• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.11a
• /
• pp.96-102
• /
• 2001

plasma-sprayed Cr$_2$O$_3$-based coatings containing MoO$_3$ were studied to gain a better understanding of the influence of MoO$_3$ composition in the coatings on their tribological behaviour. A reciprocal type tribo-tester was employed to examine friction and wear behavior of the specimens at high temperature(450。C). The physical characteristics of worn surfaces were investigated by scanning electron microscopy and chemical composition of the coating surfaces was analyzed using a X-ray photoelectron spectrometer. The results showed that friction coefficient of the MoO$_3$-added coatings were lower than those without MoO$_3$ addition. The larger protecting layers were observed at the worn surface of plasma spray coated specimens with MoO$_3$ addition. XPS analysis of the protecting layer indicated that MoO$_3$ composition was dominantly formed at the surface. MoO$_3$ composition in the protecting layer appears to be more favorable in reducing the friction.

• Korean Journal of Materials Research
• /
• v.9 no.7
• /
• pp.724-734
• /
• 1999

The adhesion characteristics of the thermoplastic resins such as PE, PP PVC, PET and PS were investigated on the surfaces of conventional steel (SS41), steel (SS41P) treated with ultrasonic waves and the SS41P coated with several ceramic powders (SS41PC) by the plasma spray. Alumina (Al$_2$O$_3$), alumina titania (Al$_2$O$_3$95%, TiO$_2$ 5%) and zirconia yttria (ZrO$_2$ 95%, $Y_2$O$_3$5% ) were used for the materials plasma spray The morphologies, surface hardness, surface roughness, and contact angles on SS41, SS41P, and SS41PC were examined. The tensile shear strength and peel strength of the polymers which were attached to the surfaces of ceramics coated on SS41P also were measured. The tensile shear strength and peel strength of polymers adhered to ceramic surface coated on steel were found to be stronger than those of conventional steel. The tensile shear strength and peel strength of the polymers adhered on the surfaces of ceramics coated steel increased in the following order PE > PET > PP > PS > PVC. The high adhesion strength of PE may be attributed to the surface roughness and its anchor effect on the ceramic surface.

• Journal of Ocean Engineering and Technology
• /
• v.19 no.5 s.66
• /
• pp.43-49
• /
• 2005

This paper is to investigate the effect of corrosion by acoustic emission method in tensile loading and the adhesiveness between substrate and coating layer. The powders used are Zn and Amdry625, respectively. They are coated on brass alloy substrate. AE signals of Zn and Amdry625 coating layer increase drastically in strain $2\%$. However, those of Zn specimen have more than those of Amdry625 specimen. When the specimens executed the corrosion test under $3.5\%$ NaCl solution for 500, 1000 hours, the salt solution penetrated into the surface of the substrate through the pores of the coating layer. As a result, corrosion production formed on the surface of the substrate. The adhesiveness between coating layers is weakened by the polarization and corrosion itself. The AE event, count, and energy of corroded coating specimens decrease, compared to specimens without corrosion. The results are summarized as follows : 1. In the tensile tests, the time that it took to start and develop the cracks and exfoliations between the surface of the substrates and the plasma spray coatings were different according to the type of plasma sprayed material, which are Zn and Amdry625. These phenomena were obvious at the strain rate 1 to $5\%$, and few available data were found after that stage. 2. The specimens with Zn coating showed the characteristics of crack, according to the changes of the tensile strength applied on the substrates while those with Amdry625 showed exfoliation as a result of low adaptation to the tensile strength. 3. The anti-corrosion specimens showed that the adhesive properties between the substrate and the plasma spray coating were strong in the order of Zn, Amdry. It showed that Corroded specimens cracked or exfoliated easily, even with the small energy, because those had a comparatively weakened adhesive property, due to corrosion. 4. Zn specimen showed no corrosion phenomena on the surface of the substrates, because they had the function of sacrifice anode however, Amdry625 specimen showed the corrosion, because it did not have that function.

