• Title/Summary/Keyword: Surface thermal resistance

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RF 유도 열플라즈마를 이용한 유기 용매로 부터의 탄화규소 나노 분말 합성 (Synthesis of Silicon Carbide Nano-Powder from a Silicon-Organic Precursor by RF Inductive Thermal Plasma)

  • 고상민;구상만;김진호;조우석;황광택
    • 한국세라믹학회지
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    • 제49권6호
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    • pp.523-527
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    • 2012
  • Silicon carbide (SiC) has recently drawn an enormous amount of industrial interest due to its useful mechanical properties, such as its thermal resistance, abrasion resistance and thermal conductivity at high temperatures. In this study, RF thermal plasma (PL-35 Induction Plasma, Tekna CO., Canada) was utilized for the synthesis of high-purity SiC powder from an organic precursor (hexamethyldisilazane, vinyltrimethoxysilane). It was found that the SiC powders obtained by the RF thermal plasma treatment included free carbon and amorphous silica ($SiO_2$). The SiC powders were further purified by a thermal treatment and a HF treatment, resulting in high-purity SiC nano-powder. The particle diameter of the synthesized SiC powder was less than 30 nm. Detailed properties of the microstructure, phase composition, and free carbon content were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), a thermogravimetric (TG) analysis, according to the and Brunauer-Emmett-Teller (BET) specific surface area from N2 isotherms at 77 K.

The Fabrication by using Surface MEMS of 3C-SiC Micro-heaters and RTD Sensors and their Resultant Properties

  • Noh, Sang-Soo;Seo, Jeong-Hwan;Lee, Eung-Ahn
    • Transactions on Electrical and Electronic Materials
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    • 제10권4호
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    • pp.131-134
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    • 2009
  • The electrical properties and the microstructure of nitrogen-doped poly 3C-SiC films used for micro thermal sensors were studied according to different thicknesses. Poly 3C-SiC films were deposited by LPCVD (low pressure chemical vapor deposition) at $900^{\circ}C$ with a pressure of 4 torr using $SiH_2Cl_2$ (100%, 35 sccm) and $C_2H_2$ (5% in $H_2$, 180 sccm) as the Si and C precursors, and $NH_3$ (5% in $H_2$, 64 sccm) as the dopant source gas. The resistivity of the poly SiC films with a 1,530 ${\AA}$ thickness was 32.7 ${\Omega}-cm$ and decreased to 0.0129 ${\Omega}-cm$ at 16,963 ${\AA}$. The measurement of the resistance variations at different thicknesses were carried out within the $25^{\circ}C$ to $350^{\circ}C$ temperature range. While the size of the resistance variation decreased when the films thickness increased, the linearity of the resistance variation improved. Micro heaters and RTD sensors were fabricated on a $Si_3N_4$ membrane by using poly 3C-SiC with a 1um thickness using a surface MEMS process. The heating temperature of the SiC micro heater, fabricated on 250 ${\mu}m$${\times}$250 ${\mu}m$ $Si_3N_4$ membrane was $410^{\circ}C$ at an 80 mW input power. These 3C-SiC heaters and RTD sensors, fabricated by surface MEMS, have a low power consumption and deliver a good long term stability for the various thermal sensors requiring thermal stability.

용사 공정에서 용융 금속 액적의 충돌현상과 응고 과정 해석 (A Study on the impact and solidification of the liquid metal droplet in the thermal spray deposition)

  • 하응지;김우승
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집D
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    • pp.214-219
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    • 2001
  • In this study, numerical investigation has been performed on the spreading and solidification of a droplet impacting onto a solid substrate in the thermal spray process. The finite difference method with volume-of-fluid approach is used to analyze the free surface flow and the source-based enthalpy method is employed to model the latent heat release during the solidification. In this work, the numerical model is validated through the comparison of the present numerical result with experimental data available for the flat substrate.

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열하중하에 있는 IC 패키지의 점탄성 파괴해석 (Visco-Elastic Fracture Analysis of IC Package under Thermal Loading)

  • 이강용;양지혁
    • 한국정밀공학회지
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    • 제15권1호
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    • pp.43-50
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    • 1998
  • The purpose of the paper is to protect the damage of plastic IC package with searching the cause of the fracture due to the delamination and crack when the encapsulant of plastic IC package is on viscoelastic behavior with the effect of creep on high temperature, The model for analysis is the plastic SOJ package with dimpled diepad in the IR soldering process of surface mounting technology. The risk of delamination with calculating the distribution of viscoelastic thermal stress in the package without the crack in the surface mounting process is checked. The package model with the perfect delamination between chip and diepad is chosen to estimate the resistance against fracture in thermal loading with calculating C (t)-integrals according to the change of the design. The optimum design to depress the delamination and crack is presented.

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공동주택에 적용 가능한 건식 외벽시스템 시공에 따른 단열성능 검토 (Thermal Performance of Developed Cladding Systems on Multi-Family Residential Buildings)

  • 홍구표;강지연;김형근
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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    • pp.267-268
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    • 2018
  • The purpose of this study was to analyze the thermal performance of a cladding system which developed for easy maintenance and flexibility and installed on a long-life housing. The developed cladding systems were finished mock-up test at an authorized certification laboratory and were satisfied with the standard of the external wall system. The surface temperature and linear thermal transmittance of the cladding system were investigated by using the THERM as a simulation program. The joining part between the cladding systems had a weakness of condensation resistance. The surface temperature of the joining part was improved by filling and adding insulation.

