Exploration Of Heat-resisting Coating Preparation On Hot-work Die Material By Powder

Mold is an important equipment in industrial production, and a large number ofparts are produced by the mold. Life of the mold has a significant impact on the costand quality of the parts, however, the life of the mold is low in our country, especiallyfor hot mold.The service performance of the mold can be improved through thesurface enhancement technology, and die life also has been enhanced. Hot diesservice under the combined effects of thermal load and mechanical load, so their lifesare usually low; It has a significant impact on reducing costs and improving thequality of components by surface hardening technology to improve the life of hot die.Hot-work dies ocurr thermal oxidation and hot corrosion under the effect of heat,which accelerates invalidation of mold. The alumina of the mold surface is denseoxidation, which can stop further oxidation. Heat resistance of mold can be improvedby aluminizing on surface of mold. The performance of single aluminizing isrelatively simple, and its application has been limited. The performance ofaluminizing coating can be improved by chromium and silicon with raising the heatresistance of coating and obtaining better comprehensive properties. The preparationof aluminide coating through solid powder embedding method has some advantages,such as simple equipment, convenient operation and cost, which is considered to beone of the ideal surface strengthening technology.In this paper, aluminum-chromizing, aluminum-chrome-siliconing has beenexplored on common hot-work die steel H13surface by powder embedding method.An ideal formula and technological parameters has been preliminarily determined bycomparative studies and high temperature thermal oxidation behavior of the coatingshas been explored. The main works in this paper include:1. Consisting of43wt.%Al2O3+5wt.%AlF3+17wt.%Al+35wt.%Cr2O3is anideal formula for aluminum-chromizing. Consisting of43wt.%Al2O3+5wt.%AlF3+17wt.%Al+28wt.%Cr2O3+7wt.%SiO2is an ideal formula for aluminum-chrome-siliconing. An ideal parameters is T=980℃、t=4h for aluminum-chromizing andaluminum-chrome-siliconing; 2. Compared with the untreated sample, surfaces of the coating have largerchange, thickness of the coatings is about15μm, and hardness of the coatings is about700HV0.05. The coating of aluminum-chrome-siliconing is composed of theelements such as aluminum, chromium, silicon;3. The coatings of aluminum-chromizing and aluminum-chrome-siliconing andhave better wear resistance and corrosion resistance than the substrate material H13.The wear resistance and corrosion resistance of aluminum-chromizing andaluminum-chrome-siliconing is hardly the same.4. The coatings degraded by oxidation of T=800℃for4hours, but comparedwith substrate material, oxidation of the coatings can be ignored.The coating canimprove the heat resistance of the substrate material, and the heat resistance ofaluminum-chrome-siliconing is better than aluminum-chromizing.