Recubrimientos duros tipo DLC depositados sobre acero inoxidable martensítico nitrurado : análisis de adhesión y resistencia a la corrosión
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2014-10-21
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Abstract
Los tratamientos de modificación superficial como la nitruración permiten mejorar las propiedades tribológicas del acero AISI 420 pero afectan la resistencia a la corrosión. Los recubrimientos tipo DLC (“Diamond Like Carbon”) se caracterizan por tener bajo coeficiente de fricción, buena resistencia mecánica y a la corrosión. En este trabajo se estudió el comportamiento a la corrosión y la adhesión del recubrimiento DLC tipo hard depositado por PACVD sobre el acero AISI 420 templado y revenido, y nitrurado (tratamiento dúplex). Se analizaron los recubrimientos por espectroscopía Raman y por EDS. Se analizó la microestructura por SEM-FIB y DRX. Se evaluó la adhesión por Scratch test y por Indentación
Rockwell C. Se realizaron ensayos de inmersión en niebla salina y ensayos electroquímicos en solución de NaCl. Los recubrimientos resultaron de tipo carbono amorfo hidrogenado. El espesor resulto de 2,5 micrones aproximadamente y la capa nitrurada de 11 micrones. Con respecto a la adhesión, puede indicarse que la capa nitrurada mejoró los resultados en el ensayo de Scratch test y de indentación. Con respecto al comportamiento a la corrosión, los recubrimientos presentaron excelente resistencia a la corrosión atmosférica, como se esperaba. Estudios preliminares de corrosión localizada mediante curvas de polarización anódica cíclica indicaron que el recubrimiento mejora el desempeño dado que se logra aumentar el potencial de corrosión y el de ruptura con respecto a las muestras nitruradas y no tratadas.
The surface modification treatments, such as the plasma nitriding improve the tribological properties of AISI 420 stainless steel; however the corrosion resistance is deteriorated. The DLC (Diamond Like Carbon) coatings have low friction coefficient, good wear and corrosion resistance. In this work, the corrosion behavior and the adhesion of the DLC hard coating deposited on nitrided and non-nitrided AISI 420 stainless steel were studied. The coatings were characterized by EDS and Raman. The microstructure of nitrided layer and the coatings was analysed by SEM-FIB and XRD. Corrosion behavior was evaluated by the Salt Spray Fog Test and cyclic potentiodynamic polarization tests in NaCl solution. The adhesion was evaluated using Indentation Rockwell C and Scratch test. The a-C:H film thickness was about 2.5 um and nitrided layer thickness was of 11um. The nitrided layer improved the adhesion in the scratch test and the indentation Rockwell C. Regarding to the corrosion behavior, the coatings had excellent atmospheric corrosion resistance. In the electrochemical tests, they had a good behavior, the rupture potential was more positive than in only nitrided.
The surface modification treatments, such as the plasma nitriding improve the tribological properties of AISI 420 stainless steel; however the corrosion resistance is deteriorated. The DLC (Diamond Like Carbon) coatings have low friction coefficient, good wear and corrosion resistance. In this work, the corrosion behavior and the adhesion of the DLC hard coating deposited on nitrided and non-nitrided AISI 420 stainless steel were studied. The coatings were characterized by EDS and Raman. The microstructure of nitrided layer and the coatings was analysed by SEM-FIB and XRD. Corrosion behavior was evaluated by the Salt Spray Fog Test and cyclic potentiodynamic polarization tests in NaCl solution. The adhesion was evaluated using Indentation Rockwell C and Scratch test. The a-C:H film thickness was about 2.5 um and nitrided layer thickness was of 11um. The nitrided layer improved the adhesion in the scratch test and the indentation Rockwell C. Regarding to the corrosion behavior, the coatings had excellent atmospheric corrosion resistance. In the electrochemical tests, they had a good behavior, the rupture potential was more positive than in only nitrided.
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DLC coating, AISI 420
Citation
Congreso Internacional de Metalurgia y Materiales SAM-CONAMET/IBEROMAT. Santa Fé. (2014).
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