【摘 要】
：
Chromate has been in use as a passivator in the preparation of Zn-Al coating for long time,however,they are target of great criticism and could be definitely banned in the near future.As a result,some
【机 构】
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Wuhan Research Institute of Materials Protection, Wuhan 430030, China;State Key Laboratory of Specia
【出 处】
：
第十一届全国表面工程大会暨第八届全国青年表面工程学术会议
论文部分内容阅读
Chromate has been in use as a passivator in the preparation of Zn-Al coating for long time,however,they are target of great criticism and could be definitely banned in the near future.As a result,some alternatives to chromate has gradually been used to prepare the non-chromium Zn-Al coating,such as phosphate,silicate,molybdate and tungstate.The actual alternatives show pros and cons when sets of key properties considerated like :surface,hardness,adhension of coating to the substrate and corrosion resistance.Phosphate,silicate,molybdate has been studied more in the last few years,there are few report about tungstate as passivator in the preparation of non-chromium Zn-Al coating.This paper will give a brief introduction of the infuence of tungstate on the properties of Zn-Al coating. The present work focus on the praparation of non-chromium Zn-Al coating using tungstate, then the influence of tungstate addtion on the surface,pencil hardness,adhension and corrosion resistance of the coating were tested respectively by Super depth 3D stereo microscope,pencil hardness test,grid method,neutral salt spray test and electrolchemical workstation.The results show that when the addtion amout of tungstate is small,the corrosion rate of coating increases due to "activation passivationbattery result from incomplete passivation film.When the addition amount is 2%,the coating has good coprehensive property.At the presence of tungstate addtion amount over 2%,the pencil hardness as well as corrosion resistance of coating decreases because that the uniformity of coating becomes worse,leading corrosion media outside to invade the coating easily .
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