TiAl合金表面等离子喷涂MCrAlY涂层热腐蚀行为研究

研究TiAl合金表面等离子喷涂NiCoCrAl-Y2O3涂层在850 ℃下对75%Na2SO4+25%NaCl熔盐的热腐蚀行为，及对TiAl金属间化合物抗高温热腐蚀性能的影响。研究表明，在850 ℃，等离子喷涂NiCoCrAl-Y2O3涂层由于生成Cr2O3，NiO和NiCr2O4等各种氧化物组成的氧化层，显著提高了TiAl基体的抗热腐蚀性能。在热腐蚀过程中，S元素以Ni元素为载体，逐步渗入涂层中，生成过渡产物Ni3S2。随着O分压的升高，反应进入了氧化阶段，生成Cr2O3、NiO等氧化物，随着两种物质含量的增加，最后发生固相反应，生成尖晶石结构的NiCr2O4化合物。过渡产物Ni3S2与腐蚀介质中的Cl-离子形成微电池，可以加快热腐蚀反应速度

Study on Hot Corrosion Behavior of Plasma-Sprayed NiCoCrAl-Y2O3 Coating on TiAl Alloy Surface

The hot corrosion behavior of plasma-sprayed NiCoCrAl-Y2O3 coating on TiAl alloy surface in the mixed melted salt of 75%Na2SO4+25%NaCl at 850 oC for 100 h and the influence of the coating on the anti-corrosion properties of TiAl intermetallics were investigated. The results show that the plasma-sprayed NiCoCrAl-Y2O3 coating could remarkably improve the hot corrosion resistance of TiAl matrix by generating a compound oxide layer of Cr2O3, NiO and NiCr2O4. In the course of hot corrosion, S, carried by Ni, gradually infiltrated into the composite coating and generated a transition product of Ni3S2. Then the partial pressure of the oxygen increased, followed by oxidation which produced oxides including Cr2O3 and NiO. As the amount of the both oxides increasing, the solid-state reaction took place and generated the NiCr2O4 compounds of spinel structure. The transition product of Ni3S2 and the chloridion contained in corrosion media jointly constituted micro-cell, thus accelerating hot corrosion