Self-dispersed molybdenum disulfide quantum dot/graphene crumpled ball as efficient high temperature lubricant additive

Inorganic nanoparticles have been proved as powerful lubricant additives at elevated temperature.However,the tribological properties are inevitably impaired due to poor dispersion and insufficient high temperature resistance of organic matter modified nanoparticles.Here,we prepare a self-dispersed molybdenum disulfide quantum dot/graphene crumpled ball(MGCB)comprising molybdenum disulfide quantum dot uniformly interspersed on the wrinkled graphene ball.The crumpled ball composite possesses excellent dispersity in polyalkylene glycol base oil without depending on surface modifiers.Compared with the conventional phosphate esters lubricant,our results indicate MGCB could vastly improve the lubrication performance of polyalkylene glycol with an extremely low concentration(0.05 wt%)at elevated temperature(150°C),showing a friction reduction of 47%and a wear reduction of 30%compared with the conventional phosphate esters lubricant(tricresyl phosphate,TCP).This is because crumpled ball potentiates synergistic lubrication effect within the boundary lubrication.Overall,we envision our designed self-dispersed MGCB has significant potential in tribological application at elevated temperature.

Fabricating Core-Shell WC@C/Pt Structures and its Enhanced Performance for Methanol Electrooxidation

The spray-dried spheres within a W/Pt multi-separation can be used to prepare discrete core-shell WC@C/Pt catalysts through a typical carburization production mechanism at 800 ℃. In contrast with previous studies of the WC/Pt synthesis, the reaction observed here proceeds through an indirect annealing thereby resulting in core-shell structure, and mechanism at 600℃ wherein species diffuse, Pt nanoparticles were successfully dispersed in size/shape and randomly scattered across the in situ produced C spheres. Through direct carburization or at higher initial hydrochloroplatiuic acid concentrations, however, complete reaction with core-shell spheres was not observed. Indirect carburization reduces the strain felt by the bonds featuring the larger WC WC and Pt nanoparticles to be reserved, stability toward methanol oxidation. particles and allows the motion of carbon around influencing the eleetrocatalytic performance and

Smart-microstructures of composites for electrical contacts with frameless packing of Cr and W in copper

W_(45)Cu_(55),Cr_(65)Cu_(35),and Cr_(32)W_(14)Cu_(54)alloys were obtained in order to study the mechanism of“smart response”of the structure of these alloys when using them as arc-resistant circuit-breakers.These alloys differ from industrial ones with frameless packing of Cr and W phases in the copper matrix.The alloy production method is based on the infiltration of copper melt into a mixture of non-compacted Cr and W powders under vibration exposure(80 Hz).The research results show an increase in the arc resistance of contacts when changing from“frame”packing of W to“frameless,”as well as the decisive role of Cr in the processes of self-dispersion of arc-resistant phases and passivation of W and Cu.Based on the obtained results,conclusions are drawn about the advantage of frameless packing of arc-resistant phases in copper and the reasons for the“smart behavior”of the structure of Cr-containing contacts in response to functional loads in the presence of oxygen and an inert atmosphere.

Preparation of porous silica spheres with self-dispersing properties

A sol-gel procedure in a water/oil emulsion was introduced for the synthesis of porous silica spheres. Tetraethoxysilane was used as the silica source. The specific surface area and total pore volume of the product reached 772.3 m2/g and 0.663 cm3/g, respectively. The electrolyte washing process conferred a surface charge to the product, which displayed self-dispersal properties in water. The porous spheres have potential applications in the fields of drug delivery, controlled release capsules, indoor air pollutant scavengers, and hydrogen storage agents. The oil phase, which accounts for over 8O% of the chemical cost of the procedure, could largely be recycled by filtering, standing, and layering. The whole procedure is suitable for application as an industrial process.