Formation, powder characterization and sintering of MgCr2O4 by the hydrazine method

Picrochromite (MgCr2O4) crystallizes at 480 degrees to 530 degrees C from an amorphous material prepared by the hydrazine method. The MgCr2O4 powders were characterized for particle size and surface area. Individual particles tend toward a hexagonal morphology above 1000 degrees C. Dense MgCr2O4 ceramics (99.5% of theoretical) with an average grain size of 2 mu m have been fabricated by spark plasma sintering for 5 min at 1400 degrees C and 30 MPa. Their fracture toughness and bending strength are 3.7 MPa.m(1/2) and 310 MPa, respectively.