Silicon Carbide in Ceramic Glazes

Silicon carbide is an increasingly popular addition to stoneware glazes and there are plenty of resources for it by searching “crater glaze”. However, before using silicon carbide in any glaze formulations there are certain things you must keep in mind before beginning use of this element.

An interesting property of sodium carbonate is its ability to create bubbling and textured finishes in cone 6 oxidation firings. There may be multiple reasons for this effect.

1. It is an abrasive

Silicon carbide (SiC) is an inorganic chemical compound of silicon and carbon. While SiC can be found naturally as the mineral moissanite, since 1893 mass production of SiC powder and crystal has taken place for use as an abrasive and advanced ceramic materials such as automobile brakes, clutches, and bulletproof vest plates require high endurance ceramic materials that have the durability of SiC for use as an abrasive.

SiC powder can also be used in cone 6 oxidation firings to produce bubbly or “crater glazes”, commonly referred to as “lava” or “crater glazes”. When exposed to oxygen and combined with silicon it forms CO2, which causes bubbles and blisters on the surface of the glaze.

Glaze formulations containing cerium oxide provide antimicrobial benefits due to electronic charge transferences facilitated by UV light absorption. This effect can be achieved by adding 2-10 weight% CeO2 [52]. Table 12.9 illustrates that all samples prepared without burnt iron oxide or without pigment have lower L*, a*, and b* values than their counterpart pigment samples [53-54].

2. It creates bubbles

Silicon carbide (SiC) particles are used in ceramic art to produce volcanic (also called crater) glazes, by mixing with barium sulphate at specific rates and at certain rates of addition, they create bubbling effects similar to that of lava or bubbles, acting like carbon release from SiC particles which reduce metallic oxides such as iron and copper oxides in the glazes.

These bubbles aren’t due to any issue with the glaze recipe or firing; rather, they’re caused by high quantities of non-gassing materials like strontium carbonate and talc which have high Loss on Ignition (LOI), producing lots of gases during decomposition during firing that get trapped within melting glaze and cause expansion when trapped; this causes holes on this piece’s glaze surface; had these gases been released at different points during firing they’d have left and it would have been smooth.

3. It is a refractory material

Silicon carbide plays a significant role in glaze composition by reducing metallic oxides like iron and copper oxides to assist with color development, while its carbon combines with oxygen to form CO2 gas that creates blistering and foaming effects in ceramic glazes (Bloomfield, 2020).

Silicon Carbide is a nonoxide material with numerous thermal and mechanical applications. With high heat/heat shock resistance, rigidity, low thermal expansion and excellent wear characteristics it has found widespread industrial application – often employed in kiln furniture such as crucibles, ladles and refractory bricks.

Refractories are used extensively within the metals industry for applications including vertical tank distillation furnace tower plates, aluminum electrolytic tanks and zinc powder furnace lining lining. Furthermore, silicon carbide bodies used as coatings in smelting applications often need coatings in order to prevent oxidation during high temperature heating processes.

4. It is a rust inhibitor

Silicon carbide (SiC) is an inorganic chemical compound made up of silicon and carbon that forms moissanite gemstones in nature and, when manufactured synthetically, as abrasive materials or refractory materials in furnace linings or bulletproof vest ceramic plates. SiC is noted for its superior temperature resistance as well as outstanding wear-resistance; additionally it’s one of the hardest materials on Earth making it suitable for machining or grinding tools.

Addition of SiC powder to glazes results in blistered surfaces that produce a crater texture, while still hiding beneath its layers and only becoming visible upon engraving or scratching of the glaze surface. Its granular form also works to reduce metallic oxides like iron and copper oxides which contributes to color development in particular with copper red hues.