Slippery Wood: Low Friction and Low Wear of Modified Beech Wood

Abstract

AbstractThis paper investigates the tribological and related properties of naturally modified beech wood (Fagus sylvatica). The modifications were performed on steamed beech wood using a variety of treatments consisting of drying, heating in an aqueous solution, impregnation with liquefied animal glue as well as beeswax followed by compression and various combinations thereof. Results indicate that an impregnation in liquefied animal glue followed by mechanical compression to 62% of the original volume leads to an increase in hardness of more than 160% as compared to steamed beech wood alone. The frictional properties of this natural polymer were further examined by sliding the wood samples against 100Cr6 (DIN 1.3505) steel spheres. Beeswax-impregnated and compressed samples showed a reduction in friction of 90% compared to steamed beech wood, with values in the regime of PTFE, over a sliding distance of 10 km with a normal load of 10 N and sliding speed of 0.1 m/s. Unlike PTFE, the low friction was also accompanied by a low specific wear rate of around 3.9 × 10−7 mm3/N m. This study demonstrates the enormous potential of modified woods as an all-natural, non-toxic, renewable, and biodegradable material to replace synthetic polymers in technical applications with practically no environmental loading.