The purpose of this study is to evaluate the properties of the functional gradient thermal barrier coatings by plasma spray process. The evaluations of mechanical and thermal properties such as fatigue, oxidation and wear-resistance at high temperatures have been conducted. Furthermore, residual stress and bond strength have been evaluated. The range of thickness of coated layers was 550~600$\mu\textrm{m}$. The range of hardness of layers was 800~900 Hv and the porosity range of coatings was about 7 to 14%. The top coating layer of $ZrO_2$ in thermal barrier was composed of tetragonal structure after spraying. The coated layers of $ZrO_2$ on the Inconel substrate is the best resistance for thermal fatigue. Those coatings had the least compressive stress in comparison with other coatings. In high temperature oxidation test, the coatings on Inconel substrate was better than the coatings on SUS substrate. The bond strength of the concave type was greater than that of linear types and convex types coatings.

Recently plasma etching research has been focused on the metal surfaces in the nuclear industry. In this study, surface etching reaction of metallic Co and Mo, principal contaminants in the spent nuclear components, in CF$_4$/O$_2$, gas plasma has been experimentally investigated to look into the applicability and the effectiveness of the technique for the surface decontamination. Experimental variables are $CF_4$/$O_2$ ratio and substrate temperature between 29$0^{\circ}C$ and 38$0^{\circ}C$. Experimental results Show that the optimum gas composition is 80%CF$_4$-20%$O_2$ and the metallic Co and Mo are etched out well enough in the temperatures range. Cobalt starts to be etched above $350^{\circ}C$ and the etching rate increases with increasing substrate temperature. Maximum rate achieved at 38$0^{\circ}C$ under 220 W r.f. plasma power is 0.06 $\mu\textrm{m}$/min. On the other hand, the metallic Mo is etched easily even at low temperature and the reaction rate drastically increases as the substrate temperature goes up. Highest rate obtained under the same conditions is $1.9\mu\textrm{m}$/min. OES (Optical Emission Spectroscopy) analysis reveals that the intensities of F atom and CO molecule reach maximum at the optimum gas composition, which demonstrates that the principal reaction mechanism is fluorination and/or carbonyl reaction. It is confirmed, therefore, that dry processing technique using reactive plasma is quite feasible and applicable for the decontamination of surface-contaminated parts or equipments.

A model for quantifying the effect of steam pressure on the oxide thickness growth was developed based on the experimental data available. First, empirical equations for the thickness estimation of oxide formed in 1 atm steam were made. The oxide growth kinetics turned out to be dependent on 0.4th power of oxidation time. With an assumption that the transition oxide thickness be only a function of temperature, a model for the enhancement of steam pressure on oxide growth was developed. The enhancement coefficient for steam pressure is calculated to be 0.01~0.013 $bar^{-}$. The developed model generally well explains the experimental data.a.

$TiB_2$ ceramics were oxidized at 800, 900 and $1000^{\circ}C$ in air for 40 hr, and their oxidation property was investigated using TGA, XRD, SEM and EPMA. The oxidation resistance decreased with an increase in oxidation temperature. The scale was essentially composed of $TiO_2$ only. $B_2$$O_3$ formed during oxidation escaped from the $TiO_2$ oxide scale owing to its high vapor pressure. This made the oxide scale highly porous and thick. The oxidation reaction was mainly governed by the inward transport of oxygen.$ TiO_2$ existing at the outermost scale grew into peculiarly shaped blades, as the reaction progressed.

10cm-diameter Si(100)∥$1.3\mu\textrm{m}$-X$1.3_2$X$1.3\mu\textrm{m}$-$SiO_2$∥Si(100) afers were prepared using a fast linear annealing (FLA) equipment. 1.3$\mu\textrm{m}$-thick $SiO_2$ films were grown by dry oxidation process. After cleaning and premating the wafers in a class 100 clean room, they were heat treated using with the FLA and conventional electric furnace. Bonded area and bond strength of wafer pairs were measured using a infrared (IR) camera and razor blade crack opening method, respectively. It was confinmed that the bonded area by FLA was around 99% and the bond strength value reached 2172mJ/$\m^2$, which is equivalent to theoritical bond strength. Our result implies that thick $SiO_2$ SOI may be prepared more easily by using $SiO_2$$SiO_2$ bonding interfaces then those of Si/$SiO_2$'s.

