Evaluation of mechanical hardness and fracture toughness of Co and Al co-doped ZnO

Abstract

Combustion synthesized nanocrystalline Co and Al co-dopedZnO powders[(Zn1 x yCoxAlyO; x¼0.04,0.03, 0.02; y¼0.01, 0.02,0.03)]were fabricated into cylindrical discs by uni-axial pressing and sintered intentionally at 1000 1C for 2h to assess the mechanical performance.The crystallinity of the pure and doped ZnO was confirmed by X-ray diffraction analysis.The microstructures of the sintered samples were investigated by scanning electronmicroscopy(SEM)to examine the density,porosity,grainsize and its distribution.Grainsof0.5–3 mm were observed for the samples sintered at1000 1C. The mechanical properties such as micro-hardness,fracture toughness and strain hardening co-efficient were investigated by the Vickers indentation method.It was found that the crack mode observed during the indentation on the samples belongs to median cracks under a load of 19.6N.Also,the hardness was enhanced with increasing mol%of Co,while the trend was reversed with the increase of Al content.In addition,the strain hardening coefficient and fracture toughness were calculated using the indentation data