Cailiao Baohu (Nov 2022)
Influence of Crystallization Behavior of the Metal/Glass - Ceramic Composite Coating on the High Temperature Oxidation Resistance of the Coating
Abstract
According to the harsh environment faced by the core thermal parts of aero - engines and the excellent high - temperature protection performance of the glass - ceramic coating, the flow - coating method was used to prepare nickel - containing B2O3 - Al2O3 - BaO - CeO2 metal/glass - ceramic composite coating (Ni/BABC) on the surface of the nickel - based alloy GH4586 for aero - engines. Differential thermal analysis (DTA), X - ray diffraction (XRD), scanning electron microscope/energy dispersive analysis (SEM/EDS), weight gain method and other test methods were used to study the effects of different nucleating agents and different heat treatment processes on the crystallization behavior of glass - ceramic with a constitution of B2O3 - Al2O3 - BaO - CeO2 and the effects of crystallization behavior on the high temperature oxidation resistance of the composite coating. Results showed that 4% (mass fraction) ZrO2 could achieve the best nucleation effect as a nucleating agent, and the precipitated crystal phase was BaAl2B2O7. The best crystallization process for the glass - ceramic was an annealing at 650 ℃ for 30 h. The longer the annealing time, the higher the crystallization rate. Additionally, after 30 h, the crystallization rate tended to be stable at about 46%. The glass - ceramic composite coating had a significant protective effect against the high - temperature oxidation of the substrate. The coating sample with a crystallization rate of 46% had the lowest oxidation weight gain rate, gaining a weight of only 1.129 0 mg/cm2 after oxidation at 900 ℃ for 30 h. Furthermore, it had the most uniform and dense structure after oxidation, its surface was smooth, and its high temperature oxidation resistance was excellent.
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