Reaction Bonded Silicon Carbide

Reaction bonded silicon carbide (RBSC) is an extremely strong and resilient ceramic that finds use in numerous applications such as gas turbine engines and wear components.

Reaction bonding involves infiltrating porous carbon material with molten silicon to produce an elastic ceramic hybrid that can be shaped using conventional ceramic forming techniques such as pressing, injection molding and extruding.

High Purity

Silicon Carbide (SiC) is one of the hardest ceramics, maintaining hardness and strength even at elevated temperatures. Chemically inert and solvent resistant, SiC boasts good thermal conductivity – half that of steel! JJISCO produces both standard and custom SiC products to provide optimal performance for industrial needs.

Reaction Bonded Silicon Carbide (RBSC) is made from a porous mixture of SiC and carbon that has been infiltrated with liquid or gaseous silicon infiltrating its pores, reacting with carbon to form additional silicon carbide which bonds its initial particles together and forms dense, strong bodies with significantly better impact and wear resistance than sintered SiC, while offering higher temperature oxidation resistance than CVD SiC.

Reaction bonded steel components (RBSC) do not rely on sintering aids that introduce impurities into the final body and thus diminish its strength, making RBSC an excellent option for high purity applications like diffusion furnace components. Mechanical seals, kiln furniture, burner nozzles and radiant tubes may also benefit from using this process, which also offers excellent temperature stability that extends life by reducing degradation caused by chemical reactions and oxidation; especially important when dealing with components that experience frequent temperature variations during operation; wear resistance and impact resistance as well as chemical resistance are all offered by this process.

High Strength

Reaction-bonded silicon carbide (RB SiC) boasts one of the highest Mohs hardness ratings among synthetic materials, making it highly durable. As such, RB SiC can withstand impact from heavy blows as well as high-speed abrasion from high temperatures; this extends its useful life in mining operations and other industries operating under high temperatures. Furthermore, its resistance to oxidation and corrosion make RB SiC ideal for chemical applications.

Reaction bonded silicon carbide is produced by infiltrating molten silicon into porous carbon or graphite preforms, where it reacts with carbon to form additional SiC particles which then bond back onto the original silicon carbide matrix. This method of manufacturing ceramics is significantly faster than traditional methods that rely on sintering aids for dense powder fusion into dense bodies; its result being highly durable materials with exceptional as-fired dimensional tolerances and excellent mechanical strength.

Reaction bonded silicon carbide (RB SiC) is significantly less costly and features lower hardness compared to sintered silicon carbide, making it suitable for applications which require greater porosity or permeability from gases and liquids. Reaction bonded silicon carbide also boasts exceptional thermal shock resistance – meaning it can withstand rapid temperature fluctuations without losing strength or properties – which makes RB SiC an excellent material choice for pumps, mechanical seals, bearings and other industrial equipment.

High Ductility

Reaction bonding is a ceramic forming technique which involves infiltrating porous, carbonaceous preforms with liquid silicon to react with carbon and form more SiC, thus adhering the original carbonaceous material together.

This process achieves much higher ductility than conventional processes and enables near net shaped complex RBSC products at significantly reduced temperatures to be produced.

Conventional sintering of RBSC requires very high temperatures; depending on the method used (reaction bonding, hot pressing or pressureless), temperatures can exceed 2200 degC. With the advent of reaction bonding technology however, the process can now be performed at much lower temperatures.

To maximize flexural strength, the liquid silicon must be infiltrated through capillary channels without blocking them. A typical process combines a-SiC powder with graphite or organic binder that increases exothermism of infiltration; this leads to formation of B-C-SiC phases and reduced residual silicon amounts [5].

Gelcasting uses gel forming systems to shape microstructure and mechanical properties of final products. Acrylicamide (AM), the most frequently employed monomer for this application, however is neurotoxic due to oxygen inhibition of its polymerization process and requires non-toxic gel formation systems as alternatives.

Lower Density

Reaction-bonded silicon carbide boasts lower hardness and strength than sintered, yet offers superior wear, thermal and chemical resistance. Available in various shapes, sizes, and tolerances, reaction bonded silicon carbide makes a versatile material perfect for mechanical seals, bearings, pipes, flow control chokes as well as larger wear components used by mining or other industries.

Reaction bonded processes for fabricating SiC ceramics involve infiltrating porous carbon or graphite preforms with liquid silicon melt, creating an in situ reaction between it and carbon to form b-SiC that bonds its original a-SiC particles together. Any capillary channels left unreacted are then filled in with residual silicon liquid.

One advantage of RBSC production is that it can be done at lower processing temperatures than sintering; however, the ceramics produced may contain significant quantities of free silicon which could fracture under pressure during handling or use.

To reduce free silicon, it is critical to maintain a short RS time and add carbon black to the preform. This can increase relative density of green body material while simultaneously increasing flexural strength and elastic modulus flexure as the carbon black content in the preform increases up to 15 weight percent.