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경질크롬도금 대체용 Ni계 합금도금 기술 (Ni-BASE ALLOY SYSTEMS AS ALTERNATIVE TO HEXAVALENT CHROMIUM)

  • Chang, Do-Yon;Lee, Kyu-Hwan;Kwon, Sik-Chol
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2003년도 추계학술발표회초록집
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    • pp.11-11
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    • 2003
  • Electroplated hexavalent chromium coatings have been used in many technical applications since it was invented by G.J. Sargent in 1920. Because of the environmental problems and health risks associated with the use of hexavalent chromium, there has been an extensive search for alternative coatings with properties such as corrosion resistance and wear resistance, at a reasonable cost. However there is no single substitute that meets all the desirable performance characteristics of chromium. Advanced techniques, such as alloy plating, electroless plating, trivalent chromium plating, plasma and thermal spray coating, PVD and ion implantation, have been applied for replacing hexavalent chromium plating.

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PTAW법에 의한 Al 합금 표면의 후막경화층 형성에 관한 연구 (A Study on Formation of Thick Hardened Layer on Al Alloy Surface by PYAW Process)

  • 임병수;김봉수;오세훈;황선효;서창제
    • Journal of Welding and Joining
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    • 제15권5호
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    • pp.92-103
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    • 1997
  • The purpose of this study is to improve the wear resistance and hardness of Al alloy by making a formation of the thick surface hardening layers. The thick surface hardening layers were formed by PTAW(Plasma Transferred Arc Welding), with the addition of metal powders (Cu), ceramics powders (NbC, TiC), and mixture powders (Cu+NbC) in Al alloy (A1050, A5083). Mechanical properties of overlaid layers (wear resistance, hardness) were investigated in relation to the microstructure. The results obtained are summarized as follows: The depth of penetration was increased with increasing powder feeding rate. It is considered that these increase were due to the thermal pinch effect by the addition of powders, especially, for the Cu powders, were due to the heat of reaction with the matrix. The hardness and wear resistance of overlaid layers were improved with increasing powder feeding rate. For the Cu powders, it is considered that these increase were due to the increase of the formation of ${\theta}(CuAl_2)$ phase with increasing feeding rate of Cu powers.

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폴리실리콘 기판 위에 형성된 코발트 니켈 복합실리사이드 박막의 열처리 온도에 따른 물성과 미세구조변화 (Characteristics and Microstructure of Co/Ni Composite Silicides on Polysilicon Substrates with Annealing Temperature)

  • 김상엽;송오성
    • 한국재료학회지
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    • 제16권9호
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    • pp.564-570
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    • 2006
  • Silicides have been required to be below 40 nm-thick and to have low contact resistance without agglomeration at high silicidation temperature. We fabricated composite silicide layers on the wafers from Ni(20 nm)/Co(20 nm)/poly-Si(70 nm) structure by rapid thermal annealing of $700{\sim}1100^{\circ}C$ for 40 seconds. The sheet resistance, surface composition, cross-sectional microstructure, and surface roughness were investigated by a four point probe, a X-ray diffractometer, an Auger electron spectroscopy, a field emission scanning electron microscope, and a scanning probe microscope, respectively. The sheet resistance increased abruptly while thickness decreased as silicidation temperature increased. We propose that the fast metal diffusion along the silicon grain boundary lead to the poly silicon mixing and inversion. Our results imply that we may consider the serious thermal instability in designing and process for the sub-0.1 um CMOS devices.

다결정 3C-SiC 멤브레인 위에 균일한 온도분포를 갖는 마이크로 히터의 제작과 그 특성 (Fabrication of micro heaters with uniform-temperature area on poly 3C-SiC membrane and its characteristics)

  • 정귀상;정재민
    • 센서학회지
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    • 제18권5호
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    • pp.349-352
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    • 2009
  • This paper describes the fabrication and characteristics of micro heaters built on AlN($0.1{\mu}m$)/3C-SiC($1{\mu}m$) suspended membranes by surface micromachining technology. In this work, 3C-SiC and AlN films are used for high temperature environments. Pt thin film was used as micro heaters and temperature sensor materials. The resistance of temperature sensor and the power consumption of micro heaters were measured and calculated. The heater is designed for operating temperature up to about $800^{\circ}C$ and can be operated at about $500^{\circ}C$ with a power of 312 mW. The thermal coefficient of the resistance(TCR) of fabricated Pt resistance of temperature detector(RTD)'s is 3174.64 ppm/$^{\circ}C$. A thermal distribution measured by IR thermovision is uniform on the membrane surface.

A study on zinc phosphate conversion coatings on Mg alloys

  • Phuong, Nguyen Van;Lee, Kyuhwan;Chang, Doyon;Kim, Man;Lee, Sangyeoul;Moon, Sungmo
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
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    • pp.17-17
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    • 2012
  • Magnesium alloys exhibit many attractive properties such as low density, high strength/weight ratio, high thermal conductivity, very good electromagnetic features and good recyclability. However, most commercial magnesium alloys require protective coatings because of their poor corrosion resistance. Attempts have been made to improve the corrosion resistance of the Mg alloys by surface treatments, such as chemical conversion coatings, anodizing, plating and metal coatings, are commonly applied to magnesium alloys in order to increase the corrosion resistance. Among them, chemical conversion coatings are regarded as one of the most effective and cheapest ways to prevent corrosion resistance. In this study, zinc phosphate conversion coatings on various Mg alloys have been developed by selecting proper phosphating bath composition and concentration and by optimizing phosphating time, temperature. Morphology, coatings composition, corrosion resistance, adhesion and its formation and growth mechanism of the zinc phosphate conversion coatings were studied. Results have shown some attractive properties such as simplicity in operation, significantly increased corrosion protective property. However, adhesions between coatings and substrate and also between coatings and paint are still not satisfied. Resolving the problems and understanding the mechanism of phosphating process are targets of our study.

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