琼脂凝胶注模成形不锈钢粉末浆料与生坯的性能

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

研究温度、琼脂质量分数、分散剂质量分数、固相体积分数等因素对浆料流变性质和生坯力学性能的影响规律,获得最优的凝胶注模工艺参数.在此实验研究基础上,对金属浆料的混合、分散、凝胶机理和生坯的烧结过程进行初步分析和探索.研究结果表明：粒径分布为2~30μm的316L不锈钢粉末,应用聚乙烯醇为分散剂,控制溶液pH值为8.5~9.5,可以制备固相体积分数达55%的悬浮液;琼脂和分散剂质量分数对浆料流变性质的影响显著,采用质量分数为1.0%的分散剂（相对于干燥的金属粉末）和3.0%的琼脂（相对于水）,可以制备表观粘度小于1 Pa.s的性能稳定的金属浆料,干燥后可得到抗弯强度达2.7 MPa的生坯;在1 300℃真空烧结30 min,可以制备相对密度为90%,抗弯强度为150 MPa的组织较均一的烧结试件.

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.