Microstructure And Properties Of Ti-Al-Si Composite Coatings Prepared By Laser Cladding Under High-frequent Light Vibration

Titanium alloy is widely used in different fields,but the low surface hardness of titanium alloy leads to its poor bearing capacity.Titanium alloy also has the disadvantages of poor wear resistance and high friction coefficient,which hinder the use of titanium alloy in the field of structural parts.In this paper,Ti-6Al-4V alloy was used as matrix to prepare Tibased composite coating by laser cladding.The microstructure and properties of Ti-Al-Si coating under different process parameters were compared and analyzed to optimize the process parameters.The hardness,wear resistance and structure of the coating were studied by adding different content of reinforcement phase.By using laser cladding equipment and high-frequent light vibration auxiliary equipment,the influence of vibration frequency on the coating is studied and the optimal frequency parameters are obtained.The results show that the quality of the coating is excellent when the laser power is1500 W and the speed is 0.0083 mm/s.The TiAlSi coating obtained by cladding mainly contains the phases of AlTi₃,TiAland Ti₅Si₃.There is an obvious interface between the substrate and the coating,and there is a good metallurgical combination between them.No obvious cracks and pores are found.TiAlSi coating is mainly composed of TiAl,Ti₃Al and Ti₅Si₃phases.After adding Al₂O₃-13%TiO₂,the coating mainly consists of Ti₃Al,Ti₃AlC₂,TiAl,?-Al₂O₃ and TiO₂.The microhardness of the composite coating was improved by adding Al₂O₃-13%TiO₂ particles.The maximum hardness of the composite coating containing 20%Al₂O₃-13%TiO₂ particles is about 770HV_0.3,which is 2.2 times of the matrix.The average friction coefficients of 0%,10%,20%and 30%Ti based composite coatings are 0.592,0.430,0.435 and 0.438,respectively.The composite coating containing 20%Al₂O₃-13%TiO₂ particles has the least wear loss,and its wear surface is much smoother without furrow.YSZ/tialsi composite coating has good metallurgical bonding with the substrate,and the coating structure is dense and uniform.YSZ/TiAlSi coating is mainly composed of Al₂O₃,TiO₂,SiO₂ and ZrO₂ phases.The microhardness of YSZ/TiAlSi composite coating increases with the addition of YSZ.When YSZ content is 5%,the maximum hardness of the coating is 803 HV_0.3,which is about 2.3 times of the matrix.The friction coefficient and wear volume loss of the composite coating with YSZ particle content of 5% are the minimum.In addition,its wear surface is smoother than other coatings.After applying high-frequent light vibration,it can be found that the bonding between coating and substrate is good,and there are no obvious holes and cracks.After adding high-frequent light vibration to the coating,the thickness of the molten pool is deepened.After adding high-frequent light vibration,the main phases are Ti₃Al,Ti₅Si₃ and Ti₃SiC₂.After the vibration was applied,the changes of the structure were obvious,mainly the orderly distribution of granular materials and some long strip structures.As the vibration frequency increases,the tissue structure becomes smaller.Under different vibration frequency,the average hardness of the coating is different.The average hardness values of 552 HZ,975 HZ,1410 HZ and 2068 HZ are 623 HV_0.3,625 HV_0.3,671 HV_0.3and 701 HV_0.3 respectively.The average hardness of the coating prepared by vibration assisted method is increased,and the higher the vibration frequency is,the higher the average hardness is.When the coating was prepared by high-frequent light vibration,the average friction coefficient of the coating remained at about 0.45,and the fluctuation range became smaller and smoother.