Since Dye sensitized solar cell (DSC) is a solar cell which uses anatase film as photo voltaic device, production cost of DSC can be very low in comparison with that of silicon solar cell. Besides, according to some theoretical discussion on DSC, the electric power conversion efficiency can be raised to 30%. Therefore, DSC will be mainly used in future. In this study, in order to develop a low cost fabrication process for photo voltaic device of DSC, photo-catalytic titanium oxide film depositions were carried out by thermal plasma CVD (TPCVD) and thermal spraying. As working gas for plasma jet, and substrate, Ar gas and 20mm×40mm×1mm copper plate were used. Feedstock materials were titanium tetra butoxide in TPCVD and rutile powder in thermal spraying. In the DSCs using these films, cathodes (titanium oxide coated electrodes) were located beneath the transparent anodes. Consequently, in the case of TPCVD, anatase dominant film could be deposited and the DSC using this TPCVD film could generate 50 mV in electro motive force. Furthermore, even in case of thermal spraying, though rutile powder was used, photo-catalytic coating (anatase and rutile mixture coating) could be obtained by cooling substrate during coating and post heat treatment. It was confirmed that the electromotive force of the DSC using this thermal spray coating was almost the same as that of the DSC using the TPCVD film. From these results, these thermal plasma processes was found to have high potential for DSC fabrication.

In order to develop a functional film deposition process with high deposition rate, as a basic study, deposition of zinc oxide film by thermal plasma CVD (TPCVD) in the air was carried out. As ingredient, working gas and substrate, ethanol diluted zinc acetate solution, Ar and 430 stainless steel were used. As for deposition condition, Ar gas flow rate was fixed at 20SLM, deposition distance (distance between substrate surface and nozzle outlet of plasma torch) was varied 50 to 200 mm, zinc acetate concentration in the ingredient was varied 20 to 50 vol%, and ingredient feed rate was varied 30 to 200 ml/h. Consequently, with varying deposition distance, not only crystallized film but also amorphous film could be deposited. In the case of crystallized film, photo-catalytic properties could be confirmed in the films by methylene blue decoloration testing and wettability testing. Besides, in this case, film structure could be changed from lamellar to columnar by decreasing zinc acetate/ ethanol ratio. From these results, this process was found to have high potential for high rate functional film deposition process conducted in the air.

This work evaluates the microstructure and composition of zirconia films produced by thermal plasma chemical vapor deposition (TPCVD). The results show that TPCVD has the potential to produce durable ceramic films with columnar structure, even in open air. Paper includes a German-language abstract.

In mechanical engineering there is an increasing demand for lightweight design and materials engineering from the view points of weight reduction, reduction of consumed energy and upgrading of performance. One major drawback of light metal alloys is their poor tribological properties concerning friction and wear under high surface loadings. This study focuses on the development of combined coatings on light metal substrates which show high wear resistance and low friction coefficients under dry sliding conditions. The combined coatings consist of a thermally sprayed ceramic or metallurgical primary coating to provide the wear resistance. Subsequently a coating with dry lubricating ability is deposited to achieve a low friction coefficient, either by application of a lubricant lacquer containing microscale solid lubricant particles (e.g. PTFE, MoS 2 ), by cathode sputtering of MoS 2 or by deposition of pure carbon containing coatings (a-C:H) by plasma assisted CVD.

Thick alumina coatings produced by Air Plasma Spraying have an interconnected porosity, thus the use of these coatings in oxidizing or corrosive environment is not suitable. In this paper, a study is developed in order to limit this problem on metallic substrates. It consists in using two successive techniques: APS and PECVD. Two parameters have been shown to be important: the roughness and the preheating temperature. Two types of duplex (PECVD coating as top coat or as bond coat) have been achieved on two substrates (TA6V and stainless steel 316L). The optimization of each process has shown that the substrate has to be grit blasted and preheated (360°C for PECVD and 250°C for APS). This study has revealed that a good (36 ± 5 MPa) APS coating adhesion was obtained on smooth TA6V substrates (due probably to a chemical reaction between TiO 2 and alumina) while for stainless steel substrates, the Ra has to be at least 2µm to achieve 66 ± 5. When observing the first APS splats sprayed on the PECVD alumina smooth layer, they exhibited a specific appearance: low flattening degree (about 2 against 5 on metallic substrates) with most of the alumina in the splat rim or some sort of lace morphology. However, as a whole, the adhesion of the APS coating on the PECVD one was excellent: 60 + 4. An electrochemical method has shown that the PECVD layer on APS coating has reduced drastically its open porosity.

This paper presents the results of a study of the morphology of alumina splats deposited on stainless steel and alumina substrates. The substrates were either plasma sprayed or coated via plasma enhanced CVD. Substrates that were plasma sprayed were annealed if necessary to get specific phase structures, then polished to around 0.4 μm (Ra). CVD-coated substrates with an Ra ~6 nm and a columnar amorphous structure were sprayed as deposited. Splat studies show that the crystal structure of alumina substrates and the release of entrapped gas have a major influence on splat formation. For plasma sprayed coatings, disk-shaped splats with excellent adhesion properties were obtained on hot γ alumina, while on α alumina, splat shape and morphology were irregular and adhesion very poor. The effect of entrapped gas, on the other hand, can be seen in the splats that formed on the CVD-coated substrates. These splats were very porous and, in many, most of alumina flowed out to rim. As the paper explains, this is the result of gas release upon impact of molten particles, which reduces wettability and thermal contact between the splat and substrate.

A diameter of 30 mm polycrystalline diamond film has been deposited by magnet-enhanced DC plasma jet CVD. The diamond film was characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and surface profilograph. Results reveal that under the same depositing parameters, magnetic field can increase purity of diamond film, improve thickness uniformity of diamond film, but no influence on crystal perfection and size of microcrystal of diamond film. A discussion on magnetic effect is presented.

Maximizing dissociated species transport in plasma assisted chemical vapor deposition (CVD), is important in many low pressure plasma jet processes. To deposit high quality diamond by low pressure plasma assisted CVD, it is important to maximize the atomic hydrogen transport to the substrate. One route to process improvement is to explore ways in which unstable species transport can be maximized. A two-dimensional computational model of a supersonic contoured nozzle attached to a dc torch will be described for examining the chemical non-equilibrium of the flow. If the fluid dynamic time scales of interest are faster than the kinetic time scales of interest, it is believed that unstable precursor transport can be controlled, improved and optimized. This paper will examine an implicit formulation for the numerical simulation of a multi-component reacting Ar-H 2 plasma. It is found that dissociation, ionization and charge exchange reactions must all be included in a reaction model. The ionic species significantly alter the temperature profiles upstream of nozzle choking. However, to increase the number of hydrogen atoms at the nozzle exit, the arc attachment should be positioned as close as possible to the converging-diverging nozzle throat.