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  • Title/Summary/Keyword: 플라즈마코팅

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Effects of Process Temperature on the Tribological Properties of Tetrahedral Amorphous Carbon (ta-C) Coating (공정 온도에 따른 사면체 비정질 카본 (ta-C) 코팅의 트라이볼로지적 특성연구)

  • Kang, Yong-Jin;Kim, Do Hyun;Ryu, Hojun;Kim, Jongkuk;Jang, Young-Jun
    • Tribology and Lubricants
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    • v.35 no.6
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    • pp.362-368
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    • 2019
  • In this study, mechanical and tribological properties were investigated by varying the process temperature (50, 100, 125 and 150℃) to reduce internal stress. The internal stress reduction by thermal dissociation ta-C coating film with increasing temperature is confirmed through the curvature radius of the ta-C coating according to the temperature of the SUS plate. As the coating temperature increased, the mechanical properties (hardness, modulus, toughness) deteriorated, which is in agreement with the Raman analysis results. As the temperature increased, the sp2 phase ratio increased owing to the dissociation of the sp3 phase. The friction and wear properties are related to the process temperature during ta-C coating. Low friction and wear properties are observed in high hardness samples manufactured at 50℃, and wear resistance properties decreased with increasing temperature. The contact area is expected to increase owing to the decrease of hardness(72 GPa to 39 GPa) and fracture toughness with increasing temperature which accelerated wear because of the debris generated. It was confirmed that at process temperature of over than 100℃, the bond structure of the carbon film changed, and the effect of excellent internal stress was reduced. However, the wear resistance simultaneously decreased owing to the reduction in fracture toughness. Therefore, in order to increase industrial utilization, optimum temperature conditions that reduce internal stress and retain mechanical properties.

Effect of Plasma Density on the Tribological Properties of Amorphous Carbon Thin Films (비정질 탄소박막의 트라이볼로지 특성에 미치는 플라즈마 밀도의 영향)

  • Park, Y.S.;Lee, J.D.;Hong, B.
    • Journal of the Korean Vacuum Society
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    • v.20 no.5
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    • pp.333-338
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    • 2011
  • In this work, we have fabricated the amorphous carbon (a-C:H) thin film by using unbalanced magnetron sputtering method with the magnetron source of inside/outside electromagnetic coils as the protective coating materials. We have investigated the tribological properties of amorphous carbon films prepared with various electromagnetic coil currents for the change of the plasma density, such as hardness, friction coefficient, adhesion, and surface roughness. Raman and HRTEM were used to study the microstructure of carbon films. In the result, the hardness and adhesion properties of a-C:H films were improved with increasing electromagnetic coil current due to the increase of the plasma density to the substrate. Thus, these results can be explained by the increase of sp2 bonding and cluster number in the amorphous carbon film, related to the improved bombardment around substrate and the increased substrate temperature.

Oxidation and Electrical Properties of (LaSr)(CrCo)3Coated STS-430 Steel by Plasma Spraying (플라즈마 스프레이 (LaSr)(CrCo)O3 코팅된 STS-430 합금의 고온 산화 거동 및 전기적 특성)

  • Lee, Chung-Hwan;Lim, Kyeong-Tae;Baik, Kyeong-Ho
    • Journal of Powder Materials
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    • v.16 no.3
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    • pp.185-190
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    • 2009
  • Fe-Cr steels are the most promising candidate for interconnect in solid oxide fuel cells. In this study, an effective, dense and well adherent (LaSr)(CrCo)O3 [LSCC] coating layer was produced onto 430 stainless steel (STS-430) by atmospheric plasma spraying and the oxidation behavior as well as electrical properties of the LSCC coated STS-430 were investigated. A significant oxidation of pristine STS-430 occurred at 800C in air environment, leading to the formation of Cr2O3 and FeCr2O4 scale layer up to 7μm after 1200h, and consequently increased an area specific resistance of 330mΩcm2. Although the plasma sprayed LSCC coating contained the characteristic pore network, the coated samples presented apparent advantages in reducing oxidation growth of STS-430, resulting a decrease in oxide scale thickness of 1μm at 800C after 1200h. The area specific resistance of the LSCC coated STS-430 was much reduced to 7mΩcm2 after exposure at 800C for 1200h, compared to that of the pristine STS-403.

