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Nanocomposite chromium coatings on aluminum alloys

Gidikova N., Valov R., Petkov V., Sułowski M., Witkowska M., Cempura G.

Prace Instytutu Odlewnictwa

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2017

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Vol. 57, no. 4

241--244

EN

Chromium coatings modified with nanodiamond particles were deposited on aluminum alloys. The concentration of the nanodiamond particles in the chrome plating electrolyte was from 5 to 25 g/l. The thickness of the layer varied between 30 and 70 μm. The layers were prepared with the same electrolytic conditions and were measured with a metallographic microscope. The maximum microhardness of the coating was 840 kg/mm2. X-ray diffraction analysis was performed with a Siemens D500 apparatus using the Bragg-Brentano technique. The distribution of Cr, Al and O in the cross section was studied by SEM-EDS. It was found that the layers were homogenous – only consisted of chromium. The coatings were also studied for non-destructivity by X-ray 3D computed tomography. It was found that the coatings were intact and continuous along the section. In order to obtain the maximum yield of chromium and maximum thickness of the layer, the optimum nanodiamond particle concentration was 10 g/l.

2

Electrolyte coatings of chromium with nanodiamonds on sintered steels

Gidikova N., Valov R., Petkov V., Salamci E., Bilgili Z., Unal R.

Prace Instytutu Odlewnictwa

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2017

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Vol. 57, no. 4

333--336

EN

Sintered ferrous components were coated with electrochemical chromium coatings modified with nanodiamond particles. The nanodiamond particles were produced by detonation synthesis with an average grain size 8 nm. The objective of this study was to determine the tribological properties and the corrosion resistance of sintered iron samples coated with an electrochemically deposited chromium layer modified with nanodiamond particles. The thickness of the obtained composite coatings was more than 25 μm. The microstructure and microhardness were determined by metallographic methods. The mechanical and chemical properties of the samples were compared to uncoated samples prepared from the same iron powder. The microhardness was 5 times higher, the wear resistance increased 6 times and the corrosion resistance in 0.1 M NaCl solution was 10 times higher.

3

Composite Coatings of Chromium and Nanodiamond Particles on Steel

Gidikova N., Sulowski M., Petkov V., Valov R., Cempura G.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

2421--2424

EN

Chrome plating is used to improve the properties of metal surfaces like hardness, corrosion resistance and wear resistance in machine building. To further improve these properties, an electrodeposited chromium coating on steel, modified with nanodiamond particles is proposed. The nanodiamond particles (average size 4 nm measured by TEM) are produced by detonation synthesis (NDDS). The composite coating (Cr+NDDS) has an increased thickness, about two times greater microhardness and finer micro-structure compared to that of unmodified chromium coating obtained under the same galvanization conditions. In the microstructure of specimen obtained from chrome electrolyte with concentration of NDDS 25 g/l or more, “minisections” with chromium shell were found. They were identified by metallographic microscope and X-ray analyser on etched section of chromium plated sample. The object of further research is the dependence of the presence of NDDS in the composite coating from the nanodiamond particles concentration in the chroming electrolyte.

4

Wear Resistant Chromium Coatings Modified with Diamond Nanoparticles

Gidikova N., Ciaś A., Petkov V., Madej M., Sułowski M., Valov R.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 4

1513--1516

EN

Electrochemical chromium coatings on steel, modified with diamond nanoparticles (NDDS), were produced by detonation synthesis. Their particle size was from 10 to 50 nm. Galvanization conditions, current density, etc., concentration of NDDS, were studied in relation to the characteristics of the chromium coatings. The optimal conditions were determined to attain the maximal values of the physical and mechanical properties of the coating. Surface topography after wear testing was examined. Compared to unmodified chromium coating, microhardness of the surface increased to 1100 kg/mm2 , wear resistance, expressed as % of mass loss, increased from 3 to 10 times.

PL

Powłoki chromowe, wytworzone elektrochemicznie na stali, modyfikowane nanocząstkami diamentu, zostały wyprodukowane w procesie syntezy detonacyjnej. Ich wielkość czastek mieściła się w zakresie od 10 do 50 nm. W artykule przedstawiono wpływ warunków galwanizacji, gęstości katodowej prądu, koncentracji nanocząstek diamentu na grubość powłoki chromowej. Podczas badań wytypowano optymalne warunki wytwarzania, pozwalające na uzyskanie warstwy chromowej o najlepszych własnościach fizycznych oraz mechanicznych. Przeprowadzono również badania odporności na ścieranie uzyskanych warstw. Na podstawie badań stwierdzono, że w porównaniu do powłok chromowych nie modyfikowanych nanocząstkami diamentu, mikrotwardość na powierzchni wzrosła do 1100 kg/mm2 , a odporność na zużycie ścierne, wyrażona jako % ubytek masy, wzrosła od 3 do 10 razy.