Investigation On Thermal Diffusion Zinc Coatinganticorrosion Technology

Thermal diffusion sherardizing is widely used by its good rust-resistance, whichwas developed as a new metal surface disposal technology at beginning of last century.Sherardizing is a thermal chemical process which the steel parts to be treated areheated in contact with zinc dust and thereby allowing the zinc to be absorbed onto thesteel surface via diffusion to form a sherardized coating. Sherardized coating isclaimed to be the hardest of all zinc coatings. This paper mainly introduced thesituation of sherardizing industy both domestic and overseas. Fundamental theory ofcorrosion, principle and techics of sherardizing and results of improvement are alsointroduced.The process of sherardizing is pervasion of solid state with long time reactionand low speed. This paper main work is discussing how to improve the techics ofsherardizing with the hope of increasing efficiency and quality. Nano technology ispaid more and more attention as a new study field. With the study going on, lots offantastic performances of it appeared. At the same time, surface nanocrystallizationhas been used in many aspects as a new way of suface disposal especially by itsadvantage in reducing of temperature and time of sherardizing. This paper mainlytalked about the application of nano technology in the improvement of sherardizingmaterials and suface quality of workpieces.The influences of nano zinc powder and rare earth in the sherardizing materialson the conventional sheradizing technology were investigated through changing thesize of ingredient to the degree of nano magnitude in this paper. The influence to layerthickness, rust resistance and friction resistance are also expounded. Experimentsshow that layer has higher average hardness after adding nano powders. Frictionresistance is improved well only by adding nano rare earth. Results is that layerthickness, rust resistance and friction resistance are also expoundedThe workpiece is nanocrystallized in advance because of the theory which thedensity of grain boundaries in the surface nanocrystallization layer is very high andthe grain boundaries are the channels for quick diffusion and transfering atoms. Thispaper mainly discussed its influence to the layer thickness, temperature and time of heatpreservation. So did the effect of additive to it. Experiments show thatnanocrystallization layer is more sensitive to the pervasion. The effect of time to the...