Простой метод изготовления нанопроволок карбида кремния

In this work, we introduce a simple and convenient approach for growing SiC nanowires (SiCNWs) directly on carbon source from graphite. The commercial SiO powder and the cheap common graphite were used as the source materials. SiCNWs have been synthesized during holding time less than 60-80 min at 1450-1500 C by using a simple and low-cost method in an industrial furnace with a resistant heater.У даній роботі представлено простий і зручний підхід для вирощування нанодротів карбіду кремнію (SiCNWs) безпосередньо на джерело вуглецю з графіту. У якості вихідних матеріалів були використані промисловий порошок SiO і дешевий звичайний графіт. SiCNWs були синтезовані за допомогою простого і недорогого методу під час витримки в промисловій печі зі стійкими нагрівачем 60-80 хв при температурі 1450-1500 С.В данной работе представлен простой и удобный подход для выращивания нанопроволок карбида кремния (SiCNWs) непосредственно на источнике углерода из графита. В качестве исходных материалов были использованы промышленный порошок SiO и дешевый обычный графит. SiCNWs были синтезированы с помощью простого и недорогого метода во время выдержки в промышленной печи с устойчивыми нагревателем 60-80 мин при температуре 1450-1500 С

Carbon ceramics from plants: Graphitization of biomorphic matrixes

Properties of matrixes obtained from plants at various pyrolysis temperatures have been discussed. The article is devoted to graphitization of carbon matrixes obtained from plants. All stages of production, starting from preparation of the precursors up to high-temperature pyrolysis, have been considered together with some specific properties of matrixes at each stage. Previously unexplored new structural surface changes have been found. The use of potassium-doped wooden precursors showed the graphitization property of the matrix surfaces and allowed to form the matrix capillary wall coating with layers of crystalline graphite as well as graphene flakes and films with a low number of defects. New possibilities to apply these matrixes as examples of ultracapacitor, power unit filter electromagnetic interference and audio power amplifier antiresonance element have been discussed as well

Simple method for SiC nanowires fabrication

In this work, we introduce a simple and convenient approach for growing SiC nanowires (SiCNWs) directly on carbon source from graphite. The commercial SiO powder and the cheap common graphite were used as the source materials. SiCNWs have been synthesized during holding time less than 60-80 min at 1450-1500 °C by using a simple and low-cost method in an industrial furnace with a resistant heater

Biomorphous SiC ceramics prepared from cork oak as precursor

Porous ceramic materials of SiC were synthesized from carbon matrices obtained via pyrolysis of natural cork as precursor. We propose a method for the fabrication of complex-shaped porous ceramic hardware consisting of separate parts prepared from natural cork. It is demonstrated that the thickness of the carbon-matrix walls can be increased through their impregnation with Bakelite phenolic glue solution followed by pyrolysis. This decreases the material's porosity and can be used as a way to modify its mechanical and thermal characteristics. Both the carbon matrices (resulted from the pyrolysis step) and the resultant SiC ceramics are shown to be pseudomorphous to the structure of initial cork. Depending on the synthesis temperature, 3C-SiC, 6H-SiC, or a mixture of these polytypes, could be obtained. By varying the mass ratio of initial carbon and silicon components, stoichiometric SiC or SiC:C:Si, SiC:C, and SiC:Si ceramics could be produced. The structure, as well as chemical and phase composition of the prepared materials were studied by means of Raman spectroscopy and scanning electron microscopy

Effect of macrostructure on the thermoelectric properties of biomorphous SiC/Si ceramics

In this work, effect of porous macrostructure on the thermoelectric properties of biomorphous SiC/Si ceramics prepared by the liquid silicon infiltration process has been investigated. Temperature dependences of the conductivity and thermal e.m.f. have been measured within the range 20-700 °C. It has been shown that electrical resistivity of the samples decreases drastically as temperature increases over the entire temperature range, indicating semiconductor behavior. All the samples demonstrate a negative thermal e.m.f. confirming the electronic mechanism of charge transfer. It is ascertained that anisotropy of porous macrostructure of the ceramics influences considerably on their electric and thermoelectric properties. The figure of merit maximum value of 1.2×10⁻⁵ K⁻¹ at 700 °C was obtained

