| LI Yang,TAN Na,LIU Jin,HU Ze-yu,ZHANG Guo-liang,YONG Qing-song.Effect of Powder Pre-oxidation on Microstructure and Properties of NiAl Laser Cladding Coating[J],52(7):358-368 |
| Effect of Powder Pre-oxidation on Microstructure and Properties of NiAl Laser Cladding Coating |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.07.033 |
| KeyWord:pre-oxidation NiAl laser cladding hardness friction and wear |
| Author | Institution |
| LI Yang |
National-local Joint Engineering Laboratory of Intelligent Manufacturing Oriented Automobile Die & Mould, Tianjin , China |
| TAN Na |
School of Mechanical Engineering, Tianjin University of Technology and Education, Tianjin , China |
| LIU Jin |
School of Mechanical Engineering, Tianjin University of Technology and Education, Tianjin , China |
| HU Ze-yu |
School of Mechanical Engineering, Tianjin University of Technology and Education, Tianjin , China |
| ZHANG Guo-liang |
School of Mechanical Engineering, Tianjin University of Technology and Education, Tianjin , China |
| YONG Qing-song |
Facility Design and Instrumentation Institute, China Aerodynamics Research and Development Center, Sichuan Mianyang , China |
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| Abstract: |
| Laser cladding is a technology with advantages of low carbon, energy saving, environmental protection and emission reduction and so on. It can obtain surface coating with excellent wear resistance, corrosion resistance and heat resistance, and its performance is better than that of the matrix material. However, it is found that the laser cladding coating often forms thick dendrites and has great cracking sensitivity. In addition, ceramic powder is very expensive as the strengthening material. According to the above technical problem, in this study, the NiAl with the great potential application was applied as the cladding material. A kind of pre-oxidation gas-solid reaction method was put forward based on effective refinement effect of the ceramic phase to the cladding ceramic coating organization with the aid of easy oxidation properties of Al material, and Al particles in oxidation atmosphere were put into furnace to make its surface evenly in situ synthesis of alumina oxide. In this way, the composite powder with alumina on the surface of aluminum powder was synthesized. Al2O3 in situ synthesized by pre-oxidation means had the minimal lattice mismatch with NiAl, which was very suitable as the enhancement phase of NiAl material, so as to refine the coarse dendrites in the coating structure and improve the performance of cladding coating. Composite powder was prepared to metallurgical coatings by laser cladding method. SEM, XRD, EDS, hardness, friction and wear tests were used to investigate the modification law of microstructure and properties of NiAl coatings by pre-oxidation. There was a very obvious "oxygen coating layer" around the pre-oxidized Al powder. The composite powder with alumina attached on the surface of aluminum powder was successfully prepared by pre-oxidation, and the pre-oxidized NiAl coating prepared by laser cladding technology formed well and had no defects. Compared with NiAl coating, the dendrites of the pre-oxidized coating were smaller, and the XRD test showed that Al2O3 existed in the pre-oxidized coating. The hardness of the pre-oxidation coating was improved by about 20% on the basis of NiAl coating. The oxygen was introduced by the pre-oxidation method which made the friction interface form a layer of oxide lubrication film, so that the friction coefficient of the coating after the pre-oxidation treatment was reduced by about 23%, at the same time, the wear resistance of the coating was also significantly improved due to the improvement of the hardness. Comprehensive analysis showed that the performance improvement was due to the synergistic strengthening mechanism of the fine grain strengthening and second phase strengthening which was brought about by the pre-oxidation method. The Al/Al2O3 composite powder in situ synthesized by pre-oxidation method owns the advantages of simple equipment and convenient operation. The complicated manufacturing process of micro and nano-particles is eliminated by simple synthesis steps. The composite powder is synthesized in situ at low cost and has significant positive benefits, and the coating can achieve a benign transformation from microstructure to properties by means of pre-oxidation. This article can provide some ideas and methods to promote the development of green low-carbon technology, high-performance new powder research and the application of NiAl coatings. |
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