AZS Refractory Exudation Reduction via Composition Control

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Solution Overview

Problem

Current AZS refractory products used in glass furnaces suffer from excessive vitreous phase exudation at operating temperatures, leading to defects and reduced yields, particularly in superstructures and crowns, which existing compositions fail to adequately address.

Innovation Solution

A fused cast AZS refractory product with a specific chemical composition, including 15.5% to 22% ZrO2, 10.5% to 15% SiO2, 1.0% to 2.5% Na2O + K2O + Li2O, and minimal impurities, optimized to reduce exudation without adding additional species, maintaining high temperature resistance and mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional AZS compositions are used in glass furnace superstructures, then basic refractory properties are maintained, but excessive vitreous phase exudation occurs at operating temperatures

Engineering Contradiction:
Improvevitreous phase exudationVSAvoidresistance to cracking and corrosion
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the chemical composition parameters of the AZS refractory product. Specifically, it limits SiO2 content to 10-18% (reduced from conventional levels), controls ZrO2 content to 20-35%, and restricts alkaline oxides (Na2O+K2O+Li2O) to 1.5-3.0%. These parameter adjustments fundamentally alter the vitreous phase behavior, reducing exudation at operating temperatures while maintaining structural integrity and resistance to cracking and corrosion.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If additional oxides are added to reduce exudation, then exudation is reduced, but manufacturing costs increase and staining problems may occur

Engineering Contradiction:
ImproveexudationVSAvoidmanufacturing cost and complexity
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent applies the extraction principle by removing harmful or unnecessary components from the conventional AZS composition. It extracts and eliminates the need for additional expensive oxides (such as B2O3, P2O5, SnO2, ZnO, CuO, MnO2) that were previously added to reduce exudation. Instead, it achieves exudation control by taking out excess SiO2 and carefully limiting alkaline oxide content, thereby simplifying the composition, reducing manufacturing costs, and avoiding staining problems associated with additive oxides.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If zirconia content is increased to improve corrosion resistance, then corrosion resistance improves, but exudation increases

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidexudation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent resolves this contradiction through coordinated parameter changes in the chemical composition. It optimizes ZrO2 content to a specific range of 20-35%, which provides sufficient corrosion resistance. Simultaneously, it reduces SiO2 content to 10-18% and controls alkaline oxides to 1.5-3.0%, thereby suppressing vitreous phase exudation. This multi-parameter optimization allows the product to achieve both high corrosion resistance and low exudation, eliminating the trade-off present in conventional compositions.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The optimized composition significantly reduces exudation, improves industrial feasibility, and enhances high-temperature mechanical strength, allowing for effective use in glass furnace superstructures and crowns with reduced manufacturing costs.

Implementation Method 1

exudation of its vitreous phase at the operating temperatures of the glass furnaces

Methodology Applied
Scientific EffectVitreous phase exudation:

Implementation Method 2

melting a mixture of suitable starting materials in an electric arc furnace

Methodology Applied
Scientific EffectElectric arc heating: Electric Arc

Implementation Method 3

controlled cooling cycle to be brought to ambient temperature without fracturing

Methodology Applied
Scientific EffectControlled cooling: Cooling

Data Source

PatentUS7642211B2Reduced sweating AZS product
Publication Date: 2010.01.05 SAINT GOBAIN CENT DE RES & DEVS & DETUD EUROEN

AI summary

An AZS type fused cast refractory product presenting the following chemical composition, as a percentage by weight: ZrO2: 15.5% to 22%; SiO2: 10.5% to 15%; Na2O+K2O+Li2O: 1.0% to 2.5%; impurities: <1%. Application to glass furnaces, in particular to the superstructures and crowns thereof.