In transmission electron microscopy (TEM), one typically considers bright-field or dark-field imaging signals, which utilize the transmitted and scattered electrons, respectively. Analytical signals such as characteristic X-Rays or primary electron beam energy losses from inelastic scattering events give rise to the energy dispersive X-Ray spectroscopy and electron energy loss spectroscopy techniques, respectively. In this paper, the detection of the electron beam absorbed current (EBAC) and electron beam induced current (EBIC) signals is reported using a specially designed scanning TEM holder and associated amplification electronics. By utilizing thin TEM samples where the beam-sample interaction volume is controlled more through the incident electron probe size, the EBAC and EBIC signal resolution is improved to the point where implant regions and Schottky junction depletion zones can be visualized.

In a cold spray technique (CS), which used for making dense and thick metallic coatings, the fine solid metallic particles are impinged and deposited on a substrate at subsonic or supersonic velocity. The property and performance of a CS metallic coating significantly depends on the bonding state of particle-substrate and particle-particle interfaces. Therefore, the deposition mechanism of the CS particles has become one of the most important research targets. However, it is difficult to experimentally evaluate the deposition mechanism due to numerous impingements of very fine particles with various size and shape. In this study, in order to evaluate the deposition mechanism, a CS emulated environment was created by a single particle shot system (SPSS) in which spherical particle with 1 mm diameter is impinged on a substrate. The influence of substrate surface oxide film on deposition behavior of a spherical Al particle with 1 mm diameter was investigated. The thickness of surface oxide film on a substrate was controlled by heat treatment and estimated by X-ray photoelectron spectroscopy (XPS). Using the SPSS, Al particles were impinged on the substrates with different surface oxide film thicknesses. The critical velocity, which means the starting velocity for particle deposition, and the microstructure of deposited particle were evaluated. From the results, it was found that the surface oxide films on substrates play important roles on the deposition behavior of the Al particle.

This study investigates the effects of spark plasma sintering (SPS) on the microstructure and properties of cold-sprayed metallic coatings. Water-atomized Cu powder was deposited on Al 5052 substrates by high-pressure cold gas spraying, and the resulting coatings were treated by spark plasma sintering and annealing heat treatment (AHT) at 200°C, 300°C, and 400 °C. To assess the effects of diffusion generated by pulsed dc power, a vertical load was not applied in the SPS system. In addition, a short duration time was used to inhibit crystal grain growth. Treated specimens were evaluated by SEM, EBSD, and hardness and tensile testing. The findings show that the microstructure and hardness of SPS specimens treated at 300 °C are close to that of AHT specimens treated at 400 °C. Tensile strength, however, is clearly higher in the SPS300 specimens, indicating that pulsed dc power accelerates particle interdiffusion due to Joule heating and electromigration, thereby increasing adhesion strength between particles in the coating.

Cold spray deposition of polycarbonate on the various substrates has been investigated. The polycarbonate particles are sieved and accelerated at elevated temperature in air through a DeLaval type nozzle, and are deposited on the metallic and ceramic substrates. The influences of the particle size, the gas temperature, the thermal conductivity and surface roughness of substrate on the deposition process are studied. As a result, the continuous deposits are formed on the metallic substrate. The powder sieved below 300 μm shows better deposition efficiency. Thin film of melted polycarbonate has been formed on the surface of substrate to act as a bonding layer, and its crystalline structure is changed to be amorphous, which is the more stable state for the polycarbonate. The coating seems to be better when the thermal conductivity of metallic substrate is low. For the ceramic substrates, there is no deposition whatever was the thermal conductivity.

Aluminium alloys are widely used for transportation facilities, because of light weight and high corrosion-resistance. If there are some cracks in transportation, sometimes they repair by welding. However, it is difficult to weld aluminium materials. Because, Aluminium has high specific thermal conductivity and high coefficient of thermal expansion compared with that of steel. The cold spray technique is known as a new technique not only for coating but also for thick depositions. It has many advantages, i.e. dense coating, high deposition rate and low oxidation. Therefore, it has a possibility to apply the cold spray technique instead of welding to repair the cracks. What seems to be lacking, however, is deposition mechanisms and mechanical properties of deposition produced by low pressure type cold spraying. This is a very important issue for applying the cold spray to repair some structures. In this study, elucidation of deposition mechanisms and evaluation of mechanical properties for the low pressure type cold sprayed aluminium depositions were investigated. As a result of elucidation of deposition mechanisms, it can be clear that the particle deposition needs to activate the surface by several impingements. Furthermore, as a result of evaluation of mechanical properties, the cold sprayed specimen showed higher strength than the monolithic specimen in the case of compressive loading to the coating.

In thermal barrier coating (TBC) system, thermally grown oxide (TGO) forms at the interface between the top-coat and bond-coat during service. Delamination or spallation at the interface can be occurred by the TGO formation and growth. Therefore, Modifications of the bond-coat materials are one means to inhibit the TGO formation and to improve the bonding strength of TBCs. In this study, morphologies of TGO were controlled by using Ce and Si addition to conventional CoNiCrAlY bond-coat material. As a result, when the TBCs with Ce added bond-coat materials were aged at 1373K for 100 hours, morphologies of TGO were changed drastically. It is expected that the morphologies can improve bonding strength of TBCs. We carried out to evaluate the bonding strength by using four-point bending tests. As a result, TBC coated with Ce added bond-coat materials indicated excellent bonding strength.