Magnesium alloys are considered one of the more promising materials for future use in many engineering applications. However, due to their high chemical and electrochemical reactivity, magnesium alloys have poor corrosion resistance in aqueous environments. Improving their corrosion resistance by coating can greatly extend their application. One promising coating method is plasma electrolytic oxidation (PEO). The nature of the coating formed, and the ultimate corrosion performance, depends on the both the processing parameters (electrolyte, current density, current mode, processing time) and specific Mg-alloy substrate. In the present study, PEO coatings were produced on three different Mg-alloys ( AJ62, AM60B and AZ91D) using different processing parameters. Optical Emission Spectroscopy (OES) was used to characterize the plasma species and other parameters and scanning electron microscopy and XRD were used to characterize the coatings. The corrosion resistance was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in an aqueous 3.5% NaCl solution. Relationships are drawn between PEO processing parameters and substrate composition and the corrosion performance.

Atmospheric plasma treatment of surfaces brings about a number of application options including inner treatment of hollow substrates and tubes. This work describes first results of both the atmospheric plasma surface treatment and the PECVD of carbonaceous films in narrow holes and tubes with the inner diameter of about 10 mm. The experiments were carried out by the Hybrid Hollow Electrode Activated Discharge (H-HEAD) atmospheric plasma source. The air plasma column inside the steel pipe increased the surface energy within seconds which provides a better adhesion of subsequent lacquers or coatings. The PECVD was tested by carbon precursors represented be alcohol vapor or a simple LPG (Liquefied Petroleum Gas). The plasma treatment was examined by the contact angle measurements. The carbonaceous coatings were studied by SEM and Raman spectroscopy. Options and arrangements for treatments of longer and broader tubes are briefly discussed.

The plasma processing is being extensively used in microelectronic industry for manufacturing various electronic devices. Presently, the semiconductor industry is looking forward to move for fabrication of electronic devices at a few tens of nano-meter level. However, the device fabrication cost increases as the size of electronic device reduces. Therefore, large area wafer size is necessary to be adopted in order to improve productivity and optimize the fabrication cost of such microelectronic devices. According to a technology trend forecast, the wafer size will be 450 mm in diameter within a few years.

The most significant challenge for fabrication on a large area wafer size is to precisely control the distribution of plasma species over the substrate. Various ideas, such as segmented and gridded antennas, capacitively coupled plasmas (CCP) and very high frequency capacitively coupled plasmas (VHF-CCPs) have been proposed and implemented to achieve large area plasma sources with enhanced discharge uniformity over the substrate. Due to ability of being operated at low pressure, high plasma density, easier plasma uniformity control and the separation of discharge production and ion acceleration mechanism of the ICP sources turned the research direction towards developing and investigating the ICP sources for large area microelectronic device fabrication. However, scaling up conventional ICP sources pose some problems such as increased antenna impedance that, in turn, increase RF voltage drop across the antenna and therefore, decrease average power transfer efficiency to the discharge and produces azimuthal non-uniformity due to the standing wave effect. To overcome this issue, a novel approach of dual frequency dual antenna inductively coupled plasma (DFDA-ICP) source has been adopted. The experiments that demonstrate center to edge plasma density control, modulation of plasma parameters, electron energy distribution (EED) and Ion Energy distribution (IED) will be described in this presentation.

Plasma immersion ion implantation (PIII) of nitrogen on titanium at variable energies has been performed. The samples after metallographic polishing and ultrasonic cleaning were placed in the evacuated chamber of the implanter. The post implanted samples were subjected to X-ray diffraction and Scanning Electron Microscopic studies for the phase analysis and surface topography. After implantation a layer of titanium nitride with crystallographic orientations (111) and (200) had been formed.

Potentiodynamic polarization tests of the post implanted samples in Hank’s solution were performed. Formation of nitrides in post implanted solution showed a higher resistance to corrosion at lower implantation energy.