Effect of WC on Microstructure and Wear Resistance of Fe-Based Coating Fabricated by Laser Cladding

Abstract

As the core component of the wind turbine transmission chain, the wind power gear plays a vital role in the safe and efficient operation of the whole machine. Wind power gears are subjected to varying degrees of wear on their contact surfaces due to alternating load impacts. For wind power gear repair and remanufacturing, laser cladding technology is proposed on the wind power gearbospline shaft. The effect of tungsten carbide (WC) addition on the laser-clad Fe-based coatings was investigated in this study. The morphology and composition of the composite coatings formed with different proportions of WC were studied using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The microhardness and wear resistance were measured with a digital microhardness tester and a wear testing machine, respectively. The coatings were compact with no apparent cracks or pores and the microstructures of the regions above the fusion zone gradually changed from planar crystal to columnar crystal and cellular crystal, while the middle and upper parts of the coating mainly consisted of equiaxed crystals. The microhardness of the coatings gradually increased with the increase of WC content. The coating with 16% WC addition reached a maximum microhardness of 826.2 HV. The increase of WC content improved the wear resistance of the laser-clad Fe-based composite coatings. The wear mechanism of the coatings was mainly abrasive wear, along with slight adhesion wear and oxidative wear.

Microstructural Evolution, Hardness and Wear Resistance of WC-Co-Ni Composite Coatings Fabricated by Laser Cladding

“…The WC-Co coatings (powder A and powder B), which formed the cladding layer with high hardness, exhibit a relatively high friction coefficient and wear loss, whereas WC-Ni coatings (Powder B) have the lowest friction coefficient and lowest wear loss. Wear resistance of the composite coatings is largely dependent on the microstructure, phase distribution, and mechanical properties of cladding layer [56], and the increased wear resistance of the cladding layer that contained WC particles is caused by their improved microhardness [57].…”

“…The effectiveness of WC particles in the cladding layer depends on the relationship between the wear mechanisms and the mechanical properties, which are related to the microstructure of the cladding layer [64]. The increased wear resistance of powder C (WC-30Ni) is ascribed to the existence of non-decomposed coarse WC particles and an abrasive wear mechanism [57,65]. When the cladding layer contains thermally decomposed WC particles with a fine particle size (e.g., powders A and B), the increase in hardness is primarily attributed to For powder D (Ni-Cr alloy), the worn surface morphology shows a combination of adhesive and abrasive wear, similar to the worn surfaces of layers produced using powder A (WC-12Co, Metco) or B (WC-12Co, HiMC) (Figure 19d).…”

“…The effectiveness of WC particles in the cladding layer depends on the relationship between the wear mechanisms and the mechanical properties, which are related to the microstructure of the cladding layer [64]. The increased wear resistance of powder C (WC-30Ni) is ascribed to the existence of non-decomposed coarse WC particles and an abrasive wear mechanism [57,65].…”

Repair of Gear by Laser Cladding Ni60 Alloy Powder: Process, Microstructure and Mechanical Performance

“…Laser cladding technology was used on the wind power gearbox spline shaft. The Fe-based coatings with different WC addition were manufactured by laser cladding to improve the wear resistance of the wind turbine gears, increasing microhardness and wear resistance with increasing WC content in ironbased coatings [19]. Although some scholars have conducted some research on deposition strategy and parameter optimization, their research studies are incomplete.…”

Research and Progress of Laser Cladding: Process, Materials and Applications

“…Compared with metal alloy powders, ceramic powders exhibit the characteristics of high hardness, high melting point and low toughness and can be used as reinforcing phases in the LC layers. At present, the most commonly used ceramic powders are carbide powders, oxide powders and nitride powders, and the carbide powders include WC, TiC, VC, SiC, NbC, ZrC, and so on [27][28][29][30][31][32]. Rare earths and their oxides are mainly used as modified materials in LC, and the addition of less than 2% can significantly improve the microstructures and properties of the LC layers.…”