A Study on the Effects of High Temperature Thermal Cycling on Bond Strength at the Interface between BCB and PECVD SiO2 Layers (고온 열순환 공정이 BCB와 PECVD 산화규소막 계면의 본딩 결합력에 미치는 영향에 대한 연구)

  • Kwon, Yongchai;Seok, Jongwon;Lu, Jian-Qiang;Cale, Timothy S.;Gutmann, Ronald J.
    • Korean Chemical Engineering Research
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    • v.46 no.2
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    • pp.389-396
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    • 2008
  • The effect of thermal cycling on bond strength and residual stress at the interface between benzocyclobutene (BCB) and plasma enhanced chemical vapor deposited (PECVD) silicon dioxide (SiO2) coated silicon wafers were evaluated by four point bending and wafer curvature techniques. Wafers were bonded using a pre-established baseline process. Thermal cycling was done between room temperature and a maximum peak temperature. In thermal cycling performed with 350 and 400C peak temperature, the bond strength increased substantially during the first thermal cycle. The increase in bond strength is attributed to the relaxation in residual stress by the condensation reaction of the PECVD SiO2: this relaxation leads to increases in deformation energy due to residual stress and bond strength.

Friction and Wear Characteristics of Plasma Coated Surface of Casting Aluminum Alloy (플라즈마 코팅한 주조용 알루미늄합금의 마찰 및 마멸특성)

  • Chae, Young-Hun;Ren, Jing-Ri;Park, Jun-Mock;Kim, Seock-Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.5
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    • pp.791-799
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    • 1997
  • The wear characteristics and wear mechanisms of plasma sprayed Al/sub 2/ O/sub 3/-40%TiO/sub 2/ and Cr/sub 2/O/sub 3/ deposited on casting aluminum alloy(AC4C) were investigated. Specimens were processed for various coating thicknesses. Ball on disk type wear tester was used for wear test. The scratch test on plasma sprayed coating surface showed that critical load to break the coating layer was greater than 40 N. The critical load increase with the increase of coating thickness of specimens. The friction coefficient of Cr/sub 2/O/sub 3/ coating layer was less than that of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer. The wear resistance of Cr/sub 2/O/sub 3/ coating layer was greater than that of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer. Microscopic observation of worn surfaces was made by SEM. SEM observation showed that the main mechanism of wear for Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer was abrasive wear under 50 N. For the case of Al/sub 2/O/sub 3/-40%TiO/sub 2/ coating layer, as the surface cracks perpendicular to sliding direction propagated, the wear debris was generated in wear track. However, the main mechanism of wear for Cr/sub 2/O/sub 3/ coating layer was brittle fracture under 150 N.

Effect of Oxidation of Bond Coat on Failure of Thermal Barrier Coating (Bond Coat의 산화가 Thermal Barrier Coating의 파괴에 미치는 영향)

  • 최동구;최함메;강병성;최원경;최시경;김재철;박영규;김길무
    • Journal of the Korean Ceramic Society
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    • v.34 no.1
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    • pp.88-94
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    • 1997
  • The oxidation behavior of the NiCrAlY bond coat and thermal fatigue failure in the plasma-sprayed thermal barrier coating system, ZrO2.8wt%Y2O3 top coat/Ni-26Cr-5Al-0.5Y bond coat/Hastelloy X superalloy substrate, in commercial use for finned segment of gas turbine burner were investigated. The main oxides formed in the bond coat were NiO, Cr2O3, and Al2O3. It divided the oxide distribution at this interface into two types whether an Al2O3 thin layer existed beneath ZrO2/bond coat interface before operation at high temperature or not. While a continuous layer of NiO was formed mainly in the region where the Al2O3 thin layer was present, the absence of it resulted in the formation of mixture of Cr2O3 and Al2O3 beneath NiO layer. Analyses on the fracture surface of specimen spalled by thermal cycling showed that spalling occurred mainly along the ceram-ic coat near ZrO2/bond coat oxide layer interface, but slightly in the oxide layer region.

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Influence of CrO3 Sealing Treatment on Properties of Plasma Sprayed Al2O3 Coating (플라즈마 용사 Al2O3 코팅의 특성에 미치는 CrO3 봉공처리의 영향)

  • Cho, Kyeong-Sik;Lee, Hyun-Kwuon;Kwon, Jeong-Cheol
    • Journal of the Korean Ceramic Society
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    • v.48 no.2
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    • pp.160-167
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    • 2011
  • Plasma sprayed ceramic coatings inherently contain pores and usually also cracks. Post-treatment of the plasma sprayed coatings is a way to close the connected pores and cracks. In this study, post-sealing treatment in plasma sprayed Al2O3 coatings was employed to overcome the reduction of coating properties. Al2O3 plasma thermal spray coating was made on aluminum alloys plate, CrO3 post coating and heat treatment at 550C was carried out in order for final Cr2O3 to be saturated through phase transformation. Chromia sealing began at the fine defect in coated microstructure, while larger pores were permeated later. The increase in concentration and treatment frequency of sealing solution resulted in the decrease of porosity of coating layer, while cracks occurred partially after the third treatment. After twice treatment of 10M CrO3 solution, microhardness and breakdown voltage of Al2O3 coatings were found to increase by 50% and 390% respectively than without post-treatment.

