Investigation of Deformation Work in Layers of Explosion-Welded Composite Al-Cr-St3

The article is aimed at studying the distribution of deformation work in the layers of the explosion-welded composite Al-Cr-St3 with a diffusion barrier. It is established that the thickness of the chromium layer does not affect the value of the total deformation work. An increase in the thickness of the chromium interlayer leads to a decrease in the proportion of deformation work and strength.

On Debris-Fretting Impact—The Study of Oxide and Chromium Layer Application

The fretting phenomenon was responsible for over 50% of fuel failure cases in the years 2010–2015 according to International Atomic Energy Agency (IAEA). It shows the scale of the problem for the nuclear power generation sector. A big share of this issue is related to debris fretting. Although debris fretting has been studied for decades, the available R&D information is scarce. The presented paper summarizes the work performed in the Research Center Řež (CVŘ) on Zr–1%Nb alloy tube specimens covered with protective coatings—passivation oxide layer and pure chromium layer. The tests included the simulation of debris-fretting conditions and detailed analysis using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and focused ion beam (FIB). Those experiments are a part of a wider project devoted to the research in the specification of the fretting wear increase after applying the protective layer. The first outputs show the positive impact even in the case of an oxide layer's presence on the cladding surface.

A Hybrid Predictive Approach for Chromium Layer Thickness in the Hard Chromium Plating Process Based on the Differential Evolution/Gradient Boosted Regression Tree Methodology

The purpose of the industrial process of chromium plating is the creation of a hard and wear-resistant layer of chromium over a metallic surface. One of the main properties of chromium plating is its resistance to both wear and corrosion. This research presents an innovative nonparametric machine learning approach that makes use of a hybrid gradient boosted regression tree (GBRT) methodology for hard chromium layer thickness prediction. GBRT is a non-parametric statistical learning technique that produces a prediction model in the form of an ensemble of weak prediction models. The motivation for boosting is a procedure that combines the output of many weak classifiers to produce a powerful committee. In this study, the GBRT hyperparameters were optimized with the help of differential evolution (DE). DE is an optimization technique within evolutionary computing. The results found that this model was able to predict the thickness of the chromium layer formed in this industrial process with a determination coefficient equal to 0.9842 and a root-mean-square error value of 0.01590. The two most important variables of the model were the time of the hard-chromium process and the thickness of the layer removed by electropolishing. Thus, these results provide a foundation for an accurate predictive model of hard chromium layer thickness. The derived model also allowed the ranking of the importance of the independent input variables that were examined. Finally, the high performance and simplicity of the model make the DE/GBRT method attractive compared to conventional forecasting techniques.

A Study of the Influence of Thickness of Anti-Diffusion Layer on the Structure and Thermal Resistance of Composite А5-Cr-St3

The paper presents the results of research on the creation of heat-resistant composite A5-Cr-St3 with diffusion barrier. It considers the influence of the thickness of the chromium layer and the kinematic parameters of the structure and thermal steel-aluminum composite.

PENGARUH ENERGI AKTIVASI LOGAM PELAPIS TERHADAP KETEBALAN DAN LAJU KOROSI PLATING

This study aims to study the effect of the activation energy gradient (∆G) of metals on the thickness and corrosion rate of Ni layers; Cr, and Ni-Cr. The layer is obtained through the Ni electroplating process; Cr, and Ni-Cr in carbon steel specimens using a variation of current strength of 1.25; 1.5 and 1.75 Ampere at constant stress and coating time (15 minutes). Nickel plating is obtained in the electric layer process using a watt's bath electrolyte solution in a mixture of 150 g / l NiSO4, 30 g / l NH4Cl, 30 g / l H3BO3 with a temperature of 25-35 oC, pH around 4-6, air agitation, Chromium plating using anode in the form of an alloy of Pb (lead) and Sn (antimony) rods, a solution in the form of an electrolyte mixture of 300 g / l CrO3, 3 g / l H2SO4 in working temperature of 40–55 oC, pH around 0.4 - 0.5 and air agitation. Corrosion thickness was observed using an optical microscope at 200 X magnification while the corrosion rate of observation was carried out based on the method of resistance polarization in the medium of 0.9% Sodium Chlorid Solution. The results showed that, in the same treatment, the thickness of the layer increased in increasing current strength, slower chromium than nickel layer and Nickel-Chromium layer. Sequential thickness of layers is obtained for Ni: 51, Cr: 39 layers, while corrosion rates occur at 1.75 A current in nickel layer 0.0017 mm / year; Chromium layer, 0.0077 mm /year and Nickel-Chromium layer 0.0231 mm / year

Modification of Surface of Basalt Fabric on Protecting Against High Temperatures by the Method of Magnetron Sputtering

Basalt fibers and fabrics made of these are characterized by excellent thermal and mechanical properties. Therefore, basalt fabrics, due to a good resistance to high temperatures, are frequently applied in the personal protection equipment (PPE). In order to improve their thermal properties and, above all, the contact heat resistance, the process of physical vapor deposition was proposed. The process of Physical Vapor Deposition (PVD) involves producing a coating on a specific substrate as a result of physical deposition of molecules, ions or atoms of the selected chemical compounds. The method selected for the test is the magnetron sputtering. It involves depositing a uniform film of chromium on the surface of the basalt fabric. In order to improve the thermal properties – especially the contact heat resistance, two values of thickness of the chromium layer deposited on the basalt fabric surface were adopted for the test. Covering 1 μm and 5 μm with the chromium layer did not fulfil the expectations and the research will be continued.

Effect of Residual Stress and Microcracks in Chrome Plating Layer to Fatigue Strength of Axle-Shaped Machine Parts

Chromium plating is used widely in industry to enhance wear, abrasion resistance and to restore the dimensions of undersized parts. However, tensile residual stress always exists in chrome layer because of hydrogen embrittlement so it affect to mechanical properties of the chromium plating machine element, especially in fatigue strength. In this paper, effect of residual stress in chrome plating layer to fatigue strength was studied. The sample (AISI 1045 steel) was plated with 10 and 60 micrometers thicknesses and residual stress in chrome plating layer was determined by X-ray diffraction technique (Cu-Kα radiation). The results showed that chromium layer thicknesses go up, tensile residual stress decrease and microcrack density increase. Consequently, fatigue strength goes down when chromium layer thicknesses increase.