FRCU - Grupos de Investigación
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Item Análisis del comportamiento al desgaste y adhesión de recubrimientos tipo DLC hard depositados sobre un acero inoxidable martensitico(2017-08-17) Uccellini Bermúdez, Massimo Nicola; Pecina, Jorge Nahuel; Dalibón Bähler, Eugenia Laura; Brühl, Sonia PatriciaLos recubrimiento tipo DLC (Diamond Like Carbon) son químicamente inertes, tienen bajo coeficiente de fricción y buena resistencia al desgate. Existen muchas publicaciones acerca del comportamiento tribológico de estas películas, pero pocas que traten de la resistencia al desgaste por fretting. En este trabajo, se estudio dicha resistencia en diferentes condiciones, cambiando lal duración del ensayo y de la carta aplicada. La película fue depositada mediante CVD asistido por plasma sobre un acero inoxidable martensitico AISI 420. La mitad de las muestras fueron nitruradas previamente a la deposición, y a estas se la denomino dúplex mientras que las que no fueron nitruradas se las nombro como solo recubiertas. El recubrimiento fue caracterizado por espectroscopia Raman. La micro estructura fue observada por OM, SEM y analizada por DRX. La dureza y el Modulo de Young fueron determinados mediante nanoindentación y la adhesión se evaluó a través de indentación ROCKWELL C y ensayos de Scratch Test. El espesor del recubrimiento fue de 2.5 um y el de lal cpa nitrurada fue de 11 um. La dureza del film fue de aproximadamente 16 GPa y el Modulo de Young, 110 GPa. En las muestras recubiertas, al ensayarlas durante 1 hora y con una carga de 1 N, se observo la rotura y el desprendimiento de la película. La carga critica determinada en el ensayo de Scratch Test fue de 47 N para las muestras dúplex y 9N para las muestras solo recubiertas. En el ensayo de Scratch Test con carga constante, se observo un modo de falla, del tipo frágil en las muestras solo recubiertas. En los ensayos de indentación Rockwell C., la adhesión solo fue aceptable en las muestras dúplex. En ambos ensayos de adhesión, la capa nitrurada reduce las tensiones y mejora la adhesión.Item Wear and adhesion properties of a PVD duplex coated medium alloy steel for plungers in the oil and gas industry(2017-07-05) Brühl, Sonia Patricia; Dalibón Bähler, Eugenia Laura; Cabo, Amado; Crimello, Pablo; Aguirre, Luis Alberto; Carfi, Guillermo RodolfoA duplex coating consisting in plasma nitriding of V820 steel (Boehler®) and a CrAlN coating (Balinit©, Oerlikon Balzers) was designed to enhance wear properties of hydraulic fracture pumps plungers used in the O&G Industry. On subsequent reciprocating motions, pumped slurry (containing solid particles) would eventually penetrate the interstice between the plunger´s operating surface and the seal, thus causing permanent damage. The duplex system was analyzed comparing to a standard treatment for these pistons (thermal sprayed coating over carbon steel): optical and electronic microscope, depth hardness profiles, EDS and DRX. Two groups of coated samples were selected with different surface finishing, and the nitrided sample was used for comparison, so as the untreated steel. Scratch Test at different constant loads and Rockwell C indentation were used to test adhesion. Abrasion wear tests were carried out following ASTM G65. Finally, laboratory results were compared to field tests. The PVD coating were 2500 HV hard, 3-4 microns thick, and the nitrided layer provided a soft hardness depth profile of about 320 microns width. The standard thermal spray coating was 800 microns thick, with an average hardness of 750 HV but with an abrupt change in hardness with the substrate. The adhesion was extremely good, critical load was 125 N. In the abrasive tests, the mass loss in the PVD coated samples was reduced 30 times respect to the standard coated samples. In the field technological test the PVD coated pistons improved the quantity of pumping cycles in almost 300%.Item Wear and adhesion properties of a PVD duplex coated medium alloy steel for plungers inthe oil and gas industry(2017-07-05) Brühl, Sonia Patricia; Dalibón Bähler, Eugenia Laura; Cabo, Amado; Cirimello, Pablo; Aguirre, Luis Alberto; Carfi, Guillermo RodolfoA duplex coating consisting in plasma nitriding of V820 steel (Boehler®) and a CrAlN coating (Balinit©, Oerlikon Balzers) was designed to enhance wear properties of hydraulic fracture pumps plungers used in the O&G Industry. On subsequent reciprocating motions, pumped slurry (containing solid particles) would eventually penetrate the interstice between the plunger´s operating surface and the seal, thus causing permanent damage. The duplex system was analyzed comparing to a standard treatment for these pistons (thermal sprayed coating over carbon steel): optical and electronic microscope, depth hardness profiles, EDS and DRX. Two groups of coated samples were selected with different surface finishing, and the nitrided sample was used for comparison, so as the untreated steel. Scratch Test at different constant loads and Rockwell C indentation were used to test adhesion. Abrasion wear tests were carried out following ASTM G65. Finally, laboratory results were compared to field tests. The PVD coating were 2500 HV hard, 3-4 microns thick, and the nitrided layer provided a soft hardness depth profile of about 320 microns width. The standard thermal spray coating was 800 microns thick, with an average hardness of 750 HV but with an abrupt change in hardness with the substrate. The adhesion was extremely good, critical load was 125 N. In the abrasive tests, the mass loss in the PVD coated samples was reduced 30 times respect to the standard coated samples. In the field technological test the PVD coated pistons improved the quantity of pumping cycles in almost 300%.