Jute fibers and powderized hazelnut shells as natural fillers in non-asbestos organic non-metallic friction composites

The paper addresses the potential application of jute fibers in combination with powderized hazelnut shells as natural and biodegradable fillers in non-asbestos organic (NAO) friction composites. Two groups of the samples, based on a combination of jute fibers and graphite as a solid lubricant, and the jute containing samples where graphite is replaced with hazelnut shells, were prepared. Friction-wear properties of the prepared samples were evaluated using the CHASE tester according to the SAE J661 recommendation. The friction-wear tests revealed the jute with graphite samples to show significant fade phenomenon if the temperature during the second fade test increases above 300 °C. The samples belonging to the jute with hazelnut shells group show better resistance against the fade phenomenon even at temperatures higher than 300 °C. Based on the comparison of the overall friction performance, the composite with 5.6 vol.% of jute fibers and 8.4 vol.% of powderized hazelnut shells (assigned as JH-5.6) was selected as the best performing, and this composite contains 14 vol.% of natural, renewable and biodegradable components. If we accept that the maximum temperature during braking will be up to 290 °C then the composite with 23.6 vol.% of jute fibers and 6.3 vol.% of powderized hazelnut shells (assigned as JH-23.6) shows an acceptable stability of the friction coefficient, whereas this composite contains almost 30 vol.% of natural, renewable and biodegradable components.