粉末特性对多孔不锈钢制备工艺和结构的影响

以凝胶注模工艺为基础,结合微波烧结技术,制备了形状和孔隙可控的多孔不锈钢材料。采用扫描电子显微镜、密度仪、抗弯实验等手段研究了粉末粒径、粉末形状、固相含量等特性对多孔不锈钢制备工艺和孔隙形貌、孔隙率的影响。结果表明:粉末粒径越小,形状因子越大,胶体固相含量越高,制备得到的多孔不锈钢的孔隙率越高;粉末形状因子越小,多孔不锈钢的孔隙越不均匀;固相含量越高,虽然坯体强度有所提高,但凝胶体系的粘度也越大,流动性较差,适合不锈钢粉末凝胶注模的最佳固相含量在58%左右。通过控制颗粒直径、颗粒形状、固相含量及采用颗粒级配的方法,可实现对凝胶注模制备多孔不锈钢的孔隙结构和孔隙率的有效控制。

Powder Characteristics Impact on the Preparation Process and Microstructure of Porous Stainless Steel

This work prepares a kind of porous stainless steel with the shape and porosity under control by combining the technologies of gelcasting and microwave sintering. Scanning electronic microscopy (SEM),densimeter and bending test were employed to investigate how the powder characteristics including diameter ,shape and solid content impact on the processing ,porous morphology and the porosity. The results show that smaller powder diameter ,higher shape factor or more solid content leads to higher porosity. Smaller the powder shape factor ,more uneven the porous microstructure is. Although the strength of green body improves with the solid content increasing ,a higher viscosity and poor mobility of the gel is achieved correspondingly. The appropriate solid content of stainless steel powder for gelcasting is about 58 %. The porous microstructure and porosity of the porous stainless steel can be controlled by configuring the powder size,powder shape,solid content and particle gradation.