School of Materials Science and Engineering, Shandong University of Science and Technology , Qingdao 266590, China.
ACS Appl Mater Interfaces. 2018 Jan 31;10(4):4250-4265. doi: 10.1021/acsami.7b17286. Epub 2018 Jan 17.
Here, a unique combination of a novel carbon-nitrogen source (g-CN) with different mole ratios of Ti/g-CN has been utilized to fabricate iron matrix composite coatings by a synchronized powder feeding plasma transferred arc (PTA) cladding technology. The results show that submicron Ti(C,N) particles are successfully fabricated in situ on a Q235 low carbon steel substrate to reinforce the iron matrix composite coatings and exhibit dense microstructures and good metallurgical bonding between the coating and the substrate. The microstructure of the coating consists of an α-Fe matrix and Ti(C,N) particles when the mole ratio of Ti/g-CN is no more than 5:1. The microhardness and wear resistance of the coating gradually improve with increasing abundance of the in-situ-synthesized Ti(C,N) particles. Interestingly, for a Ti/g-CN mole ratio of 6:1, a fine lamellar eutectic Laves phase (FeTi) appears, and this phase further improves the microhardness and wear resistance of the coating. The microhardness of the coating is 3.5 times greater than that of the Q235 substrate, and the wear resistance is enhanced 7.66 times over that of the substrate. The Ti(C,N)/FeTi and FeTi/α-Fe interfaces are very clean, and the crystallographic orientation relationships between the phases are analyzed by high-resolution transmission electron microscopy (HRTEM) and an edge-to-edge matching model. The theoretical predictions and the experimental results are in good agreement. Furthermore, based on the present study, for the solidification process near equilibrium, smaller interatomic spacing misfits and interplanar spacing d-value mismatches contribute to the formation of crystallographic orientation relationships between phases during the PTA cladding process. The existence of orientation relationships is beneficial for improving the properties of the coatings. This work not only expands the application fields of g-CN but also provides a new idea for the preparation of Ti(C,N) particle-reinforced composite coatings.
在这里，利用一种新型的碳氮源（g-CN）与不同摩尔比的 Ti/g-CN 的独特组合，通过同步粉末进料等离子转移弧（PTA）熔覆技术制备了铁基复合涂层。结果表明，成功地在 Q235 低碳钢基体上原位制备了亚微米级 Ti(C,N)颗粒，增强了铁基复合涂层的性能，表现出致密的微观结构和涂层与基体之间良好的冶金结合。当 Ti/g-CN 的摩尔比不超过 5:1 时，涂层的微观结构由α-Fe 基体和 Ti(C,N)颗粒组成。随着原位合成的 Ti(C,N)颗粒数量的增加，涂层的显微硬度和耐磨性逐渐提高。有趣的是，当 Ti/g-CN 的摩尔比为 6:1 时，出现了细小的层状共晶 Laves 相（FeTi），进一步提高了涂层的显微硬度和耐磨性。涂层的显微硬度是 Q235 基体的 3.5 倍，耐磨性比基体提高了 7.66 倍。Ti(C,N)/FeTi 和 FeTi/α-Fe 界面非常干净，通过高分辨率透射电子显微镜（HRTEM）和边缘到边缘匹配模型分析了各相之间的晶体取向关系。理论预测与实验结果吻合较好。此外，基于本研究，对于接近平衡的凝固过程，较小的原子间间距失配和晶面间距 d 值失配有助于在 PTA 熔覆过程中形成各相之间的晶体取向关系。取向关系的存在有利于提高涂层的性能。这项工作不仅扩展了 g-CN 的应用领域，也为 Ti(C,N)颗粒增强复合涂层的制备提供了新的思路。
