Study On Nano-composite Coating Process And Pereormance For Steel Wire Surface

MIG welding has been widely used in welding production for its high productivity,lower cost, and high process adaptability. So solid steel wires are in great demand. However,it has many disadvantages, such as poor adhesion，bad corrosion resistance. Moreover, a lotof welding fumes and spatters will produce for the lubricant of the wire which are harmfulfor people’s health and environment. So, developing a new "low energy consumption, highefficiency, high quality, environmental-friendly" non-copper plated welding wire is one ofproblems to be solved. In this paper, a new method of steel wire surface treatment wasdeveloped to prepared Ni/TiO2coatings of steel wire. The effect of coating parametersincluding current density, the temperature of the electrolyte, TiO2content and NiSO4content on hardness and deposits were analyzed. In addition, the bonding mechanism,corrosion resistance and rust resistance and welding process performance of coating werestudied. Results show that：1、Current density is the main factor among the four parameters. The maximum TiO2content and coating hardness can be obtained when the current density, the temperature ofthe electrolyte, the TiO2and NiSO4content in electrolyte are4A/dm2,45℃,30g/l,100g/lrespectively.2、The optimized coating processing parameters were: current density3~4A/dm2, thetemperature of the electrolyte40~50℃, TiO2and NiSO4content in electrolyte25~30g/l,100~120g/l.3、Four different coating wires were prepared based on the optimized processingparameters. It can be found that the coating has a good combination with base metal withno flaking and cracking. Salt spray test and electrochemical corrosion test show thatcorrosion resistance of sample4is better and sample1is the worst.4、The droplet transfer characteristics of the coated wire and uncoated wire under thecondition of short circuit transfer, spray transfer and fine particles transfer mode werecompared. The results showed that for short circuit transfer case with the same current andvoltage parameters, short-circuit transition frequency of the coating wire is reduced and thetransient mode changes to free transfer. For spray transfer, the arc of coating wire has atypical "bell" shape, and the transition frequency is high. However, the arc of uncoated wirehas serious deformation and the droplet transfer is unstable. For pulse droplet transfer, thedroplet of coating wire transfers smoothly with one droplet per pulse, but the transientmode of uncoated wire has large drops exclusion phenomenon.5、The weld of coated wire has good appearance and the microstructure is mainlycomposed of fine acicular ferrite.