- 學位論文
三元鎳磷鋁合金薄膜之熱穩定性、微結構、機械性質分析
Thermal Stability, Microstructure and Mechanical Properties of Ternary Ni-P-Al Coating
摘要
無電鍍鎳磷具有優越的機械性質、抗腐蝕性及耐磨耗等特性，因而在工業界廣泛應用於表面改質。鎳磷鍍膜為過飽和的非晶質固體溶液，經過適當的熱處理，膜層結構會因為鎳及鎳磷化合物的析出而強化。然而，過度的熱處理會造成晶粒成長過大，使得硬度下降。因此，本研究為了提高鎳磷鍍膜的熱穩定性，在二元鎳磷系統中加入第三元鋁元素，並探討三元鎳磷薄膜的熱穩定性、機械性質及微結構變化。 首先，藉由電鍍方式準備二元鎳磷靶材，再利用磁控濺鍍技術成功鍍製出三元鎳磷鋁薄膜。經由微結構觀察及相鑑定分析顯示，三元鎳磷鋁薄膜經過熱處理會有Ni及Ni3P析出，鋁元素則固溶於鎳基地中。因此，其強化機制為Ni及Ni3P的析出強化和Ni-Al合金的固溶強化兩種方式。鋁元素的添加並同時具有延遲化合物的析出溫度，及抑制析出相的成長速率等效果。從上述結果證明，第三元素鋁的加入，可使鎳磷薄膜在熱穩定性及機械性質都有顯著的提升。除此之外，本研究同時探討不同成分比對薄膜的結晶行為和機械性質之影響，透過鍍覆參數的控制和靶材的設計，可以精準的控制三元鎳磷鋁合金的成分，也由此控制 Ni3P析出及Ni-Al固溶量，使Ni-P-Al膜獲得最高硬度。
並列摘要
The ternary Ni–P–Al alloy coatings were fabricated by RF magnetron sputtering technique with dual targets of Ni–P/Cu as well as an additional aluminum metal. Electroplating Ni–P process was introduced to obtain the NiP compound target with various phosphorous contents after modification of the processing parameters. Thermal analysis revealed that the introduction of Al in the Ni-P coating by co-deposition retarded the Ni and Ni3P precipitation and retained the strengthening effect at elevated temperature. Microstructure evolution indicated that all coatings in the as-deposited state exhibited amorphous structure. The precipitation of Ni and Ni3P accompanied with Al dissolved into Ni matrix were the final product of the phase transformation in Ni-P-Al coatings after heat treatment. It was revealed that hardness can be engineered by the controlling of composition in the Ni-P-Al coatings. After annealing, the coating was strengthened by the precipitation of Ni-P compounds and dissolved Al in the crystallized Ni. Through quantitative analysis, the effect of strengthening in ternary Ni-P-Al coatings can be clearly demonstrated.