Self-bonded Silicon Carbide Research Articles

Lightweight ceramics based on aluminum dodecaboride, boron carbide and self-bonded silicon carbide

The correlations between structures and mechanical characteristics of α-AlB12-, AlB12C2-, B4C-based lightweight ceramics and composites synthesized or sintered by hot pressing (at 30 MPa) and SiC-based ceramics obtained by reactive sintering are compared. The effect of C, TiC and SiC additions on the properties of the resultant composites and the particularities of the ceramics destruction under shock loading are discussed. Ballistic tests performed on 10 mm thick plates fabricated from the developed ceramics (2.63 g/cm3 density; 78 wt% B4C and 22 wt% SiC composition according to X-ray diffraction analysis; B3.64CSi0.01 and SiC1.07 stoichiometry according to SEM microprobe X-ray analysis), showed that the material could withstand a 10 m distance shot using a bullet with initial kinetic energy of 3.7 kJ.

Preparation and investigation of silicon carbide materials on the basis of reaction-bonded silicon carbide

The regions of the optimum density and SiC content of the billet for the reaction-bonded silicon carbide (RBSC) technology that correspond to the maximum density of the final sample with the minimum amounts of residual carbon and silicon are calculated and experimentally proven. On the basis of the obtained data, the samples of silicon carbide ceramic showing a rather high level of physical and mechanical properties, in particular, the density in the range from 2.75 to 3.01 g/cm3, the bending strength in the range from 300 to 350 MPa, and the elastic modulus ranging from 350 to 430 GPa, and having no significant deviations from the stoichiometric composition are prepared using the RBSC technology. The developed RBSC technology allows one to produce a material which has density, elastic modulus, and compressive and bending strengths in an intermediate position between materials obtained by the siliconized graphite (SG) and self-bonded silicon carbide (SBSC) technologies.

Self-Bonded Silicon Carbide Layer on Carbon Foil: Preparation and Properties

We suggest a method of growing silicon carbide crystal layers on carbon foil. The material is produced by moving a carbon foil tape at a speed up to 2.5 m/min in dynamic vacuum against a graphite capillary feeder that contains molten silicon. As a result of various chemical vapor reactions, SiC crystals grow at a speed up to 1.5 mm/s.. The crystals and the foil form a composite material with semiconducting properties. In this article, we have discussed relevant patents. Keywords: CVD (chemical vapor deposition), graphite foil, nanocomposites, (PL) photoluminescence, semiconducting properties, XRD (X-ray diffraction).

Effect of SiC particle size on flexural strength of porous self-bonded SiC ceramics

Porous self-bonded silicon carbide (SBSC) ceramics were fabricated from SiC powders with various particle sizes (0.7 μm, 25 μm, 50 μm, 65 μm), plus Si, C and boron (as a sintering additive). The effects of submicron (0.7 μm) SiC particle incorporation into the SBSC and the SiC particle size (25 μm, 50 μm, 65 μm) on the flexural strength and porosity of the ceramics were investigated as a function of sintering temperature. Incorporating 0.7 μm SiC particles into the ceramic material containing 25 μm SiC particles increased the flexural strength by 3 times, from 11.7 MPa up to 35.5 MPa after sintering at 1800 °C. Simultaneously, the porosity was reduced by ∼5 %. Furthermore, the flexural strength of ceramic with 25 μm SiC particles was superior to that with 65 μm SiC particles. Generally, the flexural strength of the SBSC increased as, both, a function of submicron SiC particle incorporation along with relatively small micron-sized particles (25 μm) in the microstructure of the ceramic plus increased sintering temperature.