• Journal of Animal Science and Technology
• /
• v.63 no.5
• /
• pp.1076-1085
• /
• 2021

The study was conducted to evaluate the effects of spray-dried plasma (SDP) supplementation during late gestation and lactation on productive performance and immune responses of sows and their litters. Twelve sows (227.78 ± 2.16 kg average body weight; 2.0 average parity) were randomly allotted to two dietary treatments: a basal diet (CON) and the basal diet supplemented with 1% SDP. Sows were fed experimental diets from d 30 before farrowing to weaning of their piglets. Blood samples were collected from sows on d 1, 3, and 7 of lactation and from two randomly selected nursing pigs per litter on d 3 and 7 after birth, and d 1, 3, and 7 after weaning. Productive performance and immune responses of sows and their piglets were measured. There was a trend of less body weight loss in sows supplemented with SDP (p < 0.10) during the lactation period and a trend of greater (p < 0.10) average daily gain in SDP piglets compared to those in the CON group. Sows in the SDP group tended to have lower (p < 0.10) serum concentrations of tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), and cortisol on d 3 and lower serum concentration of TNF-α on d 7 compared with sows in CON group. In comparison with CON piglets, piglets from SDP sows tended to have lower (p < 0.10) serum concentrations of TNF-α, TGF-β1, and cortisol on d 7 after birth, lower (p < 0.10) serum TNF-α and C-reactive protein on d 3 and 7 after weaning, and greater (p < 0.10) average daily gain after weaning. Moreover, weaned pigs from sows fed SDP had significantly lower (p < 0.05) serum concentrations of cortisol and TGF-β1 on d 3 and 7 postweaning, respectively, than CON piglets. In conclusion, SDP supplementation in sow diets from late gestation to weaning improved the productive performance of sows and their offspring; the beneficial effects of SDP may be mediated in part through modulation of immune responses of both sows and piglets.

• Journal of Korean Ophthalmic Optics Society
• /
• v.15 no.4
• /
• pp.313-317
• /
• 2010

Purpose: The purpose of this study was to investigate the surface characteristics of plasma electrolytic oxidation (PEO) surface treatment on AZ31 magnesium alloy eyeglass frames. Methods: The plasma electrolytic oxidation (PEO) surface was created by varying the DC voltage. The oxidation layer of coating was measured using phase analysis by X-ray diffraction. The microstructural morphology was observed using a scanning electron microscopy. Coating layer and the concentration of elements were investigated using the energy dispersive X-ray spectra. Results: The MgO XRD peak was increased as the voltage increased, and the density of the surface oxide film was also increased. The changes in the composition of the EDS also showed a good agreement. Conclusions: The compound oxide crystallization of PEO oxide film layer was done by increasing formation of MgO as the voltage increased. The treatment at 65V and 60 sec showed the best results at surface state, contact angles and salt spray test.

• Composites Research
• /
• v.30 no.2
• /
• pp.84-93
• /
• 2017

This study investigates thermal and mechanical characterization of environmental barrier coating on the $SiC_f-SiC$ composites. The spherical environmental barrier coating (EBC) powders are prepared using a spray drying process for flowing easily during coating process. The powders consisting of mullite and 12 wt% of Ytterbium silicate are air plasma sprayed on the Si bondcoat on the LSI SiC fiber reinforced SiC composite substrate for protecting the composites from oxidation and water vapor reaction. We vary the process parameter of spray distance during air plasma spray of powders, 100, 120 and 140 mm. After that, we performed the thermal durability tests by thermal annealing test at $1100^{\circ}C$ for 100hr and thermal shock test from $1200^{\circ}C$ for 3000 cycles. As a result, the interface delamination of EBC never occur during thermal durability tests while stable cracks are prominent on the coating layer. The crack density and crack length depend on the spray distance during coating. The post indentation test indicates thermal tests influence on the indentation load-displacement mechanical behavior.

