Papers by Keyword: Heat-Resistance

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Authors: Li Shi Wang, Chun Xu Pan, Qi Zhou Cai, Bo Kang Wei
Abstract: This paper reports the heat-resistance of plasma electrolytic oxidation (PEO) coatings formed on AZ91D alloy in phosphate electrolytes (P-film) and silicate electrolytes (Si-film). The results showed that the P-film was mainly composed of MgAl2O4, MgO and the Si-film was composed of Mg2SiO4, MgO. Thermoanalysis results verified that all these phases contained in the two type coatings had excellent thermal stability below 800oC. Meanwhile, the total area of heat erosion formed on the surface of samples tended to be increased with the exposure time prolonged in high temperature (410 oC and air atmosphere).
2459
Authors: Kai Ju Luo, Yan Wang, Jun Rong Yu, Jing Zhu, Zu Ming Hu
Abstract: The preparation and characterizations of soluble copolymers poly (p-phenylene terephthamide-co-furandicarboxylic p-Phenylenediamine)(PPTA-co-PPF) by direct polycondensation was described. The chemical structure of polyamides was investigated by 1H NMR and FT-IR. The good solubility of copolymers in organic solvents was certified at room temperature. Their thermal stability and mechanical properties were observed by TGA and tensile testing and then compared with that of traditional high performance aromatic polyamides (PPTA and PMIA, for example, with trademarks of Kevlar® and Nomex®). The furan ring incorporated polyamide was expected to form thermal reversible cross-linked polymer network through D-A reaction.
2174
Authors: Kotoji Ando, Byung Soo Kim, Min Cheol Chu, Shinji Saitou, Sigemi Sato
175
Authors: Jin Li Zhou, Shu Zhu, Wen Pin Jia, Chao Cheng, Elwathig A.M. Hassan, Mu Huo Yu
Abstract: In order to improve the toughness of epoxy resin, hydroxyl-terminated polyethersulfone (PES) with various amounts (0 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%) were added to bisphenol A epoxy resin (DER331)/ curing agent DETDA (E100) systems, and the influence of PES contents on curing process and heat-resistance was studied. Non-isothermal DSC was used to determine the curing process of uncured DER331/E100/PES systems at heating rate of 2°C/min, 5°C/min, 7°C/min, 10°C/min and 15°C/min separately, and the apparent activation energy was calculated based on Kissinger method. The morphology of the etched cured DER331/E100/PES systems with different PES contents was observed by SEM. The heat-resistance of these systems was investigated by DSC and TGA. The results showed that with the increasing of PES content the curing exothermic peak, the heat of curing reaction, the initial and final curing temperature all decreased at the first and then increased, indicating that when the PES content was low (5 wt.%, 10 wt.%), PES can facilitate the curing process, while, when PES content up to 15 wt.%, PES can prevent or weaken the curing reaction. SEM results indicated that the phase structure changed drastically depending on the PES content. The systems with 5 wt.% and 10 wt.% PES were epoxy-rich phase, with 15 wt.% PES was co-continuity phase, and with 20 wt.% PES showed complete phase inversion (PES rich phase). The glass transition temperature and thermo gravimetric analysis demonstrated that the addition of PES can increase the heat resistance of cured DER331/E100/PES systems.
2302
Authors: Yasuhiro Gokan, Atsuya Suzuki, Shuuhei Nozawa, Ifeanyi Anthony Anyanwu, Shigeharu Kamado, Yo Kojima, Suguru Takeda, T. Ishida
451
Authors: Jeong Min Kim, Bong Koo Park, Kee Sam Shin, Joong Hwan Jun, Ki Tae Kim, Woon Jae Jung
Abstract: Effort has been devoted to develop new heat resistant diecasting alloys based on Mg-Al- Zn system in this research. Small amounts of cerium-rich misch metal and antimony additions to AZ91 alloy could enhance the tensile strength at an elevated temperature while keeping the good castability. The increase of Zn content in Mg-8(wt%)Al-xZn-0.5RE-0.5Sb alloys, was observed to significantly increase the yield strength at 175oC although the castability such as fluidity and hot cracking resistance was slightly decreased. Intensive microstructural investigation on the new Mg- Al-Zn diecasting alloys was also carried out.
525
Authors: Jeong Min Kim, Bong Koo Park, Joong Hwan Jun, Ki Tae Kim, Woon Jae Jung
Abstract: Various amounts of Ca were added to AZ91D magnesium alloy, and their effects on the die-casting abilities were investigated. It was observed that fluidity as die filling ability tends to decrease by Ca additions except for about 2%Ca. This reduction of fluidity by Ca was more significant at high superheats probably due to the high affinity between Ca and oxygen. Contrary to expectation, hot cracking resistance was found to increase by Ca additions. High Ca alloys showed some die-sticking tendency. However, the tendency was not observed below 2%Ca.
424
Authors: Keisuke Teranishi, Tomohisa Azuma, Masakazu Hirose
Abstract: The effect of adding Al2O3 to the PZT-PMN solid solution material for use for ceramic resonator was investigated. It has been found that when the amount of Al2O3 added to PZT-PMN is 0.3 wt% or below, it exists inside the crystal lattice as Al3+ ion and increases the stability of oscillation frequency over application of heat (heat resistance). It has been found that when more than 0.3 wt% of Al2O3 is added, the Al3+ ion that remained undoped will exist at grain boundary as secondary phase, and increase the strength.
19
Authors: Xian Feng Zhang, Shuang Feng Wang
Abstract: The present work experimentally investigated the operating characteristics of a miniature loop heat pipe (LHP) under different power cycle. The miniature LHP with flat evaporator of 8mm thick is made of copper. The evaporator with sintered copper power wick is in series structure with compensation chamber. Water is working fluid. It is found that the LHP can start up at heat load of 15W with temperature oscillation and the maximum heat load is 160W with Rl=0.068°C/W. The LHP operates unstably under low heat load. The oscillating frequency of temperature rises with heat load increased. The operating performance of the LHP is affected by the power cycle.
3806
Authors: A.S. Tyusenkov, A.V. Rubtsov, R.R. Tlyasheva
Abstract: Heat-resistance (scale resistance) is the steel corrosion fastness in dry gas at high temperatures. At the temperatures over 570 °С, the ferrous alloys oxidize, as ferric oxide (wustite) with simple cubic lattice appears on the metal surface. Such oxide lacks oxygen atoms (omission solid solution) and does not interfere with the diffusion between metal and oxygen. As a result of this process the brittle oxide-scale develops and the loss of metal increases. In order to increase the heat-resistance of steel, different alloying elements are included into its composition, forming oxides with the tight structure of crystal lattice. In this paper we’ve investigated the heat-resistance of some structural steels and analyzed their corrosion resistance in the high temperature aggressive environments of chemical productions.
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