目的 在钢铁材料表面制备硬质涂层,可明显改善其因表面硬度低和耐磨性差导致在摩擦工况下使用寿命低的问题。采用传统均质涂层在提高表面硬度和耐磨性的同时,通常伴随着韧性的大幅降低,即硬度（耐磨性）与韧性存在权衡关系,因此采用原位固相扩散技术在HT300表面制备一种具有双层结构的新型碳化钼复合涂层。方法 采用X射线衍射（XRD）、扫描电子显微镜（SEM）和背向散射电子衍射技术（EBSD）分析涂层的物相组成和微观形貌。用G200纳米压痕仪测试涂层截面的硬度和压入模量。通过维氏压痕测试实验评价涂层的断裂韧性。结果 当制备工艺参数为1 000 ℃、保温10 h时,涂层呈现致密结构,且涂层与基体之间无明显间隙。进一步将制备工艺参数优化为温度1 050 ℃、保温时间10 h,所制备涂层的截面微观组织呈现典型的双层结构。从复合涂层表面到基体,第1层（Ⅰ）为完全致密的Mo2C层,第2层（Ⅱ）为连接Mo2C层与HT300基体的Fe3Mo3C(Si)过渡层。Mo2C层/Fe3Mo3C(Si)层界面和Fe3Mo3C(Si)层/基体界面均呈现良好的冶金结合。当保温时间由4 h增加到10 h时,复合涂层的厚度由(15.9±0.46) μm增至(25.3±0.85) μm,且复合涂层厚度的平方与保温时间t成正比（d2=Kt,K=64.35 μm2·h）。压痕测试结果表明,复合涂层表面的硬度和断裂韧性分别达到(24.6±0.5) GPa和(3.0±0.1) MPa·m1/2。相较于未涂覆的HT300基体（(3.5±0.5) GPa）,复合涂层表面的硬度提高了约6倍。沿着厚度方向,复合涂层的硬度逐渐降低,而断裂韧性逐渐增大。结论 复合涂层内双层结构的形成可以降低复合涂层与基体之间的界面应力集中,进而改善了复合涂层与基体之间的界面结合。该新型钢铁材料表面双层结构的制备策略有效解决了钢铁材料表面硬度低和耐磨性不足的问题。
Abstract
The preparation of hard coatings on the steel/iron surface can significantly overcome the bottleneck of low service life under friction conditions due to the low surface hardness and poor wear resistance. However, for traditional homogeneous coatings, the increase in surface hardness and wear resistance is usually accompanied by a significant drop in toughness, that is, there is a trade-off relationship between hardness (wear resistance) and toughness. Therefore, the design and development of coatings with high toughness and high wear resistance are of great significance for expanding the application range of steel/iron materials. The work aims to prepare a new type of molybdenum carbide composite coating with a double-layer structure on the surface of HT300 at 1 050 ℃ by in-situ solid-phase diffusion technology, in order to achieve the synergistic improvement of surface hardness and toughness of the coating.
The cross-sectional microstructure, chemical composition, and thickness of the coating were characterized by combined scanning electron microscopy (SEM) and X-ray energy dispersive spectrometery (EDS). The phase constitution of the surface of coating was analyzed by X-ray diffraction (XRD) over 2θ angles ranging from 20° to 90°. The grain morphology and the corresponding growth orientation of the cross section of coating were investigated by electron backscatter diffraction (EBSD) technique. The nanohardness and indentation modulus of the cross section of the coating and the substrate were measured with a nanoindentation tester. Furthermore, the fracture toughness of the coating was evaluated by the Vickers indentation method.
