The Research On Processes And Properties Of Double Glow Discharge Plasma Titanizing And Powder Aluminizing On Pure Copper Surface

Pure copper is extensively used as high electrical and thermal conductors. But pure copper is relatively soft and possesses a poor strength and hardness and high temperature oxidation resistance , which is not able to meet the need of industry. In order to improve the mechanical strength of copper, in this paper double glow discharge plasma titanizing surface alloying have been carried out on copper substrate. At the same time for contrast of high temperature oxidation resistance powder aluminizing was carried out. The processes of double glow discharge plasma titanizing , surface alloying layer micro-structure and diffusion mechanism were investigated in details also. The processes of powder aluminizing, surface alloying layer micro-structure and diffusion mechanism were also investigated in details. The corrosion resistance of plasma titanizing alloying layer has been investigated by electrochemical method in 0.5mol/LH2SO4, lmol/LH2SO4, Imol/LHCK 10%HNO3 and 5%NaCl solution respectively. The high temperature oxidation resistance of plasma titanizing alloying layer and aluminium alloying layer at 400℃ and 700℃ after oxidation 100 hours were investigated. The friction wear properties and wear mechanism of plasma titanizing alloying layer were studied. The compositions and microstructure of surface alloying layer wereinvestigated by the advanced means of XRD,SEM,BES,EDS.The experimental results show that copper surface can form titanium alloying layer with double glow discharge plasma surface alloying. The thickness of diffusion layer is between 20um and 90um and the surface titanium concentration is between 30% and 90%(wt). Aluminium diffusion layer is also able to form by use of powder aluminizing. In the plasma titanizing alloying layer titanium solute in copper and form the precipitation Cu4Ti. Copper is strengthened by the dispersion of Cu4Ti. The aluminium alloying layer is made of solid solution and precipitate. The corrosion resistance experiment indicated that corrosion rate of plasma titanizing alloying layer was equal to that of titanium,0.01 times that of copper in 0.5mol/LH2SO4 solution, and was 0.1 times that of copper and was 3.2 times of titanium in 0.5mol/LH2SO4 solution.The corrosion rate of plasma titanizing alloying layer was faster than that of copper and titanium in Imol/LHCl solution , but plasma titanizing alloying layer became of passivation at the later stage ,while copper and titanium surface occurred seriously aperture corrosion. The corrosion rate of plasma titanizing alloying layer is 0.66 times that of copper and 10 times that of titanium in 10%HNO3 solution. The corrosion rate of plasma titanizing alloying layer was almost equal to that of titanium and 2 times that of copper in5%NaCl solution. The oxidation kinetics curve is worked out and the oxidation resistance mechanism is studied. The results show that plasma titanizing on copper surface can improve greatly the high temperature oxidation resistance of copper. The oxidation rate of copper is almost 10 times that of plasma titanizing sample and powder aluminizing sample. At 400 ℃ theoxidation film of plasma titanizing sample is very dense and was not easily exfoliated. The oxidation resistance of plasma titanizing sample is much belter than of powder aluminizing sample. At 700℃ the oxidation film of plasma titanizing sample is exfoliated after oxidation 80 hours, but oxidation film of powder aluminizing sample is exfoliated after oxidation 40 hours. The oxidation rate of plasma titanizing sample is less than that of powder aluminizing sample. It is indicated the oxidation resistance of plasma titanizing sample is better than that of powder aluminizing sample. The friction wear properties and wear mechanism of plasma titanizing sample at 300N,500N and 750N are studied. The results show wear quantity of plasma titanizing sample is less .It is due to improve the surface hardness of plasma titanizing sample. The wear quantity of copper is 5 times that of plasma titanizing sample at 300N, 11 times at 500N, 17 ti...