Оptimization of the chrome plating bath operation during the restoration of vehicle parts

Introduction. In the process of chrome plating of car parts, there is a change in the composition of the chrome plating bath, which affects the stability of the ongoing processes – the performance and quality of the chrome coating. Therefore, it is necessary to constantly monitor the chrome plating bath for the presence of foreign elements that can be formed during the operation of the bath during the reaction of the solution with the anode or cathode.Materials and methods. During the research, the necessary equipment was used, which made it possible to determine with sufficient accuracy the content of trivalent chromium and its effect on the electrolysis process – the performance and quality of chrome coatings. A well-known technique was used to determine the quality and performance.Results. When conducting studies of the obtained cold self-regulating chromium plating electrolyte, it was found that trivalent chromium has a significant effect on the stability of the chromium plating bath. The content of which can vary within 2...25 g/l during operation. As a result, it was found that the optimal amount of trivalent chromium is its content in the chromium plating bath from 2 to 15 g/l. With a lower or higher content, the electrolysis performance and the quality of the chrome coating decrease. It was also found that in order to maintain the optimal amount of trivalent chromium and increase the time for stable operation of the chromium bath, it is necessary to observe the ratio of the area of the anode and cathode (the coated surface of the part), the value of which is within 3...4.Discussion and conclusion. As a result of the conducted research, it will make it possible, under certain conditions, to carry out the process of chromium deposition from a cold self-regulating electrolyte, which will allow for stable chromium deposition at high productivity and the necessary quality of the coatings obtained. The main condition is to control and maintain the amount of trivalent chromium in the chromium plating electrolyte in the bath.

Study of removal Chrome (III) using Calcium Silicate Hydrate (CSH) synthesized from rice hush and CaO by hydrothermal method

The Calcium Silicate Hydrate (CSH) family mineral such as Xonotlite (X), Tobermorite (T) was synthesized by hydrothermal method using rice hush and CaO as the Si and Ca supplier. The rice hush (RH) was burnt inside the furnace at 500oC for 2hrs to obtain the rice hush ash (RHA), then mixing with CaO with the Ca/Si 1.0, and hydrothermal treatment at 110oC for 24h to obtain Xonotlite and Tobermorite mineral with micropore structure (coded as CSH-110/24). The CSH 110/24 samples were used to remove Chrome (III) in 2,4 and 6 hours, with fast removal phenomena. This research can be applied in metallurgy industry such as removal Chrome (III) during the Chrome-coating process.

Research on Chrome Plating Quality of the Internal Surfaces in the Hydraulic Drives with Hydrostatic Guideways

The article presents a study of the characteristics of experimental samples with a chrome coating: the straightness and ovality of the inner surface of the cylinder, as well as the hardness and thickness of the chrome coating. The chrome coating is obtained on a previously developed installation for applying chrome coating on the inner surfaces of hydraulic cylinders of hydraulic drives with hydrostatic guides. The measurement of the geometric characteristics of the internal surface of the samples was carried out, the values ​​of deviations from roundness and deviations from straightness were obtained. A study of the chrome coating was carried out, for this we cut out sectors from the samples, carried out their sample preparation, measured the hardness and took pictures under a microscope, measured the hardness and thickness of the chrome coating. The obtained measurement results: deviation from roundness, deviation from straightness, coating hardness, coating thickness - correspond to the specified technical requirements, the proposed construction of the installation for applying chrome coating to the inner surfaces and the electrolyte composition, selected earlier, are applicable for chrome plating of the inner surfaces.

Formation of Structure and Properties of 30HGSN2A Steel at Technological Stages of Manufacture of Heavy-Loaded Parts

The cases of premature failure of the barrel of liquid damper, made of complex alloyed high-strength 30HGSN2A steel, are analyzed. The options failure and the causes of their occurrence are established. Fatigue failure of the barrels during an operation is due to the failure of the chrome coating of the rod and the appearance of scorings on the surface of the barrel. Cases of failure of the barrels during official tests are associated with the reduced hardenability and an increased tendency to decarburize steel in the bottom of the barrel, due to the increased nitrogen content here (due to segregation). The influence treatment conditions on the structure and properties of steel are investigated. Modes of dehydration and final heat treatment of the products to eliminate their premature failures are recommended. The proposed conditions, in particular, include increasing the dehydration temperature to 200-230 oС, reducing the exposure time at the hardening temperature and reducing the tempering temperature, using vacuum heating.

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.

