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Cermet composite material based on aluminothermy

100%

Penkov I. , Petkov V. , Valov R.

tom Vol. 57, no. 4

293--296

A new method for synthesis of cermet composite materials was developed based on aluminothermy. Employing this method a cermet composite material with a high content of AlN crystal phase was synthesized. Fine powders of aluminum and silica glass were mixed and heated in a corundum crucible for 6 hours at 1100°C in air. The X-ray diffraction analysis showed that the composite material thus synthesized contains a high concentration of AlN particles (about 33 vol. %) embedded in an aluminum silicon alloy. A small amount of Al2O3 particles (about 8 vol. %) was also found. The method proposed can also be used for synthesis of aluminum matrix composite materials containing, besides AlN, other ceramic reinforcement phases. The properties of these composite materials can be tailored by choosing an appropriate composition of the initial powder mixture for aluminothermic synthesis.

Characteristics and Properties of Chromium Coatings with Diamond Nanoparticles Deposited Directly on Aluminum Alloys

89%

Petkov V. , Valov R. , Simeonova S. , Kandeva M. , Petkov V. , Valov R. , Simeonova S. , Kandeva M.

Electrochemical Deposition of Silver on Aluminum Alloys

88%

Valov R. , Petkov V. , Valkano S. , Valov R. , Petkov V. , Valkano S.

Nanocomposite chromium coatings on aluminum alloys

75%

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

tom Vol. 57, no. 4

241--244

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.

Sintered Steels Coated with a Chromium Layer Doped with Diamond Nanoparticles

75%

Petkov V. , Valov R. , Witkowska M. , Madej M. , Cempura G. , Sułowski M.

tom Vol. 64, iss. 4

1633--1638

Electrochemical Cr coatings doped with diamond nanoparticles were deposited on sintered steels with different carbon contents (0.2-0.8 wt.-%). The mechanical properties of surfaces as hardness and wear resistance increase as compared to the steel substrate. Microcutting and microgridding mechanisms were observed after tribological tests, but also adhesive wear in some areas was observed. X-ray examination indicated that the layer was textured, with the exception of the sample with the highest concentration of diamond nanoparticles in the electrolyte (42 g/l). The intensity ratio ICr110/ICr200 was calculated and compared with the indices for a standard sample. The greatest differences in the intensity ratio occurred for the samples with low carbon content (0.2% C). On the other hand, more the material is textured the greater the difference.

Wear Resistant Chromium Coatings Modified with Diamond Nanoparticles/ Odporność Na Zużycie Ścierne Powłok Chromowych Modyfikowanych Nanocząstkami Diamentu

75%

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

nr 4

Sintered Steels Coated with a Chromium Layer Doped with Diamond Nanoparticles

71%

Petkov V. , Valov R. , Witkowska M. , Madej M. , Cempura G. , Sułowski M. , Petkov V. , Valov R. , Witkowska M. , Madej M. , Cempura G. , Sułowski M.

nr 4

Composite Coatings of Chromium and Nanodiamond Particles on Steel

50%

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