Technical Science | How is fumed silica used in vacuum insulation panels (VIP)?


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Technical Science | How is fumed silica used in vacuum insulation panels (VIP)?

  • Categories:NEWS
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  • Time of issue:2022-07-01 15:49

Technical Science | How is fumed silica used in vacuum insulation panels (VIP)?

With the fresh release of Fuchang fumed silica new product fusil200, the main application points of high specific surface fumed silica such as liquid silicone rubber and high-transparency solid silicone rubber will inevitably attract attention.

However, as the application direction of fumed silica that cannot be ignored, the vacuum insulation plate (VIP) material should also be paid attention to.

As a high-performance product in the field of thermal insulation, VIP board has not been fully popularized in domestic applications due to the time of its introduction and the difficulty of current construction. Its excellent thermal insulation properties and fire resistance properties make the material have a bright future in construction, cold chain and other industries.

Fuchang currently has a variety of fumed silica products that can be used in the field of VIP insulation panels, so let's learn about this material and Fusil products related to Fuchang step by step!

Brief Introduction of Vacuum Insulation Panel

VIP panel is a vacuum insulation panel, which is the abbreviation of Vacuum Insulation Panel. It is a kind of vacuum insulation material.

It can effectively avoid heat transfer caused by air convection, and greatly reduce the thermal conductivity, even less than 0.035w/(㎡.k). Due to its environmental protection and high efficiency and energy saving characteristics, it is one of the most advanced and efficient thermal insulation materials in the world. one.

In the past, VIP was mainly used in the fields of military industry, shipping incubators and medical incubators. Now VIP has been widely used in refrigerators, freezers, refrigerated trucks, cold storage, refrigerated and refrigerated containers and other fields. In addition, in aerospace, food industry and wall Insulation and other fields have also gradually begun to be used.

As shown in the figure above, the structure of the vacuum insulation panel is composed of a core material, a diaphragm and a getter.

01. The main function of the surface diaphragm material is to ensure the vacuum degree in the vacuum insulation panel for a long time. The performance and service life of vacuum insulation panels depend to a large extent on the resistance of the surface membrane material to gas penetration during its use. The lower the degree of vacuum in the vacuum insulation panel, the better its thermal insulation performance. In order to improve the gas permeation resistance of the film, the surface film is a composite film of metal and plastic, such as aluminum foil plastic film.
02. The getter is used to create a vacuum internal environment to maximize the internal vacuum degree and reduce convection and radiation heat transfer.
03. The core material involves the application of silica products, which will be introduced in detail in the next section.

The role of core material
As the skeleton material of VIP and a necessary condition for maintaining vacuum, the core material plays a very important role in the VIP system:
01. Board wall used to support VIP
02. Control gas conduction and convection heat transfer
03. Infrared shielding and scattering

Core material classification
Core materials are divided into the following categories according to different materials:
01. Granular core material: fumed silica, silica powder, perlite, etc.
02. Foam core material: foamed polystyrene, foamed polyurethane, etc.
03. Fiber core material: glass fiber, rock wool, ceramic fiber, etc.

Advantages and applications of fumed silica core material
Compared with other core materials, fumed silica core material has lower thermal conductivity, lower vacuum degree, longer life and low sensitivity to external pressure, which can make VIP board with thinner thickness and lighter weight. Therefore, it is very suitable for making some insulation boxes, refrigerators and insulation materials in buildings. Other relevant materials have outlined the performance and application of VIP, and it is believed that fumed silica core material is most suitable as a building insulation material, and its service life can be maintained for 30 to 50 years. Therefore, fumed silica core material is widely used in buildings in European countries. Keep warm.

Relationship between thermal conductivity and internal air pressure of different VIP core materials

Another obvious advantage of fumed silica core material is that silica itself is a very good fireproof material, so buildings or products made of fumed silica VIP board have very high fire resistance. And when fumed silica is used with other types of core materials to make composite core materials, because of its fine particle size and good fusion degree, it can minimize the vacuum degree, quality and thickness of composite core materials.

Schematic diagram of the new composite core material

The recommendation of Fuchang Fusil fumed silica in the application of VIP core material

At present, only hydrophilic (untreated) fumed silica is required for VIP sheets, so Fuchang Fusil 200, Fusil 150 and Fusil 300 are highly recommended. Fuchang Fusil series fumed silica has been widely used in the production of thermal insulation vacuum materials abroad.

As a new product, Fusil 200 has better performance and cost performance, so it is highly recommended for VIP field.

Model Specific surface area Surface treatment PH SiO₂ loss on drying
m²/g (%) (%)
Fusil 150 150±15 3.8 - 4.2 > 99.8 < 1.5
Fusil 200 200±15 3.8 - 4.2 > 99.8 < 1.5
Fusil 300 300±20 3.8 - 4.2 > 99.8 < 1.5