• Title/Summary/Keyword: plasma spray

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Research on Performance of LSM Coating on Interconnect Materials for SOFCs

  • Zhai, Huijuan;Guan, Wanbing;Li, Zhi;Xu, Cheng;Wang, Wei Guo
    • Journal of the Korean Ceramic Society
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    • v.45 no.12
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    • pp.777-781
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    • 2008
  • Experiments were conducted using SUS430 and Crofer 22 APU steels coated by LSM using plasma spray and slurry spray methods, respectively. High-temperature conductivity and oxidation resistance were investigated. For comparison, SUS430 and Crofer 22 APU without LSM coating were also investigated and coefficient of thermal expansion (CTE) was measured. The results show that the materials without LSM coating exhibit almost the same CTE as YSZ electrolyte in a range of temperatures of $550{\sim}850^{\circ}C$. When coated with LSM, the oxidation rate of the steels decreases by $30{\sim}40%$ using slurry spray and by $10{\sim}30%$ using plasma spray whereas the steels using plasma spray have a better high-temperature conductivity than the steels using slurry spray. It is thus concluded that the LSM coating has a limited effect on increasing high-temperature conductivity while it can effectively reduce the oxidation of the steels.

A Study on Acoustic Emission Characteristics of MCrAlY Coated Material by Vacuum Plasma Spray Process (진공 플라즈마 용사공정에 의한 MCrAlY코팅재의 음향방출 신호 특성 연구)

  • 박진효;이구현;예경환;김정석;강명창
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.921-924
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    • 2004
  • This paper is to investigate a crack for plasma sprayed MCrAlY coated material by acoustic emission method in 4-point bending test. The CoNiCrAlY is coated on Inconel-718 by vacuum plasma spray process. Micro-hardness measurement was conducted by means of Micro Vickers-hardness indentor. The porosity of coating layer was measured using a SEM and Image Analyzer. AE monitoring system is composed of PICO type sensor, a wide band preamplifier(40dB), a PC and AE DSP(16/32 PAC) board. The AE count, Hit and energy of coating specimens is measured according to coating thickness.

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Characterization of Plasma Sprayed $Cr_2O_3$ Coatings ($Cr_2O_3$계 용사분말의 제조조건 및 용사거리에 따른 플라즈마 용사 코팅층의 특성)

  • 김의준
    • Journal of Powder Materials
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    • v.6 no.3
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    • pp.224-230
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    • 1999
  • Oxide powders of $Cr_2O_3 \;and\;Cr_2O_3+3{\%}TiO_2$ were prepared by spray drying, plasma densification and fused+crushed processes. The oxide coating layers were made by plasma spray and characterized by microstructure, hardness, adhesion strength and relative density. The optimum spray distance for the high quality coatings by spraying dried powders was found to be 9cm. A small amount addition of $TiO_2\;in\;Cr_2O_3$ powder significantly improved coating characteristics by lowering the melting point of powders. The hardness and relative density of coating layers of the plasma densified powders were comparable to fused and crushed powders, however, the adhesion strength was much higher in the former case.

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NiAl Behavior at Plasma Spray Deposition

  • Orban, Radu L.;Lucaci, Mariana;Rosso, Mario;Grande, Marco Actis
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.692-693
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    • 2006
  • Behavior of stoichiometric and near-stoichiometric NiAl at plasma spray deposition, without and with a bond coat, for coating layers realization on a low alloyed steel substrate, has been investigated. In all variants, NiAl particle melting and subsequent welding at the impact with substrate were observed, forming a relatively compact and adherent coating layer with the NiAl stability maintaining - all assuring the coating layer oxidation and corrosion resistance. Good results from these points of view, also validated through corrosion tests, were obtained for 45:55 Ni:Al composition without a bond coat but adopting an Ar protective surrounding of plasma jet.

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Surface modification of materials by thermal plasma (열플라즈마를 이용한 재료의 표면개질)

  • Kang, Seong-Pyo;Lee, Han Jun;Kim, Tae-Hee
    • Journal of the Korean institute of surface engineering
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    • v.55 no.6
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    • pp.308-318
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    • 2022
  • The surface modification and treatment using thermal plasma were reviewed in academic fields. In general, thermal plasma is generated by direct current (DC) and radiofrequency (RF) power sources. Thermal spray coating, a typical commercial process using thermal plasma, is performed by DC thermal plasma, whereas other promising surface modifications have been reported and developed using RF thermal plasma. Beyond the thermal spray coating, physical and chemical surface modifications were attempted widely. Superhydrophobic surface treatment has a very high industrial demand particularly. Besides, RF thermal plasma system for large-area film surface treatment is being developed. Thermal plasma is especially suitable for the surface modification of low-dimensional nanomaterial (e.g., nanotubes) by utilizing high temperature and rapid quenching. It is able to synthesize and modify nanomaterials simultaneously in a one-pot process.

