Two-layer laser clad coating as a replacement for chrome electroplating on forged steel

Chrome plating is one of many surface engineering techniques used for corrosion resistance, as well as a protective coating against surface damage in load bearing applications, with surface hardness in the region of 1000 Hv. Laser cladding is an alternative hardfacing technique often chosen for corrosion resistance and for increasing the surface hardness of components, through thick clad coatings. The application of chrome plating and other similar surface engineering techniques for thick coatings can be inefficient and costly with practical process limitations. The objective of this case study was to investigate the feasibility of replacing the chrome plated layer of a rod mill pinion, made of forged steel, with a Nickel-based Tungsten-Carbide (Ni-WC) composite layer and an intermediate layer of Inconel 625. Mechanical properties were obtained using microhardness and nanoindentation techniques. Three-point bend tests were performed on test specimens from a pinion sample, in order to observe crack propagation resistance, a challenging task due to the curved geometry of the pinion sample and the difference in thickness between the existing and proposed coating layers. Crack development was captured, and plastic deformation was quantified with the use of Digital Image Correlation (DIC). In bending it was found that the bond between the composite coating, Inconel 625 and the steel substrate provided improved resistance to axial crack propagation, where the composite coating could withstand more than twice the bending tool displacement than the chrome electroplating.

Formation of residual stresses during the restoration of parts by chrome electroplating

As the title implies the influence of the electrolysis on the nature and magnitude of residual stresses in the steel base and the chrome coating during restoration of parts has been considered. It has been shown that with an increase in compressive stresses on the surface, a decrease in tensile stresses in the chromium deposit and transition of tensile stresses to compressive ones near the boundary of the base are observed. A correlation between the parameters of the crystal lattice of electroplated chromium and the steel base has been established. The values of the tensile residual stresses in the chromium deposit decrease with increasing the compressive residual stresses in the base.

Influence of chrome electroplating on fatigue strength of parts

The article is devoted to the results of studies, which have been conducted on parts with electrolytic chromium in order to determine the effect of the coating on fatigue strength of their. The work was performed in observance of standards, which are fixed in GOST RV 2840-001-2008. Samples for the tests were made from standard gas turbine engine compressor blades. We used a VEDS- 1500 electrodynamic vibration stand with an UMK-12K power amplifier to excite vibrations. It has been shown that the minimum endurance limit of 46 kgf/mm2 based on 2 ∙ 107 cycles, established on uncoated parts, didn't decrease during fatigue tests of compressor blades with an electroplated chrome layer. It should be stressed that the influence of the geometry of the chrome-plated part on the reduction of the endurance limit has been established.

The Effect of Agitation Parameter on Hardness and Thickness of Decorative Nickel-Chrome Coating on A36 Steel using Electroplating Process

Electroplating is a process of settling substances (metal ions) on the electrodes (cathodes) using electrolysis. The occurrence of a precipitate in this process is due to the presence of electrically charged ions moving from an electrode through the electrolyte, the result of the electrolyte will seal on another electrode (cathode). During the process of deposition/deposit takes place a chemical reaction occurs at the electrode and electrolyte both reduction in a certain direction permanently, therefore it requires direct current and a constant voltage. Metal coatings commonly used are copper, nickel, chromium, and others. Electroplating is basically to coat the metal to make it look more attractive and protected from corrosion, and can increase the product's resistance to friction. The purpose of this study was to determine the effect of stirrer rpm variations on the thickness and thickness of the A36 steel layer in the decorative nickel-chrome electroplating process. 4 specimens in this study were 30x30x2 (mm). Nickel and chromium coatings have variations in the speed of 72, 102, 132, and 162 (rpm) with a time immersion of 22 minutes and with a temperature of 55-60 ° C. The results of this electroplating process were tested by Vickers's hardness test and observation of microstructure results. The results showed that the faster the rpm, the more hardness was obtained which increased and the thickness of the layer increased. The highest hardness and thickness values are found at a rotational speed of 132 rpm. With a hardness value of 77.5 VHN and a thickness value of 4.55 µm (Nickel) and 13.76 µm (Chrome).

Analisis Ganti Model Piston Rod Dalam Proses Electroplating Chrome Shock Absorber di PT X

One component of the manufacturing process is carried out shock absorber piston rod manufacturingprocess must be completely free of defects so that no leakage occurred at the time of use. The piston rod has afunction as a valve seat and a linear movement of rod guide. In the process of making the piston rod of theproduction cost for the plating process is still high when compared with other processes, it is necessary efficiency.Steps to be taken in such efficiency is to lower non-productive time that it becomes productive time. Based onmonthly data obtained there are some non-productive time on chrome electroplating process include: changingmodels of 35.82%, 17.1% cleaning area, the waiting time before the process of 12.02%, 11.42 engine problemsand refit the piston rod 4 , 46%.To facilitate solving the problems facing particularly non-productive time is highthen the principal take biggest problem is the process of changing the model reaches 35.82%.After making the repair process of the components supporting the process of change plating process model fell to10.59%.

PHOTOCATALYTIC REMOVAL OF TR I- AND HEXA-VALENT CHROMIUM IONS FROM CHROME-ELECTROPL ATING WASTEWATER

A novel technique based on photocatalysis was applied to eliminate chromium ions, a toxic hazardous environmental pollutant. The photoreduction of each species of chromium (total, hexavalent, and trivalent chromiums) from chrome-electroplating wastewater was investigated using a titanium dioxide suspension under irradiation by a low-pressure mercury lamp. The initial concentration of total chromium was 300 mg/l. The applied conditions were the direct photocatalytic reduction process at pH 3.65 and the indirect photocatalytic reduction with added hole scavengers at the same solution pH. Results from both processes were comparatively discussed. Result show that chromium was not efficiently removed by direct photoreduction. In contrast, with the adding of hole scavengers, which were formate ions, the photoreduction of chromium was very favorable. Both hexavalent and trivalent chromiums were efficiently removed. The photocatalytic mechanism is purposed in this study.