| In this paper,combined with the harsh working conditions of aero-engine core thermal parts and the excellent high temperature protection performance of glass-ceramic coatings,a glass-ceramic composite coating containing nano-nickel powder was prepared on the surface of nickel-based alloy GH4586 for aerospace engines by flow coating method.Layer:Ni/B2O3-A12O3-Ba O-Ce O2（N/BABC）.Using DSC,XRD,SEM/EDS,constant temperature oxidation experiment,high temperature thermal shock experiment,plasma flame ablation experiment and other test methods,the effects of different nucleating agents and different heat treatment processes on B2O3-A12O3-Ba O-Ce O2（BABC）base glass were studied.The effect of crystallization behavior and the effect of base glass crystallization behavior on the high temperature protective performance of composite coatings.The following conclusions were obtained:（1）Both the nucleating agent and the heat treatment process will affect the crystallization behavior of BABC base glass.When 4wt.%Zr O2is used as the nucleating agent,the crystallization effect of the glass is the best.Compared with the one-step crystallization process,the two-step crystallization process can improve the crystallinity of the glass-ceramic to a certain extent,but there is no difference in the types of precipitated crystal phases.（2）Glass-ceramics with different degrees of crystallinity show high hardness and density.When the crystallinity reaches 45%,the density of the glass-ceramic is 3.89g/cm3,the thermal expansion coefficient is 7.80×10-6℃-1,the hardness reaches 539HV,and the thermal conductivity is0.114W/m·k.（3）Due to the addition of nano-nickel powder,the thermal expansion coefficient of the composite coating has been greatly improved,reaching 10.78×10-6℃-1,which is more matched with the thermal expansion coefficient(14×10-6℃-1)of the nickel-based superalloy matrix.（4）With the increase of the crystallinity of glass-ceramic,the high temperature oxidation resistance of the composite coating is obviously improved.Among them,the 45%crystallinity sample has the lowest oxidation weight gain,and the cumulative oxidation weight gain is only1.1290 mg·cm-2after oxidation at 900℃for 30 h,which is nearly 40%lower than that of the bare matrix sample.（5）The composite coating has excellent high temperature thermal shock resistance,and the 45%crystallinity sample has the best performance.After 50 cycles of cooling and heating at 900℃→25℃,the coating was basically well preserved except for a small amount of shedding caused by stress concentration at the edges and corners.（6）The composite coating has good ablation resistance.After ablation at 1400℃for 100s,even if the substrate is melted,the coating does not suffer from obvious ablation,and only peels off at the melting center of the substrate;after ablation by plasma flame at 1300℃for 500s,the coating quality change rate is only-1.57×10-5g/s,there is no large-scale cracking and peeling on the surface,indicating that the coating has good structural stability and good ablation resistance.Figure 36,Tables 15,References 109. |
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