Viscosity Loss in PFPE Lubricant for Space Applications under EHL Conditions

Tribology Online

Sobahan Mia¹  Hidekazu Komiya¹  Shigeki Morita¹  Shinichiro Hayashi¹  Nobuyoshi Ohno¹  Shingo Obara² 

[1] Department of Mechanical Engineering, Saga University;Japan Aerospace Exporation Agency;

关键词: viscosity loss;    pfpe;    space application;    thrust ball bearing;    molecular decomposition;    ehl;   

DOI  :  10.2474/trol.2.54

来源: DOAJ

【 摘 要 】

An unbranched perfluoropolyether (PFPE) 815Z is the current ball bearing lubricant for space applications. Measurements of elastohydrodynamic lubrication (EHL) oil film thickness have been carried out to assess the lubricating performance of PFPE with average molecular weight of 9200 using an optical interferometric technique under mean Hertzian pressure 0.45 GPa. The film thickness of 815Z became less than predicted film thickness from Hamrock and Dowson formula for EHL central film thickness. There are two main explanations why PFPE is inferior to mineral oil in their ability to form EHL films, temporary viscosity loss and permanent viscosity loss. In order to elucidate the results, measurements of permanent viscosity loss under mean Hertzian pressure from 0.41 GPa to 2.67 GPa have been carried out using the thrust ball bearing. There results show that the degree of the permanent viscosity loss depends on Hertzian pressure, occurrence of permanent viscosity loss of 36 % with 2.67 GPa and 2 % with 0.41 GPa.

【 授权许可】

Unknown