Electrolyte temperature and cathodic current density effect on galvanic coating quality and thickness during the recovery of the mirror surface of hydraulic cylinder barrels

One of the major reasons of failure of the hydraulic cylinders is scratches and teases on the barrel mirror surface. The methods of recovery of the hydraulic cylinder barrel mirror surface are examined. These methods include methods of size repair and methods of plate applications. The galvanic method might allow the recovery of defects associated with the break of tightness. For the experiments the samples sizes 25х25х5 mm made of steel 45 GOST 1050-88 are used. Preparation of samples before the coating includes mechanical (grinding operation and polish) and chemical treatment (deoiling, descaling and activation dipping). Experimental investigations of the electrolyte temperature and cathodic current density effect on galvanic coating quality and thickness have been carried. Current densities varied from 3 to 12 A/Dm 2 with the step 3 A/Dm 2. The temperature is varied from 20 to 80° C with the step 20° C. It is found that at a temperature of 40 ° C highest thickness of the coating received in the investigated range of current densities. When the temperature of electrolyte is 80° C the coating have dendrite structure, associated with a reduction cathodic polarization. It is shown that when current density is 9 A/Dm 2 coating uniformly distributed over the surface of the sample and the porosity of coating is minimal. Increasing of porosity of the coating is associated with decreasing of the current density. When current density is 12 A/Dm 2 the coating have spongioid deposits, due to the low amount of metal ions in the electrolyte near the cathode.

hydraulic cylinder, barrel, electrolyte, temperature of electrolyte, galvanic coating, current density