The effect of porosity and grain size on the phase composition and mechanical properties of zirconium-dioxide-based ceramic

ZrO$_2$(Y) ceramic with embedded particles of a pore-forming agent—ultrahigh molecular weight polyethylene–has been studied. It has been shown that the porosity of samples after sintering changed from 2 to 42 vol % and the grain size changed from 0.5 to 1.55 $\mu$m depending on sintering regime. The strength of materials with minimum porosity was 3000 $\pm$ 200 MPa, while the strength of materials with maximum porosity was 100 $\pm$ 20 MPa, regardless of grain size. It has been shown that the tetragonal to monoclinic martensitic phase transformation related to mechanical stresses takes place in the material without any effect on the macrostrength of the material. Internal microscopic stresses decreasing with an increase in porosity and ceramic grain size are the main factor causing this transformation in a porous material.