HVOF热喷WC-12Co和Ni60涂层在不同攻角下的固体粒子冲蚀行为

Solid Particle Erosion Behavior of HVOF Thermal Spray WC-12Co and Ni60 Coatings at Different Angles of Attack

目的解决输气管线弯头冲蚀损伤而导致的刺漏问题。方法采用超音速火焰喷涂(HVOF)方法在20#钢基材上分别制备WC-12Co和Ni60涂层。采用显微硬度计测试基材及涂层截面显微硬度。采用X射线衍射仪(XRD)分析涂层表面成分。采用自制喷射式气固冲蚀试验机开展30°、50°、90°3种攻角下固体粒子冲蚀(SPE)试验。采用扫描电子显微镜(SEM)观察SPE试验前后表面和截面的微观形貌,开展基材和2种涂层的SPE机理及冲蚀速率研究。结果在30°攻角下,SPE机理以犁削为主,冲蚀速率受表面硬度的影响较大,20#钢冲蚀速率最大,而WC-12Co涂层的冲蚀速率最小;在50°攻角下,SPE机理为犁削和多冲疲劳混合机理,20#钢的冲蚀速率仍然最大,Ni60涂层和WC-12Co涂层的冲蚀速率相当,均较小;在90°攻角下,冲蚀机理以多冲疲劳损伤为主,WC-12Co涂层的缺陷较少,界面无裂纹,冲蚀速率最小,而Ni60涂层界面处存在裂纹,内部缺陷较多,抗疲劳性能差,冲蚀速率最高。结论WC-12Co涂层在3种不同攻角下都表现出优异的抗冲蚀性能,为提升输气管线弯头抗冲蚀损伤提供了有力的保障。

In order to solve the problem of penetration and leakage caused by erosion damage of elbow of gas transmission pipeline,it is found that there are many influencing factors of solid particle erosion,and the erosion attack angle is one of the most key factors.In view of the above problems,two kinds of coatings,such as WC-12Co and Ni60,were prepared on 20#steel substrate by DJ2700 high-velocity oxygen-fuel spraying(HVOF)equipment.The microstructure of the coating surface and section were observed by Nova Nano SEM450 scanning electron microscope(SEM).HXD-1000TMC/LCD microhardness tester was used to measure the hardness of coating section.XRD-6000 X-ray diffractometer(XRD)was used to analyze the coating composition of the surface coating of the samples.The self-made jet gas-solid erosion tester was used to carry out the solid particle erosion(SPE)test at three attack angles of 30°,50°and 90°,and the micro morphology of the surface before and after the SPE test was observed by scanning electron microscope(SEM).The SPE mechanism and erosion rate of the substrate and the two coatings were studied through comprehensive analysis of the above test data.The results the microhardness of 20#steel substrate was the lowest,which was 139.5HV0.1.The microhardness of Ni60 coating and WC-12Co coating were significantly improved,which were 1229.1HV0.1 and 613.1HV0.1,respectively.At the angle of attack of 30°,the SPE mechanism is mainly ploughing,and the erosion rate is greatly affected by the surface hardness.The erosion rate of 20#steel substrate is the largest,which is 0.0405 mg/g,followed by Ni60 coating,which is 0.0288 mg/g,and the erosion rate of the WC-12Co coating is the smallest,which was 0.0108 mg/g.The WC coating has the highest hardness.At small angle of attack SPE,the coating basically does not have plastic deformation,and the coating is denser with few defects.The coating surface is flat and the furrow is shallow.At the angle of attack of 50°,the SPE mechanism is a mixed mechanism of ploughing and multi-impact fatigue.The erosion rate of 20#steel is significantly lower than that of 30°,but it is still the largest,which is 0.0185 mg/g;The erosion rates of Ni60 coating and WC-12Co coating are basically similar,which are 0.0115 mg/g and 0.0117 mg/g respectively.At 90°angle of attack,the erosion rate of Ni60 coating is the highest,which is 0.0171 mg/g,followed by 20#steel substrate,which is 0.0095 mg/g,and the erosion rate of WC-12Co coating is the lowest,which is 0.0014 mg/g.The erosion mechanism is mainly multi-impact fatigue damage.The WC-12Co coating has few defects,no cracks at the interface,and the erosion rate is the lowest,while Ni60 coating has cracks at the interface,many internal defects,poor fatigue resistance and the highest erosion rate.The WC-12Co coating shows excellent erosion resistance under three different attack angles,which provides a strong guarantee for improving the erosion resistance of gas pipeline elbow.