A100超高强度钢激光熔覆CoCrNiNb_(0.1)+B_(4)C高熵合金涂层在模拟海洋环境下腐蚀行为研究  

Corrosion Behavior of CoCrNiNb_(0.1)+B_(4)C High Entropy Alloy Coating on A100 Ultra-high Strength Steel by Laser Cladding under Simulated Marine Environment

作　　者：杨文迪 赵连红 沈明禄 崔中雨 何卫平 崔洪芝 YANG Wendi;ZHAO Lianhong;SHEN Minglu;CUI Zhongyu;HE Weiping;CUI Hongzhi(School of Material Science and Engineering,Ocean University of China,Shandong Qingdao 266100,China;China Special Aircraft Research Institute,Hubei Jingmen 448001,China)

机构地区：[1]中国海洋大学材料科学与工程学院,山东青岛266100 [2]中国特种飞行器研究所,湖北荆门448001

出　　处：《表面技术》2024年第24期99-109,共11页Surface Technology

基　　金：中央高校基本科研业务费(202241012,202262011);山东省优秀青年基金(ZR2022YQ44)。

摘　　要：目的探究B4C含量对A100超高强度钢激光熔覆CoCrNiNb_(0.1)+B_(4)C高熵合金涂层的显微组织、力学性能及其耐蚀性能的影响,阐明腐蚀机制。方法探究合适的激光加工工艺参数,利用激光熔覆技术在A100钢基材表面制备了CoCrNiNb_(0.1)+xB_(4)C高熵合金涂层。通过SEM、EDS测试对涂层的显微组织和元素分布进行分析,通过XRD测试对涂层的物相组成进行分析。通过显微硬度测试对涂层的力学性能进行表征,通过电化学测试、浸泡实验对涂层耐蚀性能进行表征,并分析了涂层的腐蚀机制。结果高熵合金涂层的显微组织均由树枝晶组成,其中,Cr、Nb、B、C元素富集在枝晶间区域,Co、Cr、Ni元素均匀分布。涂层的物相组成为基体FCC相和陶瓷相,陶瓷相Cr_(7)C_(3)、(Cr,Nb)_(23)(C,B)6的含量随B_(4)C含量的升高而升高。陶瓷相的出现形成了第二相强化效应,导致涂层显微硬度升高。随着B_(4)C含量的升高,涂层的耐蚀性降低,表现为容抗弧减小、阻抗模值降低、过钝化电位降低。浸泡实验过程中,陶瓷相作为阴极相具有更高的电位,腐蚀反应的萌生位点为FCC相,两相间的电位差导致了电偶腐蚀的发生,电偶腐蚀为涂层主要的腐蚀失效机制。结论B4C的加入导致涂层显微硬度提升、耐蚀性能降低。A100 ultra-high-strength steel is one of the ideal steel choices for the landing gear of amphibious aircraft.During actual service,it is often directly exposed to the marine environment,resulting in serious corrosion risks.Without affecting the mechanical properties of A100 ultra-high-strength steel,preparing a coating on its surface has become the first choice for surface protection.The high-entropy alloy coating prepared by laser cladding can achieve good protection on the surface of A100 ultra-high-strength steel.While ensuring the excellent mechanical properties and good corrosion resistance of the high-entropy alloy coating,it can achieve the metallurgical bonding of the coating and the substrate.Compared with traditional coatings and plating,the bonding strength is greatly improved.This paper designed high-entropy coating systems with different B4C contents to explore the effect of B4C content on the microstructure,mechanical properties and corrosion resistance of laser-clad CoCrNiNb_(0.1)+B_(4)C high-entropy alloy coatings on A100 ultra-high-strength steel,and elucidate the corrosion mechanism.This article explored the optimal laser processing process parameters,comprehensively considering the coating formability and performance,and finally determined the laser processing parameters as follows:laser power was 1.4 kW,scanning rate was 300 mm/min,and spot diameter was 3 mm.Heat-treated A100 ultra-high-strength steel with a size of 100 mm×15 mm×5 mm was selected as the base material,and different proportions(0%,2%,2.5%,3%,5%mass fraction)of B_(4)C CoCrNiNb_(0.1)powder was used as coating raw material,and the coating was prepared after laser cladding.Then,the microstructure and element distribution of the coating were analyzed through SEM and EDS tests,and the phase composition of the coating was analyzed through XRD tests.The mechanical properties of the coating were characterized through microhardness testing,the corrosion resistance of the coating was characterized through electrochemical testing and imme

关 键 词：CoCrNi基高熵合金涂层 激光熔覆 海洋腐蚀 

分 类 号：TG174[金属学及工艺—金属表面处理]