Investigation of dynamic fracture toughness on zirconia ceramic grinding performance with different grain sizes.

Microcracks and surface/subsurface damage are easily generated in engineering ceramics grinding. Fracture toughness is an important mechanical property that affects the grinding performance of engineering ceramics, and dynamic fracture toughness accurately reflects the mechanism of crack generation and propagation mechanism in different grinding conditions. Considering the dynamic fracture toughness and grinding process parameters for zirconia ceramics with different grain sizes (50 nm/500 nm/5000 nm) in this paper, the critical grinding force and maximum subsurface damage depth models for the crack generation were established and verified by grinding experiments. The effects of dynamic fracture toughness on the material removal mechanism during the ductile–brittle transition with different process parameters were analyzed, and the influence of different grain sizes on grinding force, workpiece surface roughness, surface cracking rate, and subsurface damage depth were discussed. Experiment results showed that the dynamic fracture toughness values range from 13.0 to 15.0 Mpam^1/2 with grain size 50 nm, 9.8 to 11.3 Mpam^1/2 with grain size 500 nm, and 6.1 to 6.8 Mpam^1/2 with grain size 5000 nm in the experimental process parameters. The relative error of the dynamic maximum subsurface damage depth is respectively 15.77%, 11.65%, and 18.36%. And the subsurface damage depth of zirconia ceramics is respectively 27 μm, 31 μm, and 40 μm with the grain size of 50 nm, 500 nm, and 5000 nm in the 5th group process parameters, which showed that the small grain size exhibited excellent grinding quality. But the influence of grain size on dynamic fracture toughness was weaker than that of grinding process parameters. [ABSTRACT FROM AUTHOR]