Method for vacuum-compression micro plasma oxidation
View Patent ↗The inventive method and device for vacuum-compression micro plasma oxidation relate to electrochemical processing of metal, in particular to micro plasma treatment in electrolyte solutions. The aim of said invention is to develop a method for obtaining qualitatively homogeneous coatings by micro-plasma oxidation on large-sized parts, including irregular shaped parts, or simultaneously on a great number of small parts. The second aim of the invention is to design a device for processing parts, having an extended surface area, by using low-power supplies. The inventive method for vacuum-compression micro-plasma oxidation of parts consists in dipping a processable part into an electrolyte solution pre-filled in a sealed container, in generating micro-plasma discharges on the surface of said part and, subsequently, in forming a coating, wherein the micro-plasma discharges are formed in low-pressure conditions above the electrolyte solution. The device for carrying out said method comprises means for forming vacuum in the electrolyte-containing container and additional means for pumping air.
1. A method of oxide-ceramic coating of an article comprising:
immersing the article into an electrolyte solution in a container, wherein the electrolyte solution comprises a solvent having a vapor pressure;
connecting the article immersed in the electrolyte solution in the container to a power supply as an anode;
connecting the container or an electrode immersed in the electrolyte solution to the power supply as a cathode;
hermetically sealing the container;
creating above the electrolyte solution in the hermetically sealed container a gas pressure substantially equal to the vapor pressure of the solvent of the electrolyte solution; and
while the gas pressure above the electrolyte solution in the hermetically sealed container is substantially equal to the vapor pressure of the solvent of the electrolyte solution, applying a sufficient power-supply voltage between the article and the cathode to form gas bubbles on a surface of the article thereby blocking a part of the surface and, in the presence of the gas bubbles on the surface, to generate micro-plasma discharges to form oxide-ceramic coating on a the surface of the article.
2. The method of claim 1 further comprising, subsequent to the steps of claim 1 :
creating above the electrolyte solution in the hermetically sealed container a gas pressure equal to at least 1 atm by introducing gas into the container; and
while the gas pressure above the electrolyte solution in the hermetically sealed container is at least 1 atm, applying a sufficient power-supply voltage between the article and the cathode to form further oxide-ceramic coating on an oxide-ceramic coated surface of the article;
wherein the gas is air.