Grain size distribution analysis of MgO and VC inhibited zirconia toughened alumina ceramics using digital image processing

Abstract

Abnormal grain growth (AGG) of zirconia toughened alumina (ZTA) during sintering decreases phase transformability at critical temperature, leading material failure. The first-ever grain size distribution analysis using image processing in materials science identifies the impact of carbide and oxide inhibitors on tetragonality and grain refinement of ZTA ceramics. Incorporating insoluble vanadium carbide and soluble magnesium oxide inhibitor in ZTA restricts AGG, reducing average grain size of 0.5VC_ZTA by ∼ 86.84% compared to 0.5 MgO_ZTA due to Zener pinning effect of refractory carbide. The inhabitation of dehydroxylation process helps to decrease alumina crystallite size by ∼33.37% in case of VC, thereby increasing the density. Automated analysis using digital image processing makes the process less affected by user bias. A perceptible improvement in micro-mechanical properties through grain refinement of pressure-less sintered 0.5VC_ZTA confirms the structure property correlation of the matrix. This type of analysis has a beneficial aspect towards the fabrication of advanced ceramics with improved properties.