Results showed that when the coating was held at 1 000 ℃ for 10 h, it presented a dense structure and there was an obvious interface interstice between the coating and the substrate. When the preparation process parameters were optimized to 1 050 ℃for 10 h, the cross-sectional microstructure of the coating presented a typical double-layer structure. From the composite coating surface to the substrate, the first layer (Layer Ⅰ) was a completely dense Mo2C layer, and the second layer (Layer Ⅱ) was a Fe3Mo3C(Si) transition layer that connected the Mo2C layer and the cast iron substrate. The Mo2C/Fe3Mo3C(Si) layer interface and Fe3Mo3C(Si) layer/matrix interface showed good metallurgical bonding. Moreover, as the holding time (t) increased from 4 h to 10 h, the thickness (d) of the composite coating increased from (15.9±0.46) μm to (25.3±0.85) μm, and the square of the thickness of the composite coating was proportional to the holding time t (d2=Kt, K=64.35 μm2·h). The indentation test results showed that the hardness and fracture toughness of the composite coating surface reached (24.6±0.5) GPa and (3.0±0.1) MPa·m1/2. Compared with the uncoated HT300 substrate ((3.5±0.5) GPa), the hardness of the coated surface increased by about 6 times. Moreover, along the thickness direction, the hardness of the composite coating decreased gradually, while the fracture toughness increased gradually.
The study demonstrates that the formation of the double-layer structure in the composite coating significantly reduces the stress concentration at the composite coating/substrate interface, thereby greatly improving the interfacial bonding between the composite coating and the substrate. Therefore, this work provides a novel preparation strategy for a double-layer structure coating on the surface of steel/iron, effectively improving the problems of low surface hardness and insufficient wear resistance of the steel/iron.
关键词
固相扩散 /
双层结构 /
碳化钼复合涂层 /
微观组织 /
力学性能
Key words
solid-phase diffusion /
double-layer structure /
molybdenum carbide composite coating /
microstructure /
mechanical properties
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] RAJPUT A S, NEOG S P, DAS S.Effect of Tempering Conditions on Microstructure Evolution and Sliding Wear Behaviour of Continuously Cooled Carbide-Free Bainitic Steel[J]. Tribology International, 2025, 204: 110519.
[2] ZHU X T, PENG T, HUA J, et al.Wear Damage and Microstructure Evolution of High-Speed Wheel Steel under Low Slip Ratios[J]. Wear, 2025, 564: 205742.
[3] 唐珲, 周志明, 胡峰荣, 等. Cr12MoV钢表面CrAlN涂层的制备及其摩擦性能研究[J]. 铸造技术, 2021, 42(11): 983-986.
TANG H, ZHOU Z M, HU F R, et al.Research on Preparation and Tribological Properties of CrAlN Coating on Cr12MoV Steel[J]. Foundry Technology, 2021, 42(11): 983-986.
[4] BAI H Q, KANG L, ZHANG P C, et al.TiC-Fe Gradient Coating with High Hardness and Interfacial Adhesion Strength on Cast Iron Prepared by In-Situ Solid-Phase Diffusion Method[J]. Vacuum, 2023, 215: 112336.
[5] ZHANG K, LIU C H, WANG W L, et al.Microstructure, Performance, Strengthening and Toughening Mechanisms of WC-Reinforced Inconel 625 Gradient Composite Coating by Laser Cladding on Nonmagnetic Steel[J]. Surface and Coatings Technology, 2025, 496: 131657.
[6] ZHAO Z Y, TANG Y X, PAN Y, et al.Microstructure Formation Mechanism of Mo2C/W2C/Mo2C Three-Layer Film on Mo Substrate Prepared by Magnetron Sputtering and Carburization[J]. Surface and Coatings Technology, 2025, 497: 131752.
[7] WANG W Q, CAI Z Z, LI S, et al.Microstructure and Wear Resistance of In-Situ Synthesized Stellate Mo2C Reinforced WC/Amorphous Composite Coatings by Resistance Seam Welding (RSW)[J]. Tribology International, 2023, 186: 108599.
[8] FAN D, LI X, ZHANG J.Influence of Processing Parameters of Laser Clad Mo2C-Co-based Alloy on Its Microstructure[J]. Lanzhou University of Technology, 2012, 38: 1673-5196.
[9] ZHU W X, GE Y, KONG D J.Microstructure and Tribological Performance of Laser-Cladded Mo2C-Reinforced NiMo Coatings under Grease-Lubrication Condition[J]. Journal of Thermal Spray Technology, 2022, 31(8): 2635-2646.
