Hvorfor vælge ovnhylder af siliciumkarbid?

Kiln shelves serve as the support surfaces upon which ceramic ware is placed in a kiln and may be made of cordierite, alumina or nitride-bonded silicon carbide.

Selecting the appropriate material for kiln furniture components is an essential decision for any user of a kiln, and silicon carbide has proven itself as an outstanding material for furniture pieces, offering superior hardness, chemical and thermal shock resistance, as well as hardness resistance.

Material

Silicon carbide is an extremely durable material with outstanding creep resistance, making it the perfect material to construct shelves and supports for use in kiln furniture at temperatures reaching up to 1600 oC. Furthermore, its strength remains consistent even at these elevated temperatures.

Silicon carbide boasts exceptional wear resistance and hardness thanks to its granular composition, while smaller particle sizes enhance toughness and strength. When combined with its low density and load bearing capability, this makes an excellent load bearing material. Furthermore, kiln atmospheres don’t affect it and ensure years of reliable service life.

There are various types of kiln shelves available to meet your ceramic firing needs, and selecting one should take into account factors like style of firing, glazes used and weight of pottery pieces being fired. Regular maintenance such as rotating shelves and applying kiln wash will extend shelf lifespan.

Kiln wash is an additional layer of protection on your kiln shelf that works to prevent glaze drips and runs from ruining its surface. Made up of powdered silica sand, alumina hydrate and kaolin mixed with water until reaching paint-like consistency, kiln wash should then be painted onto each shelf using a brush before being left to dry between each application.

Styrke

There are various materials from which you can choose when outfitting your kiln, each offering its own set of unique qualities. Selecting the most suitable option depends on your firing environment and material to be fired; here we take a closer look at some popular choices to help guide your selection:

Cordierite Kiln Shelves

Cordierite shelves are an extremely durable magnesium aluminum silicate material used to withstand temperatures to cone 6 without warping or cracking, providing long term use without warping or warping issues. Available in various thicknesses and sizes, cordierite kiln shelves have become an indispensable part of production kilns worldwide.

High Alumina Shelves

Similar to Cordierite shelves, but made with more alumina than traditional cordierite they can withstand higher temperatures up to cone 11 without cracking under heavy loads or fast firing or cooling (especially electric kilns). Their increased content means they have much stronger construction than cordierite and weigh half or less of conventional 1″ thick cordierite shelves; additionally they’re significantly stronger under heavy loads without sagging under heavy loads and don’t sag under heavy loads – perfect for electric, gas, Salt & Soda kilns as all alumina products can crack under fast firing/crash cooling (especially electric).

Nitride Bonded Silicon Carbide Shelves

Holdbarhed

Black silicon carbide’s strength and durability makes it ideal for use as kiln shelves and other pieces of furniture that must withstand repeated exposure to high temperatures and harsh environments, including repeated exposure to extreme temperatures and environments. Hard yet brittle, it resists wear caused by abrasion. Engineered controls of macroscopic and microscopic properties enable manufacturers to optimize SiC for many different applications; typically smaller particle sizes improve toughness while grain aspect ratio and sharpness can enhance wear resistance.

Cordierite kiln shelves have long been considered an indispensable choice for potters firing to cone 10 in gas, wood and multi-fuel kilns. Their corrosion-proof oxide bond construction provides reliable service even during salt, soda and stoneware firing applications.

High alumina kiln shelves are similar to cordierite in design but feature higher concentrations of alumina for increased temperature rating up to cone 11. These more durable shelves require flipping/rotating during firing process to avoid warping as well as any sagging during firing processes.

Nitride Bonded Silicon Carbide Shelves are much thinner than cordierite or alumina shelves but offer low mass for increased energy savings. Furthermore, these shelves are easier to maintain with only requiring quick swipes with damp sponge. Also they don’t need any special kiln wash requirements (with the exception of soda firing when an alumina-based wash might be recommended).

Weight

5/16 thick shelves can save 3-3/8″ of stacking height per five layers compared to conventional 1″ shelves, significantly improving productivity, energy costs and firing cycles while simultaneously saving you more money! Their low mass and thermal conductivity also shorten firing cycles thus saving even more.

Advanced nitride-bonded silicon carbide shelves are much stronger, thinner, and have lower surface porosity than traditional oxide bonded shelves, enabling easier glazing, superior durability, and long life in demanding environments like gas reduction, wood, soda salt. No warping occurs even after multiple firings in these demanding conditions such as gas reduction, wood, soda salt or salt environments.

These low porosity kiln shelves provide the highest level of surface porosity available, meaning your glaze won’t penetrate deeply and cause any lasting damage. Furthermore, their reduced stainability also helps them remain cleaner for longer than other materials available for kiln shelfing applications.

Another advantage is their low expansion/contraction stress during firing cycles – meaning they are less prone to cracking than cordierite or alumina shelves – thus increasing shelf life by mitigating sudden temperature shifts, making these shelves especially suitable for high temperature operations or frequent operation.