Synthesis of N-doped carbon quantumn dots as lubricant additive to enhance the tribological behavioor f MoS_(2)nanofluid  

作　　者：Jiaqi HE Jianlin SUN Junho CHOI Chenglong WANG Daoxin SU 

机构地区：[1]School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China [2]Department of Mechanical Engineering,The University of Tokyo,Tokyo 113-8656,Japan

出　　处：《Friction》2023年第3期441-459,共19页摩擦（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(No.51874036);Beijing Municipal Natural Science Foundation(No.2182041).

摘　　要：In this study,a novel lubricant additive nitrogen-doped carbon quantum dot(N-CQD)nanoparticle was prepared by the solvothermal method.The synthesized spherical N-CQD nanoparticles in the diameter of about 10 nm had a graphene oxide(GO)-like structure with various oxygen(O)-and nitrogen(N)-containing functional groups.Then N-CQDs were added to MoS_(2)nanofluid,and the tribological properties for steel/steel friction pairs were evaluated using a pin-on-disk tribometer.Non-equilibrium molecular dynamics(NEMD)simulations for the friction system with MoS_(2)or MoS_(2)+N-CQD nanoparticles were also conducted.The results showed that friction processes with MoS_(2)+N-CQD nanofluids were under the mixed lubrication regime.And MoS_(2)nanofluid containing 0.4 wt%N-CQDs could achieve 30.4%and 31.0%reduction in the friction coefficient and wear rate,respectively,compared to those without N-CQDs.By analyzing the worn surface topography and chemical compositions,the excellent lubrication performance resulted from the formation of tribochemistry-induced tribofilm.The average thickness of tribofilm was about 13.9 nm,and it was composed of amorphous substances,ultrafine crystalline nanoparticles,and self-lubricating FeSO_(4)/Fe2(SO_(4))_(3).NEMD simulation results indicated the interaction between S atoms in MoS_(2)as well as these O-and N-containing functional groups in N-CQDs with steel surfaces enhanced the stability and strength of tribofilm.Thereby the metal surface was further protected from friction and wear.

关 键 词：carbon-based quantum dots(CQDs) LUBRICANT NANOFLUID molecular dynamics(MD) TRIBOFILM 

分 类 号：TB383.1[一般工业技术—材料科学与工程] O471.1[理学—半导体物理]