摘要
目的提高核电管道用合金钢材料的耐腐蚀性能。方法采用中低压冷喷涂工艺在30CrMnSi低合金钢表面制备了Ni涂层,使用数码相机、扫描电镜、电化学工作站等重点研究了喷涂工艺参数(喷涂气体压力和温度)对涂层显微组织、电化学性能和耐盐水性能的影响。结果采用CS1(0.8 MPa-150℃)、CS_(2)(1.0 MPa-200℃)、CS3(1.5 MPa-200℃)和CS4(1.7 MPa-250℃)参数制备的冷喷Ni涂层,涂层厚度由155μm增加至265μm,涂层孔隙率由3.5%降低至0.9%,自腐蚀电位(Ecorr)由‒0.623V增加至‒0.328V(vs.SCE),腐蚀电流密度(Jcorr)由4.3×10^(‒5)A/cm^(2)降低至4.4×10^(‒6) A/cm^(2);4种工艺条件下的冷喷Ni涂层经1000 h人造海水浸泡试验后,对基体仍存在腐蚀保护作用。结论冷喷Ni涂层在人造海水环境中的退化机制源于涂层表面的疏松性质和内部孔隙。浸泡初期,氯离子快速渗透进涂层内部并形成可溶性的氯化物,生成较为封闭的腐蚀坑;随着浸泡时间的延长,涂层内部的孔隙逐渐被这些产物填充满,腐蚀表层变得更加稳定和致密,并逐渐形成了保护层,从而阻断了新鲜氯离子的进一步补充;浸泡后期,阻塞区内外电化学条件的显著差异,加速了腐蚀坑内金属的腐蚀进程,堆积在表层的腐蚀产物体积膨胀或在应力作用下产生了裂纹,氯离子通道再次打开,腐蚀产物不断向外排出,腐蚀表层逐渐脱落。通过提高喷涂压力和喷涂温度,可有效提高冷喷Ni涂层的致密度和结合强度,有力抑制了涂层在盐水环境中的腐蚀扩展过程。通过积累不同工艺条件下冷喷涂Ni基涂层在人造海水环境中的腐蚀失效数据,为冷喷涂Ni基涂层工程化应用提供理论支撑。
In order to improve the corrosion resistance of metal materials for sea pipeline,Ni coating was prepared on the surface of 30CrMnSi low alloy steel by medium and low pressure cold spraying process.The effects of spraying process parameters(spraying gas pressure and temperature)on the microstructure,electrochemical properties and salt water resistance of the coatings were studied by digital camera,scanning electron microscope and electrochemical workstation.The results showed that the thickness of the cold sprayed Ni coating prepared by CS1(0.8 MPa-150℃),CS_(2)(1.0 MPa-200℃),CS3(1.5 MPa-200℃)and CS4(1.7 MPa-250℃)increased from 155μm to 265μm,the porosity of the coating decreased from 3.5%to 0.9%,and the self-corrosion potential(Ecorr)increased from-0.623 V to-0.328 V(vs.SCE).The corrosion current density(Jcorr)decreased from 4.3×10^(-5) A/cm^(2) to 4.4×10^(-6) A/cm^(2).The cold sprayed Ni coating under four process conditions still had corrosion protection effect on the substrate after 1000 h artificial seawater immersion test.The degradation mechanism of cold sprayed Ni coating in artificial seawater environment is derived from the loose properties and internal pores of the coating surface.At the initial stage of immersion,chloride ions rapidly penetrate into the interior of the coating and form soluble chlorides,forming relatively closed corrosion pits.With the prolongation of immersion time,the pores inside the coating are gradually filled with these products,and the corrosion surface layer becomes more stable and dense,and a protective layer is gradually formed,thus blocking the further replenishment of fresh chloride ions.In the later stage of immersion,the significant difference in electrochemical conditions inside and outside the blocking area accelerates the corrosion process of the metal in the corrosion pit.The volume expansion of the corrosion products accumulates on the surface or the cracks under the action of stress,the channel of chloride ions opens again,and the corrosion surface gradually falls off.By increasing the spraying pressure and spraying temperature,the density and bonding strength of the cold sprayed Ni coating can be effectively improved,and the corrosion propagation process of the coating in the salt water environment can be effectively inhibited.At present,the nickel coating prepared by medium and low pressure portable cold spraying system in China is still in the laboratory stage,and its application in industry is rarely reported.In this paper,the effects of medium and low pressure cold spraying parameters on the microstructure and properties of Ni coating on the surface of alloy steel are carried out to meet the requirements of marine equipment for the performance of cold sprayed Ni coating.The corrosion failure data of cold sprayed Ni-based coatings under different process conditions in the artificial environment are accumulated,and the advantages of flexible medium and low pressure portable cold spraying systems,small spray gun size,relatively low equipment and processing cost are fully utilized.It provides theoretical support for the preparation of corrosion protection coating in confined space and on-site repair of damaged parts.
作者
丛大龙
殷宇
张立业
代野
周富
花泽荟
王旋
白懿心
彭冬
丁星星
CONG Dalong;YIN Yu;ZHANG Liye;DAI Ye;ZHOU Fu;HUA Zehui;WANG Xuan;BAI Yixin;PENG Dong;DING Xingxing(Southwest Institute of Technology and Engineering of China South Industries Group Corporation,Chongqing 401329,China;Bohai Shipyard Group Co.,Ltd.,Liaoning Huludao 125004,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2024年第15期242-251,共10页
Surface Technology
关键词
冷喷涂
合金钢
Ni涂层
显微组织
腐蚀防护
耐盐水性能
cold spraying
alloy steel
Ni coating
microstructure
corrosion protection
salt water resistance
