Study on Dispersion Stability and Friction Characteristics of C60 Nanomicrosphere Lubricating Additives for Improving Cutting Conditions in Manufacturing Process

Antifriction lubrication is an important research hotspot in the manufacturing field. A high-performance lubricating additive is of great significance for condition monitoring in the metal cutting process system. To improve cutting conditions in manufacturing process, we study the dispersion stability and tribological properties of fullerene nanoparticles in HM32 antiwear lubricating fluid. Fullerene nanoparticles are fully integrated into HM32 antiwear lubricating fluid by electromagnetic stirring and ultrasonic oscillation. The dispersion stability of fullerene nanoparticles in HM32 antiwear lubricating fluid was comprehensively studied by microscope scanning experiment, static sedimentation experiment, and absorption experiment. The four-ball friction experiment was operated to investigate the extreme pressure property and tribological property of lubricating fluids with fullerene concentration ranging from 100 ppm to 1000 ppm. The results show that fullerene nanoparticle can significantly improve the extreme pressure property and wear resistance of HM32 basic lubricating fluid. Meanwhile, we found that an excessively high concentration of fullerene nanoparticles will increase the friction and wear of the four-ball friction pair. The best concentration of fullerene nanoparticles is 200 ppm. When the fullerene concentration reaches 200 ppm, the maximum nonsintering load is significantly increased, and the friction coefficient and the steel ball wear scar diameter are significantly reduced.

Effects of Temperature Rise of Grease on Lubricating Performance of Drive Elements under the Extreme Pressure

To transfer more power and use it in a heavy load environment, the contact surface between the ball and the track must bear great stress. The temperature always rises due to friction, which is more likely to cause problems of material deformation and fatigue failure. As a result, it will be a key technology to maintain a certain lubricating effect of the transmission components under the environment of heavy load and temperature rise. Through the analysis of friction coefficient and electrical contact resistance, the greases are used to test the lubricating effect of the transmission elements under the heavy load condition. The results will be helpful for the industry to use heavy load greases as a reference.

Sustainable lubrication: low molecular weight PTFE micro-particles as extreme pressure additives for heavy duty grease applications

Purpose The purpose of this paper is to formulate heavy-duty lithium complex grease using low molecular weight poly tetra fluoro ethylene (PTFE) micro-particles as extreme pressure (EP) additive manufactured by E-beam scissoring and ultra-high speed grinding process of pre-sintered PTFE scrap. Design/methodology/approach Lithium complex grease is formulated with PTFE micro-particles, and optimum treat rate was studied by standard bench tests by ASTM D 2266 and IP-239 for tribological properties and compared with commercially available Molybdenum Di sulphide (Moly)-based lithium complex grease. The performance of the grease was further evaluated by a cyclic load test at varying speeds and loads to simulate the operational field conditions. Findings The lithium complex PTFE grease was manufactured using PTFE micro-particles as EP additive. The PTFE micro-particles dispersed in the lithium complex grease significantly improve the anti-wear performance and load bearing properties. Further, when the product was tested under a cyclic load conditions on standard tribological bench test against commercially available Moly lithium complex grease, shows stable anti-wear properties and reduced coefficient of friction. Originality/value The low molecular weight PTFE micro-particles, manufactured in the in-house electron beam (E-beam) and ultra-high speed micronizer facility from a pre-sintered PTFE scrap has been used as EP additive for grease applications for the first time. The results on the cyclic load tests indicate significant performance improvement in retaining the anti-wear and friction properties. Thus, value addition is done in formulating superior performance grease and evaluating under cyclic load conditions similar to field operating conditions and also in creating value added additives by converting the pre-sintered PTFE scarp which is environmental hazard due to poor biodegradability, creating a cyclic economy and a sustainable concept.

High-pressure reaction profiles and activation volumes of 1,3-cyclohexadiene dimerizations computed by the extreme pressure-polarizable continuum model (XP-PCM)

Quantum chemical calculations are reported for the thermal dimerizations of 1,3-cyclohexadiene at 1 atm and high pressures up to 6 GPa. Previous experiments [Klärner et al. Angew. Chem. Int. Ed. 1986, 25, 108], based on measured activation energies and activation volumes, suggested concerted mechanisms for the formation of the endo [4+2] cycloadduct and a [6+4]-ene adduct, and stepwise mechanisms for the formation of the exo [4+2] cycloadduct and two [2+2] cycloadducts. Computed activation enthalpies (ωB97XD, CCSD(T) and SC-NEVPT2) of plausible dimerization pathways at 1 atm agree well with the experiment activation energies and the values from previous calculations [Ess et al. J. Org. Chem. 2008, 73, 7586]. High-pressure reaction profiles, computed by the recently-developed extreme pressure-polarizable continuum model (XP-PCM), show that the reduction of reaction barrier is more profound in concerted reactions than in stepwise reactions, which is rationalized on the basis of the volume profiles of different mechanisms. A clear shift of the transition state towards the reactant by high pressure is revealed for the [6+4]-ene reaction by the calculations. The computed activation volumes by XP-PCM agree excellently with the experimental values, confirming the existence of competing mechanisms in the thermal dimerizations of 1,3-cyclohexadiene.