Effect of cuttings particle content on the tribological behavior of Fe/DLC at casing and drill pipe joints: A molecular dynamics study

The presence of cuttings in the drilling fluid can exacerbate the wear of drill pipe joints and casing. Diamond-like carbon (DLC) films have ultra-low friction coefficients and high wear resistance, which have excellent research prospects in reducing the wear between drill pipe joints and casing. To investigate the impact of varying particle counts at the interface between Fe bulk and DLC film, this work builds a pertinent molecular dynamics model. The results show that the interfacial friction increases with increasing particle content, which leads to more severe abrasive wear on the Fe bulk and prevents the amorphous structure atoms in the Fe bulk from recovering to a body-centered cubic crystal structure. On the contrary, the DLC film is difficult to be affected by the particle motion because of its good tribological properties. Simultaneously, more silica particles reduce the space for the movement of water molecules and ultimately weaken the lubrication ability of water molecules.