Preparation Of Composite Coating On Titanium Surface

Titanium alloys have some excellent performances, as followings: high strength,non-magnetic and resistant to the high temperature. But there are some limited factors,such as: low surface hardness, friction and wear properties of defects and poor, limitingthe application of titanium. In this paper, to improve the surface hardness of titanium,wear resistance and corrosion resistance for the purpose. Micro-arc oxidation (MAO)and intense pulsed electron beam (HCPEB) were combined to the treatment for a newcomposites of ceramic coating in the Ti6Al4V alloy (TC4) of metal surface preparation;Scanning electron microscopy (SEM), spectroscopy (EDS), X-ray diffraction (XRD),micro hardness and universal friction and wear tester of the film morphology,distribution of the elements, phase composition, surface hardness, friction and wear, andsalt spray corrosion test chamber to the film morphology, the composition of phase,element distribution, hardness, friction and wear or corrosion resistance change.The results showed that the porous ceramic coating was formed to the silicateelectrolyte system of micro-arc oxidation for the TC4alloy. The dense metal-ceramiccoating was formed by HCPEB. In the low energy parameters of the role HCPEBprocess, MAO coating surface remaining coated fused with the gap-like and theemergence of crack-like texture. Beam intensity and the number of pulses, the specificgap disappeared completely because of the acceleration of HCPEB voltage for MAO.The distribution of the crack-like texture was more density and completely uniform.Compared with the MAO coating, composite of coating was appeared to a strongdiffraction peaks of titanium substrate, and the rutile diffraction peaks become strong,the anatase diffraction peaks become weak. Meanwhile, EDS spctra showed thattitanium atoms and oxygen atoms have achieved to the ratio of about1:3, far less than2:1when the composite surface was treated. It was because that coated by a titaniummetal matrix, composed of rutile and anatase.Hardness test results show that compared with the matrix, composite substantialincrease in the hardness of the coating; The parameters for the12kV,130A,10times,the best hardness for the1222HV. At the same time, micro-hardness presented gradient increases when the beam intensity, beam acceleration voltage and radial was at a certainstage. The wear test results showed that the friction coefficient of composite coatingsurface was almost stayed at0.2, and the wear was reduced at a twice. The wearperformance of composition coating was significantly improved. Corrosion showed thatthe corrosion potential of composite coating has already increased to0.3, and higherthan matrix which was compared. Founded by the salt spray corrosion, composite-basedcoating to pitting corrosion, while the shape of the crack-like defected in texture andthere was no obvious corrosion.