| CUI Changchun,LI Qilin,TAN Zhidong,SHAN Daping,DING Kai,HAN Jinjin,GE Yuan.Interface Structure and Mechanical Properties of Laser-brazed Diamond of Graphene-modified Ni-Cr Alloy[J],54(7):109-117 |
| Interface Structure and Mechanical Properties of Laser-brazed Diamond of Graphene-modified Ni-Cr Alloy |
| Received:June 27, 2024 Revised:November 14, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.07.009 |
| KeyWord:laser brazing graphene diamond microstructure thermal damage abrasive resistance |
| Author | Institution |
| CUI Changchun |
Jiangsu University of Technology, Jiangsu Changzhou , China |
| LI Qilin |
Jiangsu University of Technology, Jiangsu Changzhou , China |
| TAN Zhidong |
Jiangsu University of Technology, Jiangsu Changzhou , China |
| SHAN Daping |
Aecc Aviation Power Co., Ltd., Xi'an , China |
| DING Kai |
Jiangsu University of Technology, Jiangsu Changzhou , China |
| HAN Jinjin |
Jiangsu University of Technology, Jiangsu Changzhou , China |
| GE Yuan |
Meltron Metal Surface Technology Changzhou Co., Ltd., Jiangsu Changzhou , China |
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| Abstract: |
| Compared with electroplated diamond grinding wheel and sintered diamond grinding wheel, the brazed diamond grinding wheel has the characteristics of high bonding strength, large grits exposure, and high grinding performance, which is widely used in the grinding of engineering ceramics, optical glass, etc. However, thermal damage such as graphitization and residual stress will occur during the brazing of diamond with Ni-Cr alloy, which reduces the grinding performance of the brazed diamond grinding wheels remarkably. In order to solve this problem, the work aims to investigate the effect of the graphene addition on the interface structure and mechanical properties of laser-brazed diamond. ANSI 1 045 steel with size of 100 mm× 35 mm×10 mm was used as the matrix, Ni-Cr powder was evenly mixed with graphene powder of different mass fractions, i.e. 0.00%, 0.01%, 0.02% and 0.03% separately. The graphene-modified Ni-Cr alloy was then mixed with diamond by ball milling according to the mass ratio of 7∶1. The samples were prepared on the matrix by laser brazing based on coaxial-powder feeding method. The brazed samples were tested and analyzed with SEM, XRD, Laser Raman spectroscopy, Vickers hardness tester, etc. The results showed that there was significant element diffusion at the interface between the diamond surface and the brazing alloy, and the width of diffusion layer was about 2 μm, in which the concentration distribution of Cr in the interface region was relatively high, and the Cr element was obviously segregated near the diamond grit. The flake compound formed by the interface reaction was mainly Cr3C2. With the increase of graphene content, due to its large specific surface area and excellent adsorption capacity, the reaction between the C element on the diamond surface and the Cr element in the brazing alloy was inhibited and reduced and the C and Cr elements in the interface region were significantly reduced. The carbides formed by the reaction at the interface between the diamond and the brazing metal were significantly reduced, and the morphology of carbides was transformed from dense small flakes to discontinuous large flakes. The degree of graphitization of the diamond was reduced, and the residual stress decreased from 1.049 GPa to 0.693 GPa, with a decrease of about 34%. The average grain size of the brazing layer was 3.8, 2.0, 1.8 and 0.7 μm, respectively, and the grain size gradually decreased, which was significantly refined. The micro-hardness of the brazing layer gradually increased from 866.6HV to 1 119.0HV. The average friction factor decreased from 0.71 to 0.61, and the wear volume decreased from 4.03×10−2 mm3 to 1.86×10−2 mm3, with a decrease of 53.8%. Additionally, the test results showed that when the mass fraction of graphene was 0.03%, the graphitization degree and residual stress of brazed diamond were lower, and the brazed layer had better grain structure, micro-hardness and wear resistance. It is proved that the addition of graphene to Ni-Cr alloy can reduce the thermal damage such as graphitization and residual stress of brazed diamond, enhance and improve the micro-hardness and the wear properties of the brazing layer separately. |
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