Titanium Corrosion, Anti-wear, Anti-fatigue Surface Technology

For improving the wear, corrosion and fretting fatigue resistance of titanium alloy TC4, electroless plating Ni-P, Ni-P-PTFE and pretreatment for Ti alloy substrate have systematically investigated in this paper. A better pretreatment method and optimized electroless plating Ni-P and Ni-P-PTFE techniques for Ti alloy are put forward. By employing XRD, SEM and EDAX analysis methods, the structure and surface morphology of Ni-P and Ni-P-PTFE plated on titanium alloy surface have been studied. Corrosion properties, wear resistance and fretting fatigue behavior of Ti alloy specimens coated with Ni-P and Ni-P-PTFE have been evaluated by electrochemical method, ball-on-disk tests and high-frequency tests respectively. The results show that: (1)The coatings completely crystallize by annealing for 1 hour at 4000C and surface hardness of the coatings increases significantly. (2) The corrosion rate of Ni-P and Ni-P-PTFE coatings is very low in 3.5% NaCl and 10% H2S04 solutions at 80℃, that is the coatings have excellent corrosion resistance. (3) At room temperature and under non-lubricating conditions, friction coefficient and volume wear rate of Ni-P and Ni-P-PTEE coatings in contact with GCrl 5 are considerably low, especially in the situation of Ni-P-PTFE Coating.. (4) Surface treatments of combining Ni-P, N-i-P-PTFE and shot-peening improve fretting fatigue resistance of titanium alloy TC4 to some degree, but their effect is not good as that of using shot-peening only.