title: A Review on the Research Progress of Nano Organic Friction Materials.
abstract: BACKGROUND
  Traditional organic friction materials are difficult to adapt to people's growing technical requirements for stability, safety, comfort and environmental protection in the braking process. With the rapid development of nanotechnology, the brake's organic friction materials meet new opportunities. This article aims to review the research progress of organic friction materials that have applied nanotechnology.
  
  
  METHODS
  The research progress of nano organic friction materials was reviewed from four aspects in this article. Firstly, this article outlined the development history of friction materials. Secondly, two preparation methods of the nano organic friction material were summarized as by nano modifying of matrix material and by adding nanoparticles into friction material. Thirdly, it was indicated that the nano organic friction material has generally better mechanical, physical properties and tribological performance than traditional organic friction materials. And the main factors that affect the friction and wear performance were analyzed. Finally, the main existing problems in this field were summarized.
  
  
  RESULTS
  It was pointed out that the nano organic friction material may be an important developing trend of friction materials. It was also pointed out that the dispersion of nanoparticles must be a key process during preparation. What is more, the improvement mechanisms of performance by nano modifying were explained. And it was considered at the end that the functional friction material with magnetism or self-adsorption may be a leading developoing direction of nano organic friction materials in the future.
  
  
  CONCLUSIONS
  The findings of this review confirm the excellent performance of nano organic friction materials. It is concluded that the development of a new functional friction material by using the special effect of nanoparticles will be an important developing trend. Few relevant patents to the topic have been reviewed and cited.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou 221116, China. cumtbjs@cumt.edu.cn.
authors.forename: Jiusheng
authors.initials: J
authors.lastname: Bao
authors.forename: Dongyang
authors.initials: D
authors.lastname: Hu
authors.forename: Shirong
authors.initials: S
authors.lastname: Ge
authors.forename: Yan
authors.initials: Y
authors.lastname: Yin
authors.forename: Tonggang
authors.initials: T
authors.lastname: Liu