A composition for coating a refractory body. The composition comprises; an oxidizable component; and a phosphate frit comprising phosphorous oxide. The composition is substantially aluminum metal free.

A composition for coating a refractory body. The composition comprises; an oxidizable component; and a phosphate frit comprising phosphorous oxide. The composition is substantially aluminum metal free.

A refractory to be used repeatedly or for a long period of time, such as a refractory for casting, especially a nozzle for casting and an SN plate, has improved tolerance. The refractory for casting contains Al.sub.4O.sub.4C in the range of 15 to 60% by mass, both inclusive, an Al component as a metal in the range of 1.2 to 10.0% by mass, both inclusive, and a balance including Al.sub.2O.sub.3, a free C, and other refractory component; a sum of Al.sub.4O.sub.4C, Al.sub.2O.sub.3, and the Al component as a metal is 85% or more by mass; and a content of Al.sub.4O.sub.4C (Al.sub.4O.sub.4C), a content of the Al component as a metal (Al), and a content of the free carbon (C). The contact of the free carbon satisfies the following Equation 1 and Equation 2:

1.0C/(Al.sub.4O.sub.4C0.038+Al0.33)(Equation 1)

and

1.0C/(Al.sub.4O.sub.4C0.13+Al0.67)(Equation 2).

The disclosure provides a refractory brick system comprising a chromia refractory brick for operation in the slagging environment of an air-cooled gasifier. The chromia refractory brick comprises a ceramically-bonded porous chromia refractory having a porosity greater than 9% and having carbon deposits residing within the pores. The brick may be further comprised of Al.sub.2O.sub.3. The air-cooled gasifier generates a liquefied slag in contact with the refractory brick and generally operates at temperatures between 1250 C. and 1575 C. and pressures between 300 psi to 1000 psi, with oxygen partial pressures generally between 10.sup.4 and 10.sup.10 atm. The refractory brick performs without substantial chromium carbide or chromium metal formation in the low oxygen partial pressure environment. The inclusion of carbon without chromium carbide formation provides for significant mitigation of slag penetration and significantly reduced refractory wear.

The disclosure provides a refractory brick system comprising a chromia refractory brick for operation in the slagging environment of an air-cooled gasifier. The chromia refractory brick comprises a ceramically-bonded porous chromia refractory having a porosity greater than 9% and having carbon deposits residing within the pores. The brick may be further comprised of Al.sub.2O.sub.3. The air-cooled gasifier generates a liquefied slag in contact with the refractory brick and generally operates at temperatures between 1250 C. and 1575 C. and pressures between 300 psi to 1000 psi, with oxygen partial pressures generally between 10.sup.4 and 10.sup.10 atm. The refractory brick performs without substantial chromium carbide or chromium metal formation in the low oxygen partial pressure environment. The inclusion of carbon without chromium carbide formation provides for significant mitigation of slag penetration and significantly reduced refractory wear.

Disclosed are a graphene-ceramic hybrid coating layer formed from a graphene-ceramic hybrid sol solution including graphene (RGO: reduced graphene oxide) and a ceramic sol, wherein the graphene content in the graphene-ceramic hybrid coating layer is about 0.001 wt % to about 1.8 wt % based on the total weight of the graphene-ceramic hybrid coating layer, and a method for preparing the same.

A castable refractory composition may include from 5% to 95% by weight of alumina, aluminosilicate, or mixtures thereof; from 0.5% to 1.5% by weight alkaline earth metal oxide and/or hydroxide, and 0.1% to 5% by weight of silica having a surface area of at least about 10 m.sup.2/g. The refractory composition may include no more than 0.5% by weight of cementitious binder. The refractory composition may release less than 25 cm.sup.3 of hydrogen gas per kilogram of castable refractory composition upon addition of water. The refractory compositions may set on addition of water.