| WU Kang-kai,ZHANG Zi-jian,LI Song-ze,WANG Long-long,LI Ming-ke,YI Xue-mei.Preparation and Properties of Vacuum Cladding Ni-based Composite Coating[J],52(5):111-120, 130 |
| Preparation and Properties of Vacuum Cladding Ni-based Composite Coating |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.05.011 |
| KeyWord:65Mn steel vacuum cladding Ni-based alloy rare earth CeO2 wear and corrosion resistance wear mechanism |
| Author | Institution |
| WU Kang-kai |
College of Mechanical and Electronic Engineering, Northwest A&F University, Shaanxi Yangling , China |
| ZHANG Zi-jian |
College of Mechanical and Electronic Engineering, Northwest A&F University, Shaanxi Yangling , China |
| LI Song-ze |
College of Mechanical and Electronic Engineering, Northwest A&F University, Shaanxi Yangling , China |
| WANG Long-long |
College of Mechanical and Electronic Engineering, Northwest A&F University, Shaanxi Yangling , China |
| LI Ming-ke |
College of Mechanical and Electronic Engineering, Northwest A&F University, Shaanxi Yangling , China |
| YI Xue-mei |
College of Mechanical and Electronic Engineering, Northwest A&F University, Shaanxi Yangling , China |
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| Abstract: |
| As a promising technology, vacuum cladding shows significant advantages of controllable coating thickness, controllable defects, small thermal deformation of the substrate, suitable for irregular shaped parts, low cladding cost, and so on. However, due to its wettability and addition ratio, the quality of the cladding coating could be affected when cladding ceramic materials. The work aims to improve the friction and wear resistance as well as the acid and alkali corrosion resistance of 65Mn steel steel. Ni-based-WC composite coatings were prepared on the surface of 65Mn steel (10 mm×10 mm×5 mm) by means of vacuum tube furnace. The CeO2 was introduced mainly to decrease the defects in the coating. The experimental parameters were set as:vacuum degree of 10–2 Pa, cladding temperature of 1 100 ℃, holding time of 60 min, cladding thickness of 1 mm. The results indicated that the Ni-based composite coating with the combination of 30wt.%WC+2wt.%CeO2 displayed the best performance. It had the relatively uniform hardness distribution, and the average microhardness reached 900HV1-1000HV1, which was 3 to 4 times of that of the base 65Mn steel (without heat treatment). At the friction and wear test conditions of 10 N/8 Hz, 20 N/8 Hz and 30 N/6 Hz, the volume wear rates were only 17.6%, 18.8% and 16.1% of the matrix, respectively. With the addition of 2wt.% CeO2, the friction and wear performance were further improved. The wear rates reduced to only 13.1%, 17.4% and 14.3% of the matrix, and the corresponding friction coefficients were slightly higher than that of the matrix. The SEM, EDS and XRD analyses demonstrated that the coating was mainly composed of strengthening phases such as (Ni, Cr, Fe) solid solution, WC as well as W-containing reinforcing phases Cr4Ni15W and Ni17W3. The appropriate cladding temperature could make the WC distribution more uniform. The addition of CeO2 could reduce the melting point of Ni-based alloy, and promote the element diffusion between the liquid phase alloy and the substrate, making the coating diffusion layer nearly twice as wide, and forming a stronger metallurgical bond. The results of wear scar morphology analysis indicated that the hardness of the matrix 65Mn steel was much lower than that of the counter-grinding tungsten steel ball, which was characterized by adhesive wear. The coating sample was more complex, and the wear process was mainly abrasive wear, accompanied with alternating effects of selective wear, delamination wear and abrasive wear. In the acid and alkali corrosion resistance test of the coating, the electrochemical test results in the ammonia-sulfuric acid corrosion solution with pH=6 and pH=8.5 showed that with the increase of the hard phase WC content, the corrosion potential of the sample moved negatively and the corrosion current density increased as well. The corrosion current density of the coating was the smallest when the WC content was 10wt.%. It was 1.526 μA/cm2 in pH=6 solution, which was only 11.6% of the substrate, and 0.261 μA/cm2 in pH=8.5 solution, only 24.8% of the matrix. The reason is that the increase of WC leads to the decrease of coating density, and the reaction between WC, W-containing enhanced phase and corrosive liquid accelerates the corrosion process, thereby accelerating the self-corrosion of the coating in the corrosive medium, resulting in the reduced corrosion resistance of the coating in acid/alkali corrosive fluids. |
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