采用大气等离子喷涂分别以抛光的316L不锈钢和抛光的Ni Co Cr Al YTa涂层为基体依次进行7%氧化钇稳定氧化锆(7%Y2O3-Zr O2,7YSZ)粒子收集。首先研究了不同基体温度对7YSZ粒子铺展形貌的影响,其次原位观察不同基体与铺展粒子的结合形貌,使用了聚焦离子束focused ion beam进行切割;最后为进一步解释沉积粒子与不同基体的界面结合情况,采用了有限元软件ANSYS/LS-DYNA对7YSZ粒子沉积过程进行模拟。结果表明:不同类型基体的基体温度控制在250℃左右时均能获得圆盘状扁平7YSZ粒子。圆盘粒子在316L基体上铺展时边沿区域有翘曲现象,而中心区域则与基体结合紧密;圆盘粒子在Ni Co Cr Al YTa涂层基体上铺展时边沿没有翘曲现象,整个扁平粒子与基体结合紧密。另外,7YSZ粒子在2种基体上的铺展形貌ANSYS模拟结果与实际粒子沉积形貌一致。
Type Ⅰ hot corrosion behavior of SiO_2-Al_2O_3-glass composite coating based on Ti-47 Al-2 Cr-2 Nb substrate was investigated in the mixture salt of 25 wt%NaCl + 75 wt%Na_2SO_4 at 850 °C. The results showed that there was a bidirectional ion exchange between composite coating and the film of mixed salts, and the sodium ion in the molten salts penetrated into the glass matrix of composite coating, while the potassium ion in the glass matrix dissolved into the molten salts. A decrease in hot corrosion rate was achieved for the coated alloy in comparison with the bared substrate due to the composite coating acting as a diffusion barrier to sulfur and chlorine and preventing the molten salts from diffusing to the coating/alloy interface during the hot corrosion exposure. Additionally, the composite coating decreased the oxygen partial pressure at the coating/alloy interface and promoted the selective oxidation of Al to form a protective Al_2O_3 layer.
Wen-Bo LiLan-Lan LiuYing-Fei YangSheng-Long ZhuFu-Hui Wang
NiAlHf and NiAlHfCrSi coatings were deposited by electron beam physical vapor deposition(EBPVD).The grain size and orientation of NiAlHf and NiAlHfCrSi coatings were determined by electron backscatter diffraction(EBSD).The NiAlHf coating reveals a more uniform grain size compared to NiAlHfCrSi coating,while the NiAlHfCrSi coating shows a<111>preferential orientation which is parallel to the normal direction of the surface of the coating.The cyclic oxidation behavior of NiAlHf and NiAlHfCrSi coatings at 1150℃was investigated.Compared to NiAlHf coating,the NiAlHfCrSi coating shows improved resistance to cyclic oxidation and scale spallation.The effect of grain size and orientation on the cyclic oxidation behavior of NiAlHf and NiAlHfCrSi coatings were investigated at 1150℃.
