Department of Mechanical Engineering, Nitte (Deemed to Be University), NMAM Institute of Technology (NMAMIT), Nitte, Karnataka, 574110, India.
Department of Mechanical Engineering and University Centre for Research & Development, Chandigarh University, Mohali, Punjab, 140413, India.
Sci Rep. 2023 Jul 4;13(1):10778. doi: 10.1038/s41598-023-37991-4.
A typical ferrite/martensitic heat-resistant steel (T91) is widely used in reheaters, superheaters and power stations. CrC-NiCr-based composite coatings are known for wear-resistant coatings at elevated temperature applications. The current work compares the microstructural studies of 75 wt% CrC- 25 wt% NiCr-based composite clads developed through laser and microwave energy on a T91 steel substrate. The developed clads of both processes were characterized through a field emission scanning electron microscope (FE-SEM) attached with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and assessment of Vickers microhardness. The CrC-NiCr based clads of both processes revealed better metallurgical bonding with the chosen substrate. The microstructure of the developed laser clad shows a distinctive dense solidified structure, with a rich Ni phase occupying interdendritic spaces. In the case of microwave clad, the hard chromium carbide particles consistently dispersed within the soft nickel matrix. EDS study evidenced that the cell boundaries are lined with chromium where Fe and Ni were found inside the cells. The X-ray phase analysis of both the processes evidenced the common presence of phases like chromium carbides (CrC CrC, CrC), Iron Nickel (FeNi) and chromium-nickel (CrNi, CrNi), despite these phases iron carbides (FeC) are observed in the developed microwave clads. The homogeneous distributions of such carbides in the developed clad structure of both processes indicated higher hardness. The typical microhardness of the laser-clad (1142 ± 65HV) was about 22% higher than the microwave clad (940 ± 42 HV). Using a ball-on-plate test, the study analyzed microwave and laser-clad samples' wear behavior. Laser-cladding samples showed superior wear resistance due to hard carbide elements. At the same time, microwave-clad samples experienced more surface damage and material loss due to micro-cutting, loosening, and fatigue-induced fracture.
一种典型的铁素体/马氏体耐热钢（T91）广泛应用于再热器、过热器和电站。CrC-NiCr 基复合涂层是已知的高温耐磨涂层。本工作比较了通过激光和微波能在 T91 钢基体上制备的 75wt%CrC-25wt%NiCr 基复合涂层的组织研究。两种工艺制备的涂层均通过场发射扫描电子显微镜（FE-SEM）结合能谱（EDS）、X 射线衍射（XRD）和维氏显微硬度评估进行了表征。两种工艺的 CrC-NiCr 基涂层均与所选基体表现出更好的冶金结合。激光熔覆层的微观结构显示出独特的致密凝固结构，富镍相占据晶间空间。在微波熔覆层的情况下，硬铬碳化铬颗粒均匀分散在软镍基体中。EDS 研究表明，晶界上有铬，晶内有铁和镍。两种工艺的 X 射线相分析均表明存在共同的相，如铬碳化物（CrC、CrC）、铁镍（FeNi）和铬镍（CrNi、CrNi），尽管在开发的微波熔覆层中观察到铁碳化物（FeC）。两种工艺制备的熔覆层中这些碳化物的均匀分布表明硬度较高。激光熔覆层的典型显微硬度（1142±65HV）比微波熔覆层（940±42HV）高约 22%。通过球盘试验分析了微波和激光熔覆层样品的磨损行为。由于硬质碳化物元素的存在，激光熔覆层的样品表现出优异的耐磨性。同时，由于微切削、松动和疲劳引起的断裂，微波熔覆层的样品经历了更多的表面损伤和材料损失。
