陽(yáng)極氧化的電壓一時(shí)間曲線(xiàn)大致可以分為三段
The voltage curve of anodization can be roughly divided into three sections.
靠前段：無(wú)孔層形成通電開(kāi)始的幾至十幾秒時(shí)間內(nèi)，電壓隨時(shí)間急劇上升至較大值，該值稱(chēng)為臨界電壓(或形成電壓)。說(shuō)明在陽(yáng)極上形成了連續(xù)的、無(wú)孔的薄膜層(阻擋層)。此膜具有較高的電阻，因此隨著膜層的加厚，電阻加大，槽電壓急劇直線(xiàn)上升。無(wú)孔層的出現(xiàn)阻礙了膜層的繼續(xù)加厚，其厚度與形成電壓成正比，與氧化膜在電解液中的溶解速度成反比。在普通硫酸陽(yáng)極氧化時(shí)，采用高頻氧化電源13～18V槽電壓，則無(wú)孔層厚度約為0.Ol～0.Ol5μm。該段的特點(diǎn)是氧化膜的生成速度遠(yuǎn)大于溶解速度。臨界電壓受電解液溫度的影響很大，溫度高，電解液對(duì)膜層的溶解作用強(qiáng)，無(wú)孔層薄，臨界電壓較低。
The first section: the voltage rises sharply to the maximum with time, which is called the critical voltage (or the voltage) in a few to ten seconds of the starting of the electrified layer. A continuous, non porous film layer (barrier) is formed on the anode. The film has a higher resistance, so as the film thickens, the resistance increases, and the tank voltage rises sharply. The presence of a non porous layer hinders the continuous thickening of the film, which is directly proportional to the formation voltage and inversely proportional to the dissolution rate of the oxide film in the electrolyte. In normal sulfuric acid anodizing, the thickness of the non porous layer is about 0.Ol to 0.Ol5 0.Ol5 m when the frequency of the high frequency oxidation power supply is 13 ~ 18V. The characteristic of this section is that the formation rate of oxide film is much larger than that of dissolution. The critical voltage is greatly affected by the temperature of the electrolyte, the temperature is high, the electrolyte has strong dissolution effect on the film, the thin layer has no pore, and the critical voltage is low.
第二段：膜孔的出現(xiàn)陽(yáng)極電位達(dá)到較高值以后，開(kāi)始下降，其下降幅度為較大值的10%～15%。這是由于電解液對(duì)膜層的溶解作用，使氧化膜較薄的局部產(chǎn)生孔穴，電阻下降，電壓也隨之下降。氧化膜有了孔隙之后，電化學(xué)反應(yīng)可繼續(xù)進(jìn)行，氧化膜繼續(xù)生長(zhǎng)。
The second paragraph: after the anodic potential reaches the highest value, the decrease of the membrane hole is 10% to 15% of the maximum value. This is due to the dissolution of the electrolyte on the film, resulting in holes in the thinnest part of the oxide film, and the resistance decreases, and the voltage drops. After the oxide film has pores, the electrochemical reaction can continue and the oxide film continues to grow.
第三段：多孔層的增厚此段的特征是氧化時(shí)間大約20s后，電壓開(kāi)始趨于平穩(wěn)。此時(shí)，阻擋層生成速度與溶解速度達(dá)到平衡，其厚度保持不變，但氧化反應(yīng)并未停止，氧化膜的生成與溶解仍在每個(gè)孔穴的底部繼續(xù)進(jìn)行，使孔穴底部向金屬內(nèi)部移動(dòng)，隨著時(shí)間的延長(zhǎng)，孔穴加深形成孔隙和孔壁。由于孔隙內(nèi)電解液的存在，導(dǎo)電離子便可在此暢通無(wú)阻，因此在多孔層的建立過(guò)程中，電阻值的變化并不大，電壓也就無(wú)明顯的變化，反映在特性曲線(xiàn)上是平穩(wěn)段。多孔層的厚度取決于工藝條件，主要因素為溫度。在陽(yáng)極氧化過(guò)程中，由于各種因素的影響，使溶液溫度不斷提高，對(duì)膜層的腐蝕作用也隨之加大，不僅孔底，也使孔口處膜層及外表面膜層的腐蝕速度加大，因此多孔層厚度增長(zhǎng)變慢。當(dāng)孔口膜層的腐蝕速度與孔底處的成膜速度相等時(shí)，多孔層的厚度就不會(huì)再繼續(xù)增加，該平衡到來(lái)的時(shí)間越長(zhǎng)，則氧化膜越厚。
The third stage: thickening of the porous layer is characterized by a gradual stabilization of the voltage at about 20s. At this time, the formation velocity of the barrier layer is balanced with the dissolution rate, and its thickness remains unchanged, but the oxidation reaction does not stop. The formation and dissolution of the oxide film continue to be carried out at the bottom of each hole, making the bottom of the hole moving to the inside of the metal, and with the prolongation of time, the hole and the hole are formed to form pore and hole wall. Because of the existence of the electrolyte in the pores, the conductive ions can be unimpeded here, so the change of the resistance value is not significant during the establishment of the porous layer, and the voltage has no obvious change, which is reflected on the characteristic curve as a stationary phase. The thickness of porous layer depends on the technological conditions, and the main factor is temperature. In the process of anodic oxidation, the corrosion of the film is increased because of the influence of various factors, and the corrosion of the film is increased. The corrosion rate of the diaphragm and the surface film layer is increased by the hole bottom, so the thickness of the porous layer increases slowly. The thickness of the porous layer will not continue to increase when the corrosion rate of the pore layer is equal to the velocity of the film forming at the bottom of the hole. The longer the arrival time of the balance, the thicker the oxide film is.