Manufacturing multi-material ceramics by sinterjoining based on vat photopolymerization (VPP)

Abstract The combination of different ceramic materials within one component enables the targeted adjustment of material properties, allowing for enhanced performance, improved mechanical characteristics, and tailored functionality to meet specific application requirements. One promising approach for combining ceramic components is sinterjoining, where components with different shrinkage behaviors in the green or brown state are inserted into each other, forming a cohesive bond during the subsequent sintering process. In the present work, the sinterjoining approach was investigated for producing material composites from parts produced by vat photopolymerization. To do so, the shrinkage behavior of different ceramic materials of the material system Al 2 O 3 – ZrO 2 was analyzed by dilatometric analysis. In an experimental study, the influence of the sintering conditions on the material properties of several materials of the system Al 2 O 3 – ZrO 2 was investigated to derive suitable sintering conditions for a co-sintering of different materials. Sintering at 1650 °C for 2 h was identified as good compromise, leading to densities of more than 93 % for all materials considered and material-dependent hardness values between 1150 and 1500 HV2. The results were initially used for a monolithic sinterjoining approach, i.e., the combination of the same material but with different volume shrinkage in one component. For dimensioning, a factor j sinterjoining was defined, leading to suitable joining results of up to 99 % sintered boundary length (“Degree of Sintering”). Based on this, the joining of different materials of the system Al 2 O 3 – ZrO 2 was investigated. Although multi-material sinterjoining is significantly more complex, good results have been achieved for various material combinations showing Degrees of Sintering of more than 95 % for several combinations. In particular, the combination of Al 2 O 3 and an equal mass mixture of Al 2 O 3 and ZrO 2 (AZ50) appears to be promising. The results demonstrate the potential of sinterjoining for producing ceramic composites and serve as a starting point for further optimizations.