Interface Modifications And Joint Performance Of Ceramic Composite Membrane On Porous Stainless Steel

Ceramic composite membranes supported on porous metal not only have plasticity,toughness and strength of the metal, but also have the stability of ceramic,so the ceramiccomposite membranes supported on metal have received widespread concern. However, dueto the differences of thermal expansion coefficients of the two materials, there is obviousinterface between metal and ceramic, and it severely weakens the joint strength between themetal and ceramic. Soldering is often used to enhance the joint performance between denseceramic and stainless steel. For combination of porous metal and ceramic, there is no feasiblemethod. In this study, we derived copper doping Ni brazing layer between porous stainlesssteel substrate and Al2O3membrane, and doping Ni in Al2O3membrane layer improve theinvasion, and derived iron oxide connecting layer to modify interface and to alleviate theperformance differences of the two kinds of materials.We explored the synthesis technologyof preparing connecting layer and the membrane technology; we used XRD to analyse phasestructures of composite membranes with copper doping Ni layer; the adhesion strength withjoint layer or doping element were determined by scrcatch method. The main results werelisted as follows:1. The optimum conditions to prepare Al2O3membrane layer with doping elements werelisted as follows: The sintering atmosphere is chosen as air-nitrogen two-step method; theoptimum binder was PVA; the atmosphere of N2changing temperature was550℃; thecoating times of the membrane was one time. The joint strength between membrane andsubstrate is7.0N, and the contrast is4.8N, so the joint strength increased45.8%.2. The optimum conditions to prepare copper alloy connecting layer with dopingelements were listed as follows: the optimum binder was PVA; the atmosphere of N2changing temperature was550℃; the coating times of the membrane was one time. Theresults showed that CuAl2O4and CuFe2O4were generated in composite membrane beforereduction. After reductions at400℃and600℃, CuAl2O4were reduced completely, whileCuFe2O4were gradually reduced. FeCu4alloy formed after reduction at600℃. However,CuFe2O4were almost reduced completely at800℃. The joint strength between membrane andsubstrate were between20.2N and26.5N berfore reduction or after reducion at different temperatures, and reduction or not has slightly effect on joint strength. The joint strengthbetween membrane and substrate before reduction increased441.6%.3. The optimum conditions to prepare iron oxide connecting layer were listed as follows:the sintering atmosphere is chosen as air-nitrogen two-step method; the atmosphere of N2changing temperature was550℃; the coating times of the membrane was one time. The jointstrength between membrane and substrate increased270.8%.