Journal of Materials Science vol:39 issue:3 pages:881-888
The potential of electrophoretic deposition as a shaping process of free-standing objects with a gradient in composition is investigated. The capability to produce relatively thick continuously graded ZrO2-Al2O3 and WC-Co-Ti(C,N) discs was explored. After electrophoretic deposition, the dried deposits were cold isostatically pressed and pressureless sintered. In order to create a symmetric gradient profile along the thickness of the plates, a mathematical model for the EPD process was developed in order to predict the composition and slope of the gradient profile in the discs from the starting composition of the suspension, the EPD operating parameters and the powder-specific EPD characteristics. The sintered graded materials have a continuous variation in composition, microstructure and mechanical properties. In the illustrated ZrO2-Al2O3 example, the ZrO2 content increases from 0 vol% on the outer surface up to 25 vol% in the core. For the WC-Co-Ti(C,N) discs, the Ti(C,N) content decreases from 5 wt% on the outer edge to 0 wt% in the bulk of the material. In both materials, a hard outer rim and a tough core are obtained. Finally, the residual surface stresses of the densified graded ZrO2-Al2O3 discs were investigated. (C) 2004 Kluwer Academic Publishers.