• Title/Summary/Keyword: Heat-resistant

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The Study of Heat Resistant Aluminum Alloy with CrW Homogeneous Solid Solution (CrW 전율고용체 첨가 내열 알루미늄 합금에 관한 연구)

  • Kim, Jin-Pyeong;Sung, Si-Young;Han, Beom-Suck;Kim, Sang-Ho
    • Journal of Korea Foundry Society
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    • v.33 no.3
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    • pp.122-126
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    • 2013
  • Recently, heat-resistant aluminum alloy has been re-focused as a downsizing materials for the internal combustion engines. Heat-resistant Al alloy development and many researches are still ongoing for the purpose of improving thermal stability, high-temperature mechanical strength and fatigue properties. The conventional principle of heat-resistant Al alloy is the precipitation of intermetallic compounds by adding a variety of elements is generally used to improve the mechanical properties of Al alloys. Heat resistant aluminum alloys have been produced by CrW homogeneous solid solution to overcome the limit of conventional heat resistant aluminum alloy. From EPMA, it is found that CrW homogeneous soild solution phases with the size of $50-100{\mu}m$ have been dispersed uniformly, and there is no reaction between aluminum and CrW alloy. In addition, after maintaining at high temperature of 573 K, there is no growth of hardening phase, nor desolved, but CrW still exists as a homogeneous solid solution.

Heat Shock Induces Necrosis in Cisplatin-resistant Gastric Cancer Cells through Suppressing JNK1/2 Activation and HSP27 Induction (시스플라틴 내성세포주에서 열충격에 의한 세포사멸에 관한 연구)

  • Lim, Sung-Chul;Choi, Cheol-Hee;Han, Song-Iy
    • Journal of Life Science
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    • v.19 no.12
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    • pp.1705-1711
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    • 2009
  • Carcinoma cells that had acquired resistance to a chemotherapeutic drug often show cross-resistance to various other cytotoxic drugs. In the present study, we explored the effect of heat shock in cisplatin-resistant gastric cancer cells SNU601/Cis2 to figure out the efficacy of hyperthermia in drug-resistant carcinoma. While SNU601/WT cells showed a high-sensitivity response to heat shock by dying through apoptosis, SNU601/Cis2 cells were considerably resistant to mild heat shock, but died by necrosis upon treatment with harsh heat shock. The occurrence of necrosis in SNU601/Cis2 cells was linked to the suppression of both JNK1/2 activation and HSP27 induction in response to heat shock. Since necrosis is closely associated with tumor malignancy and poor prognosis through inflammatory responses, our result suggests that hyperthermic treatment should be carefully applied when it is combined with chemotherapy.

The Study on Evaluation of Weldability of Austenitic Heat Resistant Stainless Steel (오스테나이트계 내열 스테인리스강의 용접성 평가에 관한 연구)

  • 변경일;지병하;정호신
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2000.10a
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    • pp.236-239
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    • 2000
  • It is important to evaluate austenitic heat resistant stainless steel because of low weldability of austenitic heat resistant stainless steel containing high Si. This study took varestraint test for evaluation of solidification cracking sensitivity and Erichsen test for evaluation of weld metal ductility. As a result of tests, solidification crack sensitivity increased with adding $N_2$ to shielding gas, and W had detrimental effect on crack resistance, but Ce had beneficial effect on crack resistance. Under same heat input, ductility of weld metal increased with welding speed.

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Distribution of Indicator Organisms and Influence of Storage Temperature and Period in Commercial Plant Food (시판 식물성 식품의 오염지표세균 분포 및 저장온도, 기간별 오염지표세균의 변화)

