Porous Material with Rare Earth Binding Agent for Heat Shock Resistance
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Solution Overview
Problem
Conventional porous materials used for diesel particulate filters and catalyst supports lack sufficient heat resistance and resistance to heat shock, necessitating enhancement in these properties for improved performance.
Innovation Solution
A porous material composed of aggregates bound by an amorphous binding agent containing 8.0 to 15.0 mass% MgO, 30.0 to 60.0 mass% Al2O3, 30.0 to 55.0 mass% SiO2, and 1.5 to 10.0 mass% rare earth oxide, with a rare earth element such as yttrium, lanthanum, or cerium, which allows for low-temperature firing and enhanced heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a vitreous phase is used to bind silicon carbide particles, then low temperature firing is possible, but heat resisting properties and resistance to heat shock are insufficient
Solution Approach 1:
The invention uses a composite binding phase consisting of crystalline phases (mullite, forsterite, and/or enstatite) combined with an amorphous phase. This composite structure allows the material to benefit from both the low-temperature processing capability of the amorphous phase and the high heat resistance of the crystalline phases, particularly mullite which provides excellent thermal stability
Solution Approach 2:
The invention specifies precise compositional parameters for the binding phase: SiO2 (30-80 mass%), Al2O3 (5-45 mass%), MO (10-45 mass%) where M is Ca, Ba, Mg or Sr, with the amorphous phase volume percentage controlled below 20%. These parameter constraints optimize the balance between processability and heat resistance
2Ease of manufacture
If a vitreous phase is used to bind aggregates, then low temperature firing is possible, but resistance to heat shock is insufficient
Solution Approach 1:
The binding phase is designed as a composite system with crystalline phases (mullite, forsterite, enstatite) providing thermal shock resistance through their stable crystal structures, while the amorphous phase enables low-temperature processing. The controlled amorphous phase content (below 20% volume) ensures sufficient structural stability against thermal shock
Solution Approach 2:
The invention controls the amorphous phase volume percentage to be below 20% of the total binding phase, while maintaining specific compositional ranges for SiO2, Al2O3, and MO. This parameter optimization allows the crystalline phases to dominate the thermal shock resistance while retaining manufacturing advantages
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 porous material exhibits excellent heat resistance and resistance to heat shock, with a bending strength of 10 MPa or more and a bending strength/Young's modulus ratio of 1.7×10^-3 or more, suitable for high-temperature applications such as diesel particulate filters and catalyst supports.
Implementation Method 1
an amorphous binding agent to bind the aggregates to one another
Implementation Method 2
excellent resistance to heat shock
Data Source
AI summary
There are disclosed a porous material having excellent heat resisting properties and an excellent resistance to heat shock. A porous material contains aggregates and an amorphous binding agent to bind the aggregates to one another in a state where pores are formed among the aggregates, the binding agent contains a rare earth element, the amorphous binding agent preferably contains magnesium, aluminum, silicon, the rare earth element and oxygen, and the amorphous binding agent preferably contains 8.0 to 15.0 mass% of MgO, 30.0 to 60.0 mass% of Al2O3, 30.0 to 55.0 mass% of SiO2, and 1.5 to 10.0 mass% of the rare earth oxide.