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排序方式: 共有69条查询结果,搜索用时 15 毫秒
1.
《Ceramics International》2022,48(20):29959-29966
High-purity SiC ceramic devices are applied in semiconductor industry owing to their outstanding properties. Nevertheless, it is difficult to densify SiC ceramics without any sintering additive even by HP sintering. In this work, high-purity and dense SiC ceramics were fabricated by HP sintering with very low amounts of sintering aids. Residual B content was only 556 ppm and relative density was more than 99.5%. Furthermore, thermal conductivity of as-prepared SiC ceramics was improved from 155 W m?1 K?1 to 167 W m?1 K?1 by increasing holding time and their plasma corrosion resistance was promoted in the meantime. The as-prepared high-purity SiC ceramics have broad application prospects in the field of semiconductor industry. 相似文献
2.
生产电子工业用高纯氮的制氮装置 ,其要点和难点是一氧化碳和氢的清除。采用一氧化碳转换炉和特殊的冷箱内流程组织 ,可以生产纯度为 99 9999%以上的高纯氮。对制取电子工业用高纯氮制氮装置与常规制氮装置加氮终端净化器两种流程进行了比较。 相似文献
3.
本文叙述了用电解精炼法在制备高纯铅过程中,降低铜、铋、锡杂质含量的各种措施和试验结果,比较详细地介绍了用硫化法降低电解液中的铜、铋、锡杂质的新工艺。 相似文献
4.
利用天然二氧化锰粉与硫化锰精矿为原料制备高纯一水硫酸锰,并取得了初步成功。其最优工艺为:以二氧化锰与硫的摩尔比为2.25:1,在温度90~C条件下浸出3h后,除渣,再用A试剂1.5倍理论用量除去硫酸锰溶液中的钾钠,按工业硫化钡1.5倍理论用量除去各重金属,用氟化锰5倍理论用量除去钙镁后蒸发结晶烘干,得到高纯一水硫酸锰产品。 相似文献
5.
研究了在铟生产中的置换过程和电解精炼过程中的酸度对锌含量的影响,以及锌含量的控制。在置换过程中,当酸含量控制在15~25g/L时,能控制反应的速度,从而降低粗铟中锌的含量;在电解精炼中,溶液的pH值为2~3,可使铟中锌的含量降低至0 5μg/g,并提出了采用硫酸或氢氧化钠来控制溶液酸度的方法;用海绵铟熔铸阳极时,采用NaOH熔炼的同时,加入NaCl能降低碱性熔渣的黏度,提高NaOH对Zn(OH)2、Na2ZnO2等的吸收能力,降低铟中锌的含量。 相似文献
6.
Yu V. Korneeva V.B. Chzhan I.S. Tereshina T.P. Kaminskaya E.A. Tereshina-Chitrova H. Drulis K. Rogacki 《International Journal of Hydrogen Energy》2021,46(27):14556-14564
Hydrogen absorption often induces changes of various properties of rare-earth metals. In this paper, we study the influence of hydrogenation on the structural, magnetic and magnetocaloric properties of high-purity nanocrystalline terbium. Strong (00l) texture present in the parent Tb sample is practically destroyed after the hydrogenation procedure. We observe formation of agglomerates of different sizes and shapes depending on the hydrogen content in the samples. We find traces of β-hydride (TbH2) in the main α-hydride TbHx phase. For TbHx with x = 0.25 and 0.5 at.H/f.u. The effect of hydrogenation on the magnetocaloric properties is studied in magnetic fields up to 9 T. The magnetocaloric effect decreases after hydrogenation. The -ΔSM(T) curves feature a table-like effect in the vicinity of the magnetic phase transitions in magnetic fields exceeding 1 T. 相似文献
7.
《Journal of the European Ceramic Society》2017,37(4):1799-1804
CM2A8 is a solid solution of MA and CA6. As a component in the ternary phase diagram of CaO-Al2O3-MgO, it was not reported in detail. So in this work, analytically pure CaO, MgO and Al2O3 were adopted as starting materials and batched stoimotrically according to CM2A8. The raw materials were ground, mixed, shaped and reaction-sintered at different temperatures (1550 °C, 1650 °C, 1700 °C, and 1750 °C) to synthesize CM2A8. The synthesized specimens were analyzed by XRD, SEM, and TEM and the corrosion mechanism against LF slag was also researched. The results show that high-purity CM2A8 can be synthesized by reaction sintering at 1750 °C. During synthesis, granular MA and flake CA6 form and grow together; at 1650 °C, they solid-solve together to form C2M2A14. As the temperature rises, solid solution reaction goes on, which results in the disappearance of CA6, C2M2A14, and MA in succession and forms high-purity CM2A8 growing towards hexagonal column crystals. In the high temperature reaction between CM2A8 and steel slag, Ca2+ in the slag reacts with CM2A8 to form CA2, damaging the structure of CM2A8 and releasing excessive Mg2+ and Al3+ which move towards the molten slag. As the reaction between Ca2+ and CM2A8 proceeds, a dense CA2 coating forms on the surface of CM2A8. The slag viscosity increases as well because of the entrance of Mg2+ and Al3+. Thus, the formation of the CA2 coating and the enhancement of the slag viscosity restrain the penetration and corrosion of slag towards CM2A8. 相似文献
8.
A friction stir processing (FSP) technique has been developed for use with aluminum and magnesium alloys, with the goal of high-strain-rate processing. In this study, we treat the microstructures of aluminum samples, of three levels of purity, manipulating their grain sizes, making them finer, using FSP. Grain sizes decreased with an increase in the Zener-Hollomon parameter, at all purity levels. However, the recrystallized grain of FSP-ed ultra-high-purity (99.999%) aluminum was particularly large, compared to the grain sizes of lower-purity (99% and 99.99%) aluminum, when subjected to the same processing conditions. The grain size reached a certain minimum value at high-strain-rates of processing, which we report for each purity level herein. 相似文献
9.
Z. -Q. Fang B. Claflin D. C. Look L. Polenta W. C. Mitchel 《Journal of Electronic Materials》2005,34(4):336-340
High-purity semi-insulating (HPSI) 4H-SiC has been widely used as a substrate material for AlGaN/GaN high electron-mobility
transistors because of its fairly good lattice match with GaN and its high thermal conductivity. To control material quality,
it is important to understand the nature of the deep traps. For this purpose, we have successfully applied thermally stimulated
current (TSC) spectroscopy to investigate deep traps in two HPSI 4H-SiC samples grown by physical vapor transport (PVT) and
high-temperature chemical vapor deposition (HTCVD), respectively. Fundamentals of TSC spectroscopy, typical TSC spectra obtained
on the two samples, and theoretical fittings of a boron-related trap (peaked at ∼ 150 K) will be presented. Based on literature
data for deep traps in conductive 4H-SiC, the impurity and point-defect nature of several commonly observed TSC traps, peaked at ∼105 K (0.22 eV), ∼150 K (0.29
eV), ∼175 K (∼0.33 eV), ∼260 K (∼0.53 eV), ∼305 K (∼0.63 eV), and ∼360 K (0.91 eV), in the HPSI 4H-SiC will be discussed. 相似文献
10.