Emise plynných produktů třecích procesů v brzdových systémech automobilů a jejich dopad na životní prostředí

Abstract

Road transport is one of the main anthropogenic activities. It is important part of our life but it may also pose risks to the environment and human health as well. Friction composite materials used in car brake systems contain a lot of components with various chemical properties and textures. Characterization of friction composites materials is difficult and requires a combination of several methods.

Six samples of commercially available brake linings were chosen for this dissertation thesis. They were characterized using a variety of methods: determination of carbon, X-ray fluorescence spectroscopy, scanning electron microscopy, atomic emission spectrometry with inductively coupled plasma, X-ray diffraction and Raman microspectroscopy.

Samples of brake pads were tested using a full-scale dynamometer. Friction processes between pad and disc during forced deceleration is associated with relatively high temperatures and high pressures on the friction surface. During the friction process various chemical reactions can cause the modification of a friction composite. It leads to the release of wear particles and the formation of gaseous products. Gaseous emissions were collected in bags and analysed by gas chromatography and infrared spectroscopy. Gaseous samples were taken in the sorption tubes with charcoal as well, trapped organics were firstly extracted with carbon disulphide and then analysed. The obtained results were compared with the results of analyses of the gaseous products of thermal decomposition of samples of brake linings at defined temperatures in the tube furnace.

Results of gaseous emissions released during frictional process proved particularly creation of CO2. In addition, lower concentrations of CO, SO2 and light hydrocarbons were also found. As mentioned above, light hydrocarbons and also a relatively high concentration of benzene were found.

The amount of released gases varies considerably in investigated linings. Creation of gaseous products during the friction can be evidently significantly affected by composition of a friction composite.