| JIANG Kui-jing,LIU Hong,LYU Yuan-yuan,WANG Peng.Effects of Laser Annealing Processes on Microstructure and Hardness of Electroless Ni-Mo-P Coating[J],45(10):20-27 |
| Effects of Laser Annealing Processes on Microstructure and Hardness of Electroless Ni-Mo-P Coating |
| Received:May 06, 2016 Revised:October 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.10.004 |
| KeyWord:laser annealing line light spot round light spot electroless Ni-Mo-P coating microstructure hardness |
| Author | Institution |
| JIANG Kui-jing |
School of Mechanical & Automotive Engineering, Qilu University of Technology, Jinan , China |
| LIU Hong |
School of Mechanical & Automotive Engineering, Qilu University of Technology, Jinan , China |
| LYU Yuan-yuan |
School of Mechanical & Automotive Engineering, Qilu University of Technology, Jinan , China |
| WANG Peng |
School of Mechanical & Automotive Engineering, Qilu University of Technology, Jinan , China |
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| Abstract: |
| The work aims to study the effects of two kinds of laser annealing processes (line spot without overlapping scanning and round spot with overlapping scanning) on microstructural characteristics and hardness of the amorphous Ni-4.6Mo-12.4P (wt.%) coating. The electroless Ni-Mo-P coating was prepared on Q235 steel substrate, and then the coating was laser-annealed by taking advantage of two laser technologies. Crystallization degree, mass fractions of crystalline phase and grain sizes of the coatings were quantitatively analyzed by means of XRD test and Jade software, compositions and morphologies of coatings were determined by SEM/EDS measurement analyses. Hardness of coatings was tested by nanoindentation technology. Finally, two kinds of laser annealing technologies were compared. Accompanied with the formation of Ni-Mo solid solution, crystallization reaction of Ni3P phase occurred at a line light spot scanning velocity of less than 12 mm/s and a round light spot scanning velocity of less than 10 mm/s. Grain size in Ni3P phase was larger than that in Ni/Ni-Mo phase. However, the size in Ni/Ni-Mo phase was larger than that in Ni3P phase at a scanning velocity of 6 mm/s. Higher degree of crystallization and larger mass fraction of Ni3P phase were obtained on the coating of line light spot scanning than that of the round light spot scanning at the same scanning velocity. But the size in Ni3P phase with the line light spot scanning was less than that of the round light spot scanning. The hardness of line light spot scanning coating was higher at the scanning velocity of 6 mm/s to 10 mm/s, 10 mm/s was an exception. The line light spot of higher energy density without overlapping scanning is more beneficial to the precipitation of Ni3P phase than the round light spot of low energy density with overlapping scanning. However, the round light spot with overlapping scanning is beneficial to the growth of Ni3P phase. Hardness of the coating is mainly influenced by the size and mass fraction of Ni3P phase. |
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