尿素含量对泡沫不锈钢孔隙率和力学性能的影响

Effect of carbamide content on porosity and mechanical properties of stainless steel foam

采用20 vol%~80 vol%的尿素作为造孔剂制备了泡沫不锈钢。研究了尿素含量对泡沫不锈钢孔隙率、显微组织和力学性能的影响。结果表明:在1200℃下烧结5 h,泡沫不锈钢的孔隙率为18.33%~72.24%。随着尿素含量增加,生坯致密度和烧结体积收缩率增大。在尿素含量大于60 vol%时,烧结体积收缩率骤增。建立了预测孔隙率θ的模型:θ=(ψ-1)p/1-η+1,实现了对尿素含量介于0~1的孔隙率的预测。泡沫不锈钢的晶粒尺寸随着孔隙率的增加而减小,多孔结构可以有效抑制晶粒长大。泡沫的压缩屈服强度在低孔隙率时比Gibson-Ashby模型的预测值高,对模型进行修正后可以准确预测泡沫的压缩屈服强度。

20 vol%-80 vol% carbamide was used as space holder to prepare stainless steel foam. The effects of carbamide content on porosity, microstructure and mechanical properties of the stainless steel foam were studied. The results show that the porosity of the stainless steel foam sintered at 1200 ℃ for 5 h is between 18.33% and 72.24%. With the increase of carbamide content, the relative green density and volume shrinkage increase. When the carbamide content is more than 60 vol%, the volume shrinkage increases sharply. A model for predicting porosity θ is established: θ=(ψ-1)p/1-η+1, and the prediction of porosity of the specimens with carbamide content between 0 and 1 is realized. The grain size of the stainless steel foam decreases with the increase of porosity, indicating that the porous structure can effectively inhibit grain growth. The compressive yield strength of the stainless steel foam is higher than the predicted value from the Gibson-Ashby model at low porosity, and it can be predicted more accurately by modifying the model.