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| Mircrostructure and Properties of Nano-TiN-Ni45A Composite Coatings Prepared by Laser Cladding |
| WANG Cunshan ,YU Qun |
(Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education,
Dalian University of Technology, Dalian 116023, China） |
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Abstract Ni-based composite coatings with different nano-TiN additions are produced by laser cladding on
38CrMoAl substrate. The influence of nano-TiN on the mircrostructure and properties of the coating is investigated
through X-ray diffraction, scanning electron microscopy, electronic probe, Vickers hardness tester, and friction wear testing
machine. Results show that the coatings consist of γ-Ni, Ni3B, M23C6, and TiN phases, exhibiting hypoeutectic morphological
characteristics. As the addition of nano-TiN is 5.0 %, the primary γ-Ni dendrite is coarsed obviously, whose number is
increased. However, as the addition of nano-TiN is more than 5.0 %, the primary γ-Ni dendrite shows decrases in size and
number with increasing the addition of nano-TiN, whose growth morphology changes from equiaxed dendrite to columnar
dendrite. Meanwhile, the number of the micron-sized TiN particle, growing in form of agglomeration, is also increased,
and its distribution becomes more uniform. For this reason, the average hardness of the coatings gradually increases with
increasing the addition of nano-TiN as a whole, and the tribological perperty is best as the addition of nano-TiN is 15%,
showing 8.7% and 32.3% decrease in friction coefficient and wear volume as compared with the coating without TiN addition,
and a 7.0 % increase in average hardness.
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2016, 
