| In this paper, arc ion coating was used to prepare coating on 304 stainless steel, 7Cr7Mo3V2 Si steel and W6Mo5Cr4V2 steel. Ti Al N monolayer coating, Ti Al N/ nitriding double layer composite coating were prepared on 304 stainless steel; Cr N monolayer coating and Ti Al N monolayer coating were prepared on LD steel; Ti Al N monolayer coating and Ti N coating were prepared on W6Mo5Cr4V2. This paper tried to find coatings having excellent composite properties. To achieve this goal, several properties were examined such as microstructure, macro profile, phase analysis, corrosion resistance, abrasive resistance, high temperature oxidation resistance and so on.According to the results of scanning electron microscope, we can find that Ti Al N coating prepared on 304 stainless steel had good combination with the substrate, and no obvious defects were observed. At the same time, there was elements interdiffusion between coating and substate. For the sample of Ti Al N/ nitriding double layer composite coating, there was a transition layer between Ti Al N and the substrate, for which surface microhardness of the composite coating reached 1700 HV, while that of Ti Al N monolayer coating is only 390 HV. High hardness makes the double coating possess excellent abrasive resistance, while the monlayer coating only show a litter more abrasive resistance than substrate. 304 austenitic stainless steel has a good corrosion resistance for its high corrosion potential. In order to further improve its anti-corrosion, Ti Al N coating has a litter corrosion current and a lower corrosion rate compared to substrate, and its main corrosion means is pitting corrosion. Unfortunately, corrosion potential of nitriding/ Ti Al N double layer composite coated 304 decreased, and the corrosion morphology is more severe.LD-Cr N and monolayer coating had good combination with the substrate. The coating thickness was 2 um. The hardness of the Cr N coating was up to 1188 HV and the hardness of the Ti Al N coating was up to 1496 HV that was twice the matrix. The Ti Al N coating high hardness, high wear resistance. The surface of LD had a lot of corrosion products, mainly intergranular corrosion and the corrosion resistance was poor. The corrosion current of the Cr N and Ti Al N coating were decreased, and higher corrosion potential than that matrix,so the corrosion resistance was better than the matrix. The coating is mainly pitting corrosion way.Through the coating section morphology of M2-Ti N and Ti Al N observated, coating had good combination with the substrate, and no obvious defects. The hardness of the Ti N coating was up to 1397 HV and the hardness of the Ti Al N coating was up to 1496 HV that was more than the matrix of 270 HV. Ti Al N coating has good wear resistance. The wear of surface had crack coating cracking along that, but had yet to fall off. The wear surface of Ti N coating had very deep furrows and the ground pit which the ground location of fall off. From 500 ? to 900 ? in the XRD spectrum we can know that the surface of Ti N coating produced Ti O2 and nitrogen-atoms in the form of nitrogen had escaped the coating surface at 700?. At 800 ?the coating surface generated the ferric oxide, oxygen had entered the matrix and reacted with substrate, in result of coating failed. At 900 ? Ti Al N coatings product Ti O2. Microscopic surface show that many oxidation products unite together. The surface had no nitrogen and coating lost the protection effect of matrix and the failure occurred. |
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