The Studies Of Electrodeposition And Structure Of Fe-Ni-W Alloys

In recent years, electrodeposited tungsten alloy deposits were regarded as one of potential chromium substitutes for many of their excellent properties, such as decorative appearance, high thermal stability, high hardness, good wear and corrosion resistance and its potential engineering applications. Compared with chromium plating, there were many advantages in electrodeposition of tungsten alloy deposits, for example, high current efficiency, good throwing, covering power and environmently friendly. So, rencently there were extensive interest in the electrodeposition of tungsten alloy deposits. Few reports about the electrodeposition and their properties of Fe-Ni-W alloy deposits were presented. In this thesis, following research were studied in detail.1. Electrodeposition and mechanism of Fe-Ni-W alloy deposits in aqueous solution were discussed. CV methods were used to minitot the process of deposition of metal ions. The effects of bath composition and process on the appearance, composition, and cathode current efficiency of Fe-Ni-W alloy deposits were studied comprehensively for the first time. And that the W content in the deposit was found to increase with an increase iron ion, citrate concentration in the bath, cathode current density and temperature. Composition of deposits was Influenced by pH value of bath .The tungsten content has a maximum value at pH 6.2. The electrodeposition technology of the nanocrystalline Ni-Fe-W alloys have been put forward. The nanocrystalline W alloy exhibit excellent corrosion resistances and higher microhardness without annealing and can be a substitute for chrome plating.3. The effects of operating conditions and coplexes on the appearance, deposition rate, structure and microhardness of Fe-Ni-W alloy deposits were studied comprehensively for the first time. We draw the appropriate range for the electroplating amorphous alloy process conditions: the pH value was 5-10, the temperature was above 40℃, and the current density was above6 A/dm².4. The effects of Cu²⁺, Zn²⁺ in the solution on the appearance, composition, deposition rate, structure, and microhardness ,corrosion resistance of Fe-Ni-W alloy deposits were discussed in the first time. The results showed that the copper ions in a certain amount can increase plating rate, increase deposits hardness, but the apparent was poor, and the corrosion resistance weakened with the increasing concentration of copper ions in the bath. The concentration of zinc ion reduces plating rate and the deposits hardness; weaken the corrosion resistance of deposits.