Manufacturing and Properties of Low Vacuum Plasma Sprayed W-Carbide Hybrid Coating Layer (진공 플라즈마 스프레이 공정을 이용한 W계 복합 코팅층의 제조 및 특성 연구)

  • Cho, Jin-Hyeon;Jin, Young-Min;Ahn, Jee-Hoon;Lee, Kee-Ahn
    • Journal of Powder Materials
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    • v.18 no.3
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    • pp.226-237
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    • 2011
  • W-ZrC and W-HfC composite powders were fabricated by the Plasma Alloying & Spheroidization (PAS) method and the powders were sprayed into hybrid coating layers by using Low Vacuum Plasma Spray (LVPS) process, respectively. Microstructure, mechanical properties, and ablation characteristics of the fabricated coating layers were investigated. The LVPS process led to successful production of W-Carbide hybrid coatings, approximately 400 μM or above in thickness. As the substrate preheating temperature increased from 870C to 917C, the hardness of the W-ZrC coating layer increased due to decreased porosity. Vickers hardness showed higher value (about 108.4 HV) in W-ZrC hybrid coating material compared to that of W-HfC while adhesive strength was found to be similar in both coating layers. The plasma torch test revealed good ablation resistance of the W-Carbide hybrid coating layers. The relatively high performance W-ZrC coating layer at the elevated temperature is thought to be attributed to both the strengthening effect of ZrC particle remained in the layer and the formation of ZrO2 phase with high temperature stability.

Stability and Adhesion of Diamond-like Carbon Film under Micro-tensile Test Condition (미소 인장시험을 통한 다이아몬드상 카본 박막의 안정성 및 접합력 평가)

  • Choi Heon Woong;Lee Kwang-Ryeol;Wang Rizhi;Oh Kyu Hwan
    • Journal of the Korean Vacuum Society
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    • v.13 no.4
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    • pp.175-181
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    • 2004
  • We investigated the stability of the DLC film coated on 304 stainless steel substrate by Radio frequency assisted chemical vapor deposition method. Fracture and spallation behaviour of the coating was observed during micro-tensile test of the fil $m_strate composite. As the tensile deformation progressed, the cracks of the film were observed in the perpendicular direction to the tensile axis. Further deformation resulted in the plastic deformation with 45 slip bands on the substrate surface. Spallation of the film occurred with the plastic deformation, which was initiated at the cracks of the film and was aligned along the slip directions. We found that both the cracking and the spallation behaviors are strongly dependent on the pre-treatment condition, such as Ar plasma pre-treatment. The spallation of the film was considerably suppressed in an optimized condition of the substrate cleaning by Ar glow discharge. We observed the improved stability with increasing duration of Ar plasma pre-treatment.nt.

Preparation of Suspension in La2O3-Gd2O3-ZrO2 System via Planetary Mill and Characteristics of (La1-xGdx)2Zr2O7 Coatings Fabricated via Suspension Plasma Spray (유성구볼밀을 이용한 La2O3-Gd2O3-ZrO2 계 서스펜션준비와 서스펜션 플라즈마용사를 이용한 (La1-xGdx)2Zr2O7 코팅증착과 특성)

  • Kwon, Chang-Sup;Lee, Sung-Min;Oh, Yoon-Suk;Kim, Hyung-Tae;Jang, Byung-Koog;Kim, Seongwon
    • Journal of Powder Materials
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    • v.20 no.6
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    • pp.453-459
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    • 2013
  • Lanthanum/gadolinium zirconate coatings are deposited via suspension plasma spray with suspensions fabricated by a planetary mill and compared with hot-pressed samples via solid-state reaction. With increase in processing time of the planetary mill, the mean size and BET surface area change rapidly in the case of lanthanum oxide powder. By using suspensions of planetary-milled mixture between lanthanum or gadolinium oxide and nano zirconia, dense thick coatings with fully-developed pyrochlore phases are obtained. The possibilities of these SPS-prepared coatings for TBC application are also discussed.