Aspects of Applying Hard Chromium Coatings on the Inner Surfaces of Components for Hydraulic Drives with Hydrostatic Guideways

We considered the processes of chromium plating the inner surfaces of the components of cylinders with hydrostatic guideways. We demonstrated the various aspects of the chromium plating process – the limitations placed on the machinery depending on the dimensions of the parts to be plated and the unevenness of the deposition rate of chromium along the length of the part. We developed a diagram of an installation for the application of a hard chromium coating on inner surfaces, which includes a cathode, an anode, a tank, and a pipeline. The distinctive features of the installation are the method of supplying the electrolyte at an angle to the horizontal, which allows us to supply the electrolyte through a turbulent flow swirling along a helical path, and the use of a chromium-plated installation casing. We studied various modes for applying a hard chromium coating on the inner surfaces of a hydraulic cylinder. As a result, we determined the optimal composition of the chromium electrolyte – the ratio of chromic anhydride and sulfuric acid – which is 10:1, respectively, and experimentally selected deposition modes. Chromium coatings obtained through the use of the concentrated electrolyte, which we developed, and the chromium plating method have 5...20% greater hardness and a 10...30-times reduction in porosity with the formation of a shiny, lumpy sludge, which corresponds to corrosion-resistant and wear-resistant coatings needed to manufacture hydraulic drives with highly efficient hydrostatic guideways.

Optimizing the Performance of Electroplating Gas-Cleaning Equipment

Electroplating industry has by-products, most of which are harmful. The paper considers the issue of removing aerosol emissions during chrome coating. We developed a droplet separator, which was granted a patent for a useful model. Based on the model, we proposed a stage-by-stage technical procedure for cleaning gas-air mixture to optimize the performance of gas-cleaning equipment during hard chrome coating. We calculated the amounts of water vapor and chromic anhydride which is released during chrome plating without cleaning and when using the developed procedure for gas mixture cleaning. We determined maximum surface concentrations of pollutants in exhaust gases after cleaning.

X-Ray Energy Dispersion Spectrometer Analysis of Galvanized Steel with Dark Green Passivation Film

Dark green passivation film was prepared by dipping galvanized steel in a solution made of four types of acid(chromic anhydride, phosphoric acid, nitric acid and sulfuric acid) with a certain amount of stabilizer and toner. Scanning Electron Microscopy was used to observe the morphology of the film. Elements of passivation film were conformed by using EDS. SEM showed that the surface of the film was even. Cr, O, P, S, N, Zn and a small amount of Fe were found in the film by the test of EDS.