Fabrication and mechanical properties of Cr2O3 solid solution ceramics in the system Cr2O3-Al2O3

In the system Cr2O3-Al2O3, Cr2O3 solid solution (ss) powders containing up to 25 mol% Al2O3 have been prepared by the hydrazine method. Dense Cr2O3(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 Al2O3(ss) ceramics in this system. Microhardness (23.4 GPa) and fracture toughness (3.9 Mpa · m12) are not dependent on the compositions of Cr2O3(ss) ceramics. The former value is higher than that of much improved Al2O3 (Al2O3(ss)) ceramics. Bending strength increases linearly with increasing Al2O3 content; the maximum value of 380 MPa is achieved in the ceramics containing 25 mol% Al2O3.