• Tribology and Lubricants
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• 제19권5호
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• pp.274-279
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• 2003

$Al-SiC_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate. The homogeneously dispersed composite powder for thermal spray was fabricated by mechanical alloying with ball mill. The friction tests of the composite layers and commercial aluminum alloys for comparison were performed in the temperature range of 20∼$260^{\circ}C$ with the interval of $40^{\circ}C$ with steel counter-face. Friction coefficient was recorded during test sequence, and the microstructure of surface and debris was investigated by optical and scanning electron microscope. Friction coefficients of composite and aluminum alloys at room temperature were similar except pure aluminum. As the temperature increase, friction coefficient was increased rapidly in AC4C, AC2A. But friction coefficient of $Al-SiC_{p}$ composite was not increased so much up to $220^{\circ}C$. Consequently, the reinforcement of $SiC_{p}$ into aluminum matrix increased the stability of friction coefficient as well as wear resistance.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권4호
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• pp.246-248
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• 2000

Closed-form expressions for the temperature dependent breakdown voltage and the on-resistance of the Si power MOSFETs were derived by employing effective temperature dependent ionization coefficient for electrons and holes. The breakdown voltage increases by 20% and the on-resistance increases 2 times when the temperature increases from 300 K to 423 K. The analytic results normalized to the values at 300 K show good agreement with the experimental data of Motorola within 3.5% and 7% for the breakdown voltage and the on-resistance, respectively.

• Journal of Ceramic Processing Research
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• 제22권1호
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• pp.66-73
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• 2021

Ceramics have high hardness, corrosion resistance, and abrasion resistance, but are easily fractured by micro crack. Many studies on self-healing have been conducted to eliminate the risk of micro crack on the surface. SiO2 is self-healing material, in which Si and O2 are combined. TiO2-added Si3N4/SiC composites were sintered. The SiO2 colloid was coated on the surface, and heat treated. The bending strength and abrasion characteristics were evaluated. The specimen with SiO2 colloid coating had higher strength than that of the uncoated specimen, and the strength of TiO2-added specimen also increased. The friction coefficient and wear loss of SiO2 colloid coated specimens were smaller than those of the uncoated specimens. The friction coefficient and wear loss of TiO2-added specimens were smaller than those without additives. The friction coefficient and wear loss decreased with increasing bending strength. Friction coefficient and wear loss according to the heat treatment temperature showed the reverse tendency to the bending strength. Therefore, TiO2-added ceramic will ensure economic efficiency.

• 한국재료학회지
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• 제25권12호
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• pp.678-682
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• 2015

The electrical property of polymer matrix composites with added carbon powder is studied based on the temperature dependency of the conduction mechanism. The temperature coefficient of the resistance of the polymer matrix composites below the percolation threshold (x) changed from negative to positive at 0.20 < x < 0.21; this trend decreased with increasing of the percolation threshold. The temperature dependence of the electrical property(resistivity) of the polymer matrix composites below the percolation threshold can be explained by using a tunneling conduction model that incorporates the effect of the thermal expansion of the polymer matrix composites into the tunneling gap. The temperature coefficient of the resistance of the polymer matrix composites above the percolation threshold has a positive value; its absolute value increased with increasing volume fraction of carbon powder. By assuming that the electrical conduction through the percolating paths is a thermally activated process and by incorporating the effect of thermal expansion into the volume fraction of the carbon power, the temperature dependency of the resistivity above the percolation threshold can be well explained without violating the universal law of conductivity.

• 조명전기설비학회논문지
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• 제29권6호
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• pp.8-13
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• 2015

Recently, Illumination industry of LED module has been focused to industry technology for energy conservation of nation. The LED device is excellent to power efficiency due to semiconductor light source element. And the application to the lighting circuit technology can be designed to the sensitive lighting system for human sensitivity control. In this paper, as a process for analyzing the operating temperature of standardized electronic device including LED device has analyzed about fusing character with in designed micro fuse for electronic device protection from the over current. Using the de-rating technique, which is performed to micro fuse fusing test in the range of $-30^{\circ}C{\sim}120^{\circ}C$ thermostatic chamber. To the output data in each temperature zone, it is performed to first-order linear fitting. Additionally, applying the resistance temperature coefficient and statistical data for the reliable analysis has derived to the metal element resistance of micro fuse with temperature change of the thermostatic chamber. As a research result, The changed temperature effect of thermostatic chamber was confirmed regarding fusing time change.

• 전기학회논문지
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• 제67권8호
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• pp.1055-1061
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• 2018

Recently, due to the rapid development of electric vehicle and energy storage system, it is emphasized for battery management system to be needed and to be improved. BMS carries out various movement for optimization the use of the energy and safe use of secondary battery, these movement of BMS start at high wattage shunt fixed resistor which performs a function for detecting current among the BMS components. In addition, for the safe operation of secondary battery, the reliability of current voltage variation detected from shunt should be secured, and for corresponding characteristics, the quality of Temperature coefficient of resistance for BMS shunt and the quality of Thermo electromotive force all must be excellent. For these reasons, this study comes up with the stabilization plan for thermo electromotive force and temperature coefficient of resistance of BMS shunt resistor which is key to secondary battery operation.

