Corning Develops Low-Creep Zircon Material with Nano-Additives for Fusion Draw Glass Processes

Corning Incorporated inventor Yanxia Lu developed low-creep zircon material with nano-additives. The material is particularly useful for making large-size refractory bodies resistant to creep at an elevated operating temperature, such as an isopipe for fusion draw glass making processes, according to U.S. Patent Application 20100028665. The composite material consists essentially of ZrSiO4 and sintering additives selected from Type I, Type II and Type III sintering additives and combinations.

Type I: consists of Fe2O3, SnO2, oxide glasses, and mixtures and combinations used in amounts of 0.0-0.1 wt % .

Type II: consists of TiO2, SiO2, VO2, CoO, NiO, NbO, and mixtures and combinations used in amounts of 0.1-0.8 wt %.

Type III:  selected from Y2O3, ZrO2, CaO, MgO, Cr2O3, Al2O3, and mixtures and combinations and is used in amounts of 0.0-0.8 wt %. The amount of sintering additives are weight percentages on an oxide basis of the total weight of the composition. 

FIG. 2A is a SEM image of a composite material comprising TiO2 as a sintering additive but without comprising Fe2O3 as a sintering additive.

           

 FIG. 2B is a SEM image of another composite material comprising both TiO2 and Fe2O3 as a sintering additive.

FIG. 3A is a SEM image of a composite material comprising TiO2 as a sintering additive but without comprising Y2O3 as a sintering additive.

FIG. 3B is a SEM image of another composite comprising both TiO2 and Y2O3 as sintering additives.  

Each type of sintering additive has its own impact on the final sintered material. If used, Type I sintering additives can contribute to the densification of ceramic particles during sintering, resulting in a sintered material with relatively higher density. Zircon can not sinter itself very well, therefore sintering additives may be needed. However, since Type I sintering additives may not help creep resistance or even reduce the creep resistance of the sintered body, the amount used should be kept low--as long as the amount included is sufficient for the densification purpose. 

Type II sintering additive can contribute both to the creep resistance and densification. It can be used as a sole sintering additive for zircon if it provides desired density, sufficient strength and low creep at a desired level. Type III sintering additive is usually used in combination with Type I or Type II sintering additives since it typically does not make positive contribution to the densification. Combination of a plurality of sintering additives in multiple types can result in optimized combination of densification, strength and creep resistance.