reaction bonded silicon carbide crucible boasts excellent wear and impact resistance as well as resistance against acid and alkaline corrosion, high temperatures and many chemicals. RBSCs are produced using reactive melt infiltration. At temperatures above the melting point of silicon, liquid silicon penetrates porous preforms via capillary force before reacting with residual carbon to produce b-SiC.
Material
Reaction bonded silicon carbide (RBSC) is one of the world’s premier ceramic materials, boasting outstanding mechanical properties at high temperatures. Produced in various shapes and sizes, RBSC is often found inside tunnel kilns to protect molten metal inside them from being exposed to further thermal shock.
Reactive bonding of silicon with carbon forms near-net shaped silicon carbide (RBSC). Its production is less energy intensive than re-crystallization and requires lower temperatures; providing an eco-friendly option for making architectural and sanitary ceramics.
Refractory material such as alumina or graphite is formed into an ideal shape for each application, then heated above silicon’s melting point in a crucible. Once this process has completed, an RBSC preform is introduced into contact with it so that silicon infiltrates into it through capillary action before heat treating to produce reaction bonded silicon carbide [2,3].
When selecting a crucible for an industrial application, many factors must be taken into account, including its maximum temperature support for melting and holding, chemical compatibility with alloy, corrosion resistance and thermal shock protection. Unfortunately, it isn’t always possible to find one with all desired features; therefore, prioritising your list and discussing it with your supplier are best methods.
Shape
Reaction bonded silicon carbide (RBSC) can be formed into complex engineered pieces to fit equipment used in wear applications such as pumps, mechanical seals, bearings, flow control chokes and larger wear components found in mining and other industries. RBSC boasts exceptional wear, impact and chemical resistance with high strength; production involves infiltrating molten silicon into porous carbon material packed into desired shape before reacting with it to form silicon carbide which has strong and long-term durability at high temperatures while remaining strong with good dimensional stability at higher temperatures.
reaction bonded silicon carbide crucible must withstand damage from flame and adjust for rate of thermal change at metal melting/holding temperatures, while being strong enough to withstand pressure of metal being poured in it. Silicon carbide, boron nitride and graphite are commonly used materials for such crucibles.
Metal melters/holders and their suppliers must collaborate closely when selecting a crucible that suits the unique requirements of an operation. By fully comprehending how metal melting/holding works and its requirements, suppliers can match an exact match between characteristics needed and characteristics available – even in harsh operating environments – for long service life in their crucibles. Preheating them before use may help reduce corrosion by evaporating moisture build-up between uses extending their longevity further.
Heat Treatment
Duratec offers reaction bonded silicon carbide crucibles designed to withstand temperatures that will ensure they can keep up with melting and holding metals at their highest potential temperature for extended periods, making them suitable for melting copper-based alloys or more resistant metals such as molybdenum and tungsten in your facility. These unique vessels boast lower costs, greater chemical resistance and higher density compared to traditional clay graphite materials used as melting crucibles.
For creating reaction bonded silicon carbide ceramics, a granular mixture of silicon powder and thermosetting resin with high carbon retention rates such as phenol resin is mixed together to form the silicon supplying body. Once in contact with a carbon preform desired for reaction-bonding, heat processing at temperatures significantly above silicon’s melting point (for instance 1410-1550 degC) occurs; fused silicon infiltrates into its preform to create reaction bonded ceramics.
RBSC material’s high thermal conductivity makes it ideal for use in mirrors of astronomical telescopes and other scientific equipment that must withstand extremely high temperatures over long periods. Furthermore, this material features low thermal expansion and hardness properties. Aerospace and automotive applications frequently select it due to its excellent performance, cost effectiveness and durability; its crucible can come in regular shapes or be customized specifically to your equipment/production process requirements.
Application
Finding the appropriate crucible material for high-degree metal melting and holding requires taking into account numerous variables specific to each facility, including furnace types, alloy types used, working practices, metallurgical treatments and pouring arrangements. Due to this wide array of variables that contribute to their selection process, selecting an ideal crucible material for any particular application can be an extremely complex undertaking.
Clay-graphite materials tend to be the most cost-effective option when it comes to choosing crucible materials, as they are designed for temperatures up to 2000degC and offer good chemical stability and strength; making them suitable for treating refractory metals like zinc and aluminum. Unfortunately, however, they have an unfortunate tendency for scaling rapidly – potentially shortening its life considerably.
To maximize its lifespan and extend its useful life,reaction bonded silicon carbide crucible should be preheated or “seasoned” prior to each use. This involves slowly heating them between 400 to 600degC for one or two hours and maintaining this heat throughout use – this allows any moisture that has accumulated between uses to evaporate while reinforcing their silicon carbide grains for high degree metal melting and holding applications.
