Friction and wear behaviors of catalytic methylesterified bio-oil

• Two esterified bio-oils were prepared via a catalytic reaction with methanol.
• The friction and wear behaviors of the esterified bio-oils were investigated.
• The esterified bio-oils showed superior tribological properties.
• The mechanism was discussed to explain the tribological behaviors.

The friction and wear behaviors of catalytic methylesterified bio-oils were compared with those of a conventional crude bio-oil using a reciprocating friction-type tribometer. The microstructure of and typical elements in the worn surfaces were also examined. Results showed that the friction coefficient and wear loss of the frictional pairs significantly decreased after lubrication with the esterified bio-oils. This result can be attributed to the esterified bio-oils having more ester components than the crude bio-oil and to the formation of a chemical adsorption layer on the worn surfaces of the frictional pairs. The tribological mechanisms of the crude and esterified bio-oils can be ascribed to corrosive wear and to boundary lubrication, respectively.