【作者】 杨保军；

【导师】 奚正平； 汤慧萍；

【作者基本信息】 西安建筑科技大学 ， 材料学， 2008， 硕士

【摘要】 随着近代工艺的发展,在过滤分离行业中对金属多孔材料的要求具有较高的过滤精度、较大透气系数。但是传统孔结构的金属多孔材料过滤精度与透气系数是一对此消彼长的矛盾,梯度孔结构的金属多孔材料可以较好的实现高精度一大透气。其结构特点是在粗大孔径的金属多孔基体上附着一层小孔径梯度层,大孔径的金属多孔基体可保证材料有大的透过能力,梯度层使材料具有较小的孔径、较高的过滤精度。但是目前对梯度金属多孔材料的研究还处于一个起步阶段,尤其是离心沉积制备技术制备工艺,工艺参数对材料性能的影响,以及梯度层与基体的匹配性研究相对较少,而这些问题影响着梯度金属多孔材料的广泛应用,急需解决,因此本文围绕这些问题展开研究工作。本文采用离心沉积技术制备梯度金属多孔材料,以Φ50×20×2mm(直径×长度×厚度),中流量平均孔径为10.2μm,透气系数为120m~3/m~2·Kpa·h的金属多孔材料作为基体,聚乙烯醇溶液作为分散剂,球形不锈钢粉末和镍粉作为梯度层粉末,初步探讨了离心沉积制备梯度层的成形工艺条件以及工艺参数对梯度金属多孔材料性能的影响。着重研究了梯度金属多孔材料梯度层与基体的匹配性以及梯度层最佳匹配厚度。结论如下:1.采用离心沉积技术制备梯度层的工艺条件为:当在分散剂浓度为5%,离心机转速为不得小于2000rpm,离心沉积时间不得小于3min;当离心机的转速为5000rpm时,分散剂的浓度不得小于4%。2.在离心机的转速为5000rpm,分散剂浓度为5%的试验条件下,沉积时间对梯度层的最大孔径没有影响;在离心机的转速为5000rpm,离心沉积时间为5min的试验条件下,随着分散剂的浓度的增大,梯度金属多孔材料最大孔径和透气系数同时增大,但是透气系数变化不显著。3.根据试验结果,对于中流量平均孔径为10.2μm的金属多孔基体而言,采用离心机的转速为5000rpm,分散剂浓度为5%,的沉积时间为5min的制备工艺,制备最佳匹配梯度层粉末粒度应当小于16.3μm,大于0.2。4.采用离心沉积技术制备梯度金属多孔材料,在离心机转速为5000rpm,分散剂浓度为5%,沉积时间为5min的试验条件下,在中流量平均为10.2μm的金属多孔基体管内制备的梯度层存在最佳匹配厚度,且与粉末粒度和基体中流量平均孔径存在如下关系:h=6D_p+D_m更多还原

【Abstract】 It is requirements of porous metals with high accuracy of the filter and the good permeability in the filter separation with the development of modern technology.But high filter accuracy and good permeability is the illogicality in the tradition porous metals,Gradient porous matel can be very easy to solve this contradiction by structural innovation.The pore structure of gradient porous metals is that a high porous metal offering good permeability is used as a substate on which thin layers with lower and finer porosities are applied by coating the substate with a layer. However,it is the still in a preliminary stage in study on the gradient porous metals, especially in study on preparation of centrifugal deposition process,process parameters infection on the properties of metals and gradient layer matching with the substrate was scanty,The urgent solution of those problem was studied on this paper.This paper prepared by centrifugal technology Gradient metals deposition porous materials toφ50×20×2mm(diameter×length×thickness),the mean flow pore size of 10.2μm,permeability of 120 m~3/m~2·Kpa·h metal porous material as the substrate,Polyvinyl alcohol solution as a dispersant,spherical stainless steel powder and nickel powder as the gradient layers powder,.Preliminary study of the centrifugal deposition gradient of the forming process conditions and parameters of the gradient of metal properties of porous metals.Focusing on the gradient porous metal’s gradient layer match the substrate and the best matching thickness of gradient layer.The conclusions as following:1、The gradient layer would not prepared by centrifugal deposition when the suspension concentration less than 4%,the centrifugal speed under 2000rpm and deposition less than 5min。2、Moreover,with the suspension of the increase in the concentration membrane of maximum pore size and permeability increased at the same time,but the permeability coefficient changes are not very obviously.Gradient layer porosity in the same condition,with the powder particle size increases.The same size of the powder porosity increased with decreasing speed centrifugal. there is no influenced on maximum pore size but influenced on the permeability of Membrane when the deposition time more than 3min.3、In the same substance of porous metal tube,on the experiments of suspension concentration is 5%,centrifugal speed is 5000rpm and deposition time is 5 min,there is an optimal thickness of gradient layer which is preparation of centrifugal disposition.and the optimal thickness with powder size and the mean flow pore size of substance are as follows:h＝6D_p +D_m更多还原