• Asian-Australasian Journal of Animal Sciences
• /
• v.17 no.8
• /
• pp.1139-1144
• /
• 2004

In Exp. 1, a total of 36 pigs (6.55$\pm$0.10 kg average initial body weight and 21 d average age) were used in a 14 d growth study to determine the effects of replacing spray-dried plasma protein (SDPP) with spray-dried egg protein containing specific egg yolk antibody (SDEP) on growth performance and nutrient digestibility in weaned pigs. The pigs were blocked by weight and assigned to treatments based on sex. There were three pigs per pen and four pens per treatment. Dietary treatments were 0, 3, or 6% SDEP and contained 6, 3, or 0% SDPP, respectively. Through the entire experimental period, average daily gain (ADG), average daily feed intake (ADFI), and gain/feed tended to decrease as the concentration of SDEP increased in the diets. However, there were no significant differences among the treatments (p>0.05). As the addition of SDEP in the diets increased, apparent digestibilities of dry matter (DM) and nitrogen (N) were decreased without significant (p>0.05). For Exp. 2, 36 pigs (2.63$\pm$0.04 kg average initial body weight and 10 d average age) were used in a 14 d growth study to determine the effects of antibiotic replacement with SDEP on growth performance and nutrient digestibility in early-weaned pigs. The pigs were blocked by weight and assigned to treatments based on sex. There were three pigs per pen and four pens per treatment. Dietary treatments included 1) ANTIBIOTIC (corn-dried whey-soybean meal based diet+0.08% antibiotics, 4 mg of tiamuline hydrogen fumarate; 10 mg of sulfadimidine per kg of complete diet), 2) SDEP0.1 (corndried whey-SBM based diet+0.1% SDEP), and 3) SDEP0.2 (corn-dried whey-SBM based diet+0.2% SDEP). ADG and gain/feed of pigs fed the SDEP0.2 diet were higher than for pigs fed the ANTIBIOTIC diet without significant (p>0.05). Pigs fed the diet with SDEP0.2 tended to have increased apparent digestibilities of DM and N compared to pigs fed the ANTIBIOTIC diet without significant (p>0.05). In conclusion, the dietary SDEP seemed to be partial replacing the SDPP portion of high nutrient dense diet for weaned pigs. Also, dietary SDEP seemed to be approximately 0.2% or more when the pigs fed the antibiotic-free diet for early-weaned pigs.

• Korean Chemical Engineering Research
• /
• v.40 no.6
• /
• pp.752-756
• /
• 2002

Green-emitting $Zn_2SiO_4:Mn$ phosphors for PDP(Plasma Display Panel) application were synthesized by colloidal seed-assisted spray pyrolysis process. The codoping with $Gd^{3+}/Li^+$, which replaces $Si^{4+}$ site in the willemite structure, was performed to improve the luminous properties of the $Zn_2SiO_4:Mn$ phosphors. The particles prepared by spray pyrolysis process using fumed silica colloidal solution had a spherical shape, small particle size, narrow size distribution, and non-aggregation characteristics. The $Gd^{3+}/Li^+$ codoping amount affected the luminous characteristics of $Zn_2SiO_4:Mn$ phosphors. The codoping with proper amounts of $Gd^{3+}/Li^+$ improved both the photoluminescence efficiency and decay time of $Zn_2SiO_4:Mn$ phosphor particles. In spray pyrolysis, the post-treatment temperature is another factor controlling the luminous performance of $Zn_2SiO_4:Mn$ phosphors. The $Zn_{1.9}SiO_4:Mn_{0.1}$ phosphor particles containing 0.1 mol% $Gd^{3+}/Li^+$ co-dopant had a 5% higher PL intensity than the commercial product and 5.7 ms decay time after post-treatment at $1,145^{\circ}C$.

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

• Proceedings of the KWS Conference
• /
• 2003.05a
• /
• pp.111-113
• /
• 2003

The existing heating unit is indirect-heating method that make use or the nichrome wire or halogen lamp. The indirect-heating method has the demerits of long warming time, high power consumption and many organization parts. In this study, the heating unit of direct-heating method manufactured as being the thermal spray coating of conductive heating material on the surface of heating unit in order to improve the demerits of indirect-heating method. And YSZ added Ni-20Cr that had moderate electrical resistivity was chosen of the conductive heating material.