FRCU - GIS: Grupo de Ingeniería de Superficies - Artículoshttp://hdl.handle.net/20.500.12272/8122024-03-28T09:22:45Z2024-03-28T09:22:45ZTribological behaviour of a multilayer CrN/DLC coating obtained using PVD-MShttp://hdl.handle.net/20.500.12272/86882023-11-16T20:48:25Z2022-08-01T00:00:00ZTribological behaviour of a multilayer CrN/DLC coating obtained using PVD-MS
Diamond-like Carbon (DLC) coatings are used as protective layers for steel components due to their hardness, chemical inertia and interesting tribological properties. Reducing wear and friction coefficient is of great importance for industries today in order to increase energy efficiency and reduce harmful emissions to the environment. In this paper, a multilayer CrN/DLC coating is analysed. It was deposited using a commercial Plasma Enhanced Magnetron Sputtering over nitrided and not nitrided mild-alloy steel AISI 4140, produced for the first time in Argentina, at the firm Coating.Tech by Flubetech-Tantal. The base of the coating is an anchor layer made of CrN and the top layer is a chromium-dopped hydrogenated amorphous carbon (a-C:H:Cr), which provides excellent tribological properties. Wear tests were carried out in a Pin-on-Disk apparatus, using an Al2O3 ball as counterpart, with Hertzian
contact stress from 1370 up to 1460 MPa. The friction coefficient was μ~0.1, which is 80% less than the untreated steel and the wear volume loss was reduced eight times. The adhesion was evaluated by means of Scratch Test, where major improvement was noticed in the samples which were nitrided as pre-treatment, increasing critical load from 25 N up to 65 N.
2022-08-01T00:00:00ZNear superhydrophobic carbon nanotube coatings obtained via electrophoretic deposition on low-alloy steelshttp://hdl.handle.net/20.500.12272/51152022-11-15T11:08:41Z2021-01-20T00:00:00ZNear superhydrophobic carbon nanotube coatings obtained via electrophoretic deposition on low-alloy steels
Sucker rods are a key element in certain oil-extraction processes as they link the motor group on the surface with the pumps located downhole. During the transport from the production site toward the extraction well, these components are prone to corrosion. A hydrophobic carbon nanotube (CNT) coating, deposited via electrophoretic deposition (EPD), is proposed as a protective layer, shielding
the rods from harsh environmental conditions. Three different coating systems are considered and thoroughly characterized (depending on the additive that is used to deposit the CNT), namely, magnesium nitrate hexahydrate (Mg– Nit), triethylamine (TEA), and a duplex coating (DD). The latter presents an approach which combine s the advantages of each additive, mechanical stability from
Mg–Nit and strong hydrophobicity from TEA (near superhydrophobic). The former coatings are further processed to overcome their individual shortcomings,resulting in an increase in the coating’s stability for TEA coating, as well astransforming the hydrophilic Mg–Nit surface into a hydrophobic surface.
2021-01-20T00:00:00ZFretting wear resistance of DLC hard coatings deposited on nitrided martensitic stainless steelhttp://hdl.handle.net/20.500.12272/46312022-11-15T11:11:38Z2019-03-01T00:00:00ZFretting wear resistance of DLC hard coatings deposited on nitrided martensitic stainless steel
In this work, the fretting wear behavior and adhesion of DLC coatings deposited by PACVD on nitrided and non-nitrided martensitic stainless steels were studied. Fretting wear tests were carried out with different duration and loads and pin-on-disk was also performed. The adhesion was evaluated by Rockwell C indentation and scratch test with constant and variable loads. The coating thickness was 2.5 m and the nitrided layer, 11 m. The coating hardness and Young’s Modulus were about 16 and 110 GPa, respectively. The duplex samples resulted with better adhesion than the only coated samples in all test conditions. In the scratch test, the critical load in the duplex sample was 58 N and in the coated sample, 12 N, showing a brittle failure mode. In the Rockwell C indentation test, the adhesion was better in the duplex sample because the nitriding treatment changed the failure mode of the system. The wear resistance was also related to adhesion, since in the experiments with high loads and
long durations adhesive failures could be detected when stresses reached the interfac and the substrate. In the duplex sample, the nitrided case, with higher load bearing capacit than the substrate, resulted in a better wear behavior of the system.
2019-03-01T00:00:00ZCharacterization of DLC coatings over nitrided stainless steel with and without nitriding pre-treatment using annealing cycleshttp://hdl.handle.net/20.500.12272/46302022-11-15T11:12:41Z2019-04-02T00:00:00ZCharacterization of DLC coatings over nitrided stainless steel with and without nitriding pre-treatment using annealing cycles
Amorphous hydrogenated diamond-like carbon (DLC) coatings were deposited using plasma assisted chemical vapour deposition (PACVD) on precipitation hardening (PH) stainless steel. Plasma nitriding has been used as pre-treatment to enhance adhesion and mechanical properties. Chemical and mechanical properties of DLC coatings are dependent on the hydrogen content and so on the relation between sp3 /sp2 bondings. The bondings and the structure of the DLC film change with temperature. In this work, a study of the thermal degradation and the evolution of the mechanical properties of DLC coatings over PH stainless steel have been carried out, including the effect of an additional nitrided layer. Nitrided and non-nitrided steel samples were subjected to the same coated in the same conditions, and they were submitted to the same thermal cycles, heating from room temperature to 600 C in several steps. After each cycle, Raman spectra and surface topography measurements were performed ◦ and analyzed. Nanohardness measurements and tribological tests, using a pin-on-disc machine, were carried out to analyze variations in the friction coefficient and the wear resistance. The duplex sample, with nitriding as pre-treatment showed a better thermal stability. For duplex sample, the coating properties, such as adhesion, and friction coefficient were sustained after annealing at higher temperatures; whereas it was not the case for only coated sample.
2019-04-02T00:00:00Z