Synergistic regulation of current-carrying wear performance of resin matrix carbon brush composites with tungsten copper composite powder

Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flake graphite powders that were evenly loaded with tungsten copper composite powder(RMCBCs-W@Cu)exhibited a low wear rate of 1.63 mm^(3)/h,exhibiting 48.6%reduction in the wear rate relative to RCMBCs without additives(RMCBCs-0).In addition,RMCBCs-W@Cu achieved a low friction coefficient of 0.243 and low electric spark grade.These findings indicate that tungsten copper composite powders provide particle reinforcement and generate a gradation effect for the epoxy resin(i.e.,connecting phase)in RMCBCs,which weakens the wear of RMCBCs caused by fatigue under a cyclic current-carrying wear.

Influence of simulating deep-sea environmental factors on cathodic performance of seawater battery

A metal-dissolved oxygen seawater battery(SWB)uses metal and dissolved oxygen as the reactants,and it is ideal for use as a long-time low-power distributed power supply in deep sea,due to its advantages of open structure in service without electrolyte.However,several simulating deep-sea environmental factors,such as flow rate,dissolved oxygen concentration,and temperature of seawater may af fect the oxygen reduction reaction(ORR)rate and the stability of electrochemically modified polyacrylonitrile-based carbon fiber brush(MPAN-CFB)cathode,which was studied by steady-state polarization and galvanostatic discharge methods.In addition,the scales formed on MPAN-CFB surface were characterized by SEM and XRD.Results show that the ORR rate increased quickly with the increase of the seawater flow rate up to 3 cm/s,and then gradually stabilized.Moreover,the ORR rate was largely af fected by dissolved oxygen concentration,and the concentration of>3 mg/L was favorable.Compared with surface layer temperature of 15℃,the low temperature of deep sea(4℃)has a negligible ef fect on ORR rate.When the working current is too high,it will lead to the formation of CaCO_3 scales(aragonite)of at the cathodic surface,resulting in the decrease of ORR rate,and consequently the damage to the long-time stability of MPAN-CFB.