Facultad Regional Concep. del Uruguay
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Item Evaluación de la precipitación de carburos, resistencia al desgaste abrasivo y a la corrosión de fundiciones de alto cromo(2024-10-09) Bur, Emmanuel; Guitar, María Agustina; Brühl, Sonia PatriciaHigh Chromium Cast Irons (HCCI) are materials widely used in industries such as mining and slurry pumping in oil extraction due to their resistance to abrasion, impact and corrosion in aggressive environments. The excellent performance of these castings is due to the combination of eutectic carbides (EC) and secondary carbides (SC) within a tough matrix, achieved by specific heat treatments that optimise the distribution and stability of the carbides. Destabilisation of the microstructure is the most used treatment for this type of material, allowing the precipitation of SC. The temperature (980°C) and time (0 to 90 min) used during the treatment will determine the size and fraction of SC, as well as the fraction of martensite and retained austenite (RA) formed during cooling. Secondary carbides were quantified using Fiji® software with high- and low-resolution SEM images. The results show that the average particle size as well as the volume fraction of SC increased as the destabilisation time increased, on the other hand, several small particles are not detected in low resolution images. We also evaluated the effect of heating rate, observing that a slower heating rate favours the precipitation and growth of SC during the heating process. These secondary carbides have direct implications on wear properties. The response to abrasive wear according to ASTM G65 with a load of 65 N and 4800 m of sliding on a HCCI containing 26 %Cr was evaluated in three different conditions, containing varying amounts of SC, RA, and martensite: as received, destabilised by zero and ninety minutes. An improvement in abrasive wear resistance was observed in the heat-treated samples, where the material with higher CS fraction and higher hardness showed the best response. On the other hand, scratch tests were performed with a diamond tip and 90 N load. The wear profile was obtained by confocal microscopy (CLSM) where cutting and ploughing was observed as an abrasive mechanism in the heat-treated samples. In the untreated samples a large plastic deformation is observed. The effect of the amount of chromium (16 % Cr and 26 % Cr) on the corrosion behaviour was evaluated by electrochemical tests using a 3.5% NaCl solution and salt spray (ASTM B117) in a 5% NaCl solution for 100 hours. Additionally, the effect of destabilisation time on corrosion resistance was evaluated with an immersion test (3.5% NaCl) for 10, 100, and 250 hours. The material with lower Cr content showed higher corrosion, even after only 10 hours of immersion.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 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 Tribological and corrosion Behavior of Duplex Coated AISI 316L using plasma based ion implantation and deposItion(2020) Vaca, Laura Silvia; Quintana, Juan Pablo; Vega, Daniel; Márquez, Adriana Beatriz; Brühl, Sonia PatriciaThe implementation of a duplex process, which combines plasma nitriding with hard coatings obtained by cathodic arc, on stainless steel substrates has faced adhesion problems that affected the wear and corrosion behavior of the treated surfaces. One variation of the cathodic arc process, which could improve the adhesion, is its combination with plasma ion implantation. This work presents results of the wear and corrosion behavior of duplex TiTiN bilayer coatings obtained by cathodic arc deposition combined with ion implantation (PBII&D) on plasma nitrided AISI 316L stainless steel In order to compare the application of PBII&D in duplex processes against conventional cathodic arc deposition, other two types of samples were obtained; one group of samples was coated using the same experimental device with the substrate at floating potential and the other one with a commercial PVD system. The coatings were characterized by SEM, XRD, and nanoindentation. The adhesion was evaluated by the Scratch Test and Rockwell C indentation. The wear resistance was analyzed by the pin-on-disk test and the corrosion behavior was evaluated by means of anodic polarization tests in NaCl solution, as well as by the Salt pray Fog Test. The PBII&D bilayer coatings showed better adhesion while the commercial PVD TiN coatings presented the smallest wear volume loss, but the delamination inside and around the track evidenced adhesion problems. Corrosion resistance was improved in all coatings benchmarked against nitride substrates, but PBII&D processes offered better protection.Item Caracterización y análisis y de un recubrimiento multicapa con DLC como capa final(Universidad Tecnológica Nacional, 2020-10-05) Delfin, Francisco Andrés; Brühl, Sonia Patricia; Dommarco, Ricardo CésarEn este trabajo se estudia un recubrimiento multicapa DLC producido por primera vez en la industria nacional, utilizando un equipo PVD PEMS. La base es una capa de anclaje de AlTiN y la capa exterior es carbono amorfo hidrogenado dopado con cromo(DLC), que le confiere excelentes propiedades tribológicas, como un muy bajo coeficiente de fricción y una buena resistencia al desgaste. Se utiliza la nitruración iónicacomo pretratamiento, lo que mejora notablemente la adhesión al substrato, pero no incide en la resistencia al desgaste por contacto deslizanteen las condiciones que fueron ensayadas.