The Research On The Features Of Aluminum Coating Layer And Bath In The Process Of Molten Salt Plating Aluminum

In AlCl3-NaCl-KCl ternary inorganic molten salt, bath was obtained by electroplating certain thickness of aluminum layer on the Q235 steel substrate. Then, by using the optical microscope, scanning electron microscope, analytical balance, atomic absorption spectrophotometer detector, the bath element content, the aluminum layer of the surface morphology, coating thickness, deposition rate and variation of current efficiency under the conditions of different current densities and different processing time were investigated.The results showed that: with potassium ion and sodium ion concentration slight increasing, However, aluminum and chlorine content was gradually reduced with the extension of bath time. By analyzing the relationship among Al2Cl7- ion concentration, AlCl4- ion concentration and deposition rate of aluminum in the electroplating process, a cathodic electro deposition kinetics of empirical formula at low temperatures in the ternary inorganic molten salt was obtained: Formula indicates that Al2Cl7- ion concentration control the electroplating process in the acidic molten salt.Moreover, no matter at low current density and high current density, the current efficiency decreased with the extension of time in the electroplating process. Plating thickness increased with the extension of time. Coating the surface morphology and the size of the current density are associated, The results showed that under both low and high current density as the Q235 steel, the aluminum coatings on the surface were formed by small aluminum grains which continually nucleate and grow. When the current density is low, thegrowth of the aluminum grains is determined by step-mechanism.