Gel Casting of 316L Stainless Steel Powder Through Mold DIS Process

This paper presents the gel casting of metal powder by agar gelation through mold decomposed injection sculpture (DIS) process: verifying the feasibility and improving the processing parameters to prepare stable metal slurry and strong green body. The optimal processing parameters were achieved after investigating the effects of these parameters such as temperature, agar content, dispersant concentration, and solid volume loading. The rheological behavior of metal slurry and the character of formed green body were also investigated. The mixture and dispersion mechanism of metal slurry as well as the consolidation forming and sintering technology of green body were studied based on analysis of experimental results. The results show that the optimal pH range is 8.5-9.5 with the grain size distribution of 2-30 μm and 55% solid suspension, which can be prepared by adding proper dispersant (Polyvinyl Alcohol). The agar and dispersant content has great effect on the properties of slurry. When 1.0 wt.% dispersant and 0.7 wt.% agar content (referred to dry solid) are adopted, stable metal slurry with viscosity less than 1 Pa · s and green body with bending strength of 2.7 MPa are obtained. The sintered bodies with uniform structure, relative density of 90%, and yield strength of 150 MPa are prepared at 1300°C/30min in vacuum. This process can be applied in rapid prototyping of complex shape metal products such as rotor blades.