| ZHANG Yongliang,ZHANG Kejie,WEI Sheng,LAN Haiming,LI Hongpan,LI Yihan,HUANG Renzhong.Improvement Study of Bonding Performance of Cold-Sprayed Silver Coatings on 316L Stainless Steel Based on Ni and Ti Interlayers[J],54(3):230-239 |
| Improvement Study of Bonding Performance of Cold-Sprayed Silver Coatings on 316L Stainless Steel Based on Ni and Ti Interlayers |
| Received:July 26, 2024 Revised:September 20, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.03.021 |
| KeyWord:polysilicon reduction furnace cold spray transition coating silver coating bonding strength |
| Author | Institution |
| ZHANG Yongliang |
New Energy Branch, Qinghai Huanghe Hydropower Development Co., Ltd., Xining , China |
| ZHANG Kejie |
Guangzhou Research Center, Hubei Chaozhuo Aviation Technology Co., Ltd., Guangzhou , China |
| WEI Sheng |
New Energy Branch, Qinghai Huanghe Hydropower Development Co., Ltd., Xining , China |
| LAN Haiming |
Guangzhou Research Center, Hubei Chaozhuo Aviation Technology Co., Ltd., Guangzhou , China |
| LI Hongpan |
New Energy Branch, Qinghai Huanghe Hydropower Development Co., Ltd., Xining , China |
| LI Yihan |
Guangzhou Research Center, Hubei Chaozhuo Aviation Technology Co., Ltd., Guangzhou , China |
| HUANG Renzhong |
Guangzhou Research Center, Hubei Chaozhuo Aviation Technology Co., Ltd., Guangzhou , China |
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| Abstract: |
| The application of cold spray technology to deposit silver coatings on the inner walls of polycrystalline silicon reduction furnaces offers significant advantages in terms of energy conservation and prevention of impurity elements contamination. However, directly fabricating high-bond-strength silver coatings on 316L stainless steel substrates remains a challenge. Based on previous studies, even with a nickel interlayer, the bonding strength and service life of coatings are limited. The work aims to propose a novel approach of utilizing a titanium interlayer to enhance the adhesion performance of silver coatings on 316L substrates. A comprehensive suite of characterization techniques, including optical microscopy (OM), microhardness testing, scanning electron microscopy (SEM), universal tensile testing, and white light interferometry was used to systematically investigate the effect of interlayer material (Ni and Ti) and powder morphology (irregular and spherical) on the microstructure, hardness, interfacial characteristics, surface morphology, and bonding strength of coatings. This comparative analysis elucidated the underlying mechanisms responsible for the differences in coating adhesion strength observed with different interlayer materials. The results demonstrated that direct cold spray deposition of silver coating on 316L substrate failed to achieve effective deposition, while all three interlayer materials — gas-atomized spherical nickel powder (Ni), gas-atomized spherical titanium powder (Ti(s)), and irregular titanium powder (Ti(I)) prepared via the hydride-dehydride method — produced relatively dense coatings with porosity less than 0.5%. The silver coatings deposited on these interlayers also exhibited similar density and microhardness values. However, significant variations were observed in the bonding strength of the coating systems. The 316L/Ni interface exhibited the highest bonding strength (71.3±4.6) MPa, surpassing that of 316L/Ti(S) (63.2±2.9) MPa and 316L/Ti(I) (58.4±4.8) MPa. Conversely, the adhesion strength between the silver coating and the interlayer displayed an opposite trend, namely (32.1±4.1) MPa (Ni/Ag)<(42.3±3.6) MPa (Ti(s)/Ag)<(61.5±5.8) MPa (Ti(I)/Ag). These results indicate that, under the proposed conditions, employing Ti(I) as the interlayer yielded the optimal bonding strength of the coating system. To elucidate the underlying mechanism, the deposition velocity/critical velocity ratio for each interlayer powder was calculated with both CFD simulation and empirical formula methods. The Ni powder exhibited the highest ratio (1.64), followed by Ti(I) (1.56) and Ti(s) (1.27), indicating that Ni particles were more likely to achieve favorable bonding conditions with the 316L substrate, resulting in higher interfacial strength. However, SEM analysis of the coating surface morphology and quantitative surface profile measurements revealed that the Ti(S) interlayer possessed a finer surface microstructure and sharper peak profiles compared to the Ni interlayer. This finer microstructure facilitated a better synergistic deformation at the interface during silver powder deposition, especially for the relatively large microhardness differences combinations. Moreover, the ratio of actual surface area to projected area for the three interlayers (Ni 1.97, Ti(S) 2.07, Ti(I) 2.25) indicated a progressive increase in actual contact area with the silver coating, contributing to higher nominal bonding strength, highlighting that, in addition to surface roughness, the surface microstructure morphology and actual contact area also played crucial roles in determining the bonding strength of soft coatings deposited on hard substrates. In conclusion, this study offers a new solution for preparing high-bonding-strength, long-lifespan silver coatings in polycrystalline silicon reduction furnaces. |
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