摘要
鎂合金的化學性質活潑，屬於易遭受腐蝕的金屬，因此防蝕處理成為鎂合金在應用的過程中所需探討的課題。本實驗探討冷噴塗對鎂合金性質之影響，包括顯微組織、機械性質及腐蝕性質。實驗探討被噴塗基材為AZ80鎂合金及LZ91鎂合金，噴塗使用的粉末為IN625及含10%氧化鋁的鋁粉。 實驗結果發現，IN625噴塗層內部靠近鎂合金介面的粉末呈現接近圓形，並有些許圓形粉末埋入鎂合金內部；硬度值隨著接近鎂合金介面而減少。冷噴塗IN625會使得AZ80鎂合金表面產生再結晶現象，造成鎂合金表面晶粒細化，晶粒大小約3μm；而由於高溫及再結晶現象，晶粒內差排數量減少，使得表面硬度值只有些微上升。冷噴塗鋁會使得AZ80鎂合金表面有明顯加工硬化的現象。而噴塗對擠製材LZ91而言，金相與硬度的改變不明顯。 而經熱處理後的鋁塗層試片，塗層會與AZ80交互擴散，形成連續相之介金屬化合物。LZ91於介面處形成一層α相鎂，而不與鋁塗層形成化合物。腐蝕性質方面，在各項腐蝕試驗中顯示，無論IN625或鋁的塗層其腐蝕電流均比母材來得小，代表其腐蝕速率較慢，有較母材為佳的抗腐蝕性。
並列摘要
It is commonly recognized that magnesium possesses poor corrosion resistance because of its high oxidation potential and porous oxide structure. The corrosion resistance is the most important topic for magnesium alloys application The thesis aims to investigate how cold spray influences the properties of magnesium alloy, including microstructure, mechanical and corrosion property. The sprayed substrate is AZ80 and LZ91 magnesium alloy. IN625 and aluminum powder is used to spraying on the surface. After the cold spray IN625 process, the pellets bury in substrate. The shape of pellet is closely circular. In the coating, the hardness decrease with close to the interface. AZ80 substrate occurred grain refinement after spray IN625 process. The grain size is about 3μm.For the aluminum coating, it was observed that after coating process, substrate surface is obviously harder than after coating IN625 process. After annealing, the AZ80 alloy interacts with Al coating to form Mg17Al12 and Mg2Al3 compound at the interface. As to the corrosion behavior, the result of the potential-dynamic polarization curve tests reveals that, whether in the IN625 or the Al coating, the corrosion resistance are better than magnesium substrate. There are no pitting corrosion observed in the cold spray coating.
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