- 學位論文
氮化鉻鍍膜與磷酸鹽化成皮膜在鎂鋁合金上抗氧化特性的比較
The Comparative research on Anti-oxidation Characteristic of Magnesium Aluminum Alloy With CrN Coating and Phosphate Conversion Coating
摘要
中文摘要 3C(Computer、Communication、Consumer Electronic)資訊產業近年來的發展，講求輕薄趨勢下，在手機的產業中愈來愈講求所謂的外型薄型化，重量輕量化，對於結構用輕量化的材料需求又逐漸熱絡了起來。再加上環保意識的抬頭，對於降低污染，增加產品的再使用率方面，輕金屬的使用上也逐漸受到注意以及重視。輕量化的材料又以鎂合金、鋁合金、鈦合金為最主要使用材料。而在當中又以鎂合金為最具令人注意。 本研究以鎂鋁合金AZ91D為基材，最主要目的為使用較環保的物理氣相沉積PVD濺鍍鍍膜製程(Sputtering)，在鑄造件AZ91D基材上沉積氮化鉻，利用氮化鉻具有優良的抗氧化、防腐蝕能力以及相對於目前鎂鋁合金業界常用較不環保的傳統抗氧化處理為磷酸鹽皮膜化成處理做相互分析以及對照組比較。以全因子實驗法，研究氮氣流量、氬氣流量、電流、功率、時間等參數對於從其抗氧化處理方面，延伸出對於腐蝕性，導電性並輔以光學顯微鏡(OM)、場發射掃描式電子顯微鏡(FE-SEM)、能量分散光譜儀(EDS)做微結構以及成分分析比較及討論。 實驗結果顯示，靶濺鍍功率為2 kw、加熱溫度為0 ℃、氮氣流量為50 sccm、氬氣流量為30 sccm、膜厚0.055 μm為最佳參數，對於鹽霧測試，導電性，附著力上都有相當好的效果。並且與化成皮膜比較下，可得到氮化鉻鍍膜對於鎂合金的抗蝕保護能力以腐蝕面積來看，其腐蝕面積可達到<5 % ，對於在鎂合金在3C產業上的需求已能滿足。另外以導電性測試，比較鹽霧實驗前與鹽霧實驗後差異，其導通性及電阻值以四點探針量測氮化鉻薄膜與化成皮膜，實驗前兩者的導通性及電阻值差異不大分別為0.022x10-2 Ω及0.022x10-2 Ω，但在鹽霧實驗後導電性及電阻值卻有所差距。氮化鉻處理的電阻值平均為0.029x10-2 Ω；化成皮膜處理之電阻值卻高到2.3 Ω超過了標準，甚至於因氧化腐蝕現象造成量測值不易量取以及數值飄異。因此表示氮化鉻處理對於在鎂合金表面處理上，其抗氧化之優越性超越了傳統的化成皮膜處理。
並列摘要
ABSTRACT Regarding to the light-weight and lower thickness design trend of 3C industries (computer, communication and consumer industry), the growth momentum and requirement of light-metal is more and more essential, especially in the structure part of mobile phone. As well as the emphasis on environment protection issue, the recyclable light metals like Mg-alloy, Al-alloy and Ti-alloy are becoming the major choice in industrial field. In which Mg-alloy would be the most important one. The topic of this thesis is that we take AZ91D die-cast part as the substrate then adopt the green PVD process with CrN sputtering layer as the surface treatment process based on it’s good anti-corrosion capability and make the comparison study between conventional chemical process and this brand new green process. In this study, we took full-factorial experiments method. The effect of flow rate and mixture ratio of N2 and Ar gas, electric current, power and time were investigated. The performance of anti-oxidation, anti-corrosion and conductivity were compared, as well as the observation of OM, SEM, EDS and component evaluation. Through this study, the main conclusion and observation was that, the best condition would be based on 2 kw of power of sputtering target, heating at 0℃, 50 sccm of N2 volume and 30 sccm of Ar volume, 0.055 μm of film-thickness. This condition can demonstrate the best performance in salt-mist spray test, conductivity measurement and bounding strength. At the same time, comparing with conventional chemical surface treatment, CrN PVD layer can provide better anti-corrosion performance, the corrosive area was less than 5%, after 48 hr salt-mist spray test, and can fulfill the specification of mg-alloy in 3C industry. Meanwhile, regard to conductivity, comparing CrN PVD treatment with chemical surface treatment, before salt-mist spray testing, the performance was quite similar, as 0.022x10-2 Ω and 0.022x10-2 Ω respectively. However, after salt-mist spray, CrN PVD treatment can perform better and more stable conductivity, the average number was 0.029x10-2 Ω measured by four-pin conductivity measurement equipment, on the other hand, measurement number of chemical surface treatment was raising to 2.3Ω and out off required specification, and even coming with the measurement interference from the oxidized layer. In conclusion, CrN surface treatment is surpassing to chemical surface treatment in the performance of anti-oxidation.