Fabrication and tribological characterization of laser textured boron cast iron surfaces

Laser surface texturing technology was employed for fabricating textured structures on cylinder liners. The tribological behavior of the cylinder liners with different texturing structures including line, dimple and line + dimple and texturing area ratio was investigated under the lubrication of esterified bio-oil with and without MoS2 microsheets as additives. The experimental results indicated that all the three textured surfaces showed better lubricating effects than untextured one except for the line + dimple structures leading to a higher wear rate to the cylinder liner; the dimple structures have better friction and wear performance than other structures. In addition, the textured surfaces lubricated with esterified bio-oil with MoS2 microsheets presented the optimal friction reduction and antiwear properties. This might be ascribed to the fact that besides the adsorbed film composed of carbon and organics from the base oil, there was a robust complex composite tribo-film composed of MoS2, MoO3, FeOOH, FeO, Fe2O3, FeS, FeSO4 and etc. on the rubbing surfaces. Furthermore, the dimples acted as an oil reservoir and provided a sink to pull wear debris away from the contacting surfaces. The combined actions of these factors gave rise to the lowest friction and wear of the tribopairs tested. The synergistic combination of the 12% area ratio dimples and MoS2 microsheets showed great potential for application in IC engines, when coupled with bio-oil to reduce parasitic losses and energy consumption.