• Journal of Powder Materials
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• v.15 no.6
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• pp.477-481
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• 2008

Formation and characteristics of spraying powder for BSCCO High-Tc superconductor prepared by plasma spray coating were investigated. The addition of 3% of binder gives the best flowability of the powder. Ball milling for 30h and 35h gives the best flowability of powder in the case of 2001 and 0212, respectively. The withdraw ratio increases upon binder addition from 12 to 27% in the case of 2001 and from 18 to 31% in the case of 0212 for sieving powder of $30-90{\mu}m$ in size. The built-up efficiency for $100{\mu}m$ thickness of spray coating is increased more than 30% by binder addition. The microstructure of the spray coated layers was investigated by XRD and EDS analysis.

• Journal of the Korean Ceramic Society
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• v.36 no.4
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• pp.444-450
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• 1999

Hydroxyapatite(HA) was spray-coated to alloy substrate(Ti-6Al-4V) using plasma-spray process for bioceramic application The coating morphology composition and crystallinity were influenced by following process parameters ; stand-off distance spray power level and auxiliary gas pressure. These parameters have been systematically varied in the present study to evaluate their relative influence on the coating qual-ity and to seek an optimum spraying condition. Amorphicity and decomposition of HA increased with stand-off distance and the imperfect coating layer was obtained at the short stant-off distance (55mm). The cry-stallinity of HA coating decreased with spray power level and auxiliary gas pressure but the bond strength between the HA coated layer and Ti alloy substrate increased with the spray power level.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.511-512
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• 2006

Tungsten coatings with different interlayers onto the oxygen-free copper substrates were fabricated by atmosphere plasma spraying. The effects of different interlayers of NiCrAl, NiAl and W/Cu on bonding strength were studied. SEM, EDS and XRD were used to investigate the photographs and compositions of these coatings. The tungsten coatings with different initial particle sizes resulted in different microstructures. Oxidation was not detected in the tungsten coating, but in the interlayer, it was found by both XRD and EDS. The tungsten coating deposited directly onto the copper substrate presented higher bonding strength than those with different interlayers.

• Journal of the Korean Ceramic Society
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• v.38 no.7
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• pp.602-607
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• 2001

Zirconia powder containing 3 mol% yttria (3Y-PSZ) was casted on the cast iron substrate by plasma spraying method. Coated specimens were then heat treated at 500$\^{C}$ in nitrogen plasma. Wear tests were performed on nitrogen heat treated and non heat treated samples at temperatures from 25$\^{C}$ to 600$\^{C}$. Wear results showed that the friction coefficient and the wear loss of both the treated and the non-treated samples showed maximum value at 400$\^{C}$. These results were explained by low temperature thermal degradation due to the monoclinic transformation. Nitrogen plasma treatment significantly improved the tribological performance. The effect of nitrogen heat treatment on tribological behavior was explained by the increased micro-hardness and decreased monoclinic faction.

• Journal of Welding and Joining
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• v.25 no.4
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• pp.42-48
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• 2007

An inert gas atomized NiTiZrSiSn bulk metallic glass feedstock was sprayed onto the copper plate using vacuum plasma spraying process. In order to change the in-flight particle energy, that is, thermal energy, the hydrogen gas flow rate in plasma gas mixture was increased at the constant flow rate of argon gas. Coating and single pass spraying bead were produced with the least feeding rate. Regardless of the plasma gas composition, fully melted through unmelted particle could be observed on the overlay coating. However, the frequency of the unmelted particle number density was increased with the decrease of the hydrogen gas flow rate. The amorphous phase fraction within coating was also affected by the number density of the unmelted particle.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2003.05a
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• pp.16-16
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• 2003

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.179-182
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• 1998

Boron carbide coating has some very attractive properties for nuclear and semiconductor industry. The potential of atmosheric plasma spray as manufacturing methods for $B_4C$ coating was discussed. In this work, the boron carbide coating with low porosity, high microhardness and good life of thermal shock resistance was deposited by the control of spraying distance. The relationship between the properties of $B_4C$ coatings and their spraying distance was studied.

• Journal of Power System Engineering
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• v.2 no.3
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• pp.41-48
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• 1998

This study was aimed at development of fabrication process of functionally graded materials(FGM), consisting of metal and ceramic by thermal spraying method. NiCrAIY/$Al_2O_3$ FGM were made by using plasma spraying onto the SS400 carbon steel substrate. And mechanical properties such as microhardness, thermal shock resistance and adhesive strength of the coating layer were investigated. Adhesive strength was evaluated by acoustic emission method. It was resulted that NiCrAIY/$Al_2O_3$ FGM made by thermal spraying method showed excellent thermal shock resistance and adhesive strength compared to the other lamellar structures of sprayed coatings and that AE is useful tool to evaluate the defect of thermal sprayed coating layer.

• Journal of Welding and Joining
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• v.8 no.4
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• pp.58-68
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• 1990

The formation of thermal stresses by plasma spraying is generally considered as adverse. Therefore, the knowledge of stress distribution in the deposited layer during and after plasma spraying will be of special interest. In this study finite difference heat transfer analysis and finite element stress analysis were carried out to predict the change of stress distribution in the plasma coated layer with the variations of preheat temperature, number of scan, particle size, and bond coat. The results of the numerical analysis were as follows: 1) Transient stresses developed in the coated layer were up to the level of yiedl strength at the temperature. 2) The tensile stresses were developed in the deposited layer and the surface of the substrate, but the compressive stresses were developed in the rest of the substrate. 3) Transient and residual stresses were significantly affected by the preheat temperature. 4) The variations of temperature of powder particle and number of torch scan changed tensile stress distribution, but made no difference on the magnitude of the stresses. 5) Bond coated layer reduced the stree level of deposited layer.

• Journal of Welding and Joining
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• v.11 no.4
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• pp.91-102
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• 1993

The plasma sprayed $Cr_3C_2$-NiCr coatings are widely used as wear-resistant and corrosion-resistant materials. The mechanical and wear properties of the plasma sprayed $Cr_3C_2$-NiCr coating on steel plate were examined in this study. The pore in the coatings could be classified into two types, the one is the intrinsic pore originated from the spraying powder, the other is the extrinsic pore formed during spraying. During the tensile adhesion test, the fracture occured at the interface of top coating and bond coating. It is though that the compressive residual stress increases with the increase of the top coating thickness. From the wear test, it was found that the wear rate increased with the increase of the sliding velocity regardless of the temperature. It is thought that the fracture toughness reduces with the increase of the sliding velocity at $30^{\circ}C$ and that the adhesion amount increases with the increase of the sliding velocity at $400^{\circ}C$ It is concluded that the wear mechanism at $30^{\circ}C$ is the fracture and pull-out of the carbide particles due to the fatigue on sliding surface, while the wear mechanism at $400^{\circ}C$ is the adhesion of the smeared layer formed during wear process.