Employing A Diamond Film To Improve Wear Resistance Of Geo-drilling Device

This work aims to exploring a mode of improving the wear-resistant of typical geo-drilling equipment and the modification mechanism of diamond film under ultra-deep geo-drilling conditions was established.For maximize the wear-modifying function of the film,the method of macro indentation hardness and fractal dimension of the film was explored,the hardness and surface morphology can be quantitatively characterized.It provides a basis and experimental basis for the use of the diamond film to improve the wear resistance of geo-drilling equipment.The main conclusions are:(1)Analyzing the working principle of typical drilling equipment-hydraulic drilling impactor and its failure characteristics under ultra-deep drilling conditions,try to deposit diamond film on the surface of its wearing parts,and investigate its typical work through friction test.The tribological properties of the film under conditions.The a-SiC/diamond composite film is used to improve the wear resistance of the piston of the vulnerable parts.Under the simulated working conditions,the comparative study of the samples before and after coating shows that the diamond film has excellent tribological properties and can be used for the modification of the piston.The mechanism by which the diamond film improves the wear resistance of the piston is the result of three synergistic effects:(i)planarization of the contact surface during the running-in period;(ii)two-phase lubrication of the diamond particles and the drilling fluid and(iii)contact surface transfer film self-lubricating effect.(2)The diamond film indentation hardness method was obtained by establishing a macron indentation P-h curve,and the diamond film was subjected to micron indentation test.The film was subjected to macro indentation hardness test at different deposition times.Unlike the nanoindentation test method,the calibration of the frame stiffness is the key,and the indentation area correction can use the formula.For the diamond film with a deposition time of 10-30 h,the hardness increases first from 32.3GPa,reaches a maximum value of 56.3 GPa at 25 h,and then decreases.Due to the larger deformation of the matrix than the film layer,the dislocation of the interlayer of the film during nucleation and the enrichment of sp~2-C at the defect.(3)The fractal dimension theory was used to extract the surface fractal dimension from the film SEM image.The effects of key fabrication parameters on the hardness and surface fractal dimension were investigated.The pressure has the greatest influence on the indentation hardness of the diamond film.The methane concentration has the greatest influence on the fractal dimension.However,the influence of the above two on the fractal dimension is not significant.The friction coefficient of the film decreases first with the surface fractal dimension in 1.46~1.76 reached a minimum value around1.62 and increased.