Effect of yttria-titanium shell-core structured powder on strength and ageing of zirconia/titanium composites

Commercially pure titanium powder was modified by a two-step procedure involving attrition milling and subsequent coating with yttria by sol-gel. Lamellar titanium particles with a high aspect ratio were obtained by mechanical grinding. The existence of an yttria layer covering the milled titanium particles (shell-core structure) was corroborated by X-ray photoelectron spectroscopy. Zirconia/titanium (25 vol% titanium) compact specimens were processed by a wet route using the modified titanium powder, spark plasma sintered, and then characterized in terms of mechanical strength and ageing. A reinforcement mechanism arises from the special shape and disposition of the metallic particles. The stable Y2O3 barrier prevents excessive formation of side products at the metal-ceramic interface. Hence, our innovative procedure allows to develop a new ceramic-matrix composite in the interesting zirconia/titanium system with improved mechanical properties and controlled ageing compared to the composites made with commercially pure titanium.