Rapid Sintering Process Of Stainless Steel Fiber Porous Material And Its Influence On Tensile Properties

Porous stainless steel fiber material is a kind of important structural-functional material,with a three-dimensional network structure and random distribution of fibers,thus,it can be widely used in the fields of filtration and separation,sound absorption and noise reduction,damping,high efficient combustion,electronic magnetic shielding and heat transfer and so on.The three key components of porosity,sintered joint,fiber ligament are the basis of integration and diversification of structure and function of porous metal fiber materials.Porous stainless steel fiber materials prepared by traditional furnace-temperature sintering process can ensure the formation of strong sintered joint,however,the grains in fiber ligament grow abnormally,leading to significant reduction in corrosion resistance,which limits the wide application of the porous fiber materials.Therefore,the formation process and mechanism of sintered joint of porous fiber material need to be studied further to optimize the preparation process and achieve the coordinated control of sintered joint and fiber grain size,and finally to improve properties of porous fiber material.In this paper,Φ28μm 316L stainless steel fibers prepared by bundle drawing were chosen as the raw material.Porous stainless steel fiber materials were prepared by rapid sintering process.The microstructure of fiber ligament and sintered joint were characterized by optical microscope(OM),Scanning electron microscope(SEM)and synchrotron radiation X-ray computed tomography(SR-CT)technique,respectively.The influence of sintering process on grain size in fiber ligament and the formation process of sintered joint were discussed.Moreover,the neck-growth mechanism was also revealed.The tensile properties of single stainless steel fiber and porous stainless steel fiber materials were tested by universal testing machine,and the influence of sintering process on the tensile properties was discussed.The results are shown as follows:(1)To form the uniform sintered size,rapid sintering process needs far less time than traditional furnace-temperature sintering process.(2)The dominant neck-growth mechanism of sintering initial stage is dislocation diffusion.In the late period of sintering,both the dislocation diffusion and surface diffusion become the dominant neck-growth mechanism.(3)The appropriate sintering condition for porous stainless steel fiber felts is determined to be sintered at the temperature 1100℃ for 10～20min.