Investigation On Sealing Materials With Anti-Titanium-Fire And Anti-Corrosion Properties In Aero-Engines

With the implementation of the "Dark Blue Strategy",my country's advanced aero-engines have increasingly increased demand for anti-titanium fire and corrosion-resistant sealing materials.The porous Al-BN composite coating of the typical engine compressor seal material in service has the function of anti-titanium fire,but the corrosion resistance is poor;the foreign PI foam has excellent corrosion resistance,but does not have the function of anti-titanium fire.Neither Al-BN composite coating nor PI can have the dual functions of anti-titanium fire and corrosion resistance.Therefore,it is urgent to develop a new type of anti-titanium fire and corrosion-resistant sealing material.This paper studied the diffusion and transfer mechanism of A1 and NiAl-BN during high-temperature friction;explored the anti-titanium effect of Ag-BN and Ni-BN composite coatings with good corrosion resistance;prepared aluminum particles/PI composite materials and studied the material's anti-titanium fire effect and corrosion resistance.On this basis,the anti-titanium fire effect and corrosion resistance of aluminum honeycomb/PI and aluminum honeycomb/Al-BN/PI were further studied The main research contents and conclusions of the paper were as follows(1)Through the high temperature friction experiment study of Al and NiAl-BN,it was found that Al diffused and transferred to Ti6A14V alloy at 400?-600?,and at 600?,intermetallic compound TiAl3 was formed on the surface of Ti6A14V alloy.The activation energy of diffusion of aluminum was 28.22 kJ·mol-1;NiAl-BN diffused and transferred to Ti6A14V alloy at 600?.(2)Through friction experiment and high-speed scratch experiment,the anti-titanium fire effect of plasma sprayed Ag-BN and Ni-BN composite coatings was compared.The friction experiment showed that the friction coefficients of Ag-BN and Ni-BN composite coatings were 0.39-0.65 and 0.51-0.65 respectively at 25?-600?.The temperature at which Ag and Ni transfer were different,and the temperature ratio of Ag transferred was lower than that of Ni.High-speed scratching experiments showed that the scratchability indexes of the Ag-BN and Ni-BN composite coatings were 29.16 and 4.67,respectively.The Ag-BN composite coating had better scratehability,and it was opposite to the two coatings.The surface of the Ti6A14V alloy was abraded,and the anti-titanium fire effect of the two composite coatings of Ag-BN and Ni-BN was worse than that of the Al-BN composite coating.(3)The aluminum particle-reinforced PI composite material was prepared by hot pressing and sintering,and the anti-titanium fire effect and corrosion resistance of the material were analyzed.The friction experiment showed that the PI with aluminum particles had good lubricating performance at 100?-500?,and the friction coefficient at 500? was only 0.28.In friction,Al was transferred to the surface of Ti6A14V alloy,which protected the alloy from wear.The high-speed scraping experiment showed that the PI with aluminum particles had good scrapability,and the scrapability index of the material was-479,and a transfer layer was formed on the surface of the Ti6A14V alloy,and the alloy had almost no wear.During the scratching,heat accumulation occurred on the surface of the material and the alloy,and the heat accumulation led to carbonization and decomposition of PI.Therefore,the aluminum particle/PI composite material had a good anti-titanium fire effect,but the decomposition of PI was not avoided.Through salt spray corrosion experiments,it was found that after 30 days of salt spray corrosion,the morphology of aluminum particles/PI composites did not change significantly,the corrosion degree of aluminum particles was low,and the corrosion resistance of aluminum particles/PI composites was excellent.(4)Proposed aluminum honeycomb and Al-BN reinforced PI structure design and prepared new titanium fire-resistant and corrosion-resistant materials.Friction experiments showed that PI with aluminum honeycomb and Al-BN had good lubricating properties,and the friction coefficient was only 0.28 at 450?.During friction,the adhesion layer transfer occurred on the surface of Ti6Al4V alloy.The high-speed scratching experiment showed that the scrapable performance indexes of the aluminum honeycomb/PI and aluminum honeycomb/Al-BN/PI composite materials were 357.5 and-11.5,respectively,and the adhesion layer transfer occurred on the surface of the Ti6A14V alloy.Among them,the aluminum honeycomb/Al-BN/PI had better scrapability,and there was almost no wear with the alloy to be ground.During scratching,because the aluminum honeycomb played a role of heat transfer,PI did not undergo carbonization and decomposition.Therefore,aluminum honeycomb/Al-BN/PI had a good anti-titanium fire effect,and it was not easy to generate heat enrichment during friction.Through salt spray corrosion experiments,it was found that after 30 days of salt spray corrosion,the surface of the aluminum honeycomb/Al-BN/PI composite material had no obvious change.The corrosion was mainly manifested as the pitting corrosion of the aluminum honeycomb.The corrosion degree of PI and Al-BN was low,and the corrosion resistance of the composite material was excellent Based on the above experimental results,by comparing the friction coefficient,scraping performance index,wear of Ti6A14V alloy and salt spray corrosion resistance,it was found that aluminum honeycomb/Al-BN/PI was the best anti-titanium fire resistance and corrosion seal material among the above materials.