Influence of submicron SiC particle addition on porosity and flexural strength of porous self-bonded silicon carbide

In the present study, porous self-bonded silicon carbide (SBSC) ceramics were fabricated at temperatures ranging from 1700 °C to 1800 °C using SiC powders, silicon and carbon as starting materials. The amount of (Si + C) powders is fixed and the influence of submicron SiC particle content (0 wt.% to 80 wt.%) on the porosity and strength of the ceramics was studied. The experimental results illustrate that the packing efficiency increased with the increase in submicron particle content to 40 wt.%, and thereafter decreased. The green porosity largely determines the final porosity of the sintered specimens, irrespective of the submicron SiC particle content. The flexural strength increased with the addition of submicron particle content and sintering temperature. Typically, SBSC ceramics prepared using 80 wt.% submicron SiC particle content possess 46% porosity and 42 MPa flexural strength when sintered at 1800 °C.

Innovative porous SiC-based materials: From nanoscopic understandings to tunable carriers serving catalytic needs

Progress in developing a new class of catalyst carrier materials based on porous self-bonded silicon carbide (SiC) is reviewed. Since the demonstration of scalable economically viable β-SiC production process, innovative β-SiC-based materials with tunable physical and chemical properties were successfully synthesized. Silicon carbide has superior mechanical and thermal properties which, coupled to chemical inertness, avoids several of the problems inherent in the use of commercial oxide and carbon based supports and catalysts. High surface area SiC (35 m 2/g) can now be easily synthesized, with unmatched mechanical properties, tailored pore size distribution (meso- and macroporous network and total pore volume up to 1 cm 3/g) and at reasonable cost. It can be shaped directly into extrudates, (μ-) spheres, monoliths, open cell foams, 3D forms depending to the downstream applications. Furthermore, it can also be chemically modified for specific catalytic applications through the addition of promoters (oxides like Al 2O 3, TiO 2, ZrO 2, carbides and metals) rendering the fabrication simple and cost effective. In many respects, it combines the best properties of oxide and carbon based supports without suffering many of their disadvantages. New structured TiO 2/SiC composites have been prepared and are expected to be the next photocatalytic media. The ability of the SiC material to be used as catalyst support will be illustrated in the present work by two exothermic reactions, namely the selective oxidation of trace amount of H 2S and the Fischer–Tropsch synthesis. For this later, a direct comparison was also made with a traditional support, i.e. alumina.

Effect of the loading rate on the strength of self-bonded silicon carbide ceramic materials

In this paper, the procedures for testing self-bonded silicon carbide ceramic materials under static and dynamic (impact) loading are described. The results of the investigations on the effect of the loading rate on the strength variation of ceramic materials used as elements of impact-resistant barriers are presented.

알루미늄 첨가가 다공질 Self-Bonded SiC 세라믹스의 기공률과 꺾임강도에 미치는 영향

Porous self-bonded silicon carbide (SBSC) ceramics were fabricated at temperatures ranging from 1750 to 1850℃ using SiC, Si, C as starting materials and Al as an optional sintering additive. The effect of Al addition on the porosity and strength of the porous SBSC ceramics were investigated as functions of sintering temperature and Si:C ratio. The porosity increased with decreasing the Si:C ratio and increasing the sintering temperature. It was possible to fabricate SBSC ceramics with porosities ranging from 37% to 44% by adjusting the Si:C ratio and the sintering temperature. Addition of Al additive promoted densification and necking between SiC grains, resulting in improved strength. Typical flexural strengths of SBSC ceramics with and without Al addition were 44 ㎫ and 34㎫, respectively.

Formation of high-density structure of self-bonded silicon carbide

An alternative method has been developed for fabricating high-density products from ceramics based on self-bonded silicon carbide. The product blanks are formed by slip molding of thermoplastic mixtures under pressure. The composition of the polyfractional mixture has been defined and new temporary binders, whose rheological properties ensure high density of the products, have been formulated.

