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Purpose The purpose of this paper is to investigate the effect of reciprocating and unidirectional sliding motions on friction and wear of phenolic resin-based composite. Design/methodology/approach The phenolic resin-based composite was fabricated by hot press molding, and then the tribological properties were tested on a CSM tribometer with two types of friction motion modes – reciprocating friction and unidirectional friction. Findings The results showed that the composite exhibited low friction coefficient in unidirectional test. However, the wear factor recorded under unidirectional sliding condition was 12-16 times higher than the reciprocating friction results. The SEM and optical microscopy test results showed that changing the relative motion mode resulted in different topography of transfer film, which is responsible for the different friction and wear characteristics of the composite under reciprocating and unidirectional friction conditions. Originality/value Effect of different friction modes, reciprocating friction and unidirectional friction, on friction characteristics of the composite is sought. Different topography of transfer film formed under reciprocating and unidirectional friction conditions contributed to the different friction characteristics.

In this study, a new strategy to achieve high‐efficient heat transfer for non‐Newtonian fluids with slippage using a stably prepared superhydrophobic coating is presented. A superhydrophobic coating is prepared on the inner surface of a sleeve at specific shear stress. The slippage and heat‐transfer processes of the typical non‐Newtonian fluid–1% carboxymethyl cellulose solutions on the superhydrophobic coating are investigated simultaneously. A novel porous spherical type of superhydrophobic coating with a contact angle of 168° is obtained. It is found that the shear stress in electrodeposition is a key parameter to control the morphology and wetting ability of the superhydrophobic coating. The slip length and enhancement factor of heat transfer for the non‐Newtonian fluid on the coating are found in a range of 20–900 µm and 1.47 experimentally. A new parameter is proposed as Reynolds number Re divided by the dimensionless slip length ls* (Re/ls*) for the heat‐transfer enhancement with slippage, which can be used as the guide for designing coating and selecting the operating conditions. The Re/ls* is <4, which can enhance the heat transfer via the slippage.

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