摘 要
ZA鋅鋁合金擁有較鋁合金、鑄鐵和軸承青銅合金更易鑄造特性，其強度與硬度高於鑄造鋁合金和一般鑄鐵且較低廉，本研究目的係探討製程參數對熱室壓鑄ZA-12鋅鋁合金耐磨耗性之影響。採用POD(pin-on-disc)磨耗測試進行實驗，再利用OM及SEM觀察磨耗的試片顯微組織的變化，以分析不同的製程參數條件對ZA-12鋅鋁合金累積磨耗量之影響。研究結果顯示，利用150℃模具溫度的製程參數所得到ZA-12鋅鋁合金鑄件具有較低的累積磨耗量，而使用100kg/cm2鑄造壓力時，其亦具有較佳的磨耗量。但澆鑄溫度在422℃(即液相線溫度減10℃)時，其累積磨耗量為最少，且隨著澆鑄溫度之增加，ZA-12鋅鋁合金的累積磨耗量也隨著增加。ZA-12鋅鋁合金之熱室壓鑄件因磨耗摩擦產生高熱，晶粒會軟化變形，在冷卻後會產生表面硬化層，此表面硬化層愈厚，近表面的顯微組織則愈緻密，其耐磨耗性因此會愈佳。關鍵詞：ZA-12鋅鋁合金，熱室壓鑄，耐磨耗性
ABSTRACT
Zinc-aluminum (ZA) alloys possess higher strength, hardness and easier casting characteristic than aluminum alloy, cast iron and bearing bronze alloy. This study investigates the effects of hot chamber die casting process parameters on the wear-resistance of ZA-12 alloy. POD tests were performed to evaluate the cumulative wear volume of ZA-12 alloy. OM and SEM were used to observe the microstructure variation of the wear specimens to understand the effects of different process parameters on the wear-resistance of ZA-12 alloy. The study results show that ZA-12 alloy exhibit a lower cumulative wear volume at a mold temperature of 150°C and a casting pressure of 100 kg/cm2. However, its cumulative wear volume is minimum as the casting temperature is equal to 422°C (ZA-12 alloy’s liquidus temperature minus10°C). The cumulative wear volume of ZA-12 alloy is also increased with the increase of casting temperature. In addition, due to the high heat generated from wear and friction, a hardened layer will form on the wear surface of hot chamber die-castings of ZA-12 alloy after cooling. The thicker this hardened layer, the denser microstructure near wear surface will be, and the wear-resistance of ZA-12 alloy will be better.Keywords: ZA-12 alloy, hot chamber die casting, wear-resistance