Biomorphic SiC from peas and beans

Biomorphic porous SiC ceramics produced by impregnation with liquid or vapor silicon of carbon matrices derived from peas (Pisum sativum L.) and beans (Phaseolus) precursors were investigated. Optical and scanning electron microscopy was used to study the structure of ceramics. It was shown that SiC ceramics made from endosperm of peas and beans seeds has inherited the alveolate structure and possesses many hierarchical pores with diameters varying between 20 to 100 µm. Raman spectroscopy investigations showed that the 3C polytype is formed at a synthesis temperature of about 1550 ⁰C, and that both 3C and 6H-SiC are formed at temperatures of about 1800 ⁰C. It is shown possibilities of production of ceramic articles of various forms from seeds

Mechanical properties of biomorphous ceramics

Mechanical properties: The Vickers hardness and bending strength of porous biomorphic SiC (bioSiC) ceramics fabricated from different natural hardwoods were investigated. It has been found that these parameters are highly dependent on the geometrical densities of ceramics, and Vickers hardness values can be well described using the Ryskevitch-type equation. It has been shown that the data of geometrical density bio-SiC ceramics can be used to estimate mechanical parameters such as bending strength. Materials with advanced properties appropriate for surgical applications are being designed. Further ways to improve the mechanical properties of ceramics and ceramic products have been discusse

Effect of Si Infiltration Method on the Biomorphous SiC Microstructure Properties

Two types of wood-based biomorphous SiC composites with different microstructure are obtained by infiltration of carbon template with liquid or vapour silicon. The oak, pine, lilac, walnut, acacia woods available in Ukraine are used as the biological template in this work. The SEM, optical and EPR data indicate that biomorphous SiC obtained by melt infiltration consists of crystalline 3C-SiC phase while that obtained by vapour infiltration consists of both crystalline and amorphous 3C-SiC phase.Були одержані два типи деревного біоморфного SiC-композиту з різною мікроструктурою просочення вуглецевого шаблону газоподібним або рідким кремнієм. Деревина дуба, сосни, бузку, волоського горіха, акації, які поширені в Україні, використовувалися як біологічний шаблон у цій роботі. Дані оптичні, СЕМ і ЕПР показали, що одержані просоченням розтопом біоморфні композити SiC складаються із кристалічної й аморфної фаз 3C-SiC.Были получены два типа древесного биоморфного SiC-композита с различной микроструктурой пропитки углеродистого шаблона газообразным или жидким кремнием. Древесина дуба, сосны, сирени, грецкого ореха, акации, распространенные в Украине, использовались как биологический шаблон в этой работе. Данные оптические, СЭМ и ЭПР показали, что полученные пропиткой расплавом биоморфные композиты SiC состоят из кристаллической и аморфной фаз 3C-SiC

Effect of Si infiltration method on the properties of biomorphous SiC

Two types of wood-based biomorphous SiC composites with different microstructure were obtained by infiltration of carbon template with liquid or vapour silicon. The oak, pine, lilac, walnut, acacia woods available in Ukraine were used as the biological template in this work. SEM, optical and AFM data indicated that biomorphous SiC obtained by melt infiltration consists of crystalline phase of 3C-SiC, while that of vapor infiltration results in formation of crystalline and amorphous phases of 3C-SiC. The same results were obtained for infiltration of carbon fibers. Thus, it was suggested that the mechanism of SiC formation is governed by the infiltration method

The growth of weakly coupled graphene sheets from silicon carbide powder

A simple method for production of weakly coupled graphene layers by hightemperature sublimation of polycrystalline SiC is presented. The method allows manufacturing carbon-based composite with a high content of weakly coupled graphene layers in large-scale production. The study of the obtained carbon-based material by means of scanning electron microscopy, Raman spectroscopy and atomic force microscopy detected graphene plates with lateral size of up to tens of micrometers. The obtained graphene sheets are shown to have very high crystal perfection, low concentration of defects and weak interlayer coupling, which depends on the growth conditions. The proposed method of producing graphene-based composites is supposed to be very promising due to its relative simplicity and high output