• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.457-458
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• 2009

• Composites Research
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• v.33 no.4
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• pp.205-212
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• 2020

In this study, HfC was coated on two types of carbon/carbon composites coated with SiC by vacuum plasma spraying(VPS). The experiment was performed using a plasma wind tunnel with heat flux of 5.06 MW/㎡ for 120 s heat flux before and after the coating. The mass ablation rate was calculated through the mass change before and after the test, and the length change was measured by using calipers and high speed camera. The oxidation/ablation behavior were observed by FE-SEM with EDS analysis of the specimens cross section. The plasma wind tunnel test results showed that the coated specimens had low weight loss and length change, and high oxidation/ablation resistance. However, two types of the specimens tested under the same conditions were different in the ablation behavior and ablation rate, and it was evaluated that the cylindrical type had higher oxidation/ablation resistance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.603-607
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• 2009

A Ni/Cr plating process has been developed for applying to inner wall of liquid rocket engine(LRE) thrust chamber. Ni plating conditions were selected through thermal shock test and endurance verification of the plating layers was performed through hot firing test of a subscale thrust chamber with Ni/Cr plating. Test results showed that a crack or separation of the plating layers was not found. Judging from the results, Ni/Cr plating could be applied to LRE thrust chamber as a substitute of air plasma sprayed ceramic coating which is presently being used.

• Journal of the Korean Society for Heat Treatment
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• v.30 no.6
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• pp.264-270
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• 2017

In this study, while the abrasive plates for diamond have been prepared through mechanical alloying and sintering of elemental powders, a fabrication route of plasma thermal coatings has been adopted for the first time. When diamond knife is sharped or polished, a metal plate has been applied, which is made of mechanical alloying and sintering. In this study, in order to develop a cost - effective manufacturing process, plasma coatings of FeCrNi and Ti on cast iron plate were applied together with Al intermediate layer coatings. The plasma coatings were successfully performed, and the optimum coating layer conditions were discussed in terms of micro-structural observations at the interfaces.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.5
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• pp.450-457
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• 2009

Periodical thermal shock can introduce defects in thermal barrier coating made by layers of CoNiCrAlY bond coating(BC) and $ZrO_2-8wt%Y_2O_3$ ceramic top coating(TC) on Inconel-738 substrate using plasma spraying. Thermal shock test is performed by severe condition that is to heat until $1000^{\circ}C$ and cool until $20^{\circ}C$. As the number of cycle is increased, the fatigue by thermal shock is also increased. After test, the micro-structures and mechanical characteristics of thermal barrier coating were investigated by SEM, XRD. The TGO layer of $Al_2O_3$ is formed between BC and TC by periodical thermal shock test, and its change in thickness is inspected by eddy current test(ECT). By ECT test, it is shown that TGO and micro-crack can be detected and it is possible to predict the life of thermal barrier coating.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.710-714
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• 2011

In present work, $La_{0.8}Ca_{0.2}CrO_{3}$(LCC), $La_{0.8}Sr_{0.2}CrO_{3}$(LSC) and $La_{0.8}Ca_{0.2}CrO_{0.9}Co_{0.1}O_{3}$(LCCC) ceramic interconnect layer for SOFC were prepared by using thermal plasma spray coating process. The LCC, LSC and LCCC powders were characterized by x-ray diffraction(XRD), scanning electron microscopy(SEM), particle counter and BET analysis. In addition, basic and essential properties such as the surface morphology, cross section, gas leak rate, and electrical conductivity of LCC, LSC, and LCCC layers coated by thermal plasma spray coating process were analyzed and discussed. Based on these experimental results, it can be concluded that the LCCC layer coated by thermal plasma spray coating process can be suitable as a ceramic interconnect of SOFC.

• 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.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.154-154
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• 2015

현재 액체로켓 엔진 연소기 내벽은 bonding layer NiCrAlY과 Top layer $ZrO_2$가 플라즈마 용사 방식으로 형성 된다. 이는 뛰어난 열 차폐 특성과 작업시간이 짧은 장점이 있지만, bonding layer와 Top layer 사이의 열팽창 계수 차이로 인한 균열 발생 가능성이 내재 되어 있고, 연소실 내벽에 균일한 두께의 코팅층을 형성하기 어렵고 설비가 비싸다는 단점으로 인하여 세라믹 코팅 층을 금속 코팅 층으로 대체 하고자 한다. 금속 코팅층은 모재와의 밀착성이 높고, 우수한 산화 및 부식방지 기능을 가지며 저렴하다는 장점이 있다. 또한 코팅 후 연마 작업이 가능해 연소실 내부형상을 설계조건 대로 유지 할 수 있는 특징이 있다. 따라서 본 연구에서는 연소실 내벽에 적용할 모재, 무전해 Ni-P 도금과 전해 Cr 도금층 사이의 밀착력 향상을 위한 방법에 대한 연구를 하였다. 밀착력 향상을 위한 요소로 전처리 용액과 열처리 시간에 따른 영향을 알아보고자 하였으며, 이를 위해서 5가지의 산세 용액으로 각 시편을 산세 한 후, 6시간, 12시간, 18시간 열처리 하여 단면을 비교하여 열처리에 영향을 알아보고자 하였다. 연구 결과 산세 용액의 영향은 크게 나타나지 않았으며, 열처리 시간이 길수록 Ni-P/Cr의 확산이 더 잘 일어나 확산층이 더 넓어지면서 밀착력이 더 좋아 진 것으로 판단되어 진다.

• Korean Journal of Materials Research
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• v.25 no.5
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• pp.226-232
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• 2015

High temperature plasma coating technology has been applied to recover damaged aluminum dies from wear by spraying pure aluminum and alumina powder. However, the coated mixed powder layer composed of aluminum and alumina often undergoes a detachment from the substrate, making the coated substrate die unable to maintain its expected life span. In this study, in order to increase the bonding strength between the substrate and the coating layer, a pure aluminum layer was applied as an intermediate bond layer. In order to prepare the specimen with variable bond coating conditions, the bond coat layers with a various gun speed from 10 cm/sec to 30 cm/sec were prepared with coating cycle variations ranging from three to nine cycles. The specimen with a bond coat layer coated with a gun speed of 20 cm/sec and three coating cycles exhibited ~13MPa of adhesion strength, while the specimen without a bond coat layer showed ~6 MPa of adhesion strength. The adhesion strength with a variation of bond coat layer thickness is discussed in terms of coating parameters.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.52-53
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• 2020

The thermal spray coating process is being used to protect the metals and alloys from wear, abrasion, fatigue, tribology, and corrosion failure. Therefore, in the present study, Al and Zn was deposited by plasma arc thermal spray process onto the steel substrate and their performance was assessed. The bond adhesion result shows that Al coating has higher value attributed to compact, dense, and less porous compared to Zn coating which contain defects/pores and uneven morphology assessed by scanning electron microscopy (SEM). Electrochemical results show that the Al coating exhibited higher impedance value compared to Zn in artificial ocean water solution at prolonged exposure periods. However, both coatings show the increment in polarization resistance with exposure periods which reveal that porosity of coatings is filled by the corrosion products.