Preparation, structure, and properties of Cr2N reinforced Al2O3 composites

Nanosized α-Al2O3 and CrN powders were mixed in calculated proportion and homogenized by ball milling. Cr2N reinforced Al2O3 composites were prepared by hot pressing of nano CrN–Al2O3 powders. Dense sintered bodies were obtained by hot pressing at 1400–1550 °C and 30 MPa for 60 min. X-ray diffraction (XRD) analysis indicated that the CrN converted to Cr2N during the sintering process. Microstructures of the composites were studied by field emission scanning electron microscopy (FE-SEM). It was found that Cr2N particles were uniformly dispersed in the Al2O3 matrix. The bending strength of the Al2O3–Cr2N composite with the addition of 12.97 vol% Cr2N hot pressed at 1400 °C reached 848 MPa, and the fracture toughness of samples was over 4 MPa m1/2.