to 1 mass) were dry-pressed to disks or bars. Relative densities larger than 94% and apparent porosities less than 6% were achieved when the specimens were sintered at 1600 degrees C for 5 hours in air. The sintered ceramics (x = 0 to 0.7) were found to be machineable - they could be drilled easily using conventional metallic WC drills. The thermal and mechanical properties of the sintered (1-x)LaPO4 - xAl(2)O(3) composites had the following ranges: 10 x 10(-6)/degreesC (x = 0 ) to 9.0 x 10(-6)/degreesC (x = 1) (limear thermal expansion coefficient at 200 degrees -1000 degreesC); 5.0 (x = 0) to 43 W/(m.K)(x = 1) (thermal con ductivity at 25 degreesC); 140 +/- 19 (x=0) to 352 +/- 23 MPa (x = 1)(bendi ng strength at room temperature); 5.7 (x = 0) to 16.5 GPa (x = 1) (Vickers hardness); and 155 (x = 0) to 400 GPa (x = 1) (Young's modulus). (C) 2001 E lsevier Science Ltd. All rights reserved.