The Optimization Of Machining Gap Of SACE For Film Cooling Holes With TBCs And Experiments About Engraving Process

With the continuous improvement of thrust loading of aerial engine, inlet total temperature which is the key indicator of engine turbine is increasing at the speed of 25 K per year on average. While the inlet total temperature has exceeded the melting point of turbine blades material, the cooling method is applied to solve problems caused by high temperature. At present the main cooling method is film cooling holes in the turbine blade machined by a certain rule. The gas sprays out from cooling holes isolating the heat from fire chamber to achieve the turbine blade heat insulation effect. To increase thermo stability of turbine blades, a new generation of turbine blade is designed with thermal barrier coatings, which is hard to machine using traditional methods.In this paper, spark assisted chemical engraving(SACE) is applied to investigate the engraving process of TBCs. The feasibility of SACE is verified via the experiments of single hole SACE process and the products of SACE is analyzed using ICP-AES and XPS which demonstrated the material removal mechanism of SACE. Parameters, such as pulse and solution level height are optimized to maintain the stability of SACE process.The optimal machining gap of SACE is tested through SACE experiments. The relationship between engraving velocity and material removal rate is analyzed. Scanning processing parameters, such as layer thickness and engraving speed are designed by CAD/CAM system. Comprehensive parameter experiments of SACE are applied to analyze precision and efficiency.703 silica gel, spin-on glass glaze, corundum ceramic capillary tube and FCVA deposition of DLC film side-insulated electrodes are prepared and the side-insulated ability and durability are tested in SACE experiment under the condition of high temperature and high pressure. The results show that the corundum ceramic casing side-insulated electrode has a good side-insulated ability and durability compared with the experimental results. Experiment using corundum ceramic casing side-insulated electrodes is applied analyzes the effects of SACE processing.