Fe-Cr-Al alloy has been studied for application in automobile muffler materials due to good corrosion and oxidation resistance. In order to develop the automobile muffler materials, corrosion behaviors of electron beam physical vapor deposition (EB-PVD) coated surface of muffler matericls of muffler materials were investigated using potentiostat. For 0.1M NaCl solution, corrosion potential and pitting potential of Fe-20Cr-10Al was higher than that of Fe-5Cr- 10Al samples. Especially, in the case of Ti and Nb coated samples, pitting potential increased remarkably compared with non-coated samples. For 0.1M $CaCl_2$ solution, Ti-coated Fe-20Cr-10Al showed remarkably improved pitting corrosion resistance in comparison with non-coated Fe-20Cr-10Al and Fe-5Cr-10Al. The number and size of pits were decreased in the case of Ti coated samples in the 0.1M NaCl and 0.1M $CaCl_2$ solution.

The addition of organic compound containing -COOH, X$800_2$, -CHO group such as formic acid, formamide, formaldehyde or diethyleneamine to a chromium electroplating bath results in a chromium deposit in which carbon is incorporated. Such deposits have fewer defects than chromium layers produced by a conventional method. It was found that the as-deposited layers were amorphous and auger electron spectroscopy (AES) showed that carbon is distributed uniformly in the deposit. During heat treatment, Cr-C deposits began to crystallize at $400^{\circ}C$, and at $800^{\circ}C$ they were crystallized into chromium carbides and oxides. The effects of current density, amount of additives, applied current waveform on Cr-C alloy electroplating were examined.

In this work, the surface treatment of aluminum/composites (graphite-epoxy composites) was investigated. The surface of composites was treated by $Ar^{+}$ ion beam under oxygen environment. The surface of aluminum was treated by DC plasma. The optimal condition of surface treatment for the composites was determined by measuring the contact angle as a function of ion dose. The optimal treatment condition of the aluminum was determined by measuring the contact angle and T-peel strength as a function of mixture ratio of acetylene gas to nitrogen gas. The mixture ratios used were 1:9, 3:7, 5:5, 7:3, and 9:1. The results showed that the contact angle of composites decreased from$ 81^{\circ}$ to $8^{\circ}$ as the ion dose increased from zero to $1$\times$10^{17}$ions/$\textrm{cm}^2$. The optimal condition of ion dose was $1$\times$10^{16}$ions/$\textrm{cm}^2$. The results also showed that the contact angle of aluminum was a minimum for the mixture ratio of 5:5. Similarly, the T-peel strength was a maximum for the mixture ratio of 5:5, which indicates that the optimal condition of mixture ratio of acetylene gas to nitrogen gas is 5:5.

Green technology is being developed up to a point that is feasible not only in an environmental sense, but also in an economical viewpoint. This paper introduces two case studies that applied $CO_2$ technology into nuclear industry. 1) Nuclear laundry : A laundry machine that uses liquid and supercritical $CO_2$ as a solvent for decontamination of contaminated working dresses in nuclear power plants was developed. The machine consists of a 16 liter reactor, a recovery system with compressors, and storage tanks. All $CO_2$ used in cleaning is fully recovered and reused in next cleaning, resulting in no production of secondary nuclear waste. Decontamination factor is still lower than that in the methods currently used in the plant. Nuclear laundry using $CO_2$ looks promising with technical improvements-surfactants and mechanical agitation. 2) $CO_2$ nozzle decontamination : An adjustable nozzle for controlling the size of dry ice snow was developed. Using the developed nozzle, a surface decontamination device was made. Human oils like fingerprints on glass were easy to remove. Decontamination ability was tested using a contaminated pump-housing surface. About 40 to 80% of radioactivity was removed. This device is effective in surface-decontamination of any electrical devices like detector, controllers which cannot be cleaned in aqueous solution.