Mechanisms of yttrium on the wettability,surface tension and interactions between Ni-20Co-20Cr-10Al-ξY alloys and MgO ceramics

摘要

The mechanisms of Y on the wettability,surface tension,and interactions between the Ni-20 Co-20 Cr-10 Al-ξY alloys and MgO ceramics at 1873 K were investigated by sessile drop experiments.The results of nonlinear fitting showed that the equilibrium contact angles and Y concentrations were approximately in accord with the log-normal distribution law.The equilibrium contact angles changed from 101.5°to 140.5°with Y increasing from 0 wt.%to 1.23 wt.%.Cross-sectional microstructure observations revealed that the thermal dissociation of ceramics occurred and the released[O]atoms can react with Y to produce Y_(2)O_(3) reaction layer along three-phase interphase area.Wetting kinetics analyses indicated that surface tension of the melt droplets had been positively correlated with the Y concentrations,and it increased from 737.8–1045.1 mN/m.Meanwhile,the pinning effect of the rough substrate surface on the three-phase line hindered the spreading of the liquid on ceramics.The change in total free energy of the alloys/ceramics system was considered as the key factor affecting the wettability.Moreover,the surface morphology and thermodynamic stability of ceramics also had some influence on the wettability.