FRCU - GIS: Grupo de Ingeniería de Superficies - Artículos
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Item Tribological behaviour of a multilayer CrN/DLC coating obtained using PVD-MS(2022-08) Delfín, Francisco Andrés.; Brühl, Sonia PatriciaDiamond-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.Item Near superhydrophobic carbon nanotube coatings obtained via electrophoretic deposition on low-alloy steels(2021-01-20) Alderete Gómez, Bruno Martín; Suárez Vallejo, Sebastián; Mac Lucas, Timothy; Espin, Douglas; Mücklich, Frank; Brühl, Sonia PatriciaSucker 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.Item Fretting wear resistance of DLC hard coatings deposited on nitrided martensitic stainless steel(2019-03) Dalibón Bähler, Eugenia Laura; Pecina, Jorge Nahuel; Cabo, Amado; Trava-Airoldi, Vladimir Jesús; Brühl, Sonia PatriciaIn 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.Item Characterization of DLC coatings over nitrided stainless steel with and without nitriding pre-treatment using annealing cycles(2019-04-02) Dalibón Bähler, Eugenia Laura; Czerwiec, Thierry; Trava-Airoldi, Vladimir Jesús; Ghafoor, Naureen; Rogström, Lina; Odén, Magnus; Brühl, Sonia PatriciaAmorphous 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.Item Protección de acero para instrumentos quirúrgicos con recubrimientos duros en base carbono tipo DLC(2018-07-19) Pecina, Jorge Nahuel; Brühl, Sonia Patricia; Cabo, Amado; Trava-Airoldi, Vladimir Jesús; Dalibón Bähler, Eugenia LauraLos aceros inoxidables martensíticos como el AISI 420 tienen múltiples aplicaciones, entre ellas instrumentos quirúrgicos, donde se requiere buena resistencia al desgaste y a la corrosión. Los tratamientos de modificación superficial, como la nitruración iónica, permiten mejorar las propiedades mecánicas de estos aceros pero afectan su resistencia a la corrosión. Por esta razón, un tratamiento posterior de deposición de recubrimiento tipo DLC (“Diamond Like Carbon”, carbono símil diamante) puede ser conveniente. En este trabaj se estudió el comportamiento al desgaste y a la corrosión de muestras dúplex (nitruradas y recubiertas por PACVD) y se compararon con muestras nitruradas, sólo recubiertas, nitruradas y sólo templadas y revenidas. Se analizaron los recubrimientos con espectroscopia Raman y EDS. Se realizaron ensayos de desgaste tipo “pin on disk” y se evaluó la adhesión mediante ensayos de Scratch Test e indentación Rockwell C. Se midió nanodureza con indentador Berkovich. Se llevaron a cabo los ensayos propuestos para instrumentos quirúrgicos en la Norma F 1089-02 (prueba de agua hirviendo y de hisopado con sulfato de cobre) y ensayos de niebla salina. Estos recubrimientos tienen una relación ID/I de 0,8 y bajo contenido de hidrógeno aproximadamente del 20 %. El espesor de los recubrimientos fue de 2 µm y la dureza alcanzó 24 GPa. La capa nitrurada tuvo un espesor de 10 µm. Las muestras dúplex y recubierta presentaron bajo coeficiente de fricción y el volumen desgastado fue indetectable. Además, tuvieron buen comportamiento a la corrosión en el ensayo de niebla salina y en los ensayos propuestos en la Norma ASTM F 1089-02. No obstante, la muestra sólo nitrurada presentó una región corroída en el ensayo de sulfato de cobre y en el de agua hirviendo. La muestra dúplex presentó mejor adhesión que la muestra sólo recubierta en los ensayos de Scratch Test y de indentación Rockwell C.Item Carbon based DLC films : influence of the processing parameters on the structure and properties(2018-07-19) Delfin, Francisco Andrés; Brühl, Sonia Patricia; Forsich, Christian; Heim, DanielHydrogenated carbon-based films, such as DLC (“Diamond Like Carbon”), have interesting properties such as excellent tribological behavior, low friction coefficient, high superficial hardness and good wear resistance; they are chemically inert and highly corrosion resistant. They are deposited by means of PACVD (plasma-assisted chemical vapor deposition) with variable film thickness. The load carrying capacity grows with the thickness, so it is possible to deposit thick films on “soft” steels (e.g. low alloyed steels). When increasing coating thickness, surface defects are generated during the deposition process compromising their excellent properties. In this work, different metal substrates have been used to compare adhesion and quantify superficial defects: AISI 316L, DIN 42CrMo4 (AISI 4140) and Böhler K110 (AISI D2). The films were deposited at different temperatures, changing the silicon content and the coating thickness. The samples were placed in the furnace on different positions (standing, lying or up-side down). The films were analyzed with optical and electron microscopy, 3D topography profilometer, and