• Journal of Electrical Engineering and Technology
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• 제2권4호
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• pp.525-531
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• 2007

Ni(75 wt.%)-Cr(20 wt.%)-Al(3 wt.%)-Mn(4 wt.%)-Si(1 wt.%) alloy thin films were prepared using the DC magnetron sputtering process by varying the sputtering conditions such as power, pressure, substrate temperature, and post-deposition annealing temperature in order to fabricate a precision thin film resistor. For all the thin film resistors, sheet resistance, temperature coefficient of resistance (TCR), and crystallinity were analyzed and the effects of sputtering conditions on their properties were also investigated. The oxygen content and TCR of Ni-Cr-Al-Mn-Si resistors were decreased by increasing the sputtering pressure. Their sheet resistance, TCR, and crystallinity were enhanced by elevating the substrate temperature. In addition, the annealing of the resistor thin films in air at a temperature higher than $300^{\circ}C$ lead to a remarkable rise in their sheet resistance and TCR. This may be attributed to the improved formation of NiO layer on the surface of the resistor thin film at an elevated temperature.

• 한국결정성장학회지
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• 제21권2호
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• pp.60-64
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• 2011

고감도 적외선 이미지 센서에 적용이 가능한 우수한 TCR(temperature coefficient of resistance) 값을 갖고 적외선 파장영역에서 흡수 특성을 갖는 막 형성을 위해, 본 연구에서는 Silica와 Titanium 분말을 혼합비율을 달리하여 준비한 후 열 기상 증착기를 이용하여 상온에서 게르마늄과 유리 기판 위에 각각 $(SiO_2)_x-(Ti)_y$ 막을 제작하였다. 챔버 내에 위치한 혼합분말이 담겨진 텅스텐 보트와 기판 간의 거리는 15.5 cm이며, 사용된 $SiO_2$와 Ti 분말의 혼합비율 x : y는 각각 90 : 10,80 : 20, 70 : 30, 60 : 40이다. $(SiO_2)_x-(Ti)_y$ 막의 전기적 저항은 273~333 K 영역에서 온도 변화에 따라 측정하였으며, TCR 값은 측정된 막의 저항 값으로부터 계산되었다. 다양한 혼합비율 조건 하에서 형성된 $(SiO_2)_x-(Ti)_y$ 막은 수 $k{\Omega}$~수백 의 $k{\Omega}$ 저항특성을 보였으며, 이러한 막의 TCR은 $-1.4{\sim}-2.6%K^{-1}$의 다양한 값을 나타내었다.

• Corrosion Science and Technology
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• 제22권3호
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• pp.175-186
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• 2023

Effects of high-temperature environment and low-temperature environment on corrosion behaviours of 18Cr stainless steels (type 304L, type 441) in simulated selective catalytic reduction (SCR) environments were studied using weight loss test in each environment and rust analysis. With time to exposure to the high-temperature environment, type 441 was more resistant to corrosion than type 304L due to both higher diffusivity of Cr and lower thermal expansion coefficient in α-iron. The former provides a stable protective Cr₂O₃ layer. The latter leaded to low residual stress between scale and steel, reducing the spallation of the scale. With time to exposure to the low-temperature environment, on the other hand, type 304L was more resistant to corrosion than type 441. The lower resistance of type 441 was caused by Cr-depleted zone with less than 11% formed during the pre-exposure to a high-temperature environment, unlike type 304L. It was confirmed by results from the crevice corrosion test of sensitised 11Cr steel. Hence, to achieve higher corrosion resistance in simulated SCR environments, ferritic stainless steels having lower thermal expansion coefficient and higher diffusivity of Cr but containing more than 18% Cr are recommended.

• 센서학회지
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• 제27권1호
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• pp.40-46
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• 2018

In this paper, we focus on optimization of a boron ($^{11}B$)-implanted n type Si epi substrate for obtaining near-zero temperature coefficient of resistance (TCR) at temperature range from 25 to $125^{\circ}C$. The $^{11}B$-implantation on the N type-Si epi substrate formed isolation from the rest of the N-type Si by the depletion region of a PN junction. The TCR increased as the temperature of rapid thermal anneal (RTA) was increased at the temperature range from $900^{\circ}C$ to $1000^{\circ}C$ for the $p^+$ contact with implantation at dose of $1E16/cm^2$, but sheet resistance of this film was decreased. After the optimization of anneal process condition, the TCR of $1126.7{\pm}30.3$ (ppm/K) was obtained for the $p^-$ resistor-COB package chips contained $p^+$ contact with the implantation of $5E14/cm^2$. This shows the potential of the $^{11}B$-implanted n type Si epi substrate as a resistor for pressure sensor in thermal stable environment applications..