Aerogel Manufacturing via Controlled Silicate Gelation
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Solution Overview
Problem
Conventional silica aerogels have low mechanical strength and heat-insulation performance due to their network structure, and require large amounts of silylating agents and extended production times, which increase costs and reduce efficiency.
Innovation Solution
A method involving the use of an alkaline high-molar-ratio aqueous silicate solution with controlled pH adjustment and dehydration/condensation reactions to produce aerogels with optimized pore volume, mean pore diameter, and specific surface area, reducing the need for excessive silylating agents and shortening reaction times while enhancing mechanical strength and heat-insulation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silica aerogels are synthesized with a network structure of silica particles connected through point contact, then heat-insulation performance is achieved, but mechanical strength is insufficient
Solution Approach 1:
The patent combines silica particles with organic fibers to create a composite aerogel structure. The fibers form a scaffold that provides mechanical strength while the silica particles maintain the porous network for heat insulation. This composite approach resolves the contradiction by integrating two materials with complementary properties.
Solution Approach 2:
The patent creates different regions within the aerogel structure: silica particle clusters provide heat insulation in certain areas, while fiber-reinforced regions provide mechanical strength in other areas. This local differentiation allows each component to optimize its function without compromising the overall performance.
2Reliability
If a large amount of silylating agent is used to prevent gel skeleton contraction, then heat-insulation performance is improved, but production cost and time increase
Solution Approach 1:
The patent optimizes the silylating agent concentration and reaction conditions to achieve effective hydrophobization with reduced agent quantity. By carefully controlling parameters such as reaction time, temperature, and agent dosage, the patent maintains heat-insulation performance while reducing production costs and time.
Solution Approach 2:
The patent utilizes the natural hydrophobic properties of certain silica surface treatments and the self-organizing behavior of the gel network to minimize reliance on excessive silylating agents. The structure itself contributes to preventing contraction, reducing the need for chemical additives.
3Ease of manufacture
If conventional drying methods are used to remove liquid medium from gel, then production simplicity is maintained, but gel skeleton contraction and densification occur
Solution Approach 1:
The patent employs supercritical drying or freeze-drying methods that utilize phase transitions to remove liquid without causing capillary contraction. By transitioning through supercritical fluid or ice phases, the liquid is removed while maintaining the aerogel's porous structure and preventing densification.
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 method results in aerogels with higher strength and improved heat-insulation performance, suitable for use as both heat-insulation and sound-absorbing materials, with reduced production costs and time, and improved reliability.
Implementation Method 1
These materials, and a liquid medium such as water or alcohols, and a catalyst, as needed, are mixed, and the materials are hydrolyzed
Implementation Method 2
the sol materials are subjected to a polycondensation in the liquid medium to convert the sol materials into a gel
Implementation Method 3
Aging is a step for causing the polycondensation reaction of the gel to proceed, thus reinforcing the skeletons
Implementation Method 4
In this step the gel is hydrophobized with a silylating agent
Implementation Method 5
contraction of gel skeletons due to strong capillary force will occur when the liquid medium in the gel is evaporated to dry the gel
Implementation Method 6
when the liquid medium in the gel is evaporated to dry the gel
Implementation Method 7
silica aerogels have excellent heat conductivities of around 15 mW/mK
Data Source
AI summary
In a method for manufacturing an aerogel, an acid is added to a first aqueous high-molar-ratio silicate solution that includes silica particles having a mean particle diameter of from 1 nm to 10 nm and that is alkaline, to produce a gel. The gel is subjected to a dehydration condensation to obtain a hydrogel. The hydrogel is converted into a hydrophobized gel. Then, the hydrophobized gel is dried. According to the method, an aerogel having a pore volume of from 3.00 cc/g to 10 cc/g, a mean pore diameter of from 10 nm to 68 nm, and a specific surface area of from 200 m2/g to 475 m2/g can be prepared.