• Journal of Power System Engineering
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• v.6 no.4
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• pp.56-61
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• 2002

This study is to investigate the wear behaviors of thermally sprayed ceramic coating by a pin-on-disk wear testing machine. The test specimens were plasma sprayed TiO2 coating material on carbon steel substrate(S45C) with Ni-4.5%Al alloy bond coating. Wear characteristics, friction coefficient and wear rates, were conducted at the three kinds of loads and velosities. Wear environments were dry and lubrication friction. The friction coefficients of TiO2 coating specimen in dry friction were almost same according to increase the friction velocity. The wear rate increased when the friction force is high. In lubrication friction, the wear hardly occured and friction coefficient was about 0.1. The adhesiveness of TiO2 in lubrication friction is larger than that in dry one.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.58-63
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• 1995

Plasma spray has attracted attention as an effective method for obtaining protective coatings. In this paper, the physical, mechanical and thermal properties of coatings are reviewed. The microstructural features of the coatings are described. The relationship between the properties of coatings and their microstructure is also discussed. Plasma sprayed coatings are used to reduce wear and improve thermal protection on a large number of components in various industries. In some cases, the conditions of application are very aggressive and therefore the resulting maintenance costs are expensive. Improved coating materials and appropriate properties of coatings are the most promising ways to solve these problems[1,2]. The optimum coating properties depend on the microstructure of coatings[1-5]. In this paper, some ceramic coatings frequently used in industries were reported. The physical, mechanical and thermal properties of ceramic coatings are reviewed. The microstructure features of coatings are addressed. The relationship between the microstructure of coatings and their properties are discussed.

• Journal of the Korean institute of surface engineering
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• v.44 no.3
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• pp.89-94
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• 2011

In this study, the photocurrent characteristics of plasma sprayed $TiO_2$ coatings have been investigated according to additive transition metal (Fe, Mn, Nb powder) and heat treatment conditions. The plasma sprayed $TiO_2$ coatings by heat treatment at $400^{\circ}C$ and 90 min had the higher photocurrent at ultraviolet light, no photocurrent at visible light. The photocurrent of plasma sprayed $TiO_2$ coatings added by Fe, Mn, Nb (named by plasma sprayed $TiO_2$ composite coatings) was lower than that of plasma sprayed $TiO_2$ coatings at ultraviolet light, as was low in intensity ratio of XRD(101)/(110). and the atomic percentage of oxygen by plasma sprayed $TiO_2$ composite coatings was higher than that by plasma sprayed $TiO_2$ coatings. The photocurrent of plasma sprayed $TiO_2$ composite coatings in heat treatment at $400^{\circ}C$ and 90 min was higher than that of plasma sprayed $TiO_2$ coatings in same heat treatment conditions at ultraviolet and visible light, as was high in oxygen affinity by heat treatment.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.248-254
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• 2002

The most controversial topics in plasma sprayed ceramic coating system are recently mechanical properties such as bond strength, cohesive strength, toughness and so on. Determination of bond strength of coatings is one of the most important problems. In the industry, the bond strength of coating system has been estimated by Pull-off test(ASTM standard C633-79). But, without a fixed jig and specimen, it is impossible to obtain the bond strength. Therefore, it is necessary to study the critical fracture load on interface of the coating by indentation test. Because the critical fracture load plays an important role in evaluating the bond strength for plasma sprayed ceramic coating system. So, we have estimated critical fracture load in plasma sprayed ceramic coating system, and it was shown that inverse relationship between the cross-section hardness of coating and the critical fracture load(Pc). In case of the high load(1kgf, 2kgf) in $Al_{2}O_{3}+13%TiO_{2}$, it was found that the critical point(Pco), which the coating was broken on.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.3
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• pp.127-132
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• 2014

$Y_2O_3$-BN ceramic composites were fabricated from the slurries of yttria powder with average particle size of 3~10 ${\mu}m$. The slurry was fabricated by mixing PVA binder, NaOH for Ph control, PEG, BN powder and $Y_2O_3$ powder. The mixed $Y_2O_3$ powders were obtained by spray drying process from the slurry. The $Y_2O_3$-BN composite specimen was shaped in size of ${\O}14mm$ and then sintered at $1550^{\circ}C$ and $1600^{\circ}C$, respectively. The characteristics, microstructure, purities, densities, bulk resistance, thermal expansion, hardness and plasma resistance of the $Y_2O_3$-BN composites were investigated with the function of BN contents and sintering temperature.

• Korean Journal of Materials Research
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• v.24 no.2
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• pp.116-122
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• 2014

$Bi_2Sr_2CaCu_2O_x$(Bi-2212) and $Bi_2Sr_2Ca_2Cu_3O_y$(Bi-2223) high-Tc superconductors(HTS) have been manufactured by plasma spraying, partial melt process(PMP) and annealing treatment(AT). A Bi-2212/2223 HTS coating layer was synthesized through the peritectic reaction between a 0212 oxide coating layer and 2001 oxide coating layer by the PMP-AT process. The 2212 HTS layer consists of whiskers grown in the diffusion direction. The Bi-2223 phase and secondary phase in the Bi-2212 layer were observed. The secondary phase was distributed uniformly over the whole layer. As annealing time goes on, the Bi-2212 phase decreases with mis-orientation and irregular shape, but the Bi-2223 phase increases because a new Bi-2223 phase is formed inside the pre-existing Bi-2212 crystals, and because of the nucleation of a Bi-2223 phase at the edge of Bi-2212 crystals by diffusion of Ca and Cu-O bilayers. In this study the spray coated layer showed superconducting transitions with an onset Tc of about both 115 K, and 50 K. There were two steps. Step 1 at 115 K is due to the diamagnetism of the Bi-2223 phase and step 2 at 50 K is due to the diamagnetism of the Bi-2212 phase.

