Microstructure And Properties Of Wear-resistance And Self-lubricating Composite Coating Prepared By Plasma Transferred Arc Cladding

With oil exploration and development drilling technology industry advances, deep wells, ultra deep wells, cluster wells, highly slope wells and horizontal wells have emerged. There are dramatic frictions between drill pipes and casings which result in early retirements of the drill pipes and casings, because of long construction period, well depth and complex structure. On-site, the commonly measures are the preparation of banded coatings on the outer surface of tool joints, wear belts, by appropriate surface engineering technology (spray welding, bead welding, etc.) in order to avoiding the wear of tool joints and casings. So the wear belts will isolate the tool joints to casings or well wall, and protect the drill pipes and casings relying on their good wear and friction performances.Microstructure of advanced composite coatings prepared by PTA cladding technology is finer and has the typical characteristics of rapid solidification, so it can be achieve completely metallurgical bonding between the coating and the substrate. Compared with the laser and electron beam technology, PTA cladding technology has some advantages of high energy utilization, high efficiency, low cost, so it has been wide concerned in recent years.In order to explore new methods for wear belts preparation and develop new systems of advanced composite coatings with good wear resistance and anti-friction, the author individually used Fe62-WC, Ni-Cr-Si, Fe-Cr-Si, Fe-Ti-Si-Cr, Ni-Cr-C and Ni-Ti-C alloy powder as raw materials, prepared WC/y-Fe/(Fe, Cr)7C3,Cr3Si/γ-Ni, Cr3Si/γ-Fe, Fe2TiSi/γ-Fe/Ti5Si3, Cr7C3/γ-Ni and TiC/γ-Ni composite coatings, which have good metallurgical bonding with the substrate, on surface of 37CrMnMo steel by PTA cladding technology. Microstructures of the coatings were characterized by OM, SEM, XRD and EDS. Microhardness and the dry sliding friction and wear properties were tested at room temperature. The wear mechanisms were analyzed.The results showed that the average microhardness of WC/γ-Fe/(Fe, Cr)7C3 coatings was HV608, the wear resistance was 11 times higher and friction coefficient was 1.47 times lower than 37CrMnMo steel substrate; The average microhardness of Cr3Si/γ-Ni coatings was HV500, the wear resistance was 13 times higher and friction coefficient was 2.17 times lower than 37CrMnMo steel substrate; The average microhardness of Cr3Si/y-Fe coatings was HV410, the wear resistance was 11 times higher and friction coefficient was 2.17 times lower than 37CrMnMo steel substrate; The average microhardness of Fe2TiSi/γ-Fe/Ti5Si3 coatings was HV1219, the wear resistance was 30 times higher and friction coefficient was 5.69 times lower than 37CrMnMo steel substrate; The average microhardness of Cr7C3/γ-Ni coatings was HV827, the wear resistance was 28 times higher and friction coefficient was 2.76 times lower than 37CrMnMo steel substrate; The average microhardness of TiC/γ-Ni coatings was HV1289, the wear resistance was 21 times higher and friction coefficient was 3.64 times lower than 37CrMnMo steel substrate.Comprehensive analysis, compared with other coatings, the Fe2TiSi/γ-Fe/Ti5Si3 ternary intermetallic compound composite coatings prepared by PTA cladding technology has the best wear resistance, antifriction and good economic applicability, and it is expected to be applied to surface reinforcement of wear resistance and antifriction of tool joints.