The invention is directed to a method of providing a protective coating composition that protects a refractory wall or lining from chemical attack by molten aluminum and molten alkali metals. The method includes the steps of coating a refractory wall or liner with an aqueous protective composition that includes, by weight of the solids, about 20-90% Al.sub.2O.sub.3 (excluding calcined alumina), about 15-55% SiO.sub.2 and about 1-15% of a metallic non-wetting agent; and evaporating the water before contacting the protective coating with the reactive molten metal.

A ceramic foam filter for use in filtering non-ferrous metals and manufacturing method for same are disclosed. The ceramic foam filter includes calcined alumina as a core material and silica as a binder. Alternatively, the ceramic foam filter includes calcined alumina as a core material and boric oxide as a binder.

A substrate characterised in that it is at least partially surface-coated with a coating containing at least one so-called barrier layer having silica and one or more material(s) X selected from among SiC, Si, Si.sub.3N.sub.4, in which layer the amount of X varies between 25-wt. % and 50.-wt. % in relation to the total weight of the barrier layer, the barrier layer being formed by grains of one or more materials X covered at least partially in a silica shell, and the barrier layer being in direct contact with the substrate.

A refractory article used at high temperature contains a silica, calcium silicate or mullite matrix with at least a surface having an open porosity filled at least partially with a sulfate, phosphate, or carbonate salt or a mixture of sulfate, phosphate or carbonate salts. The refractory article is resistant to the corrosion and build-up of non-ferrous metals and their alloys.

A substrate, in particular intended for contact with liquid silicon, wherein it is at least partially surface-coated with a multilayer coating formed by: at least one layer, known as the adhesion layer, contiguous with the substrate, having an open porosity of at least 30%, and formed of a material comprising silica and silicon nitride, said material having a silica content of between 10 wt.-% and 55 wt.-% in relation to the total weight thereof; and a layer different from the adhesion layer, known as the release layer, located on the surface of the adhesion layer and formed of a material including silica and silicon nitride, said material having a silica content of between 2 wt.-% and 10 wt.-% in relation to the total weight thereof.

The present disclosure generally relates to a ceramic core comprising predominantly mullite, which is derived from a precursor comprising alumina particles and siloxane binders. Free silica is present in the ceramic body, but is largely unavailable for reaction with metal alloys used in investment casting. Methods of making cast metal articles are also disclosed.

The invention is directed to a method of providing a protective coating composition that protects a refractory wall or lining from chemical attack by molten aluminum and molten alkali metals. The method includes the steps of coating a refractory wall or liner with an aqueous protective composition that includes, by weight of the solids, about 20-90% Al.sub.2O.sub.3 (excluding calcined alumina), about 15-55% SiO.sub.2, and about 1-15% of a metallic non-wetting agent; and evaporating the water before contacting the protective coating with the reactive molten metal.

The invention is directed to a method of providing a protective coating composition that protects a refractory wall or lining from chemical attack by molten aluminum and molten alkali metals. The method includes the steps of coating a refractory wall or liner with an aqueous protective composition that includes, by weight of the solids, about 20-90% Al.sub.2O.sub.3 (excluding calcined alumina), about 15-55% SiO.sub.2 and about 1-15% of a metallic non-wetting agent; and evaporating the water before contacting the protective coating with the reactive molten metal.

The present disclosure generally relates to a ceramic core comprising predominantly mullite, which is derived from a precursor comprising alumina particles and siloxane binders. Free silica is present in the ceramic body, but is largely unavailable for reaction with metal alloys used in investment casting. Methods of making cast metal articles are also disclosed.

A dry substance mixture for a batch, preferably a refractory batch, for the production of a coarse ceramic, refractory, non-basic, shaped or unshaped product, such a refractory batch, such a product as well as a method for its production and a lining of an industrial furnace for the aluminum industry, and such an industrial furnace as well as a lining of a launder transport system or a mobile transport vessel for the aluminum industry, and such a launder transport system and such a transport vessel.