Lubrication and Friction of Porous Oil Bearing Materials

In order to address poor lubrication of porous bearings due to the seepage flow of oil into the porous medium, multi-layered sintered composite bearings have been developed. Multi-layered bearings achieve a combination of high strength and good lubrication. Lubrication model of the porous multi-layer materials in polar coordinates was established based on Darcy’s law. And the effect of surface Darcy flow and porous structure on the lubrication capacity were discussed by using the finite difference method. In the end, the tribology experiments of the multi-layer materials were presented on the end face tribo-tester to verify the simulation results. Results show that the lubrication performance of the multi-layer materials is better than that of the single layer materials. With the decrease of the surface porosity, the lubrication performance becomes better in the given range of surface layer. Also, it can be significantly improved if considering the surface Darcy flow. Within a certain range, the effects of surface Darcy flow on lubrication performance are more obviously with higher speed. There is a good agreement between the numerical analysis and the measurement. Research work provides a theoretical basis for analysis and design of multi-layer sintering bearing material

A wet process for oxidation-absorption of nitric oxide by persulfate/calcium peroxide

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.cej.2018.05.145 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/This study develops and evaluates a novel wet method for NO removal using a Na2S2O8/CaO2 solution. The effects of these two components both and alone in solution, Na2S2O8 concentration, CaO2 concentration, initial pH, reaction temperature, and the concentrations of NO and O2 on NO removal efficiency were evaluated using a bubbling reactor. The combination of Na2S2O8 and CaO2 had a synergistic effect on NO removal efficiency. NO removal was effected by CaO2 concentration, reaction temperature and the initial solution pH, while Na2S2O8 concentration and O2 concentration had little effect. The NO removal efficiency decreased linearly from 94.5 % to 75.1 % when the NO concentration increased from 139 to 559 ppm. The products were characterized using XRD, XPS and IC, and CaSO4·2H2O, NO3− and SO42− were found to be the main products. The EPR analysis showed that free radicals of O2−, SO4− and OH were the key species involved in the NO removal process. Finally, the corresponding reaction mechanisms were proposed.International S&T Cooperation Program of China [Grant No. 2015DFG61910

Influence of process conditions on the formation of 2-4 ring polycyclic aromatic hydrocarbons from the pyrolysis of polyvinyl chloride

Municipal solid waste (MSW) contains significant amounts of polyvinyl chloride (PVC). The reactivity of PVC may form polycyclic aromatic hydrocarbons (PAHs) during the pyrolysis of MSW, which can become a key challenge during the development of pyrolysis technologies. However, there is very limited work in relation to the influence of pyrolysis process conditions in terms of temperature and heating rate on PAHs formation during pyrolysis of PVC. In this work, the formation of 2-4-ring PAHs from the pyrolysis of PVC at temperatures of 500, 600, 700, 800, or 900°C and at fast and slow heating rates was investigated under a N2 atmosphere in a fixed bed reactor. With the increase of temperature from 500 to 900°C, HCl yield decreased from 54.7 to 30.2 wt.%, while the yields of gases and PAHs in the tar increased. Slow pyrolysis generated higher HCl yield, and lower gas and tar yield than fast pyrolysis; the PAH yield obtained from the slow pyrolysis was much lower compared to fast pyrolysis. The results suggest that for fast pyrolysis, the dehydrochlorination of the PVC might be incomplete, resulting in the formation of chlorinated aromatic compounds