they were tested under sliding wear conditions. Friction coefficient and wear volume were measured, with an average friction coefficient which resulted below 0.05. A higher amount of surface defects was obtained on lying samples compared to the ones up-side down. The quantity of defects increased with the thickness of the coating and decreased with the temperature. The geometry and the growth mechanism of the defects were analyzed.Item Comparación del comportamiento al desgaste de un acero AISI 1045 nitrurado y seguido de un temple por inducción(2016-10) Schierloh, Gonzalo José; Regis, Matías Sebastián; Charadía, Raúl; Dalibón Bähler, Eugenia Laura; Brühl, Sonia PatriciaSe estudió el comportamiento al desgaste del acero AISI1045 con un tratamiento de nitruración iónica y posterior temple por inducción. Se midió dureza en superficie y perfil en profundidad. Se analizó la microestructura y evaluó el comportamiento al desgaste. Como resultado de la nitruración se obtuvo una zona formada por una capa de compuestos seguida por una zona de difusión de nitrógeno. La dureza superficial del acero templado y revenido aumentó en un 50% y, con el temple por inducción posterior, resultó aún superior con incremento en la dureza del núcleo. El comportamiento al desgaste resultó mejor que la del acero sólo nitrurado, debido al incremento de la capacidad de soporte de carga del sistema.Item Influencia de la nitruración por plasma sobre el comportamiento a la corrosión y la adhesión de recubrimientos DLC sobre acero inoxidable AISI 420(2016-04) Pecina, Jorge Nahuel; Lover, Luis Martín; Dalibón Bähler, Eugenia Laura; Brühl, Sonia PatriciaEn este trabajo se estudió el comportamiento a la corrosión y la adhesión de dos recubrimientos DLC (“Diamond Like Carbon”), “Soft” y “Hard”, depositados por PACVD (“Plasma Assisted Chemical Vapour Deposition”) sobre acero AISI 420, templado y revenido y/o nitrurado por plasma. Se analizaron por espectroscopía Raman y midió dureza en superficie. Se observó la microestructura por OM y SEM. Se realizaron pruebas de adhesión con indentación Rockwell C. Se practicaron ensayos de Niebla Salina e inmersión en HCl. Los DLC “Soft” presentaron una dureza de 500 HV y un espesor de 20 μm, mientras que los “Hard” tuvieron 1400 HV y 2,5 μm. Ambos recubrimientos presentaron bajo coeficiente de fricción y buena adhesión sobre el sustrato nitrurado. También presentaron buena resistencia a la corrosión atmosférica. En HCl el DLC retardó la degradación que se presentó rápidamente en las muestras sin recubrir.Item Influence of the pre-treatments and process temperature on the adhesion of TiN films deposited by PBII&D over nitrided austenitic stainless steel(2019-10-28) Vaca, Laura Silvia; Quintana, Juan Pablo; Guitar, María Agustina; Vega, Daniel; Brühl, Sonia Patricia; Márquez, Adriana BeatrizIn this work the influence of pre-treatment cleaning processes in the adhesion of TiN films deposited by the plasma based ion implantation and deposition (PBII&D) process over plasma nitrided AISI 316L stainless steel was investigated, varying the gas composition, the duration of the sputtering process and the temperature in the same deposition chamber. The TiN film morphology was scrutinized with scanning electron microscopy on the surface complemented with focus ion beam for the cross section. The film microstructure was characterized with X ray diffraction. The adhesion of the coatings was studied using the Scratch Test with constant load at different values and the Rockwell C indentation method as well. It was found that only with the sputtering carried out in a H - Ar gas mixing at 300 ºC temperature used as pre-treatment was successful to prepare the nitrided surface for the subsequent TiN deposition by the PBII&D process.Item Contact fatigue behavior of α-Al PROOF 2 O -Ti(C,N) CVD coated WC-Co under dry and wet conditions(2020-11-07) Sosa, D.A.; Collado Ciprés, Verónica; García, José Luis; Dalibón Bähler, Eugenia Laura; Escalada, Lisandro; Roa, Joan Josep; Soldera, Flavio; Brühl, Sonia Patricia; Llanes, L.; Simison, SilviaThe response to cycling contact fatigue load of a WC-6%Co carbide coated with a Ti(C,N)/α-Al2O3 CVD multilayer was investigated in dry and wet conditions. Imprints in dry conditions were characterized by small thin cracksformingacircumferenceatthemaximumradiioftheimprint.Thedamagedcoatingwastotallypresentin thefinalimprintofthedrytest.Wetindentationsshowcaseanareaintheimprintwherethe α-Al2O3 layerhas beenremovedthroughoutaringbutwaskeptatthecenteroftheindentation,suggestingthatthecoatingdamageundercyclingcontactloadinwetconditionsisdominatedbyα-Al2O3degradation,associatedwithafretting effectortangentialloadsacceleratingthefatigue-corrosionofthealuminalayer.