Low friction states for thin solid lubricant film of MoS₂

Abstract

Purpose

During the operation of Wendelstein 7-X (W7-X), any mechanical disturbance such as stick-slip may cause quenching of superconducting (SC) coils. The friction behavior of MoS₂ lubrication (thin film) for narrow support elements between the SC coils in W7-X is rather important, as there is a design requirement for a coefficient of friction (COF) 0.05 between the sliding surfaces to control the stress contribution (from friction).

Design/methodology/approach

The author has carried out intensive calibrations or verifications using verified models considering previous friction tests on various samples which measured the COF in 4.2 K, 77 K and room temperature conditions (at high vacuum) to simulate the actual working condition.

Findings

The author has given useful explanations and diagnosis for previous anomalous scattered data. To improve the performance of MoS₂, the author has predicted its better COF (0.002 via tuning of the activation volume), which could be a superlubricating state for MoS₂ thin films considering the long-term operation requirement W7-X.

Originality/value

In this paper, the author has adopted Eyring’s approach to predict the low COF (0.002 via tuning of the activation volume), which could be a superlubricating state for MoS₂ thin films considering the long-term operation requirement W7-X. Finally, some recent progresses about the possible few-layer MoS₂ role in the electromagnetic loads have been provided.

Citation

Chu, K.-H.R. (2018), "Low friction states for thin solid lubricant film of MoS₂", Industrial Lubrication and Tribology, Vol. 70 No. 4, pp. 639-644. https://doi.org/10.1108/ILT-12-2016-0323