Compound · SiC

Silicon carbide

A synthetic ceramic close to diamond in hardness, and the first commercially successful manufactured abrasive.

Silicon carbide occurs naturally only as the extremely rare mineral moissanite. Essentially all of it is manufactured, by heating silica sand with carbon to around 2,000 °C.

When Edward Acheson patented the process in 1893 he had produced something genuinely new: a material harder than any abrasive then available except diamond, and vastly cheaper. It is a good example of an engineered material displacing a natural one on economics rather than performance alone.

Processing

Made by the Acheson process: silica sand and petroleum coke are heated by an electric current passed through a resistive core, over several days, reaching temperatures around 2,500 °C. Silicon carbide crystallises around the core in grades that vary with distance from it.

Uses

Abrasives were the first use and remain a large one: silicon carbide grit cuts fast and fractures to fresh sharp edges rather than blunting, which suits it to grinding wheels, cutting discs and lapping compounds.

Its refractory use is equally important — kiln furniture and furnace linings that survive repeated thermal cycling. More recently it has become a significant semiconductor. Silicon carbide power devices switch high voltages with far lower losses than silicon, which is why they now appear in electric vehicle inverters, fast chargers and grid equipment. It is also the ceramic in much modern vehicle and personal armour.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

contains

Silicon — element
Carbon — element

is sourced from

Quartz — mineral · silica sand and carbon fused in an electric furnace

is used as

Abrasive — application
Refractory lining — application · where thermal shock resistance matters more than pure refractoriness

is an alternative to

Corundum — mineral · as an abrasive; silicon carbide is harder but more friable
Technical ceramic — material
Diamond — mineral · as an abrasive: diamond cuts what silicon carbide cannot, including silicon carbide itself, and synthetic diamond made the comparison one of cost rather than of availability
Silicon — element · in power electronics: silicon carbide holds off higher voltages and runs hotter, which is why an electric vehicle inverter increasingly uses it and a mains adapter does not
Gallium nitride — compound · the two wide band gap power semiconductors, and the split is voltage: GaN is faster and cheaper below about 650 volts, and silicon carbide takes the traction inverters above a kilovolt on thermal conductivity and a vertical device structure

is produced by

Acheson process — process · the product the process was built for, crystallised out of sand and coke at around 2,500 °C
Vapour deposition — process · as the epitaxial layer that a silicon carbide power device is actually built in, on top of a wafer made the harder way

is a component of

Refractory brick — material · where abrasion and thermal shock both matter — blast furnace bosh, incinerators and kiln furniture

Sources

Material World
Our own writing
PubChem
US National Library of Medicine · Mixed — aggregated third-party content, rights retained by depositors
Wikidata
Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)

Questions this page answers

Where it comes from, and what it becomes

Follow Silicon carbide back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

Silicon carbide → is produced by (the product the process was built for, crystallised out of sand and coke at around 2,500 °C) → Acheson process → takes as input (sand and coke, heated to 2,500 °C, which is how silicon carbide has been made since 1893) → Sand → is sourced from (the ultimate source of most of it — granite weathers, the feldspar becomes clay and washes out, and the quartz survives as grains) → Granite → is composed of (by volume, alongside feldspar and lesser mica) → Quartz
Silicon carbide → is sourced from (silica sand and carbon fused in an electric furnace) → Quartz
Silicon carbide → is produced by (as the epitaxial layer that a silicon carbide power device is actually built in, on top of a wafer made the harder way) → Vapour deposition
Silicon carbide → is produced by (the product the process was built for, crystallised out of sand and coke at around 2,500 °C) → Acheson process → takes as input (as silica sand, the silicon half of the charge) → Quartz
Silicon carbide → is produced by (the product the process was built for, crystallised out of sand and coke at around 2,500 °C) → Acheson process → takes as input (sand and coke, heated to 2,500 °C, which is how silicon carbide has been made since 1893) → Sand → is composed of (almost everywhere, because quartz is what is left when everything else in a rock has weathered away — though a volcanic beach is basalt grains and a tropical one is broken shell) → Quartz
Silicon carbide → is produced by (the product the process was built for, crystallised out of sand and coke at around 2,500 °C) → Acheson process → takes as input (sand and coke, heated to 2,500 °C, which is how silicon carbide has been made since 1893) → Sand → is sourced from (the ultimate source of most of it — granite weathers, the feldspar becomes clay and washes out, and the quartz survives as grains) → Granite → is composed of (the pink or cream mineral that gives much granite its colour) → Orthoclase

These are the most distinct paths back. Silicon carbide can be traced through others besides.

Downstream — what it becomes

Silicon carbide → is a component of (where abrasion and thermal shock both matter — blast furnace bosh, incinerators and kiln furniture) → Refractory brick → is an input to (or installed unfired as a monolithic castable and cured by the furnace's own first heat) → Firing → produces (as sintering, from refined powders rather than clay) → Technical ceramic → is used in (the honeycomb monolith the metals are dispersed across, which supplies the surface area and survives the thermal cycling) → Catalytic converter → is used as (the largest catalytic application by metal value there is) → Catalysis
Silicon carbide → is used as → Abrasive
Silicon carbide → is used as (where thermal shock resistance matters more than pure refractoriness) → Refractory lining
Silicon carbide → is a component of (where abrasion and thermal shock both matter — blast furnace bosh, incinerators and kiln furniture) → Refractory brick → is an input to (or installed unfired as a monolithic castable and cured by the furnace's own first heat) → Firing → produces (fired in a continuous tunnel kiln, the atmosphere governing colour as much as the temperature) → Brick → is used in (load-bearing walls and cladding) → Construction
Silicon carbide → is a component of (where abrasion and thermal shock both matter — blast furnace bosh, incinerators and kiln furniture) → Refractory brick → is an input to (or installed unfired as a monolithic castable and cured by the furnace's own first heat) → Firing → produces (fired in a continuous tunnel kiln, the atmosphere governing colour as much as the temperature) → Brick → is used as (the same principle at a smaller and far cheaper unit size, which is why it outlasted stone for ordinary building) → Structural engineering
Silicon carbide → is a component of (where abrasion and thermal shock both matter — blast furnace bosh, incinerators and kiln furniture) → Refractory brick → is an input to (or installed unfired as a monolithic castable and cured by the furnace's own first heat) → Firing → produces (as sintering, from refined powders rather than clay) → Technical ceramic → is used as (alumina and silicon carbide are the dominant manufactured abrasives) → Abrasive

These are the most distinct paths onward. Silicon carbide ends up in others besides.