The Silicon Carbide Manufacturing Process

Silicon carbide is produced through melting silica sand with carbon sources such as coal at high temperatures; this process is known as Lely’s method.

Silica sand and graphitized petroleum coke carbon are the primary raw materials utilized in manufacturing. Additional auxiliary materials, like sawdust and salt, may also be utilized but do not contribute directly to chemical reaction.

Cold Isostatic Pressing

Silicon carbide production begins with the compaction process. Raw materials are mixed with binder and then compacted by extrusion or cold isostatic pressing into blocks or plates that will later be sintered under vacuum in order to give these finished parts their hardness and chemical resistance.

Die compaction involves rigid molds that force powder against them; with isostatic press, flexible elastomeric molds evenly apply pressure across all sides of a compacted powder compact without creating friction against its walls – eliminating lubricant use while also permitting greater size ranges and shapes than those possible with uniaxial die compaction. Furthermore, making such molds is more cost effective as these elastomeric molds may even incorporate materials that will eventually be part of a part being made; making less costly overall.

Powder for multiaxial pressing must first be prepared similarly to that for uniaxial pressing, in terms of free flowing properties and ease of compacting/sintering properties. Doping of nitrogen/phosphorus for an n-type semiconductor and doping with aluminum/boron/galium/beryllium for p-type semiconductor may then take place.

Isostatic presses can be divided into wet-bag and dry-bag methods. In the former, powder is placed in a flexible container submerged in water (or other liquids) before being subjected to isostatic pressure – this results in compressing it into green body ceramic that can then be machined into its desired form. There are over 3000 wet-bag CIP machines used worldwide while dry-bag press machines may be more frequently employed when pressing complex forms or parts that would be difficult to press uniaxial machines.

Washington Mills utilizes various furnaces for producing their crude. Washington Mills utilizes both traditional Acheson process furnaces and modern large furnace technology for this process, before further processing into grains and powders using various crushing, milling and classifying equipment that produces high-quality fused minerals that meet ANSI, FEPA and JIS standards.

Sintering

Sintering is a powder metallurgy process in which small particles of various materials are joined using heat and pressure. Sintering can produce various products including ceramics, refractory metals, spark plugs, cemented carbides and self-lubricating bearings as well as structural parts made out of magnetic, aerospace or medical applications. Furthermore, this step of manufacturing provides material strength which enables these machines to work at higher temperatures than most alternative processes would.

Sintering silicon carbide is a multi-stage process. The first stage entails dissecting raw silicon carbide into two groups of silica particles: coarse and fine groups. Coarse group particles contain large sizes while fine group have more uniform particles of smaller sizes. At 1600 degC, coarse and fine particles are mixed together and heated until fusing occurs into a solid unit; at this stage necks form and pores merge into spherical voids, expanding and contracting as one solid entity.

Once grains have sintered, they’re ready to be transformed into final products. Reaction bonding is one of the oldest techniques for doing this, involving mixing coarse silicon carbide grains, silica powder and plasticizers before shaping and heating it to high temperatures for desired shapes.

Electric current sintering, an offshoot of resistance sintering invented in 1906 by A.G. Bloxam, has since seen over 640 patents granted within the US alone and can be used to produce refractory metals, conductive nitride powders and carbide powders.

Silicon carbide sintering can be difficult due to its low melting point and high density. Sintering processes require special furnaces with high heating rates and precise control systems that guarantee ideal temperature and time conditions, along with sawing machines equipped with powerful saw blades capable of cutting dome-shaped ends of boules off quickly and precisely. STUDER, MAGERLE and BLOHM innovations have allowed chip manufacturers to cut the outer diameters faster with greater precision than ever before.

Extrusion

Extrusion is a metalworking process that applies compressive and shear forces to material as it passes through a die. This low-cost method with minimal waste allows us to form materials with otherwise fragile qualities into usable shapes. Aluminum, steel and titanium are often extruded through this method; non-metals such as ceramic, plastic, concrete and polymers may also be extruded successfully.

IPS’s extrusion process produces numerous high-performance silicon carbide products that include drainage and irrigation pipes, medical fluid tubing (IV tubing), weatherstripping strips for fencing, deck railings and window frames – as well as being used in food processing tubing, drinking straws (with “zip” strip re-sealable bags) and automotive components.

Silicon carbide is produced using an electric vacuum furnace from basic silicon and pyrolytically produced carbon at 1300-1600 degC, yielding highly efficient material with very uniform characteristics.

Material for SiC sintering must then be smelted, shaped and cooled in an autoclave or furnace to produce slabs for subsequent sintering processes. It’s critical that sintering temperatures remain as consistent as possible to ensure all crystals form evenly and that each crystal of SiC sintered successfully.

When cutting slabs into wafers, their quality has a direct bearing on their performance as final devices. Surface crack damage in particular can have devastating repercussions for an operation’s lifespan and reduce it dramatically.

Slicing SiC crystal is a delicate task, so ensuring its orientation accurately before beginning can be crucial. There are various techniques available to accomplish this feat such as normal wire electrolytic-spark hybrid machining, HS-WEDM and multi-wire sawing that may assist.

Once slicing has been completed, each piece undergoes rigorous dimensional checks and leak detection tests (leakage detection, pressure testing etc). These checks help ensure each piece satisfies its specified mechanical properties; in some instances the pieces may even be ground to fine tolerances using advanced diamond grinding technologies before inspection and approval for shipment.

Casting

Silicon carbide is an exceptional, oxygen-free ceramic with remarkable properties. It is extremely tough, stable, chemically resistant, has high melting points, good thermal conductivity and wear resistance properties making it the material of choice when producing electronics intended to withstand intense electric power (power electronics) as well as equipment exposed to heat or friction.

Casting involves the process of pouring liquid material into a mold cavity to form desired shapes, which then solidifies over time. Casting offers many advantages over other production techniques, including wide design freedom and part consolidation; additionally it’s cost-effective and efficient way to produce complex components that would be hard or impossible to produce otherwise.

Casting processes exist, with some of the more popular ones including:

Reaction Bonding

The Reaction-Bonded Silicon Carbide (RBSC) manufacturing process is an innovative new technique used to produce highly durable and hard silicon carbide ceramics. Similar to sintering, however, RBSC works by mixing coarse silicon carbide with silicon before shaping them into desired shapes using heat treatment; finally the resultant product can then be machined.

To produce RBSC, coarse silicon carbide and granular silica are combined with plasticizers in order to form an RBSC mixture containing spherical particles measuring around 145,4nm in diameter; their granulometric analysis indicates that most are composed of alpha silicon carbide with Wurtzite crystal structures while only small quantities exhibit beta silicon carbides with zinc blende structures.

Washington Mills uses various crushing, grinding and classifying equipment to mill RBSC slices into grains or powders suitable for further processing, with results meeting or exceeding ANSI, FEPA and JIS standards for crystallized SiC grains and powders produced subsequently being processed further to achieve purity with consistent grain size distribution; finally these crystallized SiC products can then be utilized across various industrial applications.