Graphene-bronze composites for improved tribological performance of a truck gearbox - GRAPHGEAR

Important results from the project

New material candidates are actively searching for the pads of the shifting forks in the gearbox of a truck. Currently, leaded bronze is used as a material of the pads the drawback being the poisonous of lead. A replacement is actively searched for, to find a material that preferably displays improved friction and wear properties compared to the currently used material. This investigation showed that bronze reinforce with toroidal graphene provides better wear properties than leaded bronze material under sliding contact situations.

Expected long term effects

In this project the potential of graphene additions in bronze for providing material properties required in the pads of shifting forks was evaluated. The tribological testing performed under reciprocating sliding contact against the steel grade of the gearbox sleeves showed that a clear improvement in wear rate was seen with an increasing content of toroidal graphene in bronze. The project showed that the new developed material type can replace the currently used leaded bronze and can provide several positive effects for the end-user.

Approach and implementation

Powder metallurgy hot isostatic pressing (PM HIP) was used to manufacture bronze samples with a varying content of toroidal graphene. Two different parameter sets were tested for the HIP densification. The experiments showed that toroidal graphene in bronze increased the strength of the material at elevated temperatures. The microstructure characteristics of the developed materials were equal in all produced materials. The tribological testing showed that a clear improvement in wear rate was seen with an increasing content of toroidal graphene in bronze.