• Title/Summary/Keyword: spraying thickness

Search Result 83, Processing Time 0.029 seconds

Thermal and Mechanical Characteristics of Functionally Graded ZrO$_2$ Thermal Spray Coating (경사기능성 지르코니아 용사피복층의 열 및 기계적특성)

  • 오동현
    • Journal of the Korean institute of surface engineering
    • /
    • v.31 no.2
    • /
    • pp.91-100
    • /
    • 1998
  • NiCrAlY/YSZ(8wt%$Y_2O_3-ZrO_2$) functionally graded thermal barrier coating (FGC) layers on a Co-base superalloy (HAYNESS 188) substrate were fabstrate were fabicated using Ar shielded single torch air plasma spraying method. Functional grading with the stepwise compositional change throughout layer thickness. Microstructural observation trvealed a successful fabrication of NiCrAlY/YSZ FGC. From the results of the curvature measurement, adhesive strength measurement and thermal shock test for the FGC, it was concluded that the optimum conditions of functionally graded coating layer thinkness and compositional pattern exit to enhance the properties of FGC, which is closely related to the internal residual stess distribution witin it.

  • PDF

Effects of the Nanometer-sized Bismuth Oxide Coating on Shadow Mask

  • Kim, Sang-Mun;Koh, Nam-Je
    • Journal of Information Display
    • /
    • v.6 no.4
    • /
    • pp.40-44
    • /
    • 2005
  • Nanometer-sized bismuth oxide with a diameter of about 80 nm was used as a new electron reflection material in a 29" Real Flat CPT. This bismuth oxide was well dispersed over pH8 in slurry. Spray coating was performed clearly and uniformly and was ensured that there was no clogging of shadow mask hole. Coating thickness was expressed to the brightness of chromaticity for the sprayed layer and was also well controlled during the spraying process. Doming was improved by about 10% in spite of the similar coating weight in comparison with the average 3.5 ${\mu}m$ of the conventional bismuth oxide.

Preparation of gas-atomized Fe-based alloy powders and HVOF sprayed coatings

  • Chau, Joseph Lik Hang;Pan, Alfred I-Tsung;Yang, Chih-Chao
    • Advances in materials Research
    • /
    • v.6 no.4
    • /
    • pp.343-348
    • /
    • 2017
  • High-pressure gas atomization was employed to prepare the Fe-based $Fe_{50}Cr_{24}Mo_{21}Si_2B_3$ alloy powder. The effect of flow rate of atomizing gas on the median powder diameter was studied. The results show that the powder size decreased with increasing the flow rate of atomizing gas. Fe-based alloy coatings with amorphous phase fraction was then prepared by high velocity oxygen fuel spraying (HVOF) of gas atomized $Fe_{50}Cr_{24}Mo_{21}Si_2B_3$ powder. Microstructural studies show that the coatings present dense layered structure and low porosity of 0.17% in about $200{\mu}m$ thickness. The Fe-based alloy coating exhibits an average hardness of about 1230 HV. Our results show that the HVOF process results in dense and well-bonded coatings, making it attractive for protective coatings applications.

Characteristics of Ni-coated diamond/Metal Composite Coatings by Cold Spray Deposition (니켈 코팅된 다이아몬드/금속 복합재의 저온분사 코팅특성)

  • Jung, Dong-Jin;Kim, Hyung Jun;Lee, Kee-Ahn
    • Korean Journal of Metals and Materials
    • /
    • v.47 no.9
    • /
    • pp.550-557
    • /
    • 2009
  • In this study, bronze or SUS304 powders blended with 10 wt.% diamond particles were used to prepare metal/diamond composite materials deposited by cold spraying. The effects of matrix metal, diamond partical size, and the thickness of the Ni coating on the diamond were studied on Al 6061 substrate. The results showed that the hardness of the metal/diamond composite coating layers was higher than that of the same composite materials when using the sintering method. The fraction of diamond content in the coated layer increased when the metal matrix was soft. When the size of the diamond particles was reduced, the fraction of the diamond particles increased. In addition, in the case of diamond with a thicker Ni-coated layer, the fracturing of diamonds was mitigated in the composite coating layers.

