Wear Failure And Surface Modification Of Composite Diamond Film For Composite Tools In Deep-bottomed Exploration

The composite diamond film with SiC transition layer was prepared by using medium frequency magnetron sputtering and hot filament chemical vapor deposition composite surface modification technology to improve the wear resistance of the moving parts of the deep bottom drilling machine.The surface of the moving parts was modified to study the effect of the main preparation parameters on the structure and surface finish of the films.The properties of the films with uniform surface orientation,high diamond content and high surface finish were obtained,and the composite diamond The modification mechanism of the composite diamond film was established,and the theoretical basis and experimental basis for the preparation of the bottom-bottom power tool parts with good wear resistance were provided for the modification effect of the film on the surface of the rotating part and the reciprocating part.The main conclusions are:(1)The composite diamond film containing SiC transition layer was prepared on 38 CrMoAl High quality alloy steel substrate by hot filament chemical vapor deposition.With the argon volume,the CH4/H2 and the power increase,the diamond film exhibits(111)crystal orientation preferential growth,accompanied by a small amount of(220)crystal orientation.The content of sp3 phase within the film was firstly increased and then decreased,and reached the maximum at 30 vol.% Ar,1.0 vol.% CH4/H2 and power of 7 KW,respectively.The surface roughness firstiy increases and then decreases,reaching the maximum at 30 vol.% Ar,1.5 vol.% CH4/H2 and power at 5 KW,respectively.(2)Analysis of tribological properties of screw motor rotor samples before and after coating by MS-T3000 wear tester.In the mud of the screw motor rotor corrosion to wear the main.With the load,the friction coefficient and the wear rate of the film increase with the increase of the load(from 1 N to 7 N),and the friction increases.The friction heat causes the diamond in the film to be converted into graphite phase.The mechanism of modification is that the friction contact surface is flattened,the frictional heat causes the contact surface to be solidified from the graphite,and the diamond chips and the graphite embedded in the film surface make the film have low coefficient of friction and high wear resistance,high binding force transition Layer makes the diamond film with easy to fall off the characteristics.(3)In the use of CSM reciprocating wear test machine analysis of drilling impactor piston coating before and after the tribological properties.The failure mechanism of drilling piston in drilling fluid is abrasive wear.With the reciprocation frequency increasing,the corresponding friction coefficient and wear rate of the film increase with the friction coefficient(friction coefficient from 0.04 to 0.08,wear rate from15 × 10-11 mm3/N · mm to 32 × 10-11 mm3/N · mm),the surface wear depth increases.The graphite phase in the film increases,but the diamond phase decreases.The mechanism is: after the friction contact,the contact surface is flattened;the drilling fluid weakens the mechanical locking effect and acts as a boundary lubrication;forming the transfer film to further reduce the friction coefficient.