Optimization of the layer quality by TiC nanoparticles in the ultrasonic excited recoating process with non-spreadable AlSi10Mg matrix B4C particle-powder composites for powder bed based additive manufacturing

High-strength and stiffness materials can further increase the lightweight construction potential of additive manufacturing. One way to achieve this, is to produce particle-reinforced aluminum matrix composites (PAMCs). A significant increase in strength can be achieved with ceramic particles smaller than 6 μm and a volume fraction of 20 to 30 % in other metallurgical processes. Due to the larger interparticle forces compared to the gravitational force, such powder mixtures are not flowable and cannot be recoated in PBF-LB with static recoaters like rubber lips and metal blades. Two approaches were compared to solve this problem. Firstly, the new broadband ultrasonic excitation of the recoater metal combs and secondly, flow enhancing with nanoparticles. The influence of the approaches was investigated by image analysis of the recoated layers for defects in an SLM 280 HL 1.0. Broadband vibration enables reliable recoating of AlSi10Mg powders mixed with up to 20 vol% 6 μm boron carbide particles without layer defects. Combined with TiC nanoparticle coating, 25 vol% are possible. The solution can securely be operated in build jobs.