Zirconia Refractory Protective Layer for Corrosion and Exudation
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Solution Overview
Problem
Fused refractory blocks with high ZrO2 content face challenges in corrosion resistance and exudation when used in glass furnaces, with existing laser treatment methods not effectively addressing these issues for blocks containing more than 10% ZrO2.
Innovation Solution
A process involving heating the surface of fused refractory products with ZrO2 content above 10% to remelt ZrO2 grains, followed by rapid cooling to form a dense and homogeneous protective layer, which also recrystallizes zirconia to enhance corrosion resistance and reduce exudation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ZrO2 content in fused refractory blocks is increased to improve corrosion resistance, then resistance to molten glass corrosion improves, but exudation increases and mechanical properties deteriorate
Solution Approach 1:
The patent applies local quality by creating a protective layer with different composition and structure from the bulk material. The surface layer contains recrystallized zirconia grains with specific orientation and reduced porosity, while the internal structure remains unchanged. This localized modification addresses corrosion resistance at the surface without affecting the bulk mechanical properties excessively.
Solution Approach 2:
The patent changes physical and chemical parameters of the surface layer through controlled recrystallization. By adjusting heating temperature, holding time, and cooling rate, the grain size, phase composition, and microstructure of the protective layer are optimized to reduce exudation while maintaining corrosion resistance. The crystalline phase transformation from amorphous to crystalline state is a key parameter change.
2Reliability
If the ZrO2 content is increased above 80% to achieve very high corrosion resistance, then resistance to molten glass and vapors improves, but the product becomes more susceptible to cracking and mechanical failure
Solution Approach 1:
The patent utilizes phase transitions of zirconia during controlled heating and cooling. The transformation from monoclinic to tetragonal phase during heating, and controlled recrystallization during cooling, creates a dense protective layer with improved mechanical interlocking. This phase transition mechanism reduces microcracks and improves overall mechanical strength while maintaining high ZrO2 content.
Solution Approach 2:
The patent applies preliminary action by performing controlled recrystallization treatment before the refractory block is put into service. This pre-treatment creates a stable, crack-free protective layer that prevents future cracking during thermal cycling and service operation. The surface imperfections are sealed and the microstructure is stabilized in advance.
3Object-affected harmful factors
If existing laser treatment methods are applied to reduce surface reactivity, then some protection against molten glass is achieved, but the treatment is ineffective for fused blocks with more than 10% ZrO2 content
Solution Approach 1:
The patent employs periodic action through controlled heating and cooling cycles during laser treatment. Multiple heating-cooling cycles are applied to progressively recrystallize the zirconia grains and form a stable protective layer. The periodic thermal treatment ensures complete transformation of the surface structure, making the treatment effective even for high ZrO2 content blocks.
Solution Approach 2:
The patent replaces conventional mechanical surface treatment methods with laser-based thermal processing. Instead of mechanical grinding or coating, laser energy is used to induce controlled melting and recrystallization of the surface layer. This substitution enables effective treatment of high ZrO2 content materials that are difficult to treat with mechanical methods.
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 process significantly improves corrosion resistance and reduces exudation in fused refractory products, maintaining mechanical properties and adhesion of the protective layer, even with high ZrO2 content, and can plug surface imperfections like cracks.
Implementation Method 1
heating at least a portion of the surface of said product, or surface to be treated, so as to melt ZrO2 grains in a superficial region
Implementation Method 2
melt ZrO2 grains in a superficial region extending to a depth of less than 2000 μm
Implementation Method 3
cooling the molten superficial region obtained in the preceding step so as to obtain a protective layer
Implementation Method 4
cooling the molten superficial region obtained in the preceding step so as to obtain a protective layer
Implementation Method 5
optionally at least partially recrystallizing the zirconia present in the amorphous phase of the protective layer
Data Source
AI summary
A process for treating a fused refractory product including more than 10% by mass of ZrO2, or “base product.” The process includes heating at least a portion of the surface of the product, so as to melt ZrO2 crystals in a superficial region extending to a depth of less than 2000 μm. The process includes cooling the molten superficial region obtained in the preceding step so as to obtain a protective layer.