Microwave Absorbing Characteristics of Silicon carbide-ferrite surface Films Produced by Plasma-spraying(I) (플라즈마 용사방식에 의해 형성된 탄화규소-페라이트 표면층의 마이크로파 흡수특성(I))

  • Shin, Dong-Chan;Son, Hyon
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.17 no.6
    • /
    • pp.580-588
    • /
    • 1992
  • Plasma-spraying was conducted to produced the microwave absorbing surface films on the alumi-num-alloy used for the fuselage to protect the aircraft against the RADAR detction. The surface films were produced by plasma-splaying the mecharucally mixed composite powders of the silicon carblde and Ni-Zn ferrite. This M /W absorbers were designed experimentally and fabricated trialty, as a result of which the rolative frequency bandwidth of 7.6 to 8.4% were obtained under the tolerance limits of the re-flection coefficients lower than -6dB(absorption ratio 75%), and the maximum absorption thickness becomes 0.5 to 0.5.imm, which Is much thinner than that of the conventional ones.

  • PDF

Fabrication of an ultra-fine ginsenoside particle atomizer for drug delivery through respiratory tract (호흡기를 통한 약액 전달을 위한 진세노사이드 초미세입자 분무장치 제작)

  • Byung Chul Lee;Jin Soo Park;Woong Mo Yang
    • Journal of Convergence Korean Medicine
    • /
    • v.2 no.1
    • /
    • pp.5-12
    • /
    • 2021
  • Objectives: The purpose of this study is to fabricate an ultra-fine ginsenoside particle atomizer that can provide a new treatment method by delivering ginsenoside components that have a therapeutic effect on respiratory diseases directly to the lungs. Methods: We fabricated the AAO vibrating mesh by using the micromachining process. The starting substrate of an AAO wafer has a 350nm pore diameter with 50㎛ thickness. A photomask having several 5㎛ opening holes with a 100㎛ pitch was used to separate each nanopore nozzle. The photoresist structure was optimized to pattern the nozzle area during the lift-off process precisely. The commercial vibrating mesh was removed from OMRON's NE-U100 product, and the fabricated AAO vibrating mesh was installed. A diluted sample of 20mL with 30% red ginseng concentrate was prepared to atomize from the device. Results: As a result of liquid chromatography analysis before spraying the ginsenoside solution, ginsenoside components such as 20S-Rg3, 20R-Rg3, and Rg5 were detected. After spraying through the AAO vibrating mesh, ginsenosides of the same component could be detected. Conclusion: A nutrient solution containing ginsenosides was successfully sprayed through the AAO vibrating mesh with 350 nm selective pores. In particular, during the atomizing experiment of ginsenoside drug solution having excellent efficacy in respiratory diseases, it was confirmed that atomizing through the AAO vibrating mesh while maintaining most of the active ingredients was carried out.

Studies on the Environmentally and Ecologically Stable Revegetation Measures on Rock Cut-Slopes - Availability of Forest Topsoil as a Hydroseeding Material in Greenhouse Experiment - (암절취(岩切取) 훼손(毁損)비탈면에 대한 환경생태적(環境生態的)으로 안정(安定)된 녹화공법(綠化工法)에 관(關)한 연구(硏究)(I) -산림표층토(山林表層土)를 이용(利用)한 녹화토(綠化土)의 효능분석(效能分析)을 위한 실내실험(室內實驗)-)

  • Woo, Bo-Myeong;Kim, Kyung-Hoon
    • Journal of Korean Society of Forest Science
    • /
    • v.87 no.2
    • /
    • pp.308-315
    • /
    • 1998
  • This study was conducted to evaluate the availability of the forest topsoil as a source of the "Native-soil(seed-fertilizer-soil materials)" for the hydroseeding measures which are environmentally and ecologically stable revegetation measures on rock cut-slopes. Soil sampling and factorial experiments were used with a split plot design(main plot : forest soil type and soil spraying thickness, subplot : seeding rate) in 1996. Results obtained in this study were summarized as follows : Because of the competition between the seeded(introduced) species and the native species, the number of naturally emerged species in the non-seeded plot and that of in the seeded plot were $5{\sim}9species/0.07m^2$ and $2{\sim}6species/0.07m^2$, respectively. As increasing the seeding rate(introduced species), the appearance ratio of naturally emerged species was decreased. The total number of individuals was high in the plot which used coniferous forest soil as a seed source, however the ratio of the individuals of naturally emerged species was high(30%) in the plot which used deciduous forest soil. The usage of the forest topsoil as seed bank source onto the "Native-soil" materials for hydroseeding could be reduce the seeding rate to $1,000seedlings/m^2$. According to the several factors which are competition between seeded species and naturally emerged species, dryness of soil materials, and seed burial, spraying thickness with more than 5cm was suitable for the growth of plants in variety.

