Fumed Silica (also known as pyrogenic silica, colloidal silicon dioxide, molecular formula: SiO2) is a nano-powder material that has seen gradually extensive understanding and usage. Currently it has been used in many fields including the production of silicone rubber, adhesives, ink coatings and resin composite materials.
(Examples of fumed silica applications)
With the iterative technology updates and the continuous expansion of downstream applications, in terms of prospects for industry application, this inorganic nanomaterial, the so called “industrial monosodium glutamate”, still has great potential to tap.
In recent years, as the country has been vigorously advocating the promotion and application of energy-saving green buildings and industrial energy-saving materials, vacuum insulation panel, a new type of product that uses vacuum porous materials as base materials, has been enjoying great popularity in the thermal insulation industry.
(Vacuum insulation panels)
Vacuum insulation panel (VIP board) has a low thermal conductivity coefficient (less than 0.035w/(㎡.k)), which helps effectively avoid heat transfer caused by air convection) and does not contain any ODS material. Good environmental protection properties and energy-efficient performance have made vacuum insulation panel currently the most advanced and efficient insulation material in the world. At present, this product is mainly used in thermal insulation applications, including household refrigerators, refrigerators for yachts and vehicles, mini refrigerators, deep freezers, electric water heaters, vending machines, cooling chambers, refrigerated containers, wall insulation and LNG storage and transportation etc.
(Vacuum insulation panels for freezers)
Generally a vacuum insulation panel is composed of three parts, namely the core material, the membrane and the getter (desiccant), among them the core material is the most important performance determining factor.
Many materials such as glass wool, micro silicon powder, aerogel, fumed silica, etc. can be used as the core materials for vacuum insulation panels. At present, due to the limitations in terms of cost and technology etc., VIP panels with core materials made from glass wool, micro silicon powder, etc. are generally prone to issues such as short service life, unstable production quality and serious heat loss during edge banding. As for aerogel, it boasts very good performance but is not suitable for large-scale promotion due to high cost. Compared with the other materials, fumed silica enjoys a cost advantage and some unique characteristics, which help it become the preferred nanomaterial for the production of high-end vacuum insulation panels.
Firstly, as an ultra-fine nanomaterial, fumed silica boasts a primary particle size of only 7-40nm and a specific surface area as high as 400㎡/g. As a result, the internal voids of its aggregates and particles are extremely small and the related porosity is relatively high; secondly, the formation process of fumed silica (three-dimensional dendritic silica aggregates formed by the fusion of primary silica particles, which then joins together by hydrogen bonding and van der Waals force connection to form silica agglomerates) determines that it has smaller bulk density (30-60g/L); in addition, fumed silica naturally has high temperature resistance as it is made in a high temperature (1200-2100°C) environment. And lastly, molding with fumed silica is relatively simple, which can be executed directly after mixing it with other additives such as infrared shielding agents, adhesives and reinforcing agents. Based on the above factors, it can be seen that compared to aerogel and other core filler materials, fumed silica has obvious advantages in terms of production cost and efficiency, electrical properties, thermal stability and service life.
With the development of technology, fumed silica's range of application range is still expanding. In the context of state-wide promotion of greenization, environmental protection, and energy conservation, vacuum insulation panels made with fumed silicas as the core materials will play an important role in the field of energy-efficient buildings.