Spherical Refractory Aggregate with Controlled Pores for Mold Strength
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Solution Overview
Problem
Existing refractory aggregates for foundry sand, particularly those made from spherical sintered particles, face issues with insufficient fluidity and mold strength, especially when used in complex shape production methods like hand molding and three-dimensional laminated molding, due to uneven surfaces and porosity affecting binder distribution.
Innovation Solution
The refractory aggregate is composed of spherical sintered particles with a roundness of 0.70 or more, an average particle size of 0.01-1.00 mm, a total pore volume of 0.20-0.50 mL/g for pores with 2-10 µm diameter, and a turbidity of 3000 NTU or less, ensuring optimal binder penetration and distribution for improved fluidity and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If spherical refractory sintered particles are used as refractory aggregate, then good sphericity is achieved, but the particle surfaces become uneven or porous leading to insufficient mold strength
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pore volume (0.20-0.50 mL/g) and pore diameter (2-10 μm) of the sintered particles, and by limiting the fine powder content (turbidity ≤3000 NTU). These parameter optimizations resolve the contradiction by creating a pore structure that allows sufficient binder penetration for strength while maintaining spherical shape for good flow characteristics.
2Strength
If the amount of binder added is increased to avoid surface condition problems, then mold strength is improved, but the foundry sand does not become fluid
Solution Approach 1:
The patent utilizes porous materials by incorporating a controlled pore structure (0.20-0.50 mL/g total pore volume with 2-10 μm diameter pores) into the refractory aggregate. This porous structure acts as a reservoir that absorbs excess binder, allowing the sand to maintain good fluidity for easy molding while the binder penetrates into the pores to provide sufficient mold strength.
3Ease of operation
If the sand surface is made less uneven, then a thick binder layer forms affecting fluidity, but uneven surfaces provide better binder distribution
Solution Approach 1:
The patent applies local quality by creating non-uniform pore distribution within the spherical particles - with pores concentrated in specific regions rather than uniformly distributed. This localized pore structure allows binder to penetrate at optimal locations while maintaining overall spherical shape, achieving both good fluidity and adequate binder distribution for mold strength.
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
This composition enhances the fluidity and mold strength of foundry sand, making it suitable for self-hardening and three-dimensional laminated molding methods, with improved performance in producing complex molds.
Implementation Method 1
a raw material composition in which alumina and silica are mixed to have a specified chemical composition is granulated into spherical particles by a method using a spray dryer or the like, and the granulated particles are then sintered in a rotary kiln or the like to produce spherical aggregate
Data Source
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Figure 3
AI summary
Provided is a refractory aggregate that is for casting sand and that comprises spherical refractory sintered particles artificially produced by a sintering method, and that can improve the fluidity of the casting sand and can achieve excellent mold strength. This refractory aggregate is for casting sand, comprises spherical refractory sintered particles artificially produced by a sintering method, is configured to have a roundness of at least 0.70 and an average particle size of 0.01-1.00 mm, and is configured such that the total volume of pores having a pore size of 2-10 µm as measured with a mercury intrusion porosimeter is in the range of 0.20-0.50 mL/g, and the amount of fine powder is additionally mixed such that the turbidity as measured by turbidimetry is at most 3000 NTU.