탄소 원료가 다공질 Self-Bonded SiC (SBSC) 세라믹스의 기공율과 곡강도에 미치는 영향

Porous self-bonded silicon carbide (SBSC) ceramics were fabricated at temperatures ranging from 1700 to 1850℃ using SiC, silicon (Si), and three different carbon (C) sources, including carbon black, phenol resin, and xylene. The effects of the Si:C ratio and carbon source on porosity and strength were investigated as a function of sintering temperature. Porous SBSC ceramics fabricated from phenol resin showed higher porosity than the others. In contrast, porous SBSC ceramics fabricated from carbon black showed better strength than the others. Regardless of the carbon source, the porosity increased with decreasing the Si:C ratio whereas the strength increased with increasing the Si:C ratio.

Si:C Ratio가 다공질 Self-Bonded SiC 세라믹스의 기공율과 곡강도에 미치는 영향

Porous self-bonded silicon carbide (SiC) ceramics were fabricated at temperatures ranging from 1750 to 1850℃ using SiC, silicon (Si), and carbon (C) powders as starting materials. The effect of the Si :C ratio on porosity and strength was investigated as a function of sintering temperature. It was possible to produce self-bonded SiC ceramics with porosities ranging from 36% to 43%. The porous ceramics showed a maximal porosity when the Si :C ratio was 2 : 1 regardless of the sintering temperature. In contrast, the maximum strength was obtained when the ratio was 5:1.

Effects of Si:C Ratio and Carbon Source on Properties of Porous Self-Bonded Silicon Carbide Ceramics

Effects of Si:C Ratio and Carbon Source on Properties of Porous Self-Bonded Silicon Carbide Ceramics

Structure Formation of Multiphase Compacts in the System SiC′ ― Carbon. Part 3. Structure Formation in the System SiC′ ― Carbon during Sintering

The effect of particle size for the original silicon carbide and carbon powders and effects connected with influence of the original components structures, as well as the structure and phase composition of self-bonded silicon carbide are studied.

Structuring of Multiphase Compacts in the SiC′ ― Carbon System. Part 2. Structuring during Sintering

We have studied the effect of particle sizes in the starting powders in the silicon carbide ― carbon system, and also effects on the structure and phase composition of self-bonded silicon carbide (SBSC) that are associated with structural interactions between the starting components.

Effect of charge composition on the structure and electrophysical properties of self-bonded silicon carbide

Computer treatment of experimental data using the method of Kriging permitted an analysis of the structure, phase composition, and electrophysical properties of silicon carbide materials produced by liquid-phase reactive sintering over a broad range of initial charge compositions. The optimal values of the electrophysical properties were determined, and the possibility of predicting the charge composition for the production of material with given electrophysical properties demonstrated.

Deformation and destruction of self-bonded silicon carbide under different loading rates

Deformation and destruction of self-bonded silicon carbide under different loading rates

Deformation characteristics of silicon carbide and chamotte refractories

It was established that silicon-carbide refractories with bonds of silicon nitride and oxynitride, and also self-bonded silicon carbide articles possess 2–3 times higher elasticity moduli compared with chamotte (firebrick) refractories.

Preparation and Properties of Self-Bonded Silicon Carbide

The preparation and properties of self-bonded silicon carbide (SBSC) are presented. The properties include Young's modulus (E), bulk modulus (μ), rigidity modulus (K), Poisson's ratio (σ) and electrical resistivity (ρ). E, μ and K for SBSC rods pressed at 76 MN.m−2 were found to be 0.329, 0.422 and 0.122 GN.m−2 respectively and ρ for the above rods varied from 0.42 to 0.22 ohm.cm at room temperature and 1000°C respectively with a minimum at 600°C.

Influence of oxidation on the destruction of self-bonded silicon carbide

The strength of self-bonded SiC in air at 700°C and above is lower than in inert medium. This is connected with the development of defects in the surface layer of the specimens of the materials studied as a result of oxidation. To improve the mechanical characteristics of the material it is necessary to reduce the concentration in it if impurities, and the size of the inclusions of free silicon. During heating in air to temperatures above 1300°C processes of mass transfer occur through the gas phase into the cracks, coming out onto the surface of the material.

Failure of self-bonded silicon carbide under dynamic pressure

Failure of self-bonded silicon carbide under dynamic pressure