Comportamiento mecánico del acero AISI 316L recubierto con a:C-H-Si previamente nitrurado
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Date
2014
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Universidad Nacional del Litoral.
Abstract
El acero inoxidable AISI 316L es ampliamente usado en la industria química y alimenticia por sus buenas propiedades anticorrosivas, sin embargo presenta baja resistencia al desgaste. Para mejorar las propiedades tribológicas se pueden utilizar técnicas asistidas por plasma, tratamientos de difusión y/o recubrimientos. Los recubrimientos de carbono amorfo a:C-H-Si tienen bajo coeficiente de fricción y buena resistencia al desgaste. Además, son químicamente inertes, aunque presentan problemas de adhesión cuando son depositados sobre metales. En este trabajo se estudió el comportamiento mecánico y la adhesión de un recubrimiento a:C-H-Si tipo soft depositado por PACVD sobre el acero inoxidable AISI 316L nitrurado (muestra dúplex) y sin nitrurar (muestra recubierta). Los recubrimientos fueron caracterizados por EDS y Raman. Se midió la dureza y el módulo elástico utilizando nanoindentación. La microestructura de la capa nitrurada y de los recubrimientos fue analizada por MO, SEM-FIB y DRX. Se realizaron ensayos de pin on disk y de deslizamiento recíproco. Se evaluó la adhesión por indentación Rockwell C y Scratch Test. Los recubrimientos de a:C-H-Si presentaron un contenido de hidrógeno mayor al 40 % y su espesor fue de 20 μm, alcanzaron una dureza de aproximadamente 13 GPa y un módulo elástico de 73 GPa. Estos recubrimientos presentaron un coeficiente de fricción inferior a 0,2 y mejoraron la resistencia al desgaste con respecto al acero sin tratar. La profundidad de las huellas en los ensayos de deslizamiento recíproco fue 6 veces menor, independientemente del tratamiento de nitruración previo. El pretratamiento de nitruración tuvo influencia en la adhesión, ya que la carga crítica fue de 16,2 N en la muestra dúplex y de 9,6 N en la sólo recubierta. En el ensayo de indentación Rockwell C, la muestra dúplex presentó mejor adhesión que la muestra sólo recubierta.
The austenitic stainless steel AISI 316L is used in chemical and industry due to their good properties, however it has a poor wear resistance. In order to improve the tribological propiertes, plasma assisted treatments can be used such as diffusion process and/or coatings. The a:C-H-Si coatings have low friction coefficient and wear resistance, in addition they are chemically inert, however they present adhesion problems when they are deposited on metallic substrates. In this work, the mechanical behavior and adhesion of the a:C-H-Si coatings deposited on nitrided AISI 316L stainless steel (duplex sample) and without nitriding (coated sample) were studied. The coatings were characterized by EDS and Raman. The hardness and Young Modulus were assessed with nanoindentation. The microstructure of nitrided layer and the coatings was analyzed by OM, SEM-FIB and XRD. Pin on disk and linear sliding tests were carried out. The adhesion was evaluated using Indentation Rockwell C and Scratch test. The coatings had high hydrogen content, over 40%, and the film thickness was about 20 m. The hardness was about 13 GPa and Young’s Modulus was 73 GPa. The friction coefficient was less than 0.2 and the wear resistance was better than in the stainless steel without treatment. In the linear sliding tests, the track depth in the duplex and coated samples was six times lower than in the untreated sample. The nitriding had influence in the adhesion; the critical load was 16.2 N in the duplex sample and of 9.6 N in the coated sample. In the indentation Rockwell C test, the duplex sample had better adhesion than the only coated sample.
The austenitic stainless steel AISI 316L is used in chemical and industry due to their good properties, however it has a poor wear resistance. In order to improve the tribological propiertes, plasma assisted treatments can be used such as diffusion process and/or coatings. The a:C-H-Si coatings have low friction coefficient and wear resistance, in addition they are chemically inert, however they present adhesion problems when they are deposited on metallic substrates. In this work, the mechanical behavior and adhesion of the a:C-H-Si coatings deposited on nitrided AISI 316L stainless steel (duplex sample) and without nitriding (coated sample) were studied. The coatings were characterized by EDS and Raman. The hardness and Young Modulus were assessed with nanoindentation. The microstructure of nitrided layer and the coatings was analyzed by OM, SEM-FIB and XRD. Pin on disk and linear sliding tests were carried out. The adhesion was evaluated using Indentation Rockwell C and Scratch test. The coatings had high hydrogen content, over 40%, and the film thickness was about 20 m. The hardness was about 13 GPa and Young’s Modulus was 73 GPa. The friction coefficient was less than 0.2 and the wear resistance was better than in the stainless steel without treatment. In the linear sliding tests, the track depth in the duplex and coated samples was six times lower than in the untreated sample. The nitriding had influence in the adhesion; the critical load was 16.2 N in the duplex sample and of 9.6 N in the coated sample. In the indentation Rockwell C test, the duplex sample had better adhesion than the only coated sample.
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Keywords
Recubrimientos DLC, PACVD, Comportamiento tribológico, Adhesión, DLC coating, Tribological behaviour
Citation
14º Congreso Internacional de Metalurgia y Materiales SAM-CONAMET (2014).
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