Refractory composition and process for forming article therefrom

Abstract

A refractory composition and processes for manufacture are provided where the compositions possess improved refractory alkali resistance and superior handling properties. Compositions and processes for their manufacture may include a plurality of ceramic particles and a binder sintered to the particles wherein the binder includes crystalline aluminum orthophosphate distributed as the result of an in situ reaction of aluminum metaphosphate with alumina. Kits provided according to the invention provide materials for use in manufacture of a composition where the kit includes aluminum metaphosphate and a nonfacile additive.

Description

REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. Provisional Patent Application Ser. No. 61 / 316,602 filed Mar. 23, 2010, the contents of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention in general relates to a refractory composition and process for forming an article therefrom, and in particular a composition having crystalline AlPO4 formed in the composition binder alone or with other binder components to produce an article with exceptional refractory corrosion resistance.BACKGROUND OF THE INVENTION[0003]Cement bonded materials largely form only mechanical bonds at ambient temperature of 20° Celsius. Adhesion of these ambient temperature cured materials occurs because of the rough surface and while convenient to bond at ambient temperature are comparatively weak as compared to elevated temperature cured material and also tend to suffer from mechanical failure during heat up or when exposed to thermal stres...

AI Technical Summary

Benefits of technology

[0005]Refractory compositions and kits and processes for forming inventive refractory compositions are provided that overcome the shortcomings of refractory materials of the prior art and improve handling characteristics and article strength. A refractory composition includes a plurality of aggregate ceramic particles and a binder sintered to the plurality of aggregate ceramic particles, where the binder includes crystalline aluminum orthophosphate distributed in the binder as the result of reaction of aluminum metaphosphate with alumina. The plurality of aggregate ceramic particles optionally include bauxite particles. In some embodiments, the plurality of aggregate ceramic particles includes at least one of silicon carbide, fumed silica, or mullite.

Problems solved by technology

Adhesion of these ambient temperature cured materials occurs because of the rough surface and while convenient to bond at ambient temperature are comparatively weak as compared to elevated temperature cured material and also tend to suffer from mechanical failure during heat up or when exposed to thermal stresses.

Unfortunately, alkali phosphates are characterized by low melting points that limit the high temperature limit of operation for the resulting material.

As a result, cement strengthening through densification is largely precluded as are often desirable handling methods such as pumping or shotcreting unless extra phosphoric acid is added to improve precured cement mixture flowability and extend working times. However, the addition of more phosphoric acid alters the phosphate:alkali ratio in the precured cement mixture and thereby invariably reduces the strength properties of cement formed with extra phosphoric acid relative to a cast precured cement mixture lacking additional phosphoric acid.

As a result of these limitations, alkali phosphate binder system based refractory cements have met with limited acceptance.