• Korean Journal of Metals and Materials
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• v.46 no.10
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• pp.646-651
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• 2008

The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. It is essential to choose the optimum material for the process equipment handling molten salt. IN713LC is one of the candidate materials proposed for application in electrolytic reduction process. In this study, yttria-stabilized zirconia (YSZ) top coat was applied to a surface of IN713LC with an aluminized metallic bond coat by an optimized plasma spray process, and were investigated the corrosion behavior at $675^{\circ}C$ for 216 hours in the molten salt $LiCl-Li_2O$ under an oxidizing atmosphere. The as-coated and tested specimens were examined by OM, SEM/EDS and XRD, respectively. The bare superalloy reveals obvious weight loss, and the corrosion layer formed on the surface of the bare superalloy was spalled due to the rapid scale growth and thermal stress. The top coatings showed a much better hot-corrosion resistance in the presence of $LiCl-Li_2O$ molten salt when compared to those of the uncoated superalloy and the aluminized bond coatings. These coatings have been found to be beneficial for increasing to the hot-corrosion resistance of the structural materials for handling high temperature lithium molten salts.

• Clean Technology
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• v.17 no.3
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• pp.250-258
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• 2011

Thermal plasma has been presented for the decomposition of perfluorocompounds (PFCs) which are extensively used in the semiconductor manufacturing and display industry. We developed pilot-scale equipment to investigate the large scale treatment of PFCs and called it a "thermal plasma scrubber". PFCs such as $CF_4$, $C_2F_6$, $SF_6$, and $NF_3$ used in experiments were diluted with $N_2$. There were two different types of experiment setup related to the water spray direction inside the thermal plasma scrubber. The first type was that the water was sprayed directly into the gas outlet located at the exit of the reaction section. The second type was that the water was sprayed on the wall of the quenching section. More effective decomposition took place when the water was sprayed on the quenching section wall. For $C_2F_6$, $SF_6$, and $NF_3$ the maximum destruction and removal efficiency was nearly 100%, and for $CF_4$ was up to 93%.

• Journal of Nutrition and Health
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• v.35 no.8
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• pp.848-853
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• 2002

For the Exp. 1, twelve Duroc $\times$ Yorkshire $\times$ Landrace pigs (6.12 $\pm$ 0.24 kg average initial body weight and 21 d average age) were used in an 8-d metabolic assay to determine the effects of replacing spray-dried plasma protein (SDPP) with spray-dried egg Protein containing egg yolk antibody (SDCEP) on nutrient and amino acids digestibility in weaning Pigs. Experimental animals were fed diets containing SDPP, SDCEP (spray-dried commercial egg protein) and SDAEP. Protein content in the SDPP, SDCEP and SDAEP were 58.20, 45.83 and 41.85%, respectively. Pigs fed the SDPP diet tended to increase the apparent digestibility of dry matter and nitrogen compared to pigs fed the SDAEP diets without significant differences. The ileal digestibility of lysine and methionine for the SDAEP were greater than those for the SDPP, however, there are no significant differences between groups. For Exp.2, 36 Duroc $\times$ Yorkshire $\times$ Landrace pigs (4.11 $\pm$ 0.05 kg average initial body weight and 14 d average age) were used in a 10-day growth assay to determine the effects on growth performance and nutrient digestibility of replacing SDPP with SDAEP in early-weaning pigs. Experimental animals were fed diets containing CON (corn-dried whey-SBM based diet), SDAEP3 (corn-dried whey-SBM based diet + 3% SDAEP), SDAEP6 (corn-dried whey-SBM based diet + 6% SDAEP). The average daily weight gain of the pigs fed the SDAEP3 diet was higher than that for the pigs fed the CON and SDAEP6 diets (p < 0.05). SDAEP3 significantly increased the digestibility of dry matter and nitrogen compared to the CON and SDAEP6 diets (p < 0.05).

• Journal of Powder Materials
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• v.7 no.2
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• pp.63-70
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• 2000

Thermal spray coating process has proven to be effective at producing hard, dense, wear resistance coatings on the relatively mild substrates. Among several spraying techniques, HVOF (High Velocity Oxygen Fuel) and plasma coating processes, which are preferentially used for the wear resistance application such as capstans, have been applied in this study. The effects of pre-treatment, it-process and post-treatment parameters on the wear and mechanical properties of WC+12%Co, Cr3C2 and Al2O3 powder coatings have been investigated and correlated with the microstructures. The results indicated that the carbide coating was more preferable to the oxide coatings and the post-treatments consisting of vacuum annealing and sealing on carbide coatings led to significant improvements in wear resistance, adhesive strength and coating phase stabilization over the other processing techniques in this application.