Thermal characteristics of novel brake friction materials for light rail transit applications

摘要

A batch of five formulations (SP1, SP2, SP3, SP4 and SP5) of novel brake friction materials are being developed and tested for light rail transit (LRT) applications. This paper presents the thermogravimetric (TG) and derivative thermogravimetric (DTG) analysis coupled with the mass spectroscopy (MS) of those friction material samples. The LRT braking system operates at elevated temperatures and may reach an upper extreme of 900℃. In this research, temperature range from ambient to 600℃ is considered the temperature zone that signifies the limits of normal braking operation and considerable weight loss. In general, all samples except SP4, decompose in four steps and registered significant weight loss averaging 5.53% (± 0.20%) of the original weight. Sample SP4 experienced the highest weight loss of 5.77% in three steps. Samples SP1 and SP5 were found to be stable, temperature wise, in decomposing compared to all other samples. Sample SP1 exhibited a controlled rate of decomposition apparently over a wider temperature range (230℃ ― 688℃) with a total loss of weight of 5.37%. In contrast, sample SP5 decomposed in a greater magnitude over a narrower temperature gap (303℃ ― 483℃) albeit the total weight reduction is 5.30%. MS signals indicating mass number of 2 and 44 was detected in all samples at critical temperature zones corresponding to substantial weight loss. This denotes the probable evolution of compounds consisting of hydrogen, helium, carbon dioxide, nitrogen oxide and propane and is related to the physical-chemical reaction which is explained in this paper.