In my mind, the holy grail for thermal insulation is a practical (i.e, inexpensive and easy to use) product that incorporates silica-based aerogel, and, at first glance, Cabot’s new Enova line of aerogel particles appears to be a step in the right direction.
Bulk silica aerogel is a hydrophobic superinsulator, but it is extremely brittle and therefore not so easy to manufacture in quantity, transport, use in large sizes, etc. Some niche applications have been found where the size of the products are small and buyers are willing to pay a premium for the extra performance.
Other companies, such as Cabot, ThermoBlok and Aspen also have been trying to find a useful middle ground, where some thickness and performance characteristics are being traded off for ease-of-use considerations. And, so far, even these are being aimed at high-payoff types of applications, such as pipelines and storage tanks where added temperature control can yield major energy savings, and to create thermal barriers in isolated construction elements, such as steel stud facings.
Cabot’s innovation in aerogel seems to be developing a product aimed specifically at the coatings market. While the reliance on particles rather than sheets of aerogel decreases the potential for insulation, this disadvantage could be offset by the advantage of being easily sprayed on using standard manufacturing and constructon equipment.
An announcement from the company, timed to coincide with the opening of the European Coatings Show, says that, “applying a 1mm coating containing Enova aerogel to a 200°C metal surface meets U.S. and European testing protocols for safe touch temperature, preventing the first-degree burns one would normally expect within five seconds of skin contact. A thicker application such as a 2mm coating results in a reduction in energy use of 30 percent for uninsulated metal vessels maintained at 70°C. This can easily translate to potential applications as wide ranging as home and commercial appliances, process piping, building and tank storage.”
Cabot says the thermal conductivity of the particles is 12 mW/mK. Although this is theoretically better than polyurethane foam (30 mW/mK), the company admits that the thermal conductivity of Enova can exceed polyurathane (30 mW/mK to 50 mW/mK) when the particles are used as an additive in a water-borne formulation. Cabot points out that this is still seven to 10 times more insulative than standard paint — and I suspect that the company will be looking to develop some partnerships with paint manufacturers and construction material suppliers.
It should be noted that the Enova brand actually encompasses three types of aerogel products, which are mainly differentiated by particle size. 0.1–0.7 mm, 0.1–1.2 mm and 2–40 µm.
So far, I have been unsuccessful in speaking with James Pidhurney, Cabot’s manager for the Enova products, (he is apparently tied up at the show), but he predicted in the company’s announcement that big changes may be in store. He says the, “Enova aerogel [additive] creates a paradigm shift in how the industry thinks about insulation and coatings, two products which were once mutually exclusive. In the past, if you wanted flexibility in a coating, you had to compromise on insulation performance. Enova additives enable a new class of coatings that deliver the performance of traditional insulation and the flexibility of a coating in a single product.”