Effect of MoO3 on the microstructure and tribological properties of laser-clad Ni60/nanoCu/h-BN/MoO3 composite coatings over wide temperature range

The samples of nickel-base self-lubricating composite (Ni60/nano-Cu/h-BN) (NSLC) with different additive amounts of MoO3 were manufactured by laser cladding on substrates of Q235 steel. The microstructure and hardness of the as-fabricated NSLCs were investigated. The wear and tribological behaviors...

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Bibliographic Details
Published in:Surface & coatings technology 2020-04, Vol.387, p.125477-9, Article 125477
Main Authors: Zhao, Yue, Feng, Kai, Yao, Chengwu, Li, Zhuguo
Format: Article
Language:English
Subjects:
Chemical reactions
Chromium
Hardness
High temperature
Killed steels
Laser beam cladding
Laser cladding
Lasers
Lubricants & lubrication
Microstructure
Molybdenum oxides
Molybdenum trioxide
Nickel base alloys
Self lubrication
Self-lubricating composite
Solid lubricants
Structural steels
Substrates
Tribological properties
Tribology
Wear
Wide temperature range
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Summary:The samples of nickel-base self-lubricating composite (Ni60/nano-Cu/h-BN) (NSLC) with different additive amounts of MoO3 were manufactured by laser cladding on substrates of Q235 steel. The microstructure and hardness of the as-fabricated NSLCs were investigated. The wear and tribological behaviors of the NSLCs with and without MoO3 from 25 °C to 800 °C were discussed. The results revealed that the addition of MoO3 resulted in the hardness improvement of the NSLCs due to the formation of Mo2C and Cr (Mo)-rich reinforcements during laser cladding process. The NSLC with 4 wt% MoO3 addition showed the best wear performance from 25 °C to 800 °C. At 600 °C and 800 °C, MoO3 solid lubricant was regenerated by oxide reaction during the wear process. Meanwhile, CuMoO4 was generated owing to a tribo-chemical reaction at high-temperature. These solid lubricants formed a lubricating transfer film, which improved the tribological properties of the coating. •MoO3 was added to increase the tribological property of the nickel-base self-lubricating composite coating.•MoO3 was transformed into Mo2C and Cr(Mo)-rich boride increased the wear resistance of the coating.•MoO3, CuO and CuMoO4 were formed at 600 °C and 800 °C, which reduced the friction coefficient of the coating.
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2020.125477