formed oxide membrane here when the velocity of dissolution and the speed of the formed oxide membrane are balanced uniform pores each having a diameter of 10 to 150 nm are formed on a surface of the cathode metal when the pores are formed the acid electrolyte and the current can come in contact with a metal base existing on the lower part of the oxide membrane consequently a very thicker membrane than an oxide membrane formed by an oxidization reaction of a voluntary metal can be formed the membrane through the above process has various physical properties according to its process conditions if an electrolyte of a lower concentration and a higher current or voltage are used a thick membrane is formed the formed oxide membrane has a thickness ranging from 0 5 to 150 u03bcm meanwhile the oxide membrane can be used for various purposes because it has high anti corrosion property and anti friction property and has regular fine pores formed in its surface so that solutions such as dyes can permeate the membrane the most widely known anodic oxidization process standard is a mil a 8625 standard in accordance with the standard an anodic oxidization process is classified into three kinds of aluminum anodic oxidization processes the three kinds of processes include an anodic oxidization process a sulphuric acid anodic oxidization process and a sulphuric acid hard anodic oxidization process membranes formed by the three processes.