Study On The Structure And Properties Of Laser Cladding Titanium-based Composite Coating On TC4 Alloy Surface

TC4 alloy has good heat resistance,plastic toughness,weldability,sheet formability,non-magnetic properties,biocompatibility,processability and corrosion resistance,is a typical representative of Ti-Al-V titanium alloy.TC4 alloy has a good comprehensive performance,and is widely used in aviation,automobile,chemical industry,ocean,architecture,sports,medical treatment and other aspects,especially in the production of aviation parts,such as aircraft fuselage,blades,pipes,seats and other components.But TC4 alloys also have many disadvantages,which have limited their promotion.At present,the main influences are low hardness,poor wear resistance and friction reduction.In order to accelerate the promotion of TC4 alloy,it is of great significance to improve the wear resistance and antifriction of TC4 alloy.In order to improve the wear-resisting and anti-friction properties of TC4 alloy,this experiment use RFL-C1000X fiber laser to prepare TC4+h-BN,TC4+Ni-h-BN and TC4+Ni/C composite powders on the surface of TC4 substrate.The microstructure of the cladding layer is analyzed,the wear resistance and antifriction performance are tested,and the wear mechanism of the coating is analyzed combined with the microstructure.The forming quality of TC4+h-BN cladding layer is not good,and there are defects such as pores and cracks.The cladding layer consists of rod-shaped phase Ti B and ternary eutectic structure?Ti-B-N?.The hardness is 997 HV_0.5,the friction coefficient is 0.58,the wear amount is 89 mg,and the wear mechanism is mainly abrasive wear.The forming quality of the TC4+Ni-h-BN cladding layer is significantly improved,and it is best when the laser scanning speed is 10 mm/s and the Ni-h-BN addition amount is 40%.At this time,the microstructure of the cladding layer detects Ti₂Ni,Ti Ni,Ti N_0.3,Ti N,Ti C,Ti B,?-Ti and other phases,the average hardness is 813.6 HV_0.5,the friction coefficient is stable at 0.45,the wear amount is 35.2 mg,the wear mechanism is dominated by slight abrasive wear,and the wear resistance is significantly improved.The TC4+Ni/C cladding layer is mainly composed of Ti C,Ti₂Ni,graphite and base?-Ti.When the Ni/C content is 25%,the cladding layer has the best forming quality,and the hardness of the cladding layer is 720 HV_0.5.The residual graphite in the cladding layer acts as a solid lubricant,which reduces the friction coefficient and wear amount to 0.28 and 25.6 mg,respectively.The main wear mechanism is adhesive wear,and the wear resistance and friction reduction performance of the cladding layer is significantly improved.The wear resistance of the cladding layer is inversely proportional to the load.When the load is 100 N,the graphite particles fall off,so the cladding layer is suitable for use under low load conditions.