The invention concerns a refractory ceramic batch as well as a refractory ceramic product.

An yttrium oxide-based sintered body includes yttrium oxide as a predominant component. The sintered body includes aluminum in an amount of 0.1 mass % to 0.5 mass % inclusive as reduced to aluminum oxide, has a metal content of 1,000 ppm or less, the metal excluding yttrium and aluminum, and has a relative density of 98% or higher. By virtue of the yttrium oxide-based sintered body, a plasma resistance comparable to that of a high-purity (99.9%) yttrium oxide sintered body can be achieved. Also, since the relative density is sufficiently high, plasma resistance can be enhanced. As a result, the yttrium oxide-based sintered body can be suitably used as a large-scale member by virtue of excellent mechanical strength.

Low-carbon monolithic refractories are provided. Methods of manufacturing glass employing low-carbon monolithic refractories are also provided. Methods and apparatuses for glass manufacture for reducing the formation of carbon dioxide blisters during glass manufacture are also provided.

The present invention relates to a zirconia mullite refractory composite comprising 55 wt.-% to 65 wt.-% Al.sub.2O.sub.3, 15 wt.-% to 25 wt.-% SiO.sub.2, 15 wt.-% to 25 wt.-% ZrO.sub.2 and less than 3 wt.-% raw material based impurities, whereby the mineralogical composition of the composite comprises 65 wt.-% to 85 wt.-% mullite and 15 wt.-% to 35 wt.-% zirconia.

The invention concerns a batch for the production of a refractory product, a process for the production of a refractory product, a refractory product as well as the use of a refractory product.

Disclosed is a refractory product for casting of steel, which is capable of forming a dense surface layer which is high in terms of a slag infiltration suppressing ability and strong, in a surface region thereof efficiently or sufficiently or in an optimum state. The refractory product contains 1 mass % or more of free carbon, and 2 mass % to 15 mass % of an aluminum component as metal, with the remainder comprising a refractory material as a main composition, wherein the refractory product has a permeability of 1×10.sup.−16 m.sup.2 to 15×10.sup.−16m.sup.2.

A sintered yttrium oxide body having a total impurity level of 40 ppm or less, a density of not less than 4.93 g/cm3, wherein the sintered yttrium oxide body has at least one surface comprising at least one pore, wherein no pore is larger than 5 μm in diameter. A process for making the sintered yttrium oxide body is also disclosed.

A refractory object may include a zircon body that is intentionally doped with a dopant including an alkaline earth element and aluminum. The refractory object can have an improved creep deformation rate. In an embodiment, the refractory object can have a creep deformation rate of not greater than about 1.8 E-5 h.sup.−1 at a temperature of 1350° C. and a stress of 2 MPa. In another embodiment, the zircon body may include an amorphous phase including an alkaline earth metal element.

Disclosed herein is a ceramic article or coating useful in semiconductor processing, which is resistant to erosion by halogen-containing plasmas. The ceramic article or coating is formed from a combination of yttrium oxide and zirconium oxide.

A method to form a machinable ceramic matrix composite comprises forming a porous ceramic multilayer on a surface of a fiber preform. In one example, the porous ceramic multilayer comprises a gradient in porosity in a direction normal to the surface. In another example, the porous ceramic multilayer includes low-wettability particles having a high contact angle with molten silicon, where an amount of the low-wettability particles in the porous ceramic multilayer varies in a direction normal to the surface. After forming the porous ceramic multilayer, the fiber preform is infiltrated with a melt, and the melt is cooled to form a ceramic matrix composite with a surface coating thereon. An outer portion of the surface coating is more readily machinable than an inner portion of the surface coating. The outer portion of the surface coating is machined to form a ceramic matrix composite having a machined surface with a predetermined surface finish and/or dimensional tolerance.