Cement Composition for Honeycomb Bodies Preventing Particle Migration
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Solution Overview
Problem
The use of colloidal silica in cement compositions for honeycomb articles leads to particle migration and non-uniform properties due to capillary forces and destabilization, resulting in reduced strength and undesirable changes in micro-cracked materials, along with time-dependent rheology issues.
Innovation Solution
A cement composition comprising an inorganic powder, a gelled inorganic binder, and an organic binder, where the gelled inorganic binder is formed by altering the pH and ion concentration, preventing particle migration and maintaining stable rheological properties over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If colloidal silica is used as inorganic binder in cement composition, then strength at high temperatures is improved, but particle migration occurs during application and drying leading to non-uniform properties
Solution Approach 1:
The patent applies a microcrack passivation treatment before applying the cement composition. This preliminary action fills microcracks with organic material to prevent colloidal silica particles from migrating into cracks during subsequent application and drying processes, thereby preventing non-uniform properties while maintaining the strength benefits of colloidal silica
Solution Approach 2:
The patent introduces an intermediary organic material to fill microcracks before cement application. This intermediary substance acts as a barrier that prevents direct interaction between colloidal silica particles and microcracks, eliminating the migration pathway while allowing the cement composition to maintain its binding and strengthening functions
2Strength
If colloidal silica particles are used, then binder strength is improved, but particles enter micro-cracks causing changed properties
Solution Approach 1:
The microcrack passivation step is performed before cement application to pre-fill cracks with organic material. This preliminary protective action prevents colloidal silica particles from entering microcracks during cement application, thereby maintaining binder strength while avoiding harmful property changes in microcracked regions
Solution Approach 2:
The patent converts the potentially harmful effect of microcracks (which would allow particle migration and property degradation) into a beneficial controlled structure by filling them with organic material. This transforms microcracks from defect pathways into protected zones that maintain material integrity
3Ease of operation
If colloidal suspension is used as binder, then initial workability is improved, but rheology changes over time due to particle aggregation
Solution Approach 1:
The patent modifies the colloidal suspension by adjusting pH and ion concentration to alter the electrochemical parameters of the system. These parameter changes stabilize the colloidal particles against aggregation over time, maintaining rheological stability while preserving the initial workability needed for application
Solution Approach 2:
The patent utilizes pH adjustment to induce phase transition behavior in the colloidal suspension. By controlling the pH and ion concentration, the colloidal particles maintain a stable dispersed phase without aggregating, thereby preserving both workability and rheological stability throughout the processing time
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 solution minimizes microcrack filling, ensures uniform properties, and prevents binder migration, resulting in improved strength and processing advantages by maintaining stable rheological properties and preventing particle migration into microcracks.
Implementation Method 1
The migration can occur during the application of cement as the water, which contains the silica particles, is pulled into the pores of the cellular ceramic honeycomb body by capillary forces
Implementation Method 2
a gelled inorganic binder, where the gelled inorganic binder is formed by altering the pH and ion concentration
Implementation Method 3
time-dependent rheology of the paste due to the finite-time the colloidal suspensions remain stable. As the colloidal suspension destabilizes, the particles bond together into larger agglomerates/flocs or networks of particles
Data Source
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AI summary
Disclosed are cement compositions for applying to honeycomb bodies as a plugging cement composition, segment cement, or even as an after-applied artificial skin or coating. The cement compositions generally comprise an inorganic powder batch mixture; an organic binder; a liquid vehicle; and a gelled inorganic binder. Also disclosed are honeycomb bodies having the disclosed cement compositions applied thereto, and methods for making same.