熱處理對銅金屬熔射層機械性質之影響

The Influence of Heat Treatment on the Mechanical Properties of Thermal-Sprayed Copper Layer

在眾多的金屬沉積技術中，銅金屬熔射因堆疊速度較快，極適合於電鑄翻模後之增厚作業。然而，質地硬脆、機械強度較差為銅金屬熔射之主要缺點。本研究係使用火焰熔射法（Flame Spray Coating）將純銅熔射於SAE1020低碳鋼基材上，再經不同溫度（200～800℃）、時間（1～8小時）之熱處理，來探討熱處理對銅金屬熔射層機械性質之影響。由硬度測試結果顯示，隨著熱處理度與時間漸增，銅熔射層硬度、電阻係數及彎曲強度均隨之下降。由實驗結果發現銅熔射層的熱處理效果與原銅材相近，印證銅熔射層可藉熱處理改變其機械性質，有助於銅溶射技術之推廣應用。由金相顯微鏡表面觀察，顯示經熱處理後之銅熔射層表面結構較緻密，界面氧化層漸趨不明顯。由腐蝕浸泡試驗結果顯示，熔射銅層經400℃熱處理8小時後，其抗蝕性亦可獲得改善。

The deposition rate of thermal spraying was much faster than the other deposition techniques. It's very suitable for back up application of electroformed mold insert. However, the major problems of thermal sprayed copper coating are poor mechanical properties and strength. In this study, we sprayed pure copper on a SAE 1020 low carbon steel substrate by flame spraying. The thermal sprayed layer was subsequently treated in distinct temperature (200 -800℃) and time(1-8 hours) to estimate the effect of heat treatment. The experimental results indicated that the hardness, electrical resistivity, and bending strength of copper layers were decreased with increasing temperature. The effect of heat treatment on thermal-sprayed copper layer was similar to the copper raw material. The observed micrographs showed that the thermal-sprayed copper layers were much more denser after heat treatment, and their oxide barrier disappeared. The results of nitric acid solution dipping also indicated that the corrosion resistance of thermal sprayed copper layer were improved after 8 hr heat treatment above 400℃.