Papers by Keyword: Plasma Immersion Ion Implantation

Abstract: The carbon vacancy (V_C) is a lifetime-killer defect that hinders the correct functionality of 4H-SiC bipolar devices. Until now, different methods based on carbon interstitial injection, have been proposed, in order to reduce its concentration. However, if on one hand these methods effectively reduce the V_C concentration in the epilayer, on the other they cannot prevent the re-generation of V_C occurring during the manufacture of a p-i-n diode, e.g., p+ implantation and activation. In the following contribution, we employ PIII of B for the formation of the anode for a p-i-n diode. We show that by PIII, it is possible to simultaneously form a p⁺n junction with a low concentration of V_C in the drift layer.

Abstract: In this contribution we investigate the formation at high temperature of an oriented 3C-SiC seed on various orientations of Si substrates “pre-carbonized” through Plasma Immersion Ion Implantation (PIII) process.

Abstract: In this contribution we investigate the possibility to obtain an oriented 3C-SiC seed on Si substrate “pre-carbonized” through Plasma Immersion Ion Implantation (PIII) process by combining PIII with high temperature annealing.

Abstract: This paper is focused on the processing of thermoplastic composite materials obtained from carbon fibers (CFs) treated by plasma assisted techniques. The treatments employed in this work were the Dielectric Barrier Discharge (DBD), which is done at atmospheric pressure, involving lower energies and the Plasma Immersion Ion Implantation (PIII), which is performed at low pressure, involving higher energies. After the treatments, samples characterizations were performed to determine which treatment is most effective to get better physico-chemical CF surface properties. The techniques employed in this work in order to evaluate the surface treatment were: scanning electron microscopy (SEM); atomic force microscopy (AFM) Raman spectroscopy and x-ray photoelectron spectroscopy (XPS). Treated and untreated CFs/Polyphenylene sulfide (PPS) composites were processed by hot-compression molding technique. These composites were evaluated by interlaminar shear tests (ILSS). After analyzing the results, it was found that the treatments increased the CF roughness and caused slight changes in the CF structure. In addition, there was an increase in the shear strength of the composites obtained from treated fibers by both plasma processes. In conclusion, DBD and PIII treatments are effective tools for improving adhesion between CF and the polymeric matrix.

Abstract: Plasma immersion ion implantation (PIII) method is often used to cleaning and enhancing mechanical properties of the surface of materials. In this work, the AISI 304 was treated in a PIII system to improve tribological and wear resistance properties. The new HV pulser was prepared to reach high average power (10 kW) using solid-state technology and a pulse transformer rather than using a conventional one based on hard-tube tetrodes with HV storage capacitors. For preliminary tests, low-density nitrogen plasma and pulses of 10 kV, 30μs width, and 1 kHz were used. A larger vacuum chamber used (600 liters) is very important for treating large area components and for batch processing. This is necessary in industrial applications and in cases that require high quality processing as in spatial or medical components. Stainless steel support was used to hold the samples in our case. XRD, SEM, and pin-on-disk surface diagnostics were used for investigation and characterization of the treated surfaces.

Abstract: The search for alloys with improved high-temperature specific strength and creep-resistance properties for aerospace applications has led in the last decades to sustained research activities to develop new alloys and/or improve existing ones. Titanium and its alloys are excellent for applications in structural components submitted to high temperatures owing to their high strength to weight ratio, good corrosion resistance and metallurgical stability. Its high creep resistance is of great importance in enhancing engine performance. However, the affinity by oxygen is one of main factors that limit its application as structural material at high temperatures. Materials with adequate behavior at high temperatures and aggressive environmental became a scientific requirement, technological and economically nowadays. The objective of this work is the mechanical and microstructural characterization of the Ti-6Al-4V alloy after treatment by nitrogen Plasma Immersion Ion Implantation (PIII) process. The aim of this process is the improvement of superficial mechanical properties of the Ti-6Al-4V alloy. The selected alloy after ionic implantation process by plasma immersion was submitted to creep tests at 600 °C, in constant load mode at 250 and 319 MPa. The techniques used in this work were optical microscopy and scanning electronic microscopy. The fractograph analysis of the samples tested in creep shows narrowing phenomena and microcavities. The creep results show the significant increase of material resistance, it can be used as protection of oxidation in high temperatures applications.

Abstract: Surfaces of titanium aluminides were treated by fluorine either physically using Plasma Immersion Ion Implantation (PI³) or chemically with a F-based polymer. By controlling the fluorination parameters, both treatments improve the oxidation resistance even in the presence of sulfur dioxide (0.1 vol%). No sulfur was detected in the oxide scale although thermodynamic calculations predict the formation of sulfides. The inward diffusion of oxygen and nitrogen in the alloy was found to be reduced in the presence of SO2.

Abstract: Plasma immersion ion implantation (PIII) is a very attractive method for the surface treatment of titanium hard tissue replacements such as hip joints and enhancement of the mechanical, chemical and biological properties of titanium. It has been considered as an alternative to form protective and hard oxide films on titanium and titanium-based implants. In this study, titanium oxide (TiO2) thin films were formed on titanium using PIII, which produces films with adhesion superior to those prepared with conventional techniques. The films were analysed by atomic force microscopy (AFM), X-ray diffraction (XRD) and pull test.

Abstract: Ultra-high molecular weight polyethylene (UHMWPE) was surface treated by nitrogen plasma immersion ion implantation (PIII), with the main aim of improving its wear resistance. Accelerating voltages (U) between 15 and 30 kV, fluences (F) between 1×1017 and 3×1017 cm-2 and fluence rates (FR) between 3×1013 and 7×1013 cm-2 s-1 have been applied. XPS was used to characterise the surface chemical composition and structure. Changes induced in the surface mechanical properties like hardness (H), reduced modulus (E) and in the tribological property of volume loss upon uniform wear test (V) were studied by nanoindentation and multipass wear measurements. The evolution of surface topography was followed by measuring the mean roughness (Ra). The macroscopic temperature (T) developed during the PIII-treatment was also studied. Incorporation of N and O took place into the surface layer. With the increase of U the surface N-content tended to decrease. The bulk plasmon loss energy of the C 1s peak increased from 20 eV up to about 25 eV, suggesting densification and the formation of amorphous hydrogenated carbon nitride-like layer. H, T and Ra increased, and V decreased upon PIII treatment, while E either decreased or increased depending on the actual process parameter set applied. In the parameter range studied Hmax, Emax and Ra,max values have been observed at Umax, Fmax and FRmin. Vmin and Tmax have been observed at Umax, Fmin and FRmax, suggesting that the thermal effect is a dominant factor in determining the extent of reduction in the wear rate.

Abstract: The near surface of the H13 steel was implanted by using Plasma immersion ion implantation (PIII) system at constant bias voltage of −20 kV with varying nitrogen (N+ ) ion dose (3, 6, 9, 12, 15×1017 ions/cm2 ). The surface properties of the N+ ion implanted steel were investigated by measuring the microhardness, wear loss and friction coefficient. As increasing N+ ion dose (12×1017 ions/cm2), both wear property and surface hardness were increased. However, these properties were decreased as the incident ion dose increased over 12×1017 ions/cm2. The elemental depth profile and surface roughness were obtained with X-ray photoelectron spectroscopy (XPS) and surface roughness tester, respectively.