Research On The Tribological Performance Of The HVOF WC-10Co4Cr Coatings In The Environment Of Drilling Fluid

The drilling machine not only suffers extrusion, shear and cyclic shear stress under that cause the action of abrasive wear, adhesive wear, fatigue wear and mechanical damage but also suffer the corrosion of drilling fluid which may cause the action of chemical damage. The thermal spraying technology in drilling machine surface preparation of a layer of strengthened layer can effectively improve the drilling tool wear and corrosion resistance, and significantly improve their work performance and service life. Therefore, the evolution of the microstructure and tribological Properties of the vulnerable parts of drilling tools and the surface strengthening layer in the drilling fluid environment is of great scientific significance to ensure the safety of drilling equipment.The WC-10Co4 Cr cermet coating about 200μm was prepared on 45 steel substrate surface by high velocity oxygen fuel spraying. Saturated salt water drilling fluid with different pH value was prepared by using industrial formulations configuration. The coating was soaked in he drilling fluid for 168 hours. Electrochemical workstation was used with the saturated salt water drilling fluid with different pH value as electrolytic solution to do the potentiodynamic polarization test and electrochemical impedance spectroscopy(EIS).The electrochemical coating failure mechanism, and the influence of the pH value of saturated salt water drilling fluid corrosion on the coating microstructure effects were analyzed.The CSM friction and wear testing machine was used to test the friction performance of the coating before and after the corrosion. The wear resistance, failure morphology, failure mechanism and the effect of corrosion of drilling fluids on the friction and wear properties of the coatings was analyzed.The RM-1 friction and wear testing machine was used to test the rolling contact fatigue performance of the coatings. The contact fatigue life, failure morphology and the failure mechanism was analyzed.Saturated salt water drilling fluid with different content of filtrate reducer and bentonite clay was prepared. The CSM friction and wear testing machine was used to test the friction performance of the coating by using the lubricant of saturated salt water drilling fluid. Systematic analyzed the failure mechanism of the coating by using the lubricant of saturated salt water drilling fluid. The influence of the content of filtrate reducer and bentonite clay to the wear properties of the coatings was researched.