Properties of Slurry and Green Body for Gel Casting of Stainless Steel Powder by Agar

The optimal processing parameters have been achieved after investigating the effects of these parameters,such as temperature,agar content,dispersant concentration,solid volume loading,etc..The rheological behavior of metal slurry and the character of formed green body have also been investigated.The mixture and dispersion mechanism of metal slurry,the consolidation forming and sintering technology of green body have been preliminary studied based on analysis of experimental results.The results showed that the suspension with 55% solids could be prepared by adding proper dispersant(polyvinyl alcohol) by using 316L stainless steel powder with grain size distribution 2~30 μm when the optimal pH range was controlled between 8.5~9.5.The agar and dispersant content had great effect on the properties of slurry: when 1.0% dispersant(referred to dry solid) and 3.0% agar(referred to water) content were adopted,stable metal slurry with viscosity less than 1 Pa·s and green body with bending strength of 2.7 MPa could be obtained.The sintered bodies with relative density of 90% and bend strength of 150 MPa,have been prepared at 1 300 ℃/30 min in vacuum.