  • 이용욱;박석기
    • Journal of Food Hygiene and Safety
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    • v.14 no.1
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    • pp.1-8
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    • 1999
  • There were few data for the distribution of the indicator organisms in the commercial plant foods, and for the normal flora and for the foodborne agents within the country. First of all it must be investigated the distribution of the indicator organisms. And also it is very important to prepare the sanitation criteria for the plant foods through the microbiological examination and the investigation of tendency to change of the indicator organisms according to the storage temperature and period. The average number of total viable counts for grains was 2.9$\times$105/g, psychrophilic bacteria 2.9$\times$105/g, heterotrophic bacteria 3.1$\times$105/g, heat-resistant bacteria 2.1$\times$103/g, Pseudomonas aeruginosa 23/g. That for beans was 6.3$\times$102/g, psychrophile 34/g, heterotroph 1.7$\times$102/g. That for sesames was 1.4$\times$105/g, coliform 350/g, psychrophile 7.4$\times$104/g, heterotroph 5.8$\times$104/g, Pseud. aeruginosa 2.3$\times$103/g. heat-resistant bacteria 150/g. That for potatoes was 2.0$\times$107/g, coliform 5.0$\times$104/g, psychrophile 1.8$\times$107, heterotroph 1.4$\times$107/g, heat-resistant bacteria 3.3$\times$104/, Staphylococcus 2.7$\times$105/g, fecal streptococcus 4.5$\times$103/g, Pseud. aeruginosa 7.0$\times$103/g. That for mushrooms was 1.2$\times$108/g, psychrophile 9.4$\times$107/g, heterotroph 1.0$\times$109/g, heat-resistant bacteria 1.6$\times$105/g, Pseud. aeruginosa 1.3$\times$103/g. That for vegetables was 5.9$\times$1011/g, coliform 1.8$\times$106g/, Staphylococcus 1.1$\times$1012/g, heterotroph 8.4$\times$1011/g, heat-resistant bacteria 7.6$\times$106/g, Staphylococcus 1.1$\times$107/g, fecal streptococcus 1.1$\times$104/g, Pseud. aerugniosa 5.2$\times$104/g. That for nuts 3.9$\times$104/g, coliform 3.9$\times$103/g, psychrophile 4.0$\times$104/g, heterotroph 3.2$\times$104/g, heat-resistant bacteria 400/g. In commercial grains and beans, SPC, psychrophile, heterotroph and heat-resistant bacteria stored at 1$0^{\circ}C$, 2$0^{\circ}C$, 3$0^{\circ}C$ were constant. Staphylococcus, coliform, Pseud. aeruginosa were decreased a little n grains, but were not detected in beans. In mushrooms, all indicator organisms were increased as time goes on and were increased rapidly at 2$0^{\circ}C$. In sesames, coliform was not detected at all temperature. psychrophile was increased for 7 days, the others were constant. In potatoes, SPC, psychrophile, heat-resistant bacteria, heterotroph had a tendency to increase and the others were constant. In vegetables, indicator organisms were had a tendency to increase, psychrophile, heterotroph were rapidly increased after 7 days. In nuts, SPC, coliform, psychrophile heterotroph, heat-resistant bacteria, Pseud. aeruginosa were constant, staphylococcus and fecal streptococcus were not detected.

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Development of heat resistant body using Sanchung Kaolin and Jangsu gobdol sludge (산청고령토와 장수곱돌 슬러지를 사용한 내열소지 개발)

  • Kim, Sanggon
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.30 no.1
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    • pp.27-32
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    • 2020
  • The main cystal phases of traditional ceramics made of clay, quartz, and feldspar are mullite and cristobalite. Although mullite can provide strength to the ceramic body, it cannot be used for the heat resistant ceramics because the thermal expansion coefficient of it is relatively high as 5.3 × 10-6/℃. In this study, development of lightweight heat resistant ceramics was tried by producing cordierite phase, of which the thermal expansion coefficient is 2.6 × 10-6/℃, instead of forming mullite phase in the ceramic body by using Sanchung Kaolin and Jangsu gobdol sludge. It was concluded that ceramics having good heat resistant, bending strength, and refractoriness under load could be fabricated when 80 wt% of Sanchung Kaolin and 20 wt% of Jangsu gobdol sludge were used as raw materials. Also, the bulk specific gravity is 1.78, which is lighter than the existing Buncheong ware.

A Study on the Oxidation Resistance of Aluminum Cast Iron by Aluminum Content (알루미늄 함량에 따른 알루미늄 주철의 내산화성에 관한 연구)

  • Kim, Dong-Hyuk
    • Journal of Korea Foundry Society
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    • v.40 no.6
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    • pp.135-145
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    • 2020
  • Aluminum cast iron has excellent oxidation resistance, sulfurization resistance, and corrosion resistance. However, the ductility at room temperature is insufficient, and at temperatures above 600?, the strength drops sharply and practicality is limited. In the case of heat-resistant cast iron, high-temperature materials containing Cr and Ni account for 30 to 50% or more. However, these high-temperature materials are expensive. Aluminum heat-resistant cast iron is considered as a substitute for expensive heat-resistant materials. Oxidation due to the aging temperature and holding time conditions increases more in 0 wt.% Al-cast iron than in 2 and 4 wt.% Al-cast iron according to oxidized weight and gravimetric oxide layer thickness measurements. As a result of observing the cross-section of the oxide layer, it was found to contain 0 wt.% of Al-cast iron silicon oxide-containing SiO2 or Fe2SiO4 oxide film. In cast iron containing aluminum, the thickness of the internal oxide layer due to aluminum increases as the aging temperature and retention time increase, and the amount of the iron oxide layer generated on the surface decreases.

