Research On Bubble Characteristics And Scanning Process Of Spark Assisted Chemical Engraving

Since the beginning of the 21st century,Cooling gas ejected from film cooling holes can form the gas film on a wall for heat insulation and heat dissipation,and this technology is applied to protect turbine blades of aero engine to operate within the environment of extreme high temperature.In order to further achieve the high thrust-weight ratio and high efficiency for the next generation of aero engines,the turbine blades will be designed as composites of ceramic thermal barriers with film holes,and it is difficult to achieve the process of film holes with complex shapes in conventional methods.Spark Assisted Chemical Engraving(SACE)technology has the possibility of realizing the non-destructive processing of the film pores of the ceramic thermal barrier layer.This article has conducted experimental research and discussion on the process.This paper first studies the theoretical model of the electrolytic bubble generation process and analyzes the law of gas film formation.Using a high-speed camera to observe the movement of bubbles,the effects of power characteristics,depth of immersion,and electrolyte concentration on the characteristics of the bubbles are investigated.The experimental parameters are optimized and it is proposed that when the voltage is 90V,the immersion depth is 2mm,and the electrolyte mass fraction is 5%,the gas film can maintain stability during the processing and help improve the processing quality.Through the use of Comsol software,an isoparticle collision response model is established,and the effect of machining gap and electrode shape on SACE machining discharge is obtained.The scanning processing experimental system is set up and the machining gap is accurately measured.The influence of hollow and solid cylindrical electrodes on the SACE scanning processing technology is studied.The quality and efficiency of the processing are comprehensively considered,and the quality of the hollow electrode scanning processing slot was higher.Finally,hollow cylindrical electrodes are used to study the influence of the regularity of bubble characteristics on the scanning process effect under different voltage and immersion depth.It is verified that the formation process of bubbles and the appearance of gas film had a significant effect on the processing results.At the same time,due to the small gap in the scanning process will affect the thickness and shape of the gas film,through the SACE scanning processing experiments of different processing gaps,the reasonable experimental parameters of the scanning processing tank are obtained,when the voltage is 90V,the immersion depth is 2mm,and Pulse width between pulses 3.2?s/4.8?s,processing gap in the 25?m?30?m,the hollow electrode processing removal amount is greater and the quality of the processing tank is better.