# Study on Cleaning the Surface of Stainless Steel 316 Using Plasma Electrolysis Technology
## 1 Introduction  
Surface cleaning of stainless steel is generally preceded by the use of an organic solvent to remove exterior grease and by alkaline or acid washing to remove dirt, inorganic substances, and oxides, followed by washing in water before subsequent processes. The surface can also be cleaned with surface sandblasting, ultrasonic cleaning, electrolytic grinding, and other methods. However, traditional cleaning methods have drawbacks, such as high cost, harmful effects upon the environment and the human body, and the need to treat the resulting waste liquid. Plasma electrolytic technology, currently used in paper processing, can ameliorate the defects of traditional processing methods, reducing the cost of surface cleaning and the level of pollution affecting the environment and human health. Plasma electrolytic technology has been widely used in engineering for coating, surface treatment, cleaning, and so on. In general, plasma electrolytic technology can be divided into anodic and cathodic electrolytic technologies, which are clearly described by [PERSON] and [PERSON] [1]. [PERSON] et al. [2] summarized plasma electrolytic technology and proposed a theoretical model that can be used for further observing the reaction process in this technology. Plasma electrolytic oxidation is usually used for metal oxidation and nanoparticles. [PERSON] et al. [3] used plasma electrolytic oxidation (PEO) in a titanium alloy and discovered the effect of the thickness of the oxidation film generated with different electrolytes. In 2004, [PERSON] et al. [4] issued a paper on the anodic PEO of an alkaline solution on an aluminum alloy. [PERSON] et al. [5] combined electric arc spraying and PEO to promote abrasion resistance and corrosion resistance in aluminum oxide double coatings on a steel plate. [PERSON] et al. [6] proposed research on the corrosion resistance of a magnesium alloy following PEO oxidation. [PERSON] et al. [7] optimized the corrosion resistance of a magnesium alloy with PEO and a method of changing the current density. [PERSON] and [PERSON] [8] proposed coating three materials on a magnesium alloy using PEO. [PERSON] [9] and [PERSON] et al. [10] treated a magnesium alloy with PEO and studied its corrosion resistance and hydrophobicity. [PERSON] et al. [11] proposed an oxidation film that could be coated on a magnesium alloy and further explored the film's hardness and corrosion resistance. Anodic electrolytic technology is currently used to make scratch-resistant layers and metal coatings to prevent surface oxidation on metal. Cathodic plasma electrolytic technology is usually used to treat a cathodic surface and includes four applications: cleaning, heat treatment, fabrication of nanostructures, and nanocrystalline coating. The solution used in cathodic plasma electrolytic technology is based mainly on a weak alkali solution. A high voltage is applied during processing to form plasma, then paint, grease, dirt, and oxide can be removed from the surface. Compared to traditional cleaning methods, this reduces harmful effects upon the environment and human health. In addition, this technology can generate nanostructures on the material's surface, making it less susceptible to dust and increasing corrosion resistance. [PERSON] et al. [12] summarized the plasma electrolytic principle and described the voltage-current curve of plasma electrolytic cleaning technology. [PERSON] et al. [13] used plasma electrolytic cleaning technology on structural steel and effectively improved its resistance to corrosion. [PERSON] et al. [14] used sodium bicarbonate as the electrolyte and cleaned the surface of low-carbon steel, then coated it with zinc and aluminum. [PERSON] and [PERSON] [15] proposed that plasma electrolytic technology could effectively remove rust and even the arc spray coating deposited on the steel surface. [PERSON] et al. [16] proposed a phased-shift resonant power system to enhance the plasma cleaning efficiency by an online measurement of plasma load.