Santamaria Razo, D., Decrock, J., Opsommer, A., Fabré, M. et al., "Promaxon® D in NAO Non Steel Disc Pad Formulations: the Importance in the Third Body Layer and its Effect on Brake Noise," SAE Int. J. Mater. Manf. 9(1):158-170, 2016, doi:10.4271/2015-01-2678.
Friction performance is the result of the interaction between rotor and friction material surfaces. Kinetic energy has to be transformed into heat, plastic deformations, chemical reactions and wear debris. The later generates the formation of the so-called third body layer and its initiation, growth and degradation will generate the actual friction coefficient and vibrations behavior.Some raw materials seem to promote third body layer formation more than others. The composition of plateaus usually contains iron oxide, copper, carbon, silicon and calcium. Since copper free materials are under development, the importance of understanding the third body layer formation has become bigger.Promaxon® D is widely used in NAO non steel formulations. It is a calcium silicate with a special morphology that influences friction material at two levels: the macro -bulk- scale and the micro -surface- scale.Bulk effect is related to the volume and porosity degree of the friction material. This affects the elastic modulus and vibration adsorption.The micrometric effect is related to the third body layer. When Promaxon® D is combined properly with an anchoring material (i.e. a fibre) it can promote the initiation and stabilization of the third body layer. As a result friction coefficient stabilization and wear will be improved. Wear is also directly related to noise as proposed by Lee et al .This paper deals with the understanding of the importance of calcium silicate morphology for the bulk properties and in the third body layer formation. It demonstrates how the raw materials morphology, regardless of its chemical composition, plays an important role at macro and micro level in NAO non steel materials.