• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1127-1134
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• 2002

Fine ceramic particles of zirconia toughened alumina (ZTA), titania toughened alumina (TTA), and zirconia-titania toughened alumina (ZTTA) have been synthesized by ultrasonic spray pyrolysis (USP) at various temperatures from starting salt solutio ns of various compositions aiming for the development of catalytic material. These particles were characterized for properties such as shape, size and size distribution, diffraction pattern, and chemical and phase composition of elements by scanning electron microscopy (SEM), particle size analyzer (PSA), x-ray diffraction (XRD), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Chemical compositions and sizes of ceramic composites have been controled by the stoichiometry of salt solutions and the flow rate of spraying solutions. The optimum experimental conditions for the various composite particle syntheses have been proposed.

• Journal of Information Display
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• v.2 no.4
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• pp.57-62
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• 2001

Green-emitting $Zn_2SiO_4$:Mn phosphor particles having a spherical shape and high luminescence intensities under VUV were prepared by spray pyrolysis process under severe preparation conditions. The type of precursor solutions affected the morphology and luminescence characteristics of the prepared particles. The particles prepared from the clear solution by laboratory-scale process had spherical shape and dense morphology, while the particles prepared from the severe preparation conditions had rough surface and collapsed structure. However, the particles prepared from the colloidal solution utilizing fumed silica were spherical in shape and filled morphology at the severe preparation conditions of high flow rate of carrier gas, high concentration of solution, and large reactor size. The prepared $Zn_2SiO_4$:Mn phosphor particles with complete spherical shape had higher photoluminescence intensity than that of the commercial product prepared by solid state reaction.

• YAKHAK HOEJI
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• v.47 no.2
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• pp.78-84
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• 2003

Local anesthetics are used to reduce pain, but they are so frequently injected to patients. So, we prepared lidocaine solid lipid microspheres (SLM) as long acting abdominal injection using spray drying method and evaluated drug entrapment, particle size, SEM, zeta potential and in vitro and in vivo drug release pattern, The particle sizes of SLM were 30∼100$\mu$m and it is enough to inject into abdominal tissue. The entrapment efficiency of SLM was over 95％ as spray drying method. Surfactant and PC decreased the burst effect by 20∼30％. In in vivo test, C-6 showed controlled release concentration profile in plasma for 8 days and C-5 sustained longer than we expected.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.215-218
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• 2015

Simultaneous laser ignition and spectroscopy is a scheme that enables rapid determination of the local equivalence ratio and condensed fuel concentration during a reaction in a two phase spray flame. We have conducted quantitative analysis of the LIBS signals according to the equivalence ratio, droplet size, droplet number density and droplet concentration as a part of novel feedback control strategy proposed for flame ignition and stabilization with simultaneous in situ combustion flow diagnostics. This is a desirable scheme since such real time information onboard an engine for instance can be constantly monitored and fed back to the control loop to enhance the mixing process and minimize emissions of unwanted species and potential combustion instability.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.6
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• pp.276-281
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• 2021

In order to manufacture a semiconductor circuit, etching, cleaning, and deposition processes are repeated. During these processes, the inside of the processing chamber is exposed to corrosive plasma. Therefore, the coating of the inner wall of the semiconductor equipment with a plasma-resistant material has been attempted to minimize the etching of the coating and particle contaminant generation. In this study, we synthesized yttrium oxyfluoride (YOF) powder by a solid-state reaction using Y₂O₃ and YF₃ as raw materials. Mixing ratio of the Y₂O₃ and YF₃ was varied from 1.0:1.0 to 1.0:1.6. Effects of the mixing ratio on crystal structure and microstructure of the synthesized YOF powder were investigated using XRD and FE-SEM. The synthesized YOF powder was successfully applied to plasma spray coating process on Al substrate.

• Tribology and Lubricants
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• v.16 no.2
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• pp.84-90
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• 2000

High Temperature wear behavior of plasma sprayed zirconia coatings containing up to 10 mol% of Fe$_2$O$_3$ were investigated. The wear test results showed that the addition of Fe$_2$O$_3$ particles to zirconia improved the wear resistance and lowered the coefficient of friction. Optimum concentration of Fe$_2$O$_3$ was about 5 mol%. Similar degradation behavior was observed at about 40$0^{\circ}C$ for both zirconia and Fe$_2$O$_3$ added zirconia coatings. The results indicated that stabilization of tetragonal phase and changes in mechanical properties such as hardness and toughness were responsible for tribological behavior of plasma sprayed zirconia contain Fe$_2$O$_3$.

• Tribology and Lubricants
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• v.11 no.5
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• pp.108-113
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• 1995

Wear and friction behavior of plasma-sprayed coatings in Mo- and Co-based alloy were studied for the application of piston-ring automobile engine. The plasma-sprayed coatings were varied with gun current density, gas flow, and distance. The surface roughness, microhardness, and wear volume were measured depending on the spray distances. The high temperature hardness value were also measured as a function of temperature. Ball-on-disc geometry configuration tribometer was utilized in air. The wear tests were performed in the temperature ranges from room temperature to 825$^{\circ}$C to investigate the tribological trend of the piston-ring materials in the lack of lubricant. The cross sections of wear track were investigated, using microscopy.

• Journal of Welding and Joining
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• v.17 no.6
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• pp.62-69
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• 1999

The advantages of Thermal sprayed coatings as a replacement for cast iron liners are reduced weight, better heat transfer and reduced cost. One of the most important performance attributes of a cylinder bore coating is its wear resistance, since it must survive the abrasive sliding of both the piston rings and the piston skirt. In this study, composite powders were prepared by ball milling of Al-13Si-3Mg(wt%) alloy with SiC particles. The concentrations of SiC were 40 and 60wt%. The composite powders were sprayed using Metco-9MB plasma torch. Plasma sprayed coatings were heat-treated at 500℃ for 3 hours. The wear resistances of the plasma sprayed coatings were found to improve with heat treatment and superior to the commercially available G.C.I.(gray cast iron). AlSiMg-40SiC heat-treated coatings showed the best wear resistance in this study.

• Journal of the Korean Ceramic Society
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• v.36 no.11
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• pp.1205-1210
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• 1999

Ceria based electrolytes were fabricated by a plasma spraying method. The porosity which was crated during the plasma spraying process was infiltrated with Ce0.8Gd0.2O2 sol by ultrasonic treatment and heat treatment at 90$0^{\circ}C$ in order to improve physical and electrical properties. The porosity decreased from 9.8% to 6.5% and gas permeability at 80$0^{\circ}C$ decreased from 16.7$\times$10-3 to 5.7$\times$10-3 cm3(STP)/cm2.s.cmHg as the number of treatment increased 10 cycles. The ionic conductivity was also increased about 30% after 10 times of sealing.

• Journal of the Korean institute of surface engineering
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• v.50 no.6
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• pp.432-438
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• 2017

AZ91D casting alloy requires an advanced plasma anodizing processing because large amount of defects are liable to generate during anodization. In this study, plasma electrolytic oxidation (PEO) of AZ91D Mg alloy was conducted by the application of either constant voltage or current using a pulse mode and its effects on pore formation, surface roughness and corrosion resistance were investigated. The PEO films showed a three-layer structure. The PEO film thickness was found to increase linearly with voltage. The surface roughness, Ra, ranged between $0.2{\mu}m$ and $0.3{\mu}m$. The corrosion resistance increased from RN 3.5 to 9.5 by the PEO treatment when evaluated according to the 72 hour salt spray test. The PEO-treated surface exhibited higher pitting potential than the raw material.