Modificação das propriedades superficiais de materiais através da implantação de cromo por recoil por meio de implantação iônica por imersão em plasma de nitrogênio / Modification of surface properties of materials by chromium recoil implantation using nitrogen plasma immersion ion implantation

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The objective of this work is the modification of the surface properties of conductive materials (carbon steel) and semiconductors (silicon) using the implantation of chromium atoms, deposited on the surface of materials as thin films, using plasma immersion ion implantation. In this study we seek to understand the basic process of recoil implantation (using silicon) and improve the mechanical, tribological and anti-corrosive properties of materials commonly used in the industry and building sites such as carbon steel. The chromium films with several thicknesses were deposited by electron beam evaporation and the nitrogen plasma immersion ion implantation was carried out varying a series of parameters, as the energy of the ions, work pressure, time of treatment and film thickness. Implantation process simulations were accomplished using the software SRIM. After treatments, silicon samples were characterized by high resolution ray-X diffraction (in Rocking Curve configuration) and Auger electron spectroscopy (AES). Steel samples were characterized by micro and nanoindentation, tribological and corrosion tests, scanning electron microscopy (SEM) and Auger electron spectroscopy (AES). The analysis of Rocking Curves showed that the increase of the energy, work pressure and treatment time increases the number of nitrogen ions implanted into the silicon, which was confirmed by AES. In carbon steel, micro and nanoindentation analyses showed that the surface hardness increased with presence of the deposited film, and it was still larger after the treatment, especially for those accomplished in high energy. The tribological tests (pin-on-disk type) showed that, after the treatment, the friction coefficient was reduced for most of the samples and there was also a reduction of the wear rate. The corrosion tests showed that the presence of the film in the surface turned the material more noble, elevating the corrosion potential, in relation to a sample without film and treatment. After treatments, that potential further rises, but for the treatments in high energy, the current density increases by one order of magnitude in relation to the sample without film and treatment, accelerating the corrosion process. The micrographics obtained by SEM revealed the structures of the surface before and after the corrosion, showing an increase of the roughness and, for some samples, a mechanism similar to pitting corrosion. The concentration profiles obtained by AES confirmed the implantation of nitrogen and of chromium, even with the excessive loss of chromium by sputtering in the treatments at moderate energy.

ASSUNTO(S)

plasma immersion ion implantation carbon steel sae 1020 engenharia e tecnologia espacial implantação por recoil caracterização space engineering and technology auger electroscopy (aes) recoil implantation implantação iônica por imersão em plasma espectroscopia de elétrons auger corrosion corrosão silicon aço carbono sae 1020 silício characterization

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