MoS2粉末於電解液中的添加對7075-T6鋁合金微弧氧化膜層之影響

Effects of adding MoS2 in electrolytes on properties of MAO coating of 7075-T6 Al alloy

林妤珈(Yu-chia Lin)

指導教授 ： 楊木榮

大同大學/工程學院/材料工程學系所/碩士(2010年)

摘要

2g/L、4g/L、8g/L之MoS2粉末至電解液中，實驗條件在定電壓及定電流下，近年來，由於全球暖化的現象越來越明顯，在環保意識抬頭和節能減碳的前提下，使得輕金屬近年來在工業上之使用量有增無減。微弧氧化技術為一種具有對環境友善性的製程，因此在輕金屬表面改質上已經受到廣大的重視，其原理是利用在陽極之工件表面產生局部高溫熔融態金屬氧化，使熔融金屬由放電孔道噴出而被電解液冷卻於試片表面而成膜，此膜層會與基材緊密連結，保護內部之金屬基材防止腐蝕，因此膜層可以具有良好之耐磨耗、絕緣性、高硬度等特性。然而，MAO膜層具有雙層結構，外層的多孔層及內層的緻密層，因此減少多孔層之孔洞成為了重要的課題。
本研究添加0g/L、1g/L、占空比為30％、處理時間20分鐘，實驗結果顯示，添加MoS2粉末後之MAO膜層其相組成與未添加MoS2粉末的膜層相同，仍是以α-Al2O3、γ-Al2O3峰值為主，皆無MoS2峰值出現；值得一提的是，當添加2g/L 之MoS2粉末後，其膜層表面形貌卻明顯產生孔洞變少的情形；由於粉末的分布不均，MoS2利用鑲嵌於孔洞中以降低膜層之孔洞。經過耐蝕性檢測，可發現在添加2g/L 之MoS2粉末皆具有最小之腐蝕電流密度，同時在定電流模式下，也可發現在添加2g/L 之MoS2粉末時，亦可得到最高的硬度1134Hv，以及最少之重量損失0.357 mg和最低之摩擦係數0.26。

關鍵字

微弧氧化 ； 二硫化鉬 ； 耐磨耗 ； 抗腐蝕

並列摘要

In recently years, becase the global warming became obvious, the light metal, such as Al, Mg, Ti, are used in today’s industry more widely. Micro-arc oxidation (MAO) is an environmental friendly process, increased attentions as a novel technique to produce ceramic coating with good properties, such as wear resistance, high hardness and good adhesion. Micro-arc oxidation is a complex process which combines diffusion, electrophoresis, thermal chemistry, phase transformation and so on. In MAO process, the local instantaneous temperature and pressure inside these microarc discharge channels lead to metal melting, and these metal molten was ejected from discharge channels, cooled by the solution. Thus, the ceramic coating was formed.However, the MAO coating exist double layer structure, including porous layer on the outer layer, and dense layer on the inner layer, so the outer layer is a disadvantage for their tribological properties and corrosion resistance. Therefore, reducing the porosity of top layer to improve the surface properties become more important.
In this study, 0g/L. 1g/L. 2g/L 4g/L and 8g/L of molybdenum disulfide (MoS2) powder (2m), a well-known dry lubricant, is added to the electrolytic solution. The parameter that anodic voltage is 400V and duty ratio are unfixed, and the treatment time is 20 minutes. The phase compositions of MoS2-dopped coating as same as MoS2-undopped coating are α-Al2O3 and γ-Al2O3. When the amount of MoS2 powders is 2 g/L, the morphology of coating indicate that adding MoS2 will reduce the pore density and the pan-like structure. This reveal that the MoS2-dopped coating become smoother.
Meanwhile, when the amount of MoS2 powders is 2 g/L in constant current, the corrosion current density of this coating will reach the minimum. In dry sliding test, adding 2 g/L MoS2 coating will obtain the highest hardness（1134Hv）, the lowest weigh loss（0.357 mg） and the lowest friction coefficient（0.26）. It can be concluded that the MoS2-dopped coatings on 7075-T6 exhibit better corrosion and wear resistance.

並列關鍵字

MAO ； MoS2 ； anti-corrossion resistence ； wear resistence

參考文獻

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