Study Of The Effect Of Aluminum Powders Activant On Mechanically Deposited Process Of Zinc-aluminum Alloy

As a new developed surface technology, mechanical plating has characteristics of high efficiency, low costs, low energy consumption, and environment protection, which makes it become a feasible way of clean production. Forming Zinc coating by mechanical plating has been applied extensively in industry; however, the process of Zn-Al alloy coating is scarcely reported. Therefore, in this thesis the activate process of aluminum powder and physical and chemical properties of Zn-Al coating is studied, which aims to optimize the stratification process and improve the quality of coating.The thesis is mainly focus on the activation of metal powder and the co-deposition of zinc and aluminum. The law of aluminum powder's activation is studied by simulating tests and sampling in the process of mechanical plating. The content of aluminum powder's activant is finally found out through orthogonal experiments. By salt immersion corrosion tests and electrochemical tests, the chemical and electrochemical corrosion resistance of Zn-Al coatings with different aluminum content is also analyzed. Zn-Al coatings'physical properties are studied by evaluating the coatings'porosity, density and surface appearance. Stereomicroscope, fluorescence spectrometer and X-ray diffraction are used to analyze Zn-Al coating's surface morphology, phases and the distribution and content of alloying elements. The role of aluminum in mechanical plating, which a non-crystallizing stratification, is also studied.The results show that it is feasible to form Zn-Al coating in mechanical plating process by using F acid as activant aluminum powder. Compared with pure zinc coating, Zn-Al alloy coating has better appearance, chemical and electrochemical corrosion resistance. By analyzing the ingredients and phases in Zn-Al coating, it is found that zinc exists in 2 theta, which equals to 144.631°,when its content is 1.0%, and the relative content of aluminum is 0.6229%. No new phases or new phenomenon crystallizations are found in Zn-Al coating.Zn-Al coating has excellent physical and chemical properties. The mechanisms of aluminum's behavior are summarized as follow:Aluminum sedimentation are mainly deposited on the surface of Zn-Al coating; due to its good corrosion resistance. Aluminum is stable in many media; Aluminum can produce a compact, adherent and anti-oxygenated film, which provides good protection for metal substrate.