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Technical Paper

Particle Size Effects of Tin Sulfides in Disc Brake Pads

1 Modern organic bonded friction linings contain both tin-(II)-sulfide and tin-(IV)-sulfide as solid lubricants. Due to their chemical and physical properties tin sulfides act as friction stabilizers and improve wear of disc and pad or lining not only in low steel and non-steel formulations but also in semimetallics. The influence of the particle size distribution in disc brake pads was investigated systematically. In the first run different particle size grades of tin sulfides were prepared: large particle, technical, fine and super fine grade. The medium diameter (D 50), surface and sieve residues were determined by using international standard testing methods. The thermal properties of the pure grades were investigated by DSC/TGA showing that the particle size distribution influences oxidation kinetics. The decomposition behavior was determined in inert atmosphere applying the same measurement system.
Technical Paper

A Comprehensive Study of Chemical and Physical Properties of Metal Sulfides

1 Natural and synthetic sulfides are important components in friction materials such as pads, linings and even clutch facings and are summarized under the term “Friction Stabilizers”. Their unique properties lead to a high and stable friction coefficient, low wear of pad and disk and decrease of vibrations. The tribological behaviour of friction stabilizers strongly depends on load and temperature. Analytical methods like DSC and TGA are used to investigate the chemical changes of these compounds during braking at high loads and temperatures. Tribological phenomena also strongly depend on the physical properties of the metal sulfides such as crystal structure, Mohs hardness and character of the chemical bonding. This discussion will cover the characteristics of classical natural sulfides like antimony, molybdenum and lead sulfide but also of synthetic complex sulfides. The obtained data are compared with practical measurements generated by dynamometer testing.