排序方式: 共有31条查询结果,搜索用时 15 毫秒
1.
Potency of Different Carbon Sources in Reduction of Microsilica to Synthesize SiC from Mechanically Activated Powder Mixtures
下载免费PDF全文
![点击此处可从《International Journal of Applied Ceramic Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Amin Jamshidi Hamid Tajizadegan Omid Torabi 《International Journal of Applied Ceramic Technology》2016,13(5):937-947
In the present study, the influences of three different types of carbon (carbon black, graphite, and petroleum coke) on SiC synthesis via mechanical activation and sintering were evaluated. In this regard, the phase components, morphology, and the formation mechanism were investigated. SiC nanoparticles were detected to be formed after 4 h of milling and sintering at 1450°C, regardless of the sources of carbon. The carbon types exert their effects on the morphology of the as‐synthesized particles, where carbon black leads to form rod‐like SiC particles and the other two carbon types result in semi‐spherical SiC particles. This is due to the dominant mechanism in the mentioned process. The rod‐like particles obtained from the carbon black‐containing powder were synthesized via the VSL mechanism, whereas the solid‐state reactions occurred to form the SiC particles in the graphite‐ or petroleum coke‐containing samples. In the VSL mechanism, any increase in the milling time leads to facilitate the SiC formation due to entrance of Fe debris, whereas in the other samples (graphite or petroleum coke) the procedure is reversed. 相似文献
2.
为探讨硅粉对混凝土绝热温升的影响,配制了15组不同水胶比、不同硅粉掺量的硅粉混凝土配比试样作半绝热温升值测量,并通过热补偿法获得绝热温升值。结果表明:硅粉能降低混凝土绝热温升量,其中掺5%硅粉降低绝热温升值1.8~7.3 ℃,掺10%硅粉降低绝热温升值3.3~10.2 ℃,绝热温升降低程度受水胶比的影响;硅粉能在要求相同强度情况下显著降低混凝土绝热温升值。基于硅粉混凝土绝热温升值结果,通过回归分析获得绝热温升值预测式,并绘制了硅粉混凝土绝热温升值设计图,可供从事混凝土温度控制的技术人员参考。 相似文献
3.
《中国有色金属学会会刊》2020,30(5):1406-1418
The main objective of this work is to research complex physical−chemical processes of Al(l)−SiO2 interface and develop a new technology for producing foundry silumins based on amorphous microsilica obtained from silicon production waste. Effective methods for producing hypoeutectic, eutectic, and hypereutectic silumins using amorphous microsilica were developed. Alloys with a silicon content of 7 wt.% were obtained by blowing preheated amorphous microsilica into the aluminum melt (t=900 °C) along with the stream of argon followed by intense mixing. Alloys with a silicon content of 21 wt.% were manufactured by induction melting of a silicon-containing mixture (60% SiO2, 40%Al + 20%3NaF·2AlF3) subjected to the presintering when the amorphous microsilica was reduced to crystalline silicon. It is found that crystalline silicon, which is formed during the roasting of the tableted burden, is smoothly absorbed by the aluminum melt. Aluminum oxide, obtained during the redox reaction, dissolves in cryolite, after which aluminum and silicon are fused together and transferred to the melt. The calculation of the economic efficiency of producing silumins using amorphous microsilica demonstrates a quick project payback period, as well as a high level of its profitability. 相似文献
4.
5.
实验以镁砂为主要原料,以硫酸镁为结合剂,以二氧化硅为辅助结合剂。骨料颗粒临界尺寸为5mm,采用连续颗粒:5—3mm、3~1mm、1~0mm、〈0.074mm进行配比。保持二氧化硅微粉加入量3%,改变硫酸镁的加入量:1%、2%、3%、4%、5%。在110℃×24h、1100℃×3h和1550℃×3h烧成。研究和测试了试样的物理性能。结果表明:硫酸镁的合适加入量为3%~4%。 相似文献
6.
7.
WEI Jiangxiong CHEN Yimin LI Yongxin 《武汉理工大学学报(材料科学英文版)》2006,21(2):88-91
It was proved that MgO and MicroSilica can react at room temperature, giving a hardened product primarily comprised of Mg ( OH )2 and Magnesium Silicate Hydrate ( M- S- H ). The reaction ratio and process and the chemical composion of M- S- H were studied and analyzed by QXRD and DTA- TG. The experimental results indicate that much Mg( OH)2 and less M-S-H were formed at early period. After 7 days there is no change in the quantity of Mg( OH)2, while M-S-H was increased slowly. The chemical composion of M-S-H would vary with the mix proportion in the hydrution process , but M1.32 SH2.37 is finally the approximute form. 相似文献
8.
Rafael Salomão Leandro Fernandes Natalia C. M. Spera 《International Journal of Applied Ceramic Technology》2021,18(5):1702-1709
The in situ formation of mullite (Al6Si4O13) is a complex process based on solid-state reactions strongly affected by the characteristics of Al2O3 and SiO2 sources. This study investigated the combined effects of variable SiO2/Al2O3 ratios and the presence of low-melting-point impurities on the physical properties and microstructure of in situ alumina-mullite ceramics. Two grades of synthetic amorphous silica, known as microsilica, of similar physical properties and significant differences in the content of alkali-based impurities (0.8 and 3.6 wt%), were combined with thin calcined alumina particles in different proportions (from silica-free up to stoichiometric mullite), pressed and sintered. The samples were tested for total porosity, flexural strength, and pore size distribution, and their crystalline phases and microstructures formed were investigated. Small amounts of both microsilica grades (up to 8.9 wt%) hindered the densification of the alumina-mullite matrix and favored grain growth events, increasing porosity and reducing strength. For samples containing higher microsilica loads (16.4–28.2 wt%), the impurities content significantly affected the amount of liquid phases formed. Such impurities altered the ratio and shape of the pores and the total amount of mullite after sintering. Therefore, different microstructures and levels of flexural strength and total porosity were observed. 相似文献
9.
10.
通过调整镁质中间包涂料的基质配比,以期提高中间包涂料的中温强度.结果表明:随着二氧化硅微粉加入量的增多,试样的体积密度与气孔率虽然没有明显的差异,但是经中温处理后,试样的抗折强度逐渐提高.当二氧化硅微粉加入量超过4%时,常温抗折强度、常温耐压强度、线变化率、抗渣等性能趋于稳定;调整硼玻璃加入量,常温抗折耐压强度均有提高,抗渣性能有所降低,硼玻璃加入量过多时,极大的降低了试样的高温抗折强度. 相似文献