No abstract

High corrosion resistance is achieved in the 300 series SS, but due to the low carbon content they do not have the carbides present in wear‐resistant steels. This paper shows results from a combined plasma nitriding surface treatment performed in AISI SS304, that led to the enhancement of 50% in microhardness and the achievement of improved tribological properties of the samples, while keeping its high corrosion resistance. A complete characterization set including results from AES, Vickers hardness, XRD, friction coefficient, and wear rate will be shown for the samples treated by this hybrid nitriding process, in comparison with the conventional ion nitriding method.

A novel source for plasma immersion ion implantation and deposition (PIII&D) was developed in order to perform surface treatment of materials with ions from vaporization of solid targets. Usually this is obtained by means of beamline ion implanters, in which three dimensional implantation requires target manipulation, or by vacuum arc discharges, in which the presence of macroparticles is the main problem to be overcame. Samples of silicon wafers immersed in a lithium plasma produced by this source were submitted to low negative high frequency pulses (3‐4 kV/6 μs/3 kHz), causing lithium implantation and deposition. A very high strain and photoluminescence measured by high resolution X‐ray diffraction and Raman spectroscopy, respectively, were observed in the analyzed layers of the samples that were immersed in this plasma. XPS measurements revealed thick Li deposition for samples treated under conditions of high lithium vaporization rate. This novel process was effective for Li implantation/deposition and shows potential for PIII or PIII&D of many different elements from solid targets as Ca, K, Mg and Al. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The deposition of Diamond-like carbon (DLC) films brings excellent mechanical, chemical, optical and electronic properties to a large range of materials. However, a problem to be overcome is its poor adhesion on metallic substrates. Usually, a silicon layer must be deposited on the surface of metals previous to DLC film deposition. In fact, in our experiments using conventional Magnetron Sputtering (MS) technique for deposition of DLC film on metal surfaces (AISI 304 stainless steel, Al 2024, Ti-6Al-4V), the silicon interlayer was crucial to avoid delamination. However, a combined process using MS and high frequency and moderate energy pulses (2.5kV/6µs/1.25 kHz), was successful to grow DLC film without the interlayer. Additionally, by monitoring the stress and the thickness in silicon samples after the processes, it was possible to correlate the conditions of operation with such characteristics. Stress measurements carried out by a profilometer and calculated by Stoney´s equation varied from 2 GPa to 10.5 GPa depending on the conditions of operation of the process (pressure, distance source-substrate, frequency, length and intensity of the pulse). The thickness, the composition, the structure and the morphology of DLC coatings deposited in such metallic surfaces were obtained. Tribological and corrosion tests were also performed.