High Temperature Corrosion Properties of Heat Resistant Chrome Steels in SO2 Atmosphere (고온 이산화황 환경 내 내열 크롬강에 대한 부식특성 연구)

  • Lee, Han-sang;Jung, Jine-sung;Kim, Eui-hyun
    • Korean Journal of Metals and Materials
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    • v.47 no.2
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    • pp.99-106
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    • 2009
  • The high temperature corrosion properties of heat resistant steels were investigated in oxidation atmosphere including sulfur dioxide. The heat resistant steels of T22, T92, T122, T347HFG and T304H were evaluated at 620, $670^{\circ}C$ for 400 hours. The corrosion rates showed a decreasing tendency while chrome contents of those steels increased from 2 mass.% to 19 mass.%. The in crease in temperature increasement has an more effect on the corrosion rates of low chrome steels than high chrome steels. The weight gains of T22, T92, T304H at $670^{\circ}C$ were 3.7, 1.65, 1.23 times compared with those at $620^{\circ}C$. The external scale formed on T22 was composed of hematite, magnetite and Fe-Cr spinel and internal layer including iron oxide mixed with sulfide. The scales formed on T92, T122, T304H consisted of an outer layer of hematite and inner layer of chrome oxide and hematite. The proportion of chrome oxide at inner layer was increased when the chrome contents in heat resistant steels were increased.

Characteristics and Development Trends of Heat-Resistant Composites for Flight Propulsion System (비행체 추진기관용 내열 복합재의 특성 및 개발 동향)

  • Hwang, Ki-Young;Park, Jong Kyoo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.9
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    • pp.629-641
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    • 2019
  • In order to limit the temperature rise of the structure to a certain level or less while maintaining the aerodynamic shape of solid rocket nozzle by effectively blocking a large amount of heat introduced by the combustion gas of high temperature and high pressure, the heat-resistant materials such as C/C composite having excellent ablation resistance are applied to a position in contact with the combustion gas, and the heat-insulating materials having a low thermal diffusivity are applied to the backside thereof. SiC/SiC composite, which has excellent oxidation resistance, is applied to gas turbine engines and contributes to increase engine performance due to light weight and heat-resistant improvement. Scramjet, flying at hypersonic speed, has been studying the development of C/SiC structures using the endothermic fuel as a coolant because the intake air temperature is very high. In this paper, characteristics, application examples, and development trends of various heat-resistant composites used in solid rocket nozzles, gas turbine engines, and ramjet/scramjet propulsions were discussed.

Examination of Ingredients of High Temperature Heat Resistant Inorganic Fire-Resistant Adhesive Using XRD Analysis (XRD 분석을 이용한 고온가열 무기계 내화 접착제의 성분검토)

  • Cho, Hyeon-Seo;Ji, Woo-Ram;Shin, Ki-Don;Lee, Gun-Cheol
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2018.11a
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    • pp.81-82
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    • 2018
  • The structure of the RC structure is actively reinforcing the structure of the building which has suffered from aging, artificial and natural damage of the building. Among various reinforcement methods, epoxy adhesive is used to attach FRP in FRP reinforcement method which is reinforcing by attaching FRP to the structural part. At this time, the epoxy adhesive having a low critical temperature has a sudden adhesive failure upon exposure to heat, and thus, the development of an inorganic fireproof adhesive having a high critical temperature has progressed. Therefore, in this study, the compositional change of inorganic fire - resistant adhesive exposed to high temperature heat was analyzed by XRD.

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A Study on Heat Resistance of High Temperature Resistant Coating

  • Zhang, Liping;Wang, Xueying;Zhang, Qibin;Qin, Yanlong;Lin, Zhu
    • Corrosion Science and Technology
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    • v.4 no.2
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    • pp.60-63
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    • 2005
  • A high temperature resistant coating has been developed, which is mainly for heavy oil production pipes deserved the serious corrosion. The coating has excellent physical and mechanical performance and corrosion resistance at room and high temperature. In order to simulate the underground working condition of heavy oil pipes, the heat resistance of the high temperature resistant coating has been studied. The development and a study on the heat resistance of the DHT high temperature resistance coating have been introduced in this paper.