文献类型：期刊文献

中文题名：预热与重熔处理对激光熔覆Ni基/WC涂层的影响

英文题名：Effect of Preheating and Laser Remelting on Laser Cladding of Ni-Based/WC Coating

作者：梁飞龙[1,2];李凯玥[3];师文庆[2,3,4];朱志凯[3];王立珺[1,2]

机构：[1]广东海洋大学船舶与海运学院,广东湛江524005;[2]广东海洋大学广东省南海海洋牧场智能装备重点实验室,广东湛江524088;[3]广东海洋大学电子与信息工程学院,广东湛江524088;[4]广东海洋大学材料科学与工程学院,广东阳江529500

年份：2024

卷号：51

期号：20

起止页码：103

中文期刊名：中国激光

外文期刊名：Chinese Journal of Lasers

收录：北大核心2023、CSTPCD、、EI(收录号：20244317255217)、ESCI(收录号：WOS:001352130100025)、Scopus、CSCD2023_2024、WOS、北大核心、CSCD

基金：国家自然科学基金(62073089);广东省普通高校重点领域专项资金(2020ZDZX2061)。

语种：中文

中文关键词：激光熔覆;复合涂层;碳化钨;激光重熔;电化学腐蚀

外文关键词：laser cladding;composite coating;tungsten carbide;laser remelting;electrochemical corrosion

中文摘要：为提高316L基材的耐腐蚀性能,延长其在海洋环境下的使用寿命,利用激光熔覆技术在316L基材上通过不同温度的预热及激光重熔处理,制备了Ni基WC/CeO_(2)复合涂层。利用扫描电子显微镜、能谱仪、显微硬度计、电化学工作站以及摩擦磨损试验机对熔覆层的显微组织、显微硬度、耐腐蚀性能以及耐磨损性能进行了测试并分析了其腐蚀行为和机理。结果表明:通过预热处理可以减少涂层的裂纹,提高抗点蚀能力。另外,通过重熔法处理涂层,可以促进涂层中的大尺寸WC颗粒进一步分解,从而使碳化物硬质相的分布更加均匀,进而提高熔覆层的硬度、增强耐腐蚀性能。当预热温度为350℃时,经重熔处理的涂层表现出优良的耐磨和耐腐蚀性能,相比于未经处理的Ni基WC/CeO_(2)复合涂层,其自腐蚀电流由11.51μA·cm^(-2)降低至4.232μA·cm^(-2),磨损体积由6.8×10^(-3) mm^(3)降至1.7×10^(-3) mm^(3)。预热处理提高了涂层的耐腐蚀性能,重熔处理过程中产生的小尺寸碳化物颗粒在摩擦过程中不易脱落,提高了涂层的耐磨性能。

外文摘要：Objective 316L stainless steel has emerged as one of the most extensively utilized stainless steels in the fabrication of marineengineering equipment components.Components that operate in harsh environments are susceptible to damage and failure.To minimize surface damage caused by wear and corrosion,high-performance coatings are typically necessitated on components that operate in the offshore-platform environments.Ni-based/WC composite coatings prepared via laser cladding exhibit remarkable wear and corrosion resistance.Employing these coatings can be instrumental in enhancing the surface characteristics of 316L stainless steel,thus ultimately extending its service life in the demanding marine environment.However,challenges arise due to significant differences in the thermal expansion coefficient and thermal conductivity between Ni-based alloy powder and WC powder.Combining this with the substantial temperature gradient resulting from rapid heating and cooling during laser cladding renders the coating susceptible to significant residual thermal stresses,thus causing cracks to emerge in the coating.To mitigate these challenges and further enhance the coating properties,Ni-based WC/CeO_(2) composite coatings with auxiliary treatments are prepared on a 316L substrate via laser cladding.Methods In this study,substrate preheating and laser melting are performed to optimize a Ni-based WC/CeO_(2) composite coating.Three types of powders are uniformly mixed and preplaced on a polished substrate using a planetary ball mill.The coatings are prepared using a laser-cladding device with a laser power of 1200 W,scanning speed of 800 mm/min,spot diameter of 3 mm,and track spacing of 1.2 mm.The substrates are preheated on a heating plate,and the coatings are fused at room temperature(25±2)℃,200℃,and 350℃,whereas another set of samples are fused under the same preheating conditions.The same laser processing parameters are used for remelting,and the samples are continuously heated to maintain a fixed temperature during laser processing.The microstructures and chemical compositions are characterized via scanning electron microscope(SEM)and energy dispersive spectroscope(EDS),and crystal structures of the coatings are analyzed using X-ray diffraction(XRD).The microhardness of the cladding coatings is tested using a digital microhardness tester.The electrochemical corrosion property of the samples is evaluated using a three-electrode measurement system installed on an electrochemical workstation.Experimental samples are soaked in a solution of NaCl with a mass faction of 0.035 at a temperature of(25±1)℃for 30 d.The friction coefficient of the coatings and the surface contour after the abrasion are tested using a tribometer.Subsequently,the wear and corrosion morphologies of the coatings are characterized using SEM.Results and Discussions Based on the results of flaw-detection experiments(Fig.3),the number of cracks in the Ni-Based WC/CeO_(2) composite coating decreases as the preheating temperature increases.Laser remelting further disintegrates the WC in the coatings and smoothes out the coatings,thus resulting in a more uniformly dense tissue distribution(Fig.4).Based on the XRD patterns(Fig.7),the coating primarily comprises theγ-Ni solid solution phase and carbide hard phase,and the preheating and laser melting minimally affect the phase composition of the coatings.The microhardness of the coating is shown in Fig.8.The average microscopic hardness of the coating without auxiliary treatment is 820.3 HV.Preheating reduces the cooling rate of the melting pool,increases the grain growth time,and reduces the average microhardness to 660.1 HV.Laser remelting facilitates the further decomposition of WC and the even distribution of carbonates,thus causing the microhardness to increase slightly.The electrochemical properties of the coating are shown in Table 4 and Fig.10.The preheating of the substrate reduces the passivation current density from 19.29 mA·cm^(-2) to 17.72 mA·cm^(-2).By increasing the overall resistance of the coating via laser remelting,the corrosion current is decreased from 11.51μA·cm^(-2) to 4.848μA·cm^(-2).Combining the above with the corrosion morphologies(Fig.11),large areas of corrosion occur primarily near the cracks,and reduced fissures effectively inhibits corruption.As shown in Table 5 and Fig.13,the wear volume of the coating without auxiliary treatment is 6.8×10^(-3) mm^(3).Preheating increases the wear volume to 11.4×10^(-3) mm^(3),whereas laser remelting reduces the wear volume to 6.1×10^(-3) mm^(3).The wear morphologies(Fig.14)indicate that the strengthening phases in the coating subjected to preheating and laser remelting are not easily removed during wear.Conclusions In this study,preheating and laser remelting auxiliary treatments are applied to prepare a Ni-based WC/CeO_(2) laser cladding coating on a 316L stainless steel surface.Preheating reduces the number of cracks in the coating and decreases the coating hardness.Laser remelting reduces the electrical corrosion of the coating in the corrosive solution and improves its corrosion resistance.The WC particles of the coating subjected to remelting are removed easily during wear,and their wear resistance depends primarily on the strength of the Ni base.The reduced hardness decreases the wear resistance.Laser remelting can refine carbide in the coatings.In particular,laser remelting at a temperature of 350℃can refine the carbides in the coating while improving the bonding of carbides with the Ni substrate.In summary,the coating subjected to two auxiliary treatments can effectively reduce cracks while improving both wear and corrosion resistance.