The Influence Of Heat Treatment Temperature/Time On The Structure Of TC4 Titanium Alloy Copper Coating

Titanium and titanium alloy has good mechanical properties and shows excellent corrosion resistance in a variety of medium, which can be widely used in the pipes、aerospace、biomedical and oil chemical industries. However, titanium alloy has the defect of low thermal conductivity and poorly wear resistance. In order to solve these problems, In this paper, the method of electroplating copper(Cu) was employed to TC4 titanium alloy surface treatment. In the process of electroplating, the internal stress in plating film could make the matrix deform and produce crack. Diffusion heat treatment can make the plating film and matrix form new phase, which forming metallurgical bonding force added the binding force between the plating film and matrix. Based on the above reasons, the article mainly studied the influence of heat treatment temperatures and times on the electroplating copper’s coating structures.Using the analysis methods of metallographic microscope、SEM and EDS、X-ray diffraction et al to analysis the different heat treatment temperatures and times on the influence rules of plating coating structure. like the phase composition of copper coatings、metallographic structure、micro-morphology、Cu/Ni、Ni/Ti and Cu/Ni/Ti interface atomics’ diffusion action et al. The results show that: after different heat treatment temperatures, The interfaces appear obvious diffusion dissolve areas, This illustrates the interface atoms happen the phenomenon of mutual diffusion. As the temperature elevated the diffusion layer thickness increased, in addition, the heat treatment temperature was the primary influence factor of atoms diffusion coefficient; The interface atoms diffusion is mainly Cu atoms diffusion, which through Cu/Ni interface diffused to Ni plating film and Ti matrix. after different heat treatment temperatures, the Cu4Ni、NiCu and NiTi phases were mainly formed between plating coating and substrate, secondly, Ti2Ni、CuTi and Cu2 Ti et al were formed. These new phases are all beneficial to making the bond ways between copper film and matrix transform from the original mechanical bond to metallic bond. Once the metallic bond was formed, which can improve the binding force between the coating and matrix; after different heat treatment temperatures, The micro-hardness and scratch test of TC4 titanium alloy copper coating were tested to check the bonding strength of copper coating, The results turn out to be that the micro-hardness of copper coating improves as the heat treatment temperatures increases; the bonding strength of copper coating was obvious improved than that having not heat treatment. When isothermal heat treatment, with the holding time extended, the diffusion layer thickness、atomic diffusion speed and copper coating micro-hardness is also increased, but the increasing trend is not obvious compared with heat treatment; after different heat preservation time, the bonding strength of copper coating is also enhanced, but the diffusion layer thickness is not the main influence factor for the improving of the bonding strength of copper coating.