Study Of Wear Transfer Behavior Of Sealing Coatings Based On Microparticle Contact

Abradable sealing coating is a medium to low temperature protective coating applied to a number of parts of the aircraft engine rotating parts,airflow passages and magazine gaps.It protects the blades and the engine by abrasion,control the clearance between the compressor rotor and the mating cassette,reduces the engine’s wheeze,reduces fuel consumption,improves the thrust-to-weight ratio,engine efficiency and service life.The temperature generated during the high speed scraping and grinding process between the sealing coating and the blade is much higher than the working temperature of the aero-engine.In this thesis,based on the micro-convex body contact theory,the radial and tangential forces during the scraping process are measured by a high-speed rotor test rig and the scraping temperature curve is fitted.The wear and adhesion transfer behaviour of the sealant coating under different scraping conditions is investigated in depth.The main research elements are as follows.Firstly,this thesis uses the atmospheric plasma spraying method to prepare Al Si-PHB medium and low temperature seal coatings with different polyphenylene ester contents,and conducts high-speed scraping tests on them with different single cutting volume conditions,and investigates the scraping morphology of the coating and the leaf tip and the adhesion morphology of the leaf tip,and obtains the scraping morphological characteristics of the coating and the leaf tip under different scraping conditions.Secondly,the fractal dimension is introduced to characterise the degree of undulation and undulation difference of the coating morphology,and the difference method is used to calculate the relevant parameters.The surface roughness is used to compare the undulations on the front side of the tip feed with those on the rear side to analyse the scraping mechanism under different scraping conditions.The scraping mechanism is verified by analysing the weight loss rate of the coating and the tip as well as the adhesion of the tip.Finally,based on the flash point temperature in the contact model of the micro-convex body,this thesis modified the traditional Hertz bump model,and fitted the scratching temperature curve with time through the radial force and tangential force in the process of high-speed scratching.The changing trend and heating rate of scraping temperature were analyzed by combining weight loss rate and scraping force ratio of coating.It is found that the modified model can be used to analyze the radial scraping force.In the process of high speed scraping,the change trend of peak temperature is similar to the change trend of coating weight loss rate.When the coating weight loss rate is low,the heating rate of scraping is slow and the blade tip is lumpy adhesion;when the coating weight loss rate is high,the heating rate of scraping is fast and the blade tip is lamellar adhesion.In this thesis,the relationship between coating and tip morphology and scraping temperature is analysed through the parameters of scraping morphology,surface undulation,weight loss rate,adhesion rate and scraping temperature,and a linear relationship between adhesion morphology and scraping temperature is established in relation to the coating weight loss rate.A linear relationship was established between adhesion morphology and scouring temperature.This provides a reference for determining the effect of different scouring morphologies on the coating performance.