Study On The Preparation Of Micro-Arc Oxidation Coating On Aluminum LC4 And Its Characteristic

Micro-arc oxidation is a new surface treatment technology based on anodicoxidation. Compared with the traditional anodic film, micro-arc oxidation coating hasmany advantages, such as firmly attaching to the substrate and resisting corrosion,abrasion and high temperature ablation well. Thus it can solve the problems whichconventional surface treatment technologies can't. But there is much work needing to bedone on the preparation of micro-arc oxidation coating without loose layer, as well ascontrollable and predictable preparation process, mechanism and so on. So it is essentialto further research on the preparation of micro-arc oxidation coating without loose layer,as well as controllable and predictable preparation process, in order to meet theapplication requirements from national defense, aerospace, weapons and equipment andother areas well.In this paper, a preparation method of MAO hard and thin coating without looselayer on aluminum LC4 substrate with a short time was developed. The influences ofMAO parameters were studied deeply. The relationship equations of the thickness andhardness with each parameter were fitted by least-square method and the optimum rangeof each parameter was also determined. Through orthogonal rotation experiments, thequadratic regression equations of thickness and hardness are established and theoptimized result of MAO hard and thin coating without loose layer on aluminum LC4was given according to principles of optimization.The microstructure, elemental composition and phase composition of MAO hardand thin coating without loose layer were tested by using the modern testing methodssuch as SEM, EDS and XRD, the reactions occurring in MAO process were deducedand its growth mechanism was analyzed. By thermodynamic theory, the phasetransformation driving force and temperature ofγ-Al2O3 transformation toα-Al2O3 wascalculated. The bonding strength between MAO hard and thin coating without looselayer and substrate aluminum LC4, performance against high temperature ablation hasalso been studied by experimental research.