Investigation Into The Wear Process Of Laser Cladding From TiC Multilayer Coating For GTE Shrouded Blade Platforms

It is well known that during the operation of a gas turbine engine(GTE),the fan blades are subjected to periodically changing forces,causing vibrational bending and torsional stresses.To reduce the magnitude of vibrational stress,a shrouded blade platform is used,which significantly changes the vibration characteristics of the blades and the shoulder blade as a whole.Providing zero clearance between the shrouded blade platforms contact surfaces in working condition eliminates the most dangerous first form of the blades bending vibrations.Therefore,the timely preservation of the platform surface geometry is an important condition for the reliability and resources of the fan.During the operation of the engine in stationary mode,the oscillatory movements of the blades and the blade rim lead to micro displacements of the platforms contact surfaces.In transient modes of operation,there is also a mutual displacement of contact surfaces,but under conditions of variable contact pressure,therefore experimental studies are great practical importance for the contact surfaces fretting resistance.Since the titanium alloys used for the fan blades manufacture have extremely low resistance under fretting conditions,it makes it almost impossible to operate the blades without a hardening coating on the shrouded blade platforms contact surfaces.The purpose of this study was to obtain information on the microshear resistance of titanium carbide coatings obtained by the LMD method,as well as to consider the possibility of using this method for the modernization and repair for GTE shrouded blade platforms.This paper describes the tribological test results of coatings obtained by powder materials laser cladding.To study the composite coating fretting resistance,samples with different ratios of Ti-6Al-4V / Ti C components were prepared: 10/90,15/85,20/80,25/75,30/70(by volume,%).The fretting resistance tests were carried out on a model 3308 specialized friction machine with relative reciprocal sliding of flat samples.During the test,the functional dependence of the rolling process and type of the sample was studied in detail.The wear time and friction time of the optical system for observing and measuring the friction zone were passed without removing the sample.Performance evaluation of the coating material is carried out at different stages of running-in and wear.In the experimental setup for fretting wear and fretting corrosion,the possibility of up to 1.0 GPa and the contact pressure were significantly improved(this condition is easy to implement considering the exposure conditions of the corrosive environment required).The test results were compared with the coating used in the standard friction units,based on WC-8Co,obtained by soldering with high-temperature solder Vpr6(???6).The studies showed that the technology of laser surfacing of the Ti-6Al-4V / Ti C powder material composition provides higher fretting resistance of the protected surfaces in comparison with a standard coating based on WC-8Co.The optimum ratio of powder materials for coating was determined based on the test results.The results can be used to improve the design and technical development of friction problems in GTE shrouded blade platforms,as well as to improve the application of hardened coatings to GTE components.