Papers by Keyword: Silicon Oxycarbide

Abstract: Lithium Titanate (LTO) is one of the anode materials that has good performance because of its unique properties, which is zero-strain. In this study, LTO was synthesized using the sol-gel method and mechanochemical hydrothermal with LiOH as the source of lithium-ion. Silicone oxycarbide (SiOC) is a ceramic material synthesized through a simple pyrolysis process of silicone oil precursors. Carbon used in this study is a carbon activated process so that activated carbon is obtained with a large pore size. The addition of activated carbon to the LTO is done during the sol-gel process, while the addition of SiOC to LTO-C is performed during the slurry making process. SEM-EDS shows the extent of the elements in the sample where Ti, F, Si, O, and C are present. Also, SEM-EDS characterization shows an increase in the amount of carbon in each sample. XRD shows the presence of the LTO spinel phase and impurity phases such as TiO₂ rutile and anatase, and Li₂TiO₃. In EIS performance testing, low resistivity expresses high conductivity. In this research, high conductivity is owned by LTO-1% C/SiOC. In addition, CV and CD performance tests were performed where the highest specific capacity was obtained in the LTO-5%/SiOC samples.

Abstract: In this paper, Hf element was introduced into the Si-O-C network by the sol-gel method using the dimethyldiethoxysiloxane (DMDES, (CH3)2Si(OC2H5)2) and hafnium tetra(n-butoxide) (HfOR, Hf(OC4H9)4) as raw materials. The SiOC/HfO2 ceramic composite was obtained by pyrolyzing Si-Hf-O-C gel at 1000 °C in argon. FT-IR spectra revealed the presence of Si-O-Hf peaks at 932 cm-1. The weight loss of the as-prepared SiOC/HfO2 was about 0.2 wt.% under argon atmorsphere up to 1550 °C, which was much lower than the hafnia-free SiOC composites and exhibited a remarkable improved thermal stability.

Abstract: Silicon oxycarbide（SiCO）thin films is a kind of glassy compound materials, which possess many potential excellent properties such as thermal stability, wide energy band, high refractive index and high hardness, and have many potential applications in space. The preparation processes of SiCO thin films by RF magnetron sputtering with different substrate temperature, working pressure and sputtering power were studied. And various surface analysis methods were used to characterize the optical properties of SiCO thin films. The dependence of the properties on the process parameters was also studied. The tested properties of SiCO thin films deposited on K9 glass indicated that lower substrate temperature and sputtering power, higher working pressure could get SiCO thin films with better light penetration and the refractive index of SiCO thin films had a large varying region with the change of the process parameters. With different substrate temperature, working pressure or sputtering power, the maximum refractive index at 633nm（wavelength） are 2.20051, 2.12072 and 1.98959, respectively, and the minimum ones are 1.89426, 1.83176 and 1.8052, respective.

Abstract: Sol-Gel technology was used to develop carbon, silicon and oxygen based ceramics as well as their composites with Carbon fiber and nano siliconcarbide as reinforcements. Gels with different composition were prepared from TEOS, HMDSO and DEDMS. Dried gels were post-cured in air and pyrolyzed at 1000oC in nitrogen atmosphere. Each step of sol-gel process was characterized for density, thermal behaviour and functionality. Composites were prepared using different sols (derived from TEOS, HDMSO and DEDMS) as matrix precursors and carbon fabric as reinforcement. To some composites another phase of solid, micro/nano powder precursor of SiC was added to decrease number of impregnation cycles. Latter composites resulted in higher density. Green composites were post-cured and pyrolyzed. These composites were characterized for density and microstructure. It revealed that the resulting matrix was solid glasses and addition of SiC powder facilitated the rapid densification. Composites prepared with SiC nanparticles as well as Carbon fabric as reinforcement exhibit higher flexural strength than those made without nanoparticles. The fracture behaviour is also seen to be of mixed mode failure type.

Abstract: The aim of the present work was to investigate the high temperature reaction between Si- C-O fibres and Cl2, and to correlate the carbon layer growth kinetics with their initial composition and structure. Large disparities have been observed between the various materials reaction rates. If a large amount of mixed silicon atom environments increases the reactivity of Si-O-C materials with Cl2, this sole feature does not explain all the experimental results. Traces of heteroelements (Ti, Zr, Al…) or percolated free carbon both appear to bear on the reaction rate. For a better understanding of the fibres reaction behaviour, this study was extended to other model materials (oxycarbide glasses, oxygen-free Si-C fibres, SiC).

Abstract: Melt spinnable silicone resin with a low carbon content was spun to fiber form with an averaged diameter of 16.8 m. When the resin fiber was cured by SiCl4 vapor and pyrolyzed at 1273K in inert atmosphere, Si-O-C fiber with smooth surface was obtained. The measured tensile strength was relatively low. The fiber, however, showed oxidation resistance during high temperature exposure under an air flow. When the fiber was cured by TiCl4 with an increased vapor pressure at 313K, 40% mass gain was observed after the curing. SiO2-TiO2 fiber was obtained by pyrolysis in an air flow, while SiOC-TiO2 fiber was obtained by pyrolysis in an inert atmosphere. Structure of TiO2 and the resulting fiber surface morphology strongly depended on the temperature and the atmosphere during the pyrolysis.

Abstract: Polymethylsilsesquioxane (PMSQ) fiber was exposed to metal chloride vapors in a controlled atmosphere or electron beam irradiation in air to promote the curing process. The cured fibers were pyrolyzed at 1273K to compare the efficiency of individual curing method. The cured fibers were investigated by FT-IR, an optical microscope and TG analysis. In the case of successful curing, averaged diameter and tensile strength were analyzed on the obtained Si-O-C fibers.