Purpose
This paper aims to investigate the temperature dependence of transfer film formation and friction coefficients in NAO friction materials with four different abrasive components, ZrO2, ZrSiO4, Al2O3 and Fe3O4.
Design/methodology/approach
8.5% SnS2 was added as a lubricating component to friction materials. Friction tests comprised 100 times of consecutive braking application for each friction material under constant temperature of 300°C, 400°C, 500°C and 600°C. After the friction tests, the friction surfaces of the counterpart disks were examined by scanning electron microscope to access the formation of transfer film.
Findings
Coefficients of friction depended on not only friction temperature but also friction history which is related to development of transfer film. The effect of the transfer film formation was to reduce the friction coefficients for most friction materials. Quantities of the transfer film formation varied with friction materials; at low temperature below 400° the transfer film formation was most active in the Fe3O4 materials, while at 600° it was the most active in the Al2O3 material. The effect of the lubricating component SnS2 was to suppress the formation of transfer film, thus enhancing friction coefficients.
Social implications
The enhancement of friction coefficients with addition of small amount of lubricating components such as SnS2 is expected to open a new approach in developing high performance-brake pads.
Originality/value
Temperature was the controlling parameter in the present test. Under these test modes, transfer film could be fully developed to access the role of the transfer film.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0427/
