aluminum-anodizing Rev.C阳极处理.ppt

1、Anodizing of Aluminum,陽極氧化處理入門,Physical property of pure Aluminum 物理性質,item property Chemical symbol 元素符號 Al Atomic weight 原子量 26.97 Atomic number 原子序 13 Specific gravity 比重 2.70 (20) Dissolving point 熔點 658 Boiling point 沸點 2057 Dissolving latent heat(cal/g) 熔解熱 94.55 Vaporization latent heat(cal/g

2、) 汽化熱 about 2,000,property of pure Aluminum純鋁的特性,兩性金屬,化學性活潑易於空氣中生成氧化物,氧化鋁可阻止繼續氧化,鋁純度愈高膜層愈均勻,耐蝕性愈佳。 對還原劑易起做用.但對氧化劑則有耐蝕功能.純鋁在濃硝酸下呈鈍態. 比重輕,為地球表面存在最高之金屬,且表面處理形態多樣化,工業廣為應用. 導電率約為銅的60%.熱傳導率為銅的1/2鐵的3倍.,鋁 合 金 的 分 類,Definition,Anodizing is the successful development and control of a natural oxidation process

3、 that occurs when aluminum is exposed to the atmosphere. Electricity and chemicals are used jointly to produce a hard, transparent surface that is integral with base Aluminum. 鋁於大氣環境下即會產生一層氧化皮膜.鋁底材接陽極電流於電解液中產生一層硬而透明的表面, 此電化學反應稱之為”陽極處理”,Characteristics陽極處理的特性,Hard, comparable to a sapphire (藍寶石) Tran

4、sparent, similar to glass (透明,接近玻璃) Insulative and static-resistant (絕緣,防靜電) Wide variety of colors and finishes (顏色外觀多變) Integral with Aluminum surfaces, non-flaking (與鋁表面完全結合且不碎裂),Physical property of Aluminum anodizing陽極處理的物理性質,Porosity density 陽極孔密度 6x1010/cm2 Coefficient of thermal conductivity

5、 0.16cal/cm.sec. 熱傳導係數 Electrical resistance 電阻 1213M-cm Potential resistance 耐電壓 400V Film thickness 膜厚 520m(normal) ,30100m(hard anodizing) Porosity ratio 孔隙率 2030% Hardness 硬度 200250Hv(normal),400450Hv(hard anodizing) Density 密度 3.18g/cm3(20) Heat resistance 耐熱溫度 300 coefficient of thermal expans

6、ion 熱膨脹係數 4.5x10-6M/,Applications for anodizing 陽極處理的應用,Increased corrosion resistance 增加耐蝕性 Increased wear abrasion resistance 增加耐磨耗性 Improved base for paint adhesion 改善底材與塗膜之密著 Provides an electrically non-conductive surface 提供絕緣表面 Provides thermal insulation 隔熱 Protects polished and other mechani

7、cally finished surfaces 保護拋光及機械加工過的表面 Improves appearance of the substrate 改善外觀,How to form the porous film?陽極膜的生成,nm,Difference between the anodic oxidation and the plating陽極處理與電鍍的差異,Anodizing structure陽極膜的結構,Anodizing process陽極處理的流程,Pretreatment (前處理) The Aluminum surface is first cleaned then che

8、mically treated. Etching 、chemical polish results in a desirous appearance. 包含清潔脫脂、蝕刻、化學拋光等 Anodizing (陽極處理) Once the surface is prepared, the anodic film is built. Post Treatment (後處理) The porous anodic film can be colored in this stage. Sealing(封孔) Many of the colors are fade-resistant. Sealing th

9、e anodic film normally consists of a hot water bath that basically swells the pores shut.,Sealing process封孔流程,Reaction Formula反應方程式,As the anode reaction 2Al = 2Al3+ + 6e 2H2O =O2 + 4H+ + 6e 4Al3+ + 3O2 = 2Al2O3 + 12e As the cathode reaction 2H+ + 2e- = H2 ,Surface Preparation前加工製程,Mechanical Polish 機械拋光 Scrubbing 刷磨(如拉髮線等) Sandblasting 噴砂 Chemical Polish 化學拋光 Etching 蝕刻、霧化,Mil Spec 8625 F Type I AConventional coatings produced from chromic acid bath Thickness0.5-7.6 Type I BLow voltage chromic acid anodizing (20 volts)Used for 7xxx series alloys0.5-7