Research Of Chlorine Corrosion And Erosion Resistance On Precursor-derived Ceramic Coating

Chlorine corrosion is a serious problem in biomass boiler and refuse incinerator.In order to solve this problem,polysilazane was used as precursor,glass powder and zirconia were added as fillers to prepare composite ceramic coating on TP347 substrate.In this paper,the pyrolysis of polysilazane was studied by TG and FTIR,the effect of temperature and fillers on coating structure was studied by microscopic analysis.The corrosion and erosion resistance of coating were also tested.TG-FTIR experiments show that the pyrolysis of polysilazane can be divided into two stages,the first stage from room temperature to 500 ℃,which separate out ammonia,the second stage between 500 ℃ and 700 ℃,which separate out methane in nitrogen atmosphere and methane,carbon monoxide,carbon dioxide,water in air atmosphere.The yield of ceramics is higher and the temperature requirment for pyrolysis is lower when pyrolysis in air atmosphere.The pyrolysis process conforms to the first-order kinetic model,and the most suitable mechanism function is f(a)=(1-a).Glass powder can improve the critical thickness and hardness of the coating,but the coating with glass powder is easy to produce large pores in sintering process,which can avoid by adding inert fillers such as zirconia and increasing sintering temperature.The The formulation of the best structure coating was obtained through experiments,and the corrosion test of the coating was carried out.corrosion test shows that the HCl corrosion resistance and KCl corrosion resistance of the coated samples are better than TP347 substrate.The HCl corrosion resistance of the coating is 7.4 times,3.1 times and 3.2 times higher than TP347 substrate at 500 ℃,525 ℃ and 550 ℃ respectively.However,the glass powder will soften at high temperature.When testing temperature exceeds glass softening temperature,the corrosion resistance of the coating will decrease.Therefore,the working temperature of coating should be controlled under the glass powder softening temperature as far as possible.The coating has good resistance to friction and erosion.The erosion resistance of coating is slightly lower than substrate at room temperature and 400 ℃.With the increase of temperature,the erosion resistance of the coating is gradually enhanced,even exceeding substrate.