FRCU - GIS: Grupo de Ingeniería de Superficies - Artículos
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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 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 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.Item Soft and thick DLC deposited on AISI 316L stainless steel with nitriding as pre-treatment tested in severe wear conditions(2020) Dalibón Bähler, Eugenia Laura; Moreira, Ramiro Damián; Heim, Daniel; Forsich, Christian; Brühl, Sonia PatriciaThick and soft DLC coatings were deposited over stainless steel to improve their surface properties, protecting them from wear in different conditions. When a protective film is thick, it can be considered as selfsustaining in terms of loadcarrying capacity during wear situations even if the substrate is soft or hard. Thin and hard DLC coatings are well known for having high hardness and low friction coefficient; however they have adhesion problems when deposited on soft steels and many of their wear properties also depend on adhesion. For this reason, a previous plasma nitriding process may be convenient. In this work, the fretting and erosion wear behaviour of DLC soft coatings deposited on nitrided and nonnitrided austenitic stainless steel was evaluated using high loads and long tests both simulating severe conditions wear. The aim is to analyse under which conditions the film thickness is not enough to withstand wear damage when deposited onto soft steels. The results showed that in the fretting tests, the duplex sample presented better resistance than the only coated sample in all tested conditions, except for the minimum load, 12 N. In slurry erosion tests, the mass loss was similar in both samples until nine hours, when the influence of the nitrided layer became noticeable as a hard layer since the coating partially removed.Item Corrosion behaviour of a SiOxNy coated and nitrided ph stainles steel(Elsevier, 2015) Dalibón Bähler, Eugenia Laura; Moscatelli, Mauro Nicolás; Simison, Silvia; Escalada, Lisandro; Cabo, Amado; Lasorsa, Carlos; Brühl, Sonia PatriciaPrecipitation hardening stainless steels are used in applications where wear and corrosion resistance are required. To improve the surface properties, thermochemical treatments in combination with hard coatings can be used. In this work, the corrosion behaviour of SiOxNy coatings deposited on nitrided and non-nitrided Corrax® PH stainless steel were evaluated comparing them with the behaviour of samples which were only nitrided (two different conditions of nitrogen percentage in the working gases were used). The microstructure was analyzed. Corrosion behaviour was evaluated by the Salt Spray Fog Test and cyclic potentiodynamic polarization in NaCl solution. Erosion-corrosion tests were conducted. The thickness of the coating was about 1.4 microns, and its hardness was 2300 HV. The film had better erosion and corrosion behaviour when it was deposited on the nitrided steel. This fact demonstrated that the nitrided layer results in a good interface that improves the adhesion and mechanical support.