Study On Hydrophobicity And Tribological Properties Of Plasma Sprayed Fe-based Amorphous Coatings

In the process of geological drilling,complex downhole working conditions put forward stringent requirements on the drilling performance and reliability of drilling tools.Coating the surface of the drill tool steel with a wear-resistant,corrosion-resistant and hydrophobic amorphous coating can effectively increase its service life.Plasma spraying(APS)is one of the common methods for preparing wear-resistant coatings.Iron-based amorphous alloy coating is suitable for further processing of drill steel body due to its excellent corrosion resistance and wear resistance,strong amorphous forming ability,and low economic cost.In this paper,APS technology is used to prepare Fe₄₈Cr₁₅Mo₁₄C₁₅B₆Y₂ at.%Fe-based amorphous alloy coatings on 35Cr Mo substrates,and perform vacuum heat treatments at different temperatures and laser texture designs with different micro-textures.The effect of heat treatment on the coatings is explored.The influence of wear mechanism and basic properties and the influence of surface laser texturing on the hydrophobic properties of the coating.The main research contents are as follows:(1)Fe₄₈Cr₁₅Mo₁₄C₁₅B₆Y₂ at.%Fe-based amorphous alloy coating was prepared by APS spraying technology on the 35Cr Mo substrate,and the amorphous degree and phase structure of the coating were analyzed by XRD;the coating was observed by SEM and EDS Cross-section microscopic morphology and element distribution;use differential thermal analysis(DSC)to detect the heat release curve of the coating;apply vacuum heat treatment at different temperatures and laser texture design with different micro-textures to the coating.(2)Carry out vacuum heat treatment at different temperatures on the prepared iron-based amorphous alloy coatings,and perform reciprocating sliding friction experiments under dry friction and corrosion wear on the coatings before and after heat treatment to study the effect of heat treatment on APS The impact of the coating's wear resistance and its wear mechanism are analyzed.In order to simulate real working conditions,simulated seawater drilling fluids with different p H values were configured to study the corrosion resistance of the coating before and after heat treatment in the drilling fluid.The coating after heat treatment at 850?has the best anti-wear performance under both dry friction and corrosion wear,while the non-heat-treated coating is in 3.5 wt.%Na Cl solution and simulated seawater drilling fluid with different p H values.Both have the best corrosion resistance.(3)Laser modification is used to obtain surface textures with different shape parameters on the iron-based amorphous alloy coatings prepared,and the effect on the contact angle of the coatings is studied.High-speed cameras are used to verify the hydrophobicity of the coatings in practical applications.The feasibility of the system and its hydrophobic mechanism are analyzed.The shape,center distance and spacing of the laser surface texture have varying degrees of influence on the hydrophobic properties of the coating surface.The surface of the pit-like texture with a center distance of 200?m and the honeycomb-like texture coatings with different pitches have good hydrophobicity.The hydrophobicity of the honeycomb textured surface has no obvious change trend with the increase of the center distance,while the hydrophobic angle of the pit-like textured coating surface becomes smaller as the center distance of the pits increases.