Mechanical Plating Of Al-zn Alloy

The mechanical plating is a new surface engineering technology that has some merits such as high efficiency, low cost, low energy-consume and little pollution. The mechanical plating of zinc is already and very extensive industry applications, but the mechanical plating of Al-Zn alloy almost have no an solid industry example. The main purpose of this thesis is to study the regulation of accumulating, construction characteristic and performance of the mechanical plating of Al-Zn alloy.According as the craftwork of the mechanical plating of zinc and the relevant information, the craftwork of the mechanical plating of Al-Zn alloy is made sure and two kinds of the coatings of Al-Zn alloy are prepared. The substance of the coatings are analyzed by X-ray diffraction, and the results show that the coatings fundamentally are constituted by single metal of aluminum, zinc, tin etc. The transect of the two coatings are scanned by SEM, the results show that tin metal separates out at the joint of the powder of Al and Zn metals, but the aggradations of Al powder departures the theoretic account very much. The reason is in the grain of the aluminum powder and the craftwork both side. The grain size of the using Al powder is larger than the thickness size of the coating, and the grain size of Al powder roughly is 3~5 times to the Zn powder, therefore only the Al powder which has the same size of the coating and the Zn powder can sink to accumulate the coating. The craftwork is made according to the craftwork of the mechanical plating of zinc, so the quantity and the joining sequence of all kind of material in the liquid system are not suitable of the Al-Zn alloy coating which is made by the means of the mechanical plating.The theory of the mechanical plating is mainly to be constituted by third aspects. The first is the function of the driving metals, the second is the function of the activator, the third is the function of the movement of the matter in the barrel used for the mechanical plating. The function of the driving metals can be explained by the theory of" activated point reaction". At the becoming of the coating, the positive ions of the driving metal are adsorbed and replaced at the live points of metal powder and Fe-matrix, then the branch crystals of the driving metals outgrow at these live points, at last the coating comes into being and incrassates by the means of the attraction and interleaving of the branch crystals of the driving metals. The alloy theory of the coating of Al-Zn prepared by the mechanical plating is the theory of the function of the driving metals. The driving metals, Al powder and Zn powder all are felted by the branch crystals of the driving metals to form the alloy coating.The combinative performance of the coating is divided into two aspects: the adhering intention between the coating and the matrix, and the anti- breakage ability of the coating itself. A new method is developed to evaluate the anti- breakage ability of the coating itself and named the "pit calculation method". It can be used to measure the anti- breakage ability of the coating itself, but the traditional examining method can only estimate the adhering intention between the coating and the matrix.Some traditional methods to measure the corrosion speed of coatings have a lot of weakness such as long experiment period, complicated equipments and inconvenient operation etc. A new method is developed to measure the corrosion speed of coatings, which is more simple and efficient than the traditional methods. It is named the "method of measuring the electric current of self-corrosion", the little the electric current of self-corrosion of coatings, the lower the corrosion speed and the higher the corrosion resistance of coatings.