Key Takeaways & Executive Findings
- •• Laser cladding produces Fe-based alloy coatings with superior interfacial bonding and finer microstructure compared to traditional methods, but they suffer from lower hardness and wear/corrosion resistance. • Doping with rare earth oxides (La2O3, CeO2, Y2O3) significantly enhances the microstructure, hardness, wear, corrosion, and oxidation resistance of laser-cladded Fe-based alloy coatings. • The concentration of rare earth oxides critically influences coating properties; optimal doping levels refine grains and reduce defects like pores and cracks. • This review consolidates mechanisms by which rare earth oxides improve coating performance, providing a reference for advancing laser cladding technology for Fe-based alloys.
Abstract
Conventional Fe-C alloy parts used in mechanical transmission and braking systems exposed to the external environment often suffer from wear and corrosion failures. Surface coating strengthening technologies have been explored to improve the surface performance and prolong service life of these parts. Among these technologies, laser cladding has shown promise in producing Fe-based alloy coatings with superior interfacial bonding properties to the Fe-C alloy substrate. Additionally, the microstructure of the Fe-based alloy coating is more uniform and the grain size is finer than that of surfacing welding, thermal spraying, and plasma cladding, and the oxide film of alloying elements on the coating surface can improve the coating performance. However, Fe-based alloy coatings produced by laser cladding typically exhibit lower hardness, lower wear resistance, corrosion resistance, and oxidation resistance compared to coatings based on Co and Ni alloys. Moreover, these coatings are susceptible to defects such as pores and cracks. To address these limitations, the incorporation of rare-earth oxides through doping in the laser cladding process has garnered significant attention. This approach has demonstrated substantial improvements in the microstructure and properties of Fe-based alloy coatings. This paper reviewed recent research on the structure and properties of laser-cladded Fe-based alloy coatings doped with various rare earth oxides, including La2O3, CeO2, and Y2O3. Specifically, it discussed the effects of rare earth oxides and their concentrations on the structure, hardness, friction, wear, corrosion, and oxidation characteristics of these coatings. Furthermore, the mechanisms by which rare earth oxides influence the coating’s structure and properties were summarized. This review aimed to serve as a valuable reference for the application and advancement of laser cladding technology for rare earth modified Fe-based alloy coatings.
1. Introduction
Fe-C alloy parts utilized in mechanical transmission and braking systems, which are exposed to external environments, are susceptible to corrosion and wear [1-2]. Examples include steel shaft components in mechanical transmission equipment within powder, chemical, and metallurgical industries, as well as cast-iron brake discs used in trains operating at speeds below 200 km·h-1. Moreover, replacing these parts prematurely leads to resource wastage and economic losses. Enhancing the wear and corrosion resistance of Fe-based alloy parts through surface coating technologies can notably enhance their performance and prolong their operational lifespan [3].
Laser cladding technology, as shown in Fig. 1, adopts a high-energy laser beam as a heat source to melt the powder material. After rapid solidification, a metallurgically bonded coating is deposited onto the substrate. This technology results in a minimal heat-affected zone on the substrate, low dilution, low porosity, and a fine structure. Consequently, it finds extensive application in the surface modification of metal materials and the repair of damaged mechanical parts. It is more suitable for strengthening the surface properties of Fe-based alloys than coating remanufacturing techniques such as arc overlay welding [4], thermal spraying [5], and plasma cladding [6].
By selecting different cladding materials, one can achieve a coating possessing excellent properties such as wear resistance, fatigue resistance, corrosion resistance, and oxidation resistance [7-9]. Commonly used cladding coating materials include self-fluxing powders and composite powders containing ceramics. Among these, self-fluxing powders of Fe-, Co-, and Ni-based alloys are extensively utilized. Fe-based alloy powders, utilized as cladding materials, exhibit exceptional interfacial bonding strength with Fe-based substrate materials compared to Co-based and Ni-based powders, while also offering cost advantages [10-11]. These alloy powders contain alloying elements along with oxygen, carbon, and iron, which contribute to the formation of a passivation layer and hard phases. These components enhance the corrosion resistance and wear resistance of the Fe-based alloy coating. Additionally, Fe-based alloy powders containing B and Si demonstrate self-deoxidizing and slag-forming properties, thereby lowering the alloy’s melting point, improving alloy infiltration and fluidity, and reducing surface tension. Ultimately, these properties positively influence the interfacial bonding performance between the coating and the substrate [12-13].
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Han-yu Zhou, Li-yao Li, Yang Zhao, Ming-xue Shen, Huo-ping Zhao, Ye-long Xiao, Shao-peng Liu (2025). Review of rare earth oxide doping-modified laser cladding of Fe-based alloy coatings. China Foundry. https://doi.org/10.1007/s41230-024-3072-3
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Frequently Asked Questions
What is the main challenge of laser-cladded Fe-based alloy coatings?
Laser-cladded Fe-based alloy coatings typically exhibit lower hardness, wear resistance, corrosion resistance, and oxidation resistance compared to Co- and Ni-based coatings, and are prone to defects like pores and cracks.
How do rare earth oxides improve the properties of Fe-based alloy coatings?
Rare earth oxides such as La2O3, CeO2, and Y2O3 refine the microstructure, reduce defects, and enhance hardness, wear, corrosion, and oxidation resistance through mechanisms like grain refinement and oxide film formation.
What are the common rare earth oxides used in doping?
The common rare earth oxides used are La2O3, CeO2, and Y2O3.
What is the significance of this review?
This review summarizes recent research on the effects of rare earth oxide doping on the structure and properties of laser-cladded Fe-based alloy coatings, providing a reference for advancing this technology.
What are the potential applications of these coatings?
These coatings are used for surface modification of Fe-based alloy parts in mechanical transmission and braking systems to enhance wear and corrosion resistance, extending service life.
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