Tribological Performance of a Polymer Blend of NBR Used for Stern Bearings

Qin Hongling*, 1, 2, 3, Zhou Xincong1, 2, Xu Chuntao1, 2, Wang Hao1, 2, Liu Zhenglin1, 2
1 Reliability Engineering Institute School of Energy and Power Engineering, Wuhan University of Technology, Wuhan Hubei 430063, China
2 Key Laboratory of Marine Power Engineering & Technology ( Ministry of Communications) Wuhan University of Technology, Wuhan Hubei 430063, China
3 Hubei Key Laboratory of Hydroelectric Machinery Design & Maintenance, China Three Gorges University, Yichang 443002, China

© 2012 Hongling

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the School of Energy and Power Engineering, Wuhan University of Technology, Y130 Post Box, Yujiatou Campus, Wuhan University of Technology, Wuhan 430063, China; Fax/Tel: +86-717-6397559; E-mail:


Nitrile-butadiene rubber (NBR) and another polymer with an excellent self-lubricating property are blended to develop a new kind of polymer used for water-lubricated stern bearings. The tribological performance of the new Polymer Blend of NBR (PBN), with the comparison of a rubber common used for most stern bearings, was studied using a stern bearing test rig of SSB-100. The results showed that the friction coefficients of PBN are lower than those of NBR under water-lubricated conditions. And the difference is the most evident at speeds of 0.1 ~ 2.0m/s. So PBN will change to Plasto-Elastohydrodynamic (PEH) Lubrication at lower speed to reduce the critical speed of bearing squeal. This indicates blending rubber with other polymers is an effective means to develop low-friction stern bearing materials. Furthermore, test results revealed that reducing the rubber layer thickness and hardness will reduce the friction coefficients. So in the structure design of water-lubricated rubber bearings, selecting proper structural parameter will improve the tribological performance.

Keywords: Nitrile -butadiene rubber(NBR), polymer blend, tribological performance, stern bearing.