Variation of Mechanical Properties with Powder Spraying Conditions in Mo and Co Alloy (Mo 및 Co계 분말의 용사조건에 따른 기계적 특성 변화)

  • 하국현
    • Journal of Powder Materials
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    • v.2 no.3
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    • pp.201-207
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    • 1995
  • In general, the characteristics of plasma spray coating are strongly dependent on process conditions. In this paper, Mo and Co alloy coating layers were made by plasma spraying with different spray parameters and characterized using X-ray diffraction, scanning electron microscopy(SEM), hardnass test, and wear test. It was found that the coating characteristics were mainly affected by phase composition of the powder, spray distance, arc current, and gas flow rate.

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A Study on Acoustic Emission Characteristics through the Cyclic Thermal Test of Thermal Barrier Coating by Plasma Spray Process (플라즈마 용사법에 의한 열차폐 코팅의 열피로에 따른 AE신호 특성 연구)

  • Park J.H.;Lee K.H.;Ye K.H.;Kim S.T.;Jeon C.H.;Kim J.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1349-1352
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    • 2005
  • This paper is to investigate a defect for thermal barrier coating layers by acoustic emission method in 4-point bending test. The two-layer thermal barrier coating is composed of $150\mu{m}\;CoNiCrAlY\;bond\;coating\;by\;vacuum\;plasma\;spray(VPS)\;process\;and\;250\mu{m}\;ZrO_2-8wt%Y_2O_3$ ceramic coating layer by air plasma spray(APS) process on Inconel-718. The specimen prepared by cyclic thermal test(500, 1000, 2000cycle) at $1050^{\circ}C$ The AE monitoring system is composed of PICO type sensor, a wide band pre-amplifier(40dB), PC and AE DSP(16/32 PAC) board. The AE event, amplitude, Cumulative energy and count of coating specimens is evaluated according to cyclic thermal test.

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Fracture Analysis of Plasma Spray Coating by Classification of AE Signals (AE파형분류에 의한 용사코팅재의 파손해석)

  • Kim, G.S.;Park, K.S.;Hong, Y.U.
    • Journal of Power System Engineering
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    • v.6 no.3
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    • pp.24-30
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    • 2002
  • The deformation and fracture behaviors of both Al2O3 and Ni 4.5wt.%Al plasma thermal spray coating were investigated by an acoustic emission method. Plasma thermal spray coating is formed by a process in which melted particles flying with high speed towards substrate, then crash and spread on the substrate surface cooled and solidified in a very short time, stacking of the particles makes coating. A tensile test is conducted on notch specimens in a stress range below the elastic limit of substrate. A bendind test is done on smooth specimens. The waveforms of AE generated from the both test coating specimens can be classified by FFT analysis into two types which low frequency(type I) and high frequency(type II). The type I waveform is considered to corresponds exfoliation of coating layers and type II waveform corresponds the plastic deformation of notch tip. The fracture of the coating layers can estimate by AE event and amplitude, because AE features increase when the deformation generates.

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Thermal Barrier Efficiency and Endurance of Ni-Cr Coating in Liquid Rocket Engine Combustor (액체로켓엔진 연소기에 적용된 니켈-크롬 코팅의 열차폐 효율과 내구성)

  • Lee, Kwang-Jin;Lim, Byoung-Jik;Kim, Jong-Gyu;Han, Yeoung-Min;Choi, Hwan-Seok
    • Aerospace Engineering and Technology
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    • v.8 no.1
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    • pp.138-143
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    • 2009
  • Thermal barrier efficiency and endurance of coatings in liquid rocket engine combustor were evaluated for air plasma spray coating and electro/electroless plating. The result of firing tests has revealed occasional occurrence of local delamination of $ZrO_2$, NiCrAlY coating obtained by the method of air plasma spray in the region of supersonic flow and it necessitated a new coating method as a substitution. It was found that Ni-Cr coating by means of electro/electroless plating can substitute $ZrO_2$, NiCrAlY coatings of air plasma spray in terms of thermal barrier efficiency and endurance.

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Effect of the Raw Material and Coating Process Conditions on the Densification of 8 wt% Y2O3-ZrO2 Thermal Barrier Coating by Atmospheric Plasma Spray

  • Oh, Yoon-Suk;Kim, Seong-Won;Lee, Sung-Min;Kim, Hyung-Tae;Kim, Min-Sik;Moon, Heung-Soo
    • Journal of the Korean Ceramic Society
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    • v.53 no.6
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    • pp.628-634
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    • 2016
  • The 8 wt% yttria($Y_2O_3$) stabilized zirconia ($ZrO_2$), 8YSZ, a typical thermal barrier coating (TBC) for turbine systems, was fabricated under different starting powder conditions and coating parameters by atmospheric plasma spray (APS) coating process. Four different starting powders were prepared by conventional spray dry method with different additive and process parameter conditions. As a result, large- and small-size spherical-type particles and Donut-type particles were obtained. Dense structure of 8YSZ coating was produced when small size spherical-type or Donut-type particles were used. On the other hand, 8YSZ coating with a porous structure was formed from large-size spherical-type particles. Furthermore, a segmented coating structure with vertical cracks was observed after post heat treatment on the surface of dense structured coating by argon plasma flame at an appropriate gun distance and power condition.