[10] KUMAR D D, KUMAR N, PANDA K, et al.Tribochemistry of Contact Interfaces of Nanocrystalline Molybdenum Carbide Films[J]. Applied Surface Science, 2018, 447: 677-686.
[11] AVDYUKHINA V M, KHRUSHCHOV M M, SULYANDZIGA D A, et al.X-Ray Diffraction Studies of the Effect of Phase Composition and Structural State Characteristics on the Tribological Behavior of the Molybdenum-and Tungsten-Based Strengthening Coatings[J]. Crystallography Reports, 2023, 68(3): 468-477.
[12] WANG X H, HAN F, LIU X M, et al.Effect of Molybdenum on the Microstructure and Wear Resistance of Fe-Based Hardfacing Coatings[J]. Materials Science and Engineering: A, 2008, 489(1/2): 193-200.
[13] ÇÖMEZ N, YURDDASKAL M, GÜL C, et al. Fe-Cr-C-V Hardfacing Coatings with Molybdenum Addition: Wear, Corrosion, and Cavitation Performances[J]. Surface and Coatings Technology, 2024, 482: 130715.
[14] ZHAO Z Y, HUI P F, WANG T, et al.Fabrication of Mo2C Coating on Molybdenum by Contact Solid Carburization[J]. Applied Surface Science, 2018, 462: 48-54.
[15] KANG Q P, HE X B, REN S B, et al.Effect of Molybdenum Carbide Intermediate Layers on Thermal Properties of Copper-Diamond Composites[J]. Journal of Alloys and Compounds, 2013, 576: 380-385.
[16] WANG K M, CHANG B H, CHEN J S, et al.Effect of Molybdenum on the Microstructures and Properties of Stainless Steel Coatings by Laser Cladding[J]. Applied Sciences, 2017, 7(10): 1065.
[17] 成永健. 工模具TiAlSiN多元多层涂层的制备与性能研究[D]. 武汉: 华中科技大学, 2023: 35-44.
CHENG Y J.Study on Preparation and Properties of TiAlSiN Multielement and Multilayer PVD Coatings on Tool and Die Steel[D]. Wuhan: Huazhong University of Science and Technology, 2023: 35-44.
[18] KIM J H, KIM S J.The Effect of Molybdenum on Cavitation Erosion and Corrosion Resistance of Fe-Cr-C-Si Hardfacing Alloys[J]. Journal of Nuclear Science and Technology, 2008, 45(Sup. 5): 93-96.
[19] CAI X L, GUO L, CAO B W, et al.Structure and Mechanical Properties of WC Interlayers between Iron Substrate and Thin Tungsten Plate[J]. Vacuum, 2021, 194: 110599.
[20] MA Y, ZHANG Y, YAO X H, et al.Characterization of Mo Surface Modified Ti by Indentation Techniques[J]. Surface and Coatings Technology, 2013, 226: 75-81.
[21] NIIHARA K, MORENA R, HASSELMAN D P H. Evaluation of Kic of Brittle Solids by the Indentation Method with Low Crack-to-Indent Ratios[J]. Journal of Materials Science Letters, 1982, 1(1): 13-16.
[22] LAUGIER M T.New Formula for Indentation Toughness in Ceramics[J]. Journal of Materials Science Letters, 1987, 6(3): 355-356.
[23] 黄儒明, 代明江, 林松盛, 等. 调制周期对Cr/CrN多层膜结构及性能的影响[J]. 热加工工艺, 2019, 48(10): 136-139.
HUANG R M, DAI M J, LIN S S, et al.Effect of Modulation Periods on Structure and Properties of Cr/CrN Multilayer Films[J]. Hot Working Technology, 2019, 48(10): 136-139.
基金
国家自然科学基金（52461030）; 陕西省重点研发计划（2025CY-YBXM-020）; 榆林市科技计划（2024-CXY-065）; 陕西省教育厅一般专项科学研究计划（25JK0757）; 榆林市科协青年人才托举计划（20240622）
PDF(4339 KB)
渝公网安备 50010702501715号 渝ICP备15012534号-3