SELECTION OF RATIONAL POLISHING MODES FOR CLADDED CHROME COATINGS

As a result of experimental and statistical modeling, dependencies were obtained that establish the effect of polishing modes (the number of passes of the polishing wheel, the value of the wheel tightness) on the roughness and thickness of the chrome coating obtained by the method of deformation cladding with a flexible tool. It was found that within the selected intervals of variation of the factors, an increase in the tightness of the polishing wheel and the number of passes of the wheel leads to a decrease in both the parameter of the roughness Ra and the thickness of the coating, however, with different degrees of intensity. The number of passes of the polishing wheel has a decisive effect on the value of the surface roughness of the clad layer after polishing. The effect of polishing modes on the thickness of the cladded coating is more complex, since it is demonstrated both in the individual comparable influence of both factors and in their interaction. The optimal modes of polishing of hydraulic cylinder rods subjected to chromium plating by the method of deformation cladding with a flexible tool have been determined. After the experimental check in the conditions of JSC “Minsk Automated Lines Plant named after P.M. Masherov” (Republic of Belarus), the established technological modes of polishing were added to the technological process of chromium plating of rods. It confirms the effectiveness of using the calculated dependencies.

Pengaruh Suhu dan Waktu Proses Hard Chrome pada Pelat Baja ST37 Terhadap Kekerasan dan Ketebalan Lapisan

The thickness and hardness affect the service life of ST37 steels. The temperature and duration of the coating process affect the hard chrome layer's thickness and hardness. The purpose of this study is to determine the effect of temperature and coating duration of the ST37 steel plate using the hard chrome coating method on the thickness and hardness of the coating. This research is an experimental study in which the treatment used is the temperature and duration of the metal plating process with hard chrome. The temperatures used were 45 °C, 50 °C, and 55 °C, and the coating time was 10 minutes, 20 minutes, and 30 minutes. After the hard chrome plating process is complete, the thickness and hardness of each specimen were tested. This research uses descriptive analysis. The results obtained from the thickness test are the highest average layer thickness of 8.9 µm at 45 °C, 9.1 µm at 50 °C, and 9.2 µm at 55 °C, respectively. The coating hardness test result shows an average value of 323.28 VHN at 45 °C, 333.01 VHN at 50 °C, and 466.51 VHN at 55° C, respectively. It can be concluded that the duration of the metal plating process with the controlled temperatures proportionally affects the thickness and hardness of the coating.Ketebalan dan kekerasan berpengaruh terhadap masa pakai logam baja ST37. Suhu dan lama proses pelapisan mempengaruhi tingkat ketebalan dan kekerasan lapisan hard chrome. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh suhu dan lama pelapisan pelat baja ST37 menggunakan metode pelapisan hard chrome terhadap ketebalan dan kekerasan lapisan. Penelitian ini merupakan penelitian eksperimen di mana perlakuan yang digunakan adalah suhu dan lama proses pelapisan logam dengan hard chrome. Suhu yang digunakan adalah 45°C, 50°C, dan 55°C, dan lama pelapisannya yaitu 10 menit, 20 menit, dan 30 menit. Setelah proses pelapisan hard chrome selesai, selanjutnya dilakukan pengujian ketebalan dan kekerasan lapisan pada masing-masing spesimen. Analisis yang digunakan pada penelitian ini adalah analisis deskriptif. Hasil yang didapatkan dari pengujian ketebalan yaitu menghasilkan nilai rata-rata ketebalan lapisan tertinggi sebesar 8,9µm pada suhu 45°C, 9,1 µm pada suhu 50°C, dan 9,2 µm pada suhu 55°C. Hasil pengujian kekerasan lapisan yang didapatkan yaitu menghasilkan nilai rata-rata sebesar 323,28 VHN pada suhu 45°C, 333,01 VHN pada suhu 50°C, dan 466,51 VHN pada suhu 55°C. Dapat disimpulkan bahwa semakin lama proses pelapisan logam dengan suhu 45°C, 50°C, dan 55°C maka ketebalan dan kekerasan lapisan akan bertambah.

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).

Experimental Study of Pure Steam and Steam-Air Mixture Condensation on a Vertical Chrome-Plated Tube

To investigate the heat transfer characteristics of the chrome-plated tube and hope it could be used on the internal heat exchanger of passive containment cooling system (PCS), an experimental investigation has been conducted. In this experiment, a series of steam condensation experiments are performed under pure steam and steam-air mixed conditions over chrome-plated tube for a variety of chromium coating thickness (1μm and 10μm), total pressure, air mass fraction and wall subcooling. Condensation heat transfer coefficient was obtained for the total pressure ranging from 0.2 MPa to 0.4 MPa, air mass fraction ranging from 0.10 to 0.71, and wall subcooling from 10°C to 70°C. Moreover, the designed visualization experimental device makes the experimental phenomenon can be directly observed through the observation window. Under the pure steam condition, the results show that droplet condensation and filmwise condensation is co-existed on both two kinds of chrome-plated tubes, the chrome coating thickness of 10μm tube shows better heat transfer ability. Under the steam-air mixed condition, the condensation heat transfer coefficient of both two kinds of tubes increases with total pressure, and decrease with the air mass fraction and wall subcooling, while the influence of chrome coating thickness on heat transfer is no longer noticeable. The results also indicate that the thickness of the chromium coating will affect the surface microstructure of the chrome-plated tube and then affect the heat transfer ability of the chrome-plated tube.