无气喷涂MoS2/Cu/C复合涂层对海上管柱螺纹抗粘扣性能的影响

目的 采用无污染的无气喷涂表面处理工艺，制备MoS₂/Cu/C复合涂层，提高海上管柱螺纹抗粘扣性能。方法 在MoS₂/C涂层中掺杂纳米级Cu粉末，采用无气喷涂+高温固化+喷砂处理工艺，制备MoS₂/Cu/C复合涂层。通过显微组织、硬度测定和摩擦试验，分别评价MoS₂/Cu/C复合涂层的微观组织、显微硬度和摩擦系数，并通过扫描电子显微镜对MoS₂/Cu/C复合涂层进行形貌分析。最后，在实物试样上进行上卸扣试验，测试其抗粘扣性能。结果 无气喷涂+高温固化过程中，半熔融粉末经过多次叠加，沉积形成致密的结构，未见明显孔隙。对MoS₂/Cu/C复合涂层进行喷砂预处理，可明显提高涂层的均匀度，增加涂层的粘结强度。涂层与基体之间呈锯齿形紧密机械结合，喷砂无气喷涂前后，基体硬度未发生改变，未对金属基体造成不利影响。MoS₂/Cu/C复合涂层在螺纹表面结合形成光滑的保护膜，螺纹表面摩擦系数降低，上扣扭矩降低幅度为19%～23%。结论 在Mo S2/C涂...

Effect of Airless Spray MoS2/Cu/C Composite Coating on Buckle-resistant Performance of Offshore Pipe String Threads

Threaded pipes deliver offshore oil or gas under high pressure. Thus, threaded connections must be gas or liquid tight in the severe offshore environment. Uneven force or deformation on the surface of the thread tooth will cause galling and even lead to thread failure. Galling is the key that affects the safety and life of the pipe strings and restricts the quality and efficiency of offshore drilling and well completions. In addition, environmental protection has become the primary concern in recent years. This paper aims to innovatively prepare MoS2/Cu/C composite coatings using a non-polluting airless spray coating technology to improve the anti-galling performance of the threads of the offshore pipe strings. MoS2/C coating is a well-known solid lubricant that can reduce drag. Further, nano-scale Cu powder has good thermal conductivity. The prepared MoS2/Cu/C composite coatings provide a thin layer of heterogeneous composite materials with good thermal conductivity, and excellent friction reduction on the thread surface of the offshore pipe strings. The MoS2/Cu/C composite coatings are prepared by doping MoS2/C coating with nano-scale Cu powder and adopting airless spraying and high-temperature curing. Properties of the composite coatings, including microstructure, microhardness, and friction coefficient, are evaluated first. Then, the morphology of the prepared MoS2/Cu/C composite coatings is analyzed by scanning electron microscopy. Finally, make-up and breakout tests are conducted on the pipe string samples with the prepared MoS2/Cu/C composite coatings to test their anti-galling performance. As a result, the semi-molten powder is superimposed and deposited multiple times during airless spraying and high-temperature curing, forming a dense structure without apparent pores. Besides, sandblasting pretreatment of MoS2/Cu/C composite coatings significantly improved the uniformity and adhesive strength of the coatings. Moreover, the coatings and the metal substrate are tightly combined in a zigzag shape. The hardness of the metal substrate does not change before and after sandblasting and airless spraying. The MoS2/Cu/C composite coatings formed a smooth protective film on the thread surface and had no detrimental effect on the metal substrate. The friction coefficient of the thread surface is reduced. The make-up torque is reduced by 19% to 23%. In conclusion, doping nano-scale Cu powder in MoS2/C coating to form MoS2/Cu/C composite coatings effectively reduce the friction coefficient of the thread surface without reducing the strength of the metal substrate. The MoS2/Cu/C composite coatings obtained by airless spraying and high-temperature curing can effectively improve the anti-galling performance of the threads of the offshore pipe strings. Pipe strings with the prepared MoS2/Cu/C composite coatings have been successfully applied to offshore drilling and well completions. The prepared MoS2/Cu/C composite coatings turn out to prolong the life of the pipe strings and enhance the efficiency of offshore drilling and well completions, saving a substantial amount of money for the oil and gas industry. Overall, the technology presented in this paper has excellent reference significance and is recommended for offshore drilling and well completions.