| The zinc-aluminum based water-soluble metallic micro-powder coating is a new type anticorrosion coating for mainly iron and steel. It appeared in the end of 1960s, and developed so rapidly because of its advantages such as anticorrosion property, no hydrogen embrittlement, less pollution and having lots of product kind of this processing that at present it holds an important place in metal finishing industry. Although it was applied widely in US, Japan and Europe, it just steps in initial stage of apply in China. The study of the zinc-aluminum based water-soluble metallic micro-powder coating is expected in be very important in both theory and practice. Existing product and current research belong to tiny powder coat with zinc fund mainly, and in coat chromium content is high. To replace hexavalent chromium in this coating and to develop it into a more "green" technology depends on studies of the coating in detail.The zinc-aluminum based water-soluble metallic micro-powder coating's process and its anticorrosion mechanism are this paper's research focal point. The components of the coating processing liquid have been provised. The preparation process of the coating has been established. Roles of each component in the zinc-aluminum based water-soluble metallic micro-powder coating and factors effecting coating's capability were studied in this thesis. Anticorrosion performances of this coating were evaluated. An anticorrosion mechanism was proposed based on the studies of coating's structure and corrosion behavior.The appearance of aluminum-zinc alloy powder were studied having the aid of SEM. Some conclusions were educed, such as the dimension of flake aluminum powder minished obviously, the dimension of globular zinc didn't minish but its shape was greater changed.Having collected plenty of information and having analysed the function of every handle liquid's composition through experiments. Wetter was found to be a key to coating preparation. It not only wetted and dispersed metal powder but also acted as reductor during the period of sintering. At the same time have compared magnetic force stir with supers-onic scatter this two metal powders the method of scattering. Because of the cavitation of the supersonic frequency of adopting, role is strong , has destroied the leaf buoyancy of metal powder and makes handling liquid stability drop , so this paper adopt magnetic force stirrer scatter metal powder.Through orthogonality experiment and interactive orthogonality experiment, have determined coat to handle liquid best prescription. And through the technology parameter of the other factor that tests to determine to affect coat performance, such as swing liquid technology parameter, dry te-chnology parameter (80C , 10 min ), sintering technology par-ameter( 300 C, 20 min).With immersion experiment and atmosphere expose tested detection the coating's anticorrosion property. Detection result showed the coating's anticorrosion property met 3 ~ 4 levels in 10 sexual level standard. This showed the coating's anticorrosion property was excellent.Reference national standard GB5270-85, using the stroke shelf method inspected the coating's strength. It got 9 mark (full mark was 10).With coat section metallographic, X-ray diffraction and scanning electrical mirror analysis method, have studied coat microscopic shape look, organization structure and the coating's composition. In coat flake form aluminium powder basically is layer upon layer overlay, zinc powder did not distribute evenly in aluminium powder, glue knoted together between metal powder. X-raydiffraction analysis result showed the main substances in the coat, including Al, Zn, ZnCr2O4, A1PO4, Zn3(PO4)2, CrO3.According to above research result had put forward the coating's anticorrosion mechanism. Divided the coating's corrosion protection for steel or iron into two stages. First stage was rampart protect stage, the flat proliferation of flake form aluminium powder for corrosion factor had lateral lead role. Second stage was sa... |
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