Jianhua Xiang

An Innovative Fabrication Process of Porous Metal Fiber Sintered Felts with Three-Dimensional Reticulated Structure

A novel porous metal fiber sintered felt (PMFSF) with a three-dimensional reticulated structure has been produced by the solid-state sintering of copper fibers. The copper fibers, with several microstructures distributed onto the surface, were fabricated using the cutting method. The Scanning Electron Microscope (SEM) results revealed that there were two kinds of sintering joints present in the PMFSFs: fiber-to-fiber surface contact and crossing fiber meshing. In the sintering process, the surface microstructures of the fibers helped to improve the forming process of the PMFSFs, as a result of high surface energy. Furthermore, the effect of different sintering parameters on the forming process of the PMFSFs was studied in detail, including the sintering temperature and holding time. The sintering temperatures had a significant influence on the surface microstructures of single fiber and specific surface area of the PMFSFs, but the holding time did not. The optimal PMFSF with a three-dimensional reticulated structure and larger specific surface area was produced by sintering copper fibers at 800°C for 30 minutes in the reduction atmosphere.

Compound forming technology of outside 3D integral fin of copper tubes

Abstract Using rolling-ploughing-extrusion compound processing methods, a 3D integral-fin structure on outside surface of red copper tube with diameter of 16.0 mm and wall thickness of 1.5 mm was obtained. When both rolling depth and ploughing-extrusion (P-E) depth were 0.2 mm, rotating speed was 50 r/min, feed speed was 0.16 mm/r, 3D fin structures with height of 0.25 mm were gotten. Two different fin structures were obtained in grooves formed with rolling-ploughing-extrusion compound forming technology and observed by scanning electron microscope(SEM). One is the compound structure with V-shaped groove and U-shaped groove, and the other is the single structure with V-shaped grooves. Two kinds of groove structures obtained by rolling processing and ploughing extrusion processing are restricted together by groove interval and rolling depth, and pitch and P-E depth, respectively. Based on the analysis of interaction of rolling and P-E processing, it is found from the result that the outside 3D integral-fin can be achieved by rolling-ploughing-extrusion compound processing when single V-shaped groove structures are formed by both rolling and P-E processing.