Study On The Process And Performance Of Plasma Deposited Silicon Coatings

Harsh service environments can reduce the corrosion resistance of steel surfaces,leading to oil pollution deposits and water vapor permeation.This can creat significant challenges to the safety,reliability and service life of metal piping systems.To extend the service life of parts,surface coating of metallic materials has become an essential method.Atmospheric pressure and plasma surface modification technologies are highly favored due to their efficiency,low damage and strong controllability.However,further studies are necessary to de-termine the optimal thickness of plasma-deposited coatings,growth mechanism,and corrosion path for surface coatings on steel.To address these issues,this paper employed atmospheric pressure low-temperature plasma jet technology to prepare a Si O_x-like coating with anti-corrosion functionality on the surface of alloy steel.Microscopic and macroscopic studies were conducted to analyze the mechanism of coating performance improvement and provided a foundation for optimizing coating preparation technology.The specific research content and outcomes as follows:(1)Plasma simulation and the preparation of uniformly coated steel sur-faces were carried out.First,discharge simulation analysis revealed that the electron density and surface flux increase after grounding,validating the effec-tiveness of the metal base method in enhancing the coating’s compactness.To optimize coating uniformity,a mobile plasma jet deposition experimental plat-form was designed and constructed,where parameters such as deposition time and moving speed were varied.Using atmospheric pressure plasma jet technol-ogy,large-area uniformly coated alloy steel surfaces were successfully prepared.Electrical and optical analysis indicated that the energy conversion efficiency of atmospheric pressure plasma jet deposition of silicon coatings reached 63.1%.(2)Analysis of coating properties and effectiveness in protecting metals from corrosion.The physical and chemical properties of Si O_x coatings were studied under various process conditions.The results indicated that Si O_x coating primarily consisted of a network structure composed of Si-O-Si,Si-OH and a small amount of C-H groups,with good uniformity in thickness and composi-tion.The deposition rate could reach up to 1.47μm/min,and the coating with two layers of thickness had the smallest porosity.The corrosion resistance of coatings with different thicknesses was assessed through electrochemical meth-ods and immersion corrosion experiments.Furthermore,the corrosion behavior characteristics of the coatings were analyzed.The results demonstrated that the dense silicon oxide coating significantly reduced the corrosion current density of the metal material,improving its corrosion resistance by an order of magni-tude or more.The corrosion resistance efficiency could reach 94.76%under op-timal conditions.In the immersion corrosion experiment,pitting corrosion oc-curred mainly on the surface of the bare steel samples,with the pits distributed unevenly.However,the coating remained intact,with no signs of pitting or crev-ice corrosion.(3)The influence of coatings on the self-cleaning stability of metals and the mechanism for enhancing their performance were investigated.The coatings were evaluated for their self-cleaning and aging properties using water-oil con-tact angle tests.The results revealed that the coatings were able to effectively shield the metal surface from oil contamination and corrosion,displaying a sig-nificant level of self-cleaning effect and stability.Furthermore,friction experi-ments demonstrated excellent wear resistance of the coatings,while the Ba-guette test provided evidence that the adhesion between the coating and the sub-strate met the required standard.The growth mode of Si O_x coatings deposited by plasma jet was characterized by island coalescence,with limited diffusion and lateral diffusion during the early growth pattern.As the coating thickness exceeded the critical thickness of about 3μm,the growth rate increased ran-domly before reaching zero.The optimal bonding site displayed prominent structural characteristics,growing longitudinally.