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This paper investigates the friction and friction heat of the micronscale iron under the influences such as the velocity of the slider and temperature of the substrate by using the smoothed particle hydrodynamics simulations. It is found that in the velocity range of 10–100 m/s, the sliding velocity–friction coefficient relationship well complies with the fitted exponent or hyperbolic tangent function, and the friction coefficient approaches a stable value of 0.3 at around the velocity of 50 m/s after a rapidly increasing situation. The steady friction coefficient maintains over the temperature range of 200–400 K. The friction heat is detailed analyzed versus the sliding time. The sliding time–system temperature relationship is well fitted by the sigmoidal functions, except the interfacial particle layers. The layer causing friction shows the highest steady temperature and largest temperature rise. The increment between the initial temperatures of the slider and the substrate strongly results in the temperature rise while it does not affect the configuration of the sliding time–system temperature curves.

The present study uses the SPH and DEM coupling to investigate influence of the hBN particles on friction of the elastic coarse-grained micronscale iron. Lubrication by the hBN particles significantly improves the friction performance of iron in various simulation behaviors. Size of the particles, the background (air/water) containing the particles and its temperature result in reduction of the friction coefficient. The surface mending, the protective film and the energy dissipation are the main mechanisms related to the friction reduction. Additionally, it is worthy to note that the static friction and the kinetic friction can be obviously observed by this elastic coarse-graining.

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