Fabrication and mechanical properties of Cr 2O 3 solid solution ceramics in the system Cr 2O 3-Al 2O 3

Abstract

In the system Cr 2O 3-Al 2O 3, Cr 2O 3 solid solution ( ss) powders containing up to 25 mol% Al 2O 3 have been prepared by the hydrazine method. Dense Cr 2O 3( ss) ceramics (99–99.2% of theoretical) have been fabricated by HIPing (1500 °C/2h/196MPa) of the compacts sealed under reduced pressure. Their mechanical data are discussed, in comparison with those of Al 2O 3( ss) ceramics in this system. Microhardness (23.4 GPa) and fracture toughness (3.9 Mpa · m 1 2 ) are not dependent on the compositions of Cr 2O 3( ss) ceramics. The former value is higher than that of much improved Al 2O 3 (Al 2O 3( ss)) ceramics. Bending strength increases linearly with increasing Al 2O 3 content; the maximum value of 380 MPa is achieved in the ceramics containing 25 mol% Al 2O 3.