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孔隙使粉末烧结材料的机械性能低于通常冶金材料。但在润滑、过滤和消声等方面,它又起着可贵的作用。而这些作用发挥的程度又决定于孔隙组织的形态,可见对孔隙形态(包括孔隙度)的分析是十分重要的。金相孔隙组织分析直观且应用广泛,但孔隙的存在增加了制样的难度。为此,人们采用真空浸渗塑料和重复抛光、浸蚀等方法来显示孔隙,均收到一定效果。不足的是,前者对材料中的不连通孔隙(闭孔)无法充塑并且要求真空设备,操作复杂;另外在制样切割时,切割面塑变堵塞孔隙,使原来的连通孔隙(通孔)不能被完好地填充及显示。后者对抛光技术要求较高,且在密度小于6.0g/cm~3的多孔材料上孔隙显示存在失真,并随密度的降低而愈加严重。此外,多次抛光使材料中的未溶相和夹杂物严重脱落,给分析烧结扩散效果带来困难。
Pores allow sintered powders to have lower mechanical properties than conventional metallurgical materials. But it also plays a valuable role in lubrication, filtration and silencing. The extent to which these effects are exerted depends on the morphology of the pore structure. It is therefore important to analyze the pore morphology (including porosity). Metallographic pore structure analysis is intuitive and widely used, but the presence of pores increases the difficulty of sample preparation. To this end, people use vacuum infiltration of plastic and repeated polishing, etching and other methods to display the pores, have received some results. The disadvantage is that the former can not mold the unconnected pores (closed cells) in the material and requires vacuum equipment, and the operation is complicated. In addition, during the sample preparation, the cutting surface is plasticized to block the pores so that the original communication pores (through holes) can not Well filled and displayed. The latter requires high polishing techniques, and the presence of porosity on porous materials with a density of less than 6.0 g / cm ~ 3 shows distortion and becomes more and more severe as the density decreases. In addition, multiple polishing makes the material undissolved phase and inclusions serious off, to analyze the sintering diffusion effect difficult.