| CHANG Qingcheng,REN Libing,LIU Ying,XIE Yongxin,LI Wei.Microstructure and High Temperature Wear Resistance of Laser Cladding NbC/Ni60 Composite Coating on H13 Die Steel[J],53(5):108-114 |
| Microstructure and High Temperature Wear Resistance of Laser Cladding NbC/Ni60 Composite Coating on H13 Die Steel |
| Received:March 01, 2023 Revised:October 09, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.05.011 |
| KeyWord:laser cladding NbC/Ni60 composite coating microstructure microhardness high temperature wear resistance |
| Author | Institution |
| CHANG Qingcheng |
Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou , China |
| REN Libing |
Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou , China |
| LIU Ying |
Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou , China;Research Institute of Shaoguan, Jinan University, Guangdong Shaoguan , China |
| XIE Yongxin |
Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou , China |
| LI Wei |
Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou , China |
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| Abstract: |
| Composite coatings on H13 steel are fabricated with NbC and Ni60 mixture powders by laser cladding to improve the wear resistance of matrix materials. In this study, the effect of NbC content on microstructure, hardness and high temperature tribological behavior of the coatings was investigated. The NbC particles reinforced Ni60 alloy composite coating with different NbC contents (0%, 10%, 20%, 30%) was fabricated by laser cladding with a pulsed Nd-YAG laser of a wavelength of 1 064 nm and a beam diameter of 1 mm under argon shielding gas, and with the Ni60 and NbC mixed powders by ball-milling method and H13 die steel as the substrate. The microstructure and phases were analyzed with a scanning electron microscope (SEM) and X-ray diffraction (XRD). The section micro-hardness distribution of composite coatings were studied with a micro-hardness tester. The friction and wear properties of the composite coatings were carried out on a high temperature friction wear tester at 400 ℃ in a vacuum environment. The Ni60 laser cladding layer was mainly composed of γ-(Ni,Fe) solid solution, Ni2Si, Fe3C, CrB and Cr23C6. With the addition of NbC, a new hard-phase NbC was introduced in NbC/Ni60 laser cladding coatings and the microstructure was modified. The cladding layer was dominated by columnar crystals and dendritic structure, in which the dendrite spacing became smaller and the grain size was refined. During laser processing, the added NbC melts, and decomposes, and subsequently, a number of fine NbC precipitates formed and grew up during the solidification. NbC phases evolved and existed as particles, flakes, blocks or snowflakes distributed some uniformly in the coating. The amount of NbC addition had a strong influence on the morphology and size of NbC particles. When the mass fraction of NbC was above 20%, the dispersed NbC particles became aggregated between the dendrites. When the mass fraction of NbC was 30%, much grown and bigger block-shaped NbC, snowflake-shaped NbC was generated in the cladding layer. It was observed that the microhardness of NbC/Ni60 composite coatings were significantly higher than that of the H13 matrix, which increased with the increase of NbC content from 635HV to 848HV when 30% NbC was added. The NbC/Ni60 coating containing 20% NbC had the smallest wear mass loss, namely the the best wear resistance under the wear conditions of load 100 N, speed 100 r/min and time 7 200 s at 400 ℃ in vacuum. The NbC/Ni60 coating containing 10% NbC had the lowest friction coefficient and the more NbC addition reversedly improved friction coefficient. The NbC/Ni60 coating can be metallurgically bonded to the substrate and increase its wear resistance greatly. The NbC works as a hard enhanced phase and increases the hardness and wear resistance of the composite coatings, but the coarse NbC phase is not conducive to further improvement of wear resistance. The main wear mechanisms of H13 steel are adhesive wear and abrasion wear. Moreover, the dominant wear mechanisms of the NbC/Ni60 composite coatings are abrasion wear and fatigue spalling wear. |
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