Tribological Properties Of Two Carbon-Based Nano-Particles As Lubricant Oil Additive

Friction and wear is one of the main causes of the failure of mechanical parts. Among them, the black solid particles of diesel produced by incomplete combustion not only cause damage to the engine, but also an important source of PM2.5. Due to the color and morphology of the particle, the maybe as a good lubricating oil additives. At present, studies have confirmed that the particle will aggravate the wear of the machine, but not comprehensive. In addition, the surface micro-texture technology has received wide attention in recent years, micro-texture can significantly improve the anti-wear ability of materials, reduce the loss of material.In this paper, UTM-2 machine was used with ball-plate contact form and reciprocating movement. The experiment was carried out under different lubricating oils, the base oil and the nano-particle-based oil, at different temperatures (25 ℃,100 ℃,175 ℃) and textured surfaces. The nano-diesel soot particles and nano-graphite were characterized by the atomic force microscope(AFM)、 XRD, infrared spectroscopy (FT-IR), Raman spectroscopy (Raman).And adopted the optical microscopy (OM), scanning electron microscopy (SEM), two-dimensional profile, hardness tester, energy dispersive spectroscopy (EDX) and Raman spectroscopy (Raman) to analyze the worn scars and the lubrication mechanism. The friction and wear behavior of the nano-particles as lubricating oil additives on different surfaces was studied systematically. Accordingly, the main conclusions can be drawn as following:1:Atomic force microscopy showed that diesel soot particle diameter size was between the 20nm-70nm, while nano-graphite powder for 10nm-30nm, slightly less than the diesel soot particle size. And the nano-graphite crystalline was better than nano-diesel soot particles, the structure was more complete. The effect of Span-80 as lubricating oil additive dispersing agent is well.2:When taken alloy cast iron as the lower samples, compare to the pure PAO4 lubricating oil, adding 0.01wt% diesel soot or 0.01 wt% nano-graphite did not aggravate the wear, but improve the anti-wear effect. Friction coefficient reduced 2-5 times, at 25 ℃ and 100 ℃, the friction coefficient of the nano-particles were stable in the vicinity of 0.15;at 175 ℃, due to the serious oxidation, the friction coefficient between the 2000-3000s sharply increased to about 0.5. Although the friction coefficient was not stable at 175 ℃, but the wear rate was still reduced by 40%-60%. The worn surfaces of the adding nano-particle s were more smoother, less of the furrow. The lubrication mechanism of maybe a protective film layer formed on the worn surfaces, which changed the contact environment. The property of nano-particles as lubricating oil additives was relate to the dispersion stability, particle size, chemical physical properties.3:When used the 65Mn spring steel as the lower sample, the nano-particles also showed excellent friction and wear behavior. When adopted higher hardness materials as substrate, the tribological performance of the diesel soot particles was better than that of nano-graphite particles. At the micro worn area, the smoother surface can be observed of the diesel soot, but the plough can be seen on the worn surface of the nano-graphite. To further complete the mechanism of nano-particles as lubricating oil additives, the mechanism of nano-particles as lubricating oil additives mainly by rolling bearing, friction chemical and electrochemical etc.4:Under the condition of PAO4 base oil, at 25 ℃,100 ℃ and 175℃, the average friction coefficient of the textured surfaces of the laser etching method were highest at 100℃. The area ratio of 19.6%,22.1% of the texture increased the friction coefficient, but the wear rate was significantly reduced; the texture with the higher area ratio, illustrated the better anti-wear performance. After adding diesel soot particles, different textures of the friction coefficient were not very different, but the specimens’wear rate were reduced significantly. This was due to the self-lubrication properties of the particles and the storage function of the micro-texture. The mutual coupling effect of surface texture and nano-particles particles showed excellent anti-wear and decrease friction performance.