The Study Of Powder Metallurgy Materials With Corrosion Resistance To Zinc Liquid

Giant expense may be resulted from the corrosion of iron and steels. Hot-dip galvanizing, as one of the basic protective means, is playing an important role in reducing this kind of loss.The heating problem for zinc coating pot has never been satisfactorily solved in the hot-dip galvanizing industry, which produces such serious problems as high consumption of energy and Zinc, short life of devices, environment pollution, bad working conditions, etc., thus greatly hampering the development of hot-dip galvanizing industry. The immersion heating technique with the zinc holding ceramic pot is one of the ways to solve the difficult above-mentioned problems.But the material of outer cannula with resistance to zinc corrosion is the key factor of this technique. And the application and generalization of the immersion heating technique has been restricted greatly due to the lack of this ideal material presently. Hence, this thesis studies this kind of material thoroughly and deeply and at length has developed the ideal materials with corrosion resistance to liquid zinc.Firstly, the corrosion mechanism of zinc liquid to steel materials is studied, then the materials with corrosion resistance to zinc are selected on the basis of theory and former studies, and defines Fe-B-(Mo,W,Cr) as the studied materials with corrosion resistance to zinc in the endSecondly, this thesis pays much attention on the preparing method of powder metallurgy and its capability of resisting the corrosion of zinc liquid.During preparing the materials by the method of powder metallurgy, sintering technics, the key process, is studied deeply. After a great deal of experiments, the sintering technics, sintering course and influencing factors of preparing the materials with corrosion resistance to zinc are summed up. This paper points out that the studied materials are sintered in a way of reactive liquid phase sintering and in which the influencing factors contain sintering temperature, sintering time, heating rapidity and added elements. The dense sintered specimen can be prepared by reasonable sintering technic and rational added elements.After many experiments of corrosion resistance to zinc liquid, the results show that the service lives of Fe-7B-30Mo and Fe-7B-13Mo-6Cr alloys with sound properties of corrosion resistance to zinc and application can reach 2.5 ~ 5 years in zinc liquid, which is much higher than that of boronized materials, inorganic nonmetallic materials and iron base materials which can only be used several months. The cost of each pipe can decrease by more than 6000 yuans, the applied temperature can increase by 800癈 compared to W-Mo alloy although their lives of corrosion are equivalent. Therefore, the studied alloys can meet the necessities of most factories due to its lower cost and super properties. Then they are of extensive applicable prospect.