| In recent years,the traditional fossil-fuel power station was gradually replaced by ultra-supercritical due to the advantages of low coal consumption and less pollutants emission.However,in the environment of high temperature and high speed fly ash,the lifespan of supercritical units(such as the sounding horn of the ultra-supercritical high-strength sonic ash removal equipment)faces great challenges.In order to solve this problem,the high temperature oxidation resistance and high temperature wear resistance of high temperature alloy materials must be studied and optimized in process.In this thesis,we mainly use plasma spraying technology to improve the high temperature resistance of alloy.First of all,we use the orthogonal test to design and optimize of technological parameters of plasma spraying,and finally fabricate three kinds of coating(NiCoCrAlY,NiCoCrAlY-Al2O3 and NiCoCrAlY-ZrO2)in 253 MA heat-resistant austenitic stainless steel substrate surface.Secondly,high temperature oxidation experiment,high temperature friction and wear test and high temperature plasma erosion test were carried out to simulate the actual operating conditions of the ultra-supercritical,respectively.At the same time,XRD,SEM and EDS characterization were conducted to study the oxidation mechanism,the wear mechanism and the mechanism of erosion resistance,assessing the antioxidant property of coatings by calculating,exploring the improvement of high temperature performance about substrate with coating.Our research provides a theoretical reference to the application of 253MA in the sounding horn of the ultra-supercritical high-strength sonic ash removal equipment.The final experimental results show that the bonding strength of the coating prepared by the optimized process parameters was improved before the optimization about 10.98%,4.35%and 11.08%.In addition,these three coatings all improved the high temperature performance of the substrate.The ZrO2 coating had the highest high temperature performance improvement of the substrate.The wear rate of substrate was reduced by 24%at 600 ℃.The highest rate of antioxidant property had been achieved at 800℃.The oxidation weight gain of substrate was reduced by 29%and the erosion weight gain was reduced by 57%at 1000 ℃. |