  • PDF

Cyclic Oxidation Behavior of Vacuum Plasma Sprayed NiCoCrAlY Overlay Coatings (진공 플라즈마 용사법을 통해 형성된 NiCoCrAlY 오버레이 코팅의 반복 산화 거동)

  • Yoo, Yeon Woo;Nam, Uk Hee;Park, Hunkwan;Park, Youngjin;Lee, Sunghun;Byon, Eungsun
    • Journal of the Korean institute of surface engineering
    • /
    • v.52 no.6
    • /
    • pp.283-288
    • /
    • 2019
  • MCrAlY overaly coatings are used as oxidation barrier coatings to prevent degradation of the underlying substrate in high temperature and oxidizing environment of the hot section of gas turbines. Therefore, oxidation resistance in high temperature is important property of MCrAlY coatings. Also, coefficients of thermal expansion (CTE) of MCrAlY have middle value of that of Ni-based superalloys and oxides, which have the effect of preventing the delamination of the surface oxides. Cyclic oxidation test is one of the most useful methods for evaluating the high temperature durability of coatings used in gas turbines. In this study, NiCoCrAlY overlay coatings were formed on Inconel 792(IN 792) substrates by vacuum plasma spraying process. Vacuum plasma sprayed NiCoCrAlY coatings and IN 792 susbstrates were exposed to 1000℃ one-hour cyclic oxidation environment. NiCoCrAlY coatings showed lower weight gain in short-term oxidation. In long-term oxidation, IN 792 substrates showed higher weight loss due to delamination of surface oxide but NiCoCrAlY coatings showed lower weight loss. X-ray diffraction (XRD) analysis showed α-Al2O3 and NiCr2O4 was formed during the cyclic oxidation test. Through cross-section observation using scanning electron microscopy (SEM) and electron back scatter diffraction (EBSD) analysis, thermally grown oxide (TGO) layer composed of α-Al2O3 and NiCr2O4 was formed and the thickness of TGO increased during 1000℃ cyclic oxidation test. β phase in upper side of NiCoCrAlY coating was depleted due to oxidation of Al and outer beta depletion zone thickness also increased as the cyclic oxidation time increased.

Growth and Flowering of Cut Spray Chrysanthemum 'Gama' by Daminozide (스프레이 절화국화 '가마'의 daminozide에 의한 생육 및 개화반응)

  • Lee, Chang Hee;Park, In Moon
    • FLOWER RESEARCH JOURNAL
    • /
    • v.17 no.2
    • /
    • pp.121-127
    • /
    • 2009
  • This study was conducted to improve commercial quality of a cut spray chrysanthemum 'Gama' bred in Korea by foliar application of daminozide (DMZ), suppressing excessive elongation of peduncle caused by high temperature in summer season production. Applications were made at three floral bud developmental stages (I, II, and III), and concentrations used were 0, 500, 1000, and $2000mg{\cdot}L^{-1}$. Both cut flower length and peduncle length showed the greatest suppression of elongation by DMZ treatments at stage II. DMZ also gradually reduced values of those in a concentration-dependant manner. Stem thickness and flower diameter reduced compared to control as DMZ was sprayed at later stage and those two characteristics decreased in a concentration-dependant manner. The number of paralleled flowers neighboring apical part of whole plant showed the best results at stage I and II. As for DMZ concentration, those increased effectively at $500-1,000mg{\cdot}L^{-1}$. Among all combinations, $1,000mg{\cdot}L^{-1}$ DMZ at stage II recorded the most paralleled flowers and showed 24.2% increment as compared to control. The number of fully expanded flowers and total floral buds also showed the highest values using $1,000mg{\cdot}L^{-1}$ DMZ at stage II than the other treatments. In cut spray chrysanthemum cultivar 'Gama' bred in Korea, foliar-spraying with $1,000mg{\cdot}L^{-1}$ DMZ at stage II most effectively suppressed excessive peduncle elongation, parallelled flower cluster arrangement, and increased the number of flowers in summer. However, this combination affected negatively the other commercial qualities, reducing cut flower length, stem thickness, and flower diameter. Therefore, we recommended that foliar-spraying stage and DMZ concentration was stage I and $1,000mg{\cdot}L^{-1}$, respectively, in a practical culture for 'Gama'.