| 학회 | 한국재료학회 |
| 학술대회 | 2015년 가을 (11/25 ~ 11/27, 부산 해운대그랜드호텔) |
| 권호 | 21권 2호 |
| 발표분야 | D. 구조 재료 |
| 제목 | Solid lubricant thickness dependency on the low rotational friction coefficient of ball bearing cage in cryogenic environment |
| 초록 | Recently, the experiment of solid lubricants is performed on space systems. Among them, if the projectile goes up into space by withstanding extreme vibration, it will be recurred into high vacuum, cryogenic, and high temperature condition. The ball bearings of the turbo pump in the projectile is driven in a cryogenic environment, and it has no additional lubrication system. The solid lubricant is essential and makes surface smooth. Also, soft metal lubricant is only used in extreme environment. Silver is used as an extreme environment lubricant because it has good processability and mechanical properties. Ball bearing raceway was coated with silver as a solid lubricant. To control the tribological parameters, such as friction and wear, we choose the current density and processing time of electroplating to change the thickness of silver layers. Also, after the rotational friction test as an experimental observation, lubricated and oxidized surface layer was observed by SEM and XPS. Our experimental results show the thickness of solid lubricant can affect the metallic coating behavior and the rotational friction coefficient. When the variation in thickness was given, the changes on friction coefficient were observed during rotating friction test to check the transfer from solid lubricant to cage materials in lubrication mechanism. We showed the optimum thickness of solid lubricant to minimize the friction coefficient and improve the long term reliability of cryogenic ball bearing. Also, we could see the amounts of the oxide-containing ion, and we observed chemical bonding and the changes of molecular structure in interface elements of wear imprint among cage material and other ball bearing materials by XPS analysis. Finally, we knew that the thickness variation have good effects to the results of a rotating wear test. |
| 저자 | 이전국1, 김영도2, 이용복1, 곽원일1, 최복성1, 서우석1, 김초희1 |
| 소속 | 1한국과학기술(연), 2한양대 |
| 키워드 | Silver; Solid lubricant; Electroplating; Thickness dependency; Friction coefficient |
