C.B. Wei

Surface modification of TiNi alloy through tantalum immersion ion implantation

Abstract TiNi alloy samples were implanted with tantalum at a dose of 3.1×1017 N/cm2 by means of Plasma immersion ion implantation (PIII) method. The surface morphology, chemical composition was characterized by Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance, were determined by electrochemical methods in 0.9% NaCl solution at 37 °C. The results show that PIII treatment can increase the open-circuit corrosion potential (Ecorr) and decrease the corrosion current density (Icorr). The pitting potential (Ebr) for the tantalum implanted TiNi alloy is approximately 810 mV, more than 200 mV higher than that of the unimplanted one. The corrosion hystersis loop of the unimplanted TiNi alloy is larger than that of the implanted material, indicating improvement of the repassivating ability and pitting resistance of the TiNi alloys.

Long-term antibacterial effect of nano-skeletoned Cu-TiN films by dual magnetron sputtering

Antibacterial fabrication has increasingly gained more attention. We present the fabrication processes related to nano-layer antibacterial films containing copper in this ppaer. TiN/Cu-Zn multilayers were deposited on stainless steel by dual magnetron sputtering. The copper content in each layer has to be optimized to form copper clusters. Consequently the TiN may grow on or between the copper clusters and TiN skeleton with copper located inside may be fabricated for long-term antibacterial effect. Influence of modulation period of multilayers on corrosion resistance and antibacterial properties was also investigated. The relationship of corrosion and antibacterial characteristics was also studied. The results show that good corrosion resistance has been achieved in multilayers when Cu-Zn layers are thin and the corrosion resistance increases with increased thickness of TiN layers. However, the corrosion resistance of multilayers decreased dramatically with increasing thickness of Cu-Zn layers. There exists a proper modulation period of nano-multilayer contributing to high antibacterial effect as well as good corrosion resistance.

Improvement of surface properties of magnesium alloy by plasma immersion ion implantation-deposition

Summary form only given. Magnesium and its alloys have received interest due to its low mass density as potential applications in the construction and environmental industry. However, its poor corrosion resistance has hampered wide acceptance in the industry. In this work, we conduct plasma immersion ion implantation-deposition (PIII-D) on magnesium alloys and have found that PIII-D processes can effectively improve the corrosion resistance of the materials. The technique can also treat objects possessing irregular shape thereby boding well for commercial components. In addition, the sticking force between the deposited film and substrate can be enhanced by ion beam mixing that is intrinsic to the technique. In our experiments, we employ a chromium cathodic arc to generate a metal plasma for the deposition and investigate the influence of the bias voltage on the surface conditions. The anti-corrosion behavior of the samples is evaluated using immersion and potentiodynamical polarization tests whereas the film structure and chromium in-depth distribution are determined using X-ray diffraction and Rutherford backscattering spectrometry.