Research On Bubble Characteristics And Deposition Behavior Of Electrolyte Vacuum Boiling Electrodeposition

The technology of electrolyte vacuum boiling electrodeposition is a kind of new technology which has been proved that high-quality electrodeposition coating and part(without deposition defect amostly, with favorable physical and mechanical property etc) can be producted under conditions of high depositin speed and without any additions. But its mechanization has not been revealed or cognized completely. So follow our team’s research, this dissertation which was supported by National Natural Science Foundation(51175152) and Henan Province University Science and Technology Innovation Talent Support Plan(2012HASTIT012), will focus on three topics: to describe the macro-phenomenon and typical characteristics of electrolyte vacuum boiling electrodeposition, to represent bubble dynamics qualitatively and quantitatively, and to reveal their relationship with process behavior of electrodeposition, morphology and to estimate micro-texture of nickel coating. The concrete contents are as follows:(1)The phenomenon and dynamic behavior of electrolyte vacuum boiling electrodeposition were observed by experiment, and the change of nucleating site distribution with the core parameters of bubble dynamic was researched together. The results show that:(a) The evolution of single electrolyte vacuum boiling electrodepositon bubble and electrolyte vacuum boiling bubble are same amostly, but the boiling effect caused by them is different markedly;(b) Single bubble’s evolution is hardly changed with diverse environment and operating conditions, while the typical core parameters(such as average bubble growth period, growth speed, shrinking period and depature diameter) are changed distinctly;(c) The phenomenons of coalescence and supper bubble emerged under some special conditions;(d) The electrolytic bubble sites will translate to boiling sites absolutely, if some requirements are satisfied;(e) The number and distribution of bubble nucleating sites will change along with electrodeposition process, but the number of nucleate sites will be constant with time finally.(2) The cathode chronopotentiometry, risistance between cathode and anode, mass transfer of cathode, and their relationships with bubble were measured and researched. The results show that:(a) The chronopotentiometry of nickel electrodeposition under electrolyte vacuum boiling condition is lower than non-boling condition apparently, and amplitude of fluctuation is different under different severe degree of boiling also;(b) The risistance between cathode and anode is larger than non-boling condition evidently;(c) The speed of convection mass transfer around cathode is coincident with the severe degree of boiling;(d) The cathode mass transfer will become quicker with the decrease of vacuum degree or the rise of cathode temperature, but there is a limit.(3) The discrepancies between bubble fixed affected area and bubble random affected area of electrodeposition nickel coating was researched, and the nickel coating is deposited using electrolyte vacuum boiling deposition technology. The results shows that: The surface of bubble fixed affected area is brighter and more smooth than random affected area, its surface microstructure and grain size are smaller and more compact than bubble random affected area, but grain index and texture coefficient are same amostly.