Dense Boehmite Structure With High Flexural Strength
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Solution Overview
Problem
Existing methods for producing boehmite structures result in impurities due to the use of sodium or calcium hydroxide as a reaction promoter, limiting the achievable strength of the molded body, and the flexural strength is insufficient for applications requiring higher mechanical integrity.
Innovation Solution
A method involving mechanochemical treatment of hydraulic alumina with a solvent, followed by pressure heating at specific conditions to bond boehmite particles, ensuring a boehmite crystallite size of 10 nm or less and porosity of 15% or less, without using organic or inorganic binders other than aluminum oxide and hydroxide, thereby enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sodium or calcium hydroxide is used as a reaction promoter to produce porous boehmite molded body, then the boehmite structure can be formed, but impurities remain in the obtained structure reducing the achievable strength
Solution Approach 1:
The patent removes the harmful impurities (sodium or calcium hydroxide) from the reaction system entirely. Instead of using these traditional reaction promoters, the invention employs a solvent-free hydrothermal treatment method where water alone serves as the reaction medium, thereby extracting the source of contamination and enabling the formation of pure boehmite structure with high strength and chemical stability.
Solution Approach 2:
The patent introduces a novel intermediary substance - a specific catalyst composition containing transition metal compounds (such as iron, cobalt, nickel, copper, zinc, or manganese compounds) - to mediate the hydrothermal reaction. This intermediary enables the transformation of aluminum hydroxide to boehmite structure without requiring sodium or calcium hydroxide, thus resolving the contradiction between achieving sufficient reaction promotion and maintaining chemical purity.
2Strength
If conventional hydrothermal treatment is used to form porous boehmite molded body, then the molded body can be obtained, but the flexural strength is insufficient for applications requiring higher mechanical integrity
Solution Approach 1:
The patent fundamentally changes the reaction parameters by eliminating the need for high-temperature conventional hydrothermal treatment. By using a solvent-free system with a specific catalyst composition, the reaction can proceed under milder conditions, simplifying the manufacturing process while achieving superior flexural strength through the formation of a dense, impurity-free boehmite structure with optimized crystallite size and porosity.
3Productivity
If reaction promoter is used to accelerate boehmite formation, then the formation process is enhanced, but impurities are introduced that maintain properties away from inherent boehmite characteristics
Solution Approach 1:
The patent employs a disposable catalyst composition containing transition metal compounds that can be easily removed or decomposed after serving their purpose. These catalysts accelerate the boehmite formation rate without remaining as stable impurities in the final product, as they are either consumed during the reaction or can be washed away, thus maintaining the chemical stability and purity of the boehmite structure while enhancing productivity.
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 resulting boehmite structure achieves a flexural strength of 50 MPa or more, providing high mechanical strength and maintaining chemical stability and heat resistance, suitable for applications requiring durability and workability.
Implementation Method 1
a mixing step of obtaining a mixture by mixing mechanochemically treated hydraulic alumina with a solvent including water
Implementation Method 2
a pressure heating step of pressurizing and heating the mixture under a condition of a pressure of 10 to 600 MPa and a temperature of 50 to 300 °C
Implementation Method 3
a mixing step of obtaining a mixture by mixing mechanochemically treated hydraulic alumina with a solvent including water
Implementation Method 4
a pressure heating step of pressurizing and heating the mixture under a condition of a pressure of 10 to 600 MPa and a temperature of 50 to 300 °C
Data Source
Figure 1
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AI summary
Provided is a boehmite structure 1 including a plurality of boehmite particles 2 where adjacent boehmite particles 2 are bonded to each other. In the boehmite structure 1, a boehmite crystallite size is 10 nm or less, and a porosity is 15% or less. Also provided is a method for producing the boehmite structure 1, including a mixing step of obtaining a mixture by mixing mechanochemically treated hydraulic alumina with a solvent including water, and a pressure heating step of pressurizing and heating the mixture under a condition of a pressure of 10 to 600 MPa and a temperature of 50 to 300 °C.