| The corrosion behavior of metals poses enormous economic losses and consumption of resources to the social development. Meanwhile, it is also one of the sources leading to equipment failure and accidents. So the research of metal corrosion and protection is of great significance. Cathodic protection is an effective method to prevent or slow down the metal corrosion. This zinc-nickel alloy used as a low electrode potential corrosion-resistant alloys, carried out by oxyacetylene flame spraying protective coatings by cathode protection on the metal substrate.Allowing for there is huge difference between the melting point of zinc and nickel and those two kinds of metals are hard to solute with each other, the zinc-nickel alloy was prepared by mechanical alloying, and the affects of how processing parameters acts on mechanical alloying results were discussed and finally the optimal parameters were available in this paper. At the same time, this paper also has analyzed the mechanism of mechanical alloying. Prepared by using an oxyacetylene flame spraying zinc-nickel alloy coating, the coating performance was analyzed. The main content and the results of this paper are shown as follows:1:The preparation of zinc-nickel alloy was designed and optimized by mechanical alloying process to which the theoretical analysis was conducted. According to the process parameters of the effects of ball milling and the phase of the powder after ball milling, the orthogonal experiment was designed, and optimum process parameters and principle of those parameters affecting the process were obtained. In general, in the zinc-nickel alloying process, the milling speed was confined between 400r/min-500 r/min; the milling time was 70-80h; and the ball ratio was 10:1. And then with ethanol as milling media the full reacted zinc-nickel alloy powder can be obtained. A long-time ball milling is prone to the shortcomings of the powder's being too small and easily oxidized. So the appropriate process should be adopted to keep the powder from oxidation.2. Miedema theory was applied to calculate the formation free energy of alloys ordered intermetallics-8.07 (KJ/mol)> solid solution-6.02 (KJ/mol)> amorphous -5.47 (KJ/mol). Milling process grain refinement of interfacial energy, mechanical grinding accumulation of lattice distortion energy and antisite defects can be the main reason for the formation of intermetallic compounds.3:Oxyacetylene flame was used to spray on zinc-nickel alloy and supersaturated solid solution of nickel alloy coating was obtained. The potential of the coating was-0.32V, lower than the potential of stainless steel (-0.20V) under the same condition, so the coating was of the characteristics of a low electrode potential. Meanwhile, the coating from corrosion current (1.556×10-4mA/cm-2) being lower than that of stainless steel from corrosion current (6.751×10-4mA/cm-2), it was showed that this coating was of low change electrode potential and corrosion-resistance, and can meet the service needs. After strong acid and alkali and salt corrosion, the coating showed good corrosion resistance. |
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