High Temperature Moisture Barrier


Cerablak® UTF (for planar surfaces) and Cerablak® HTS (for porous substrates) can serve as highly effective and durable moisture barriers at elevated temperatures (up to 1400°C).  Corrosion by atmospheric moisture is well known, but moisture can cause devastating degradation on materials at elevated temperatures.  An order of magnitude improvement in durability of expensive advanced materials can be achieved via ATFI’s unique glass barriers deposited via low-cost, scalable, and environmentally-friendly processes.

 

Moisture Problem

Corrosion of mild steel under atmospheric conditions due to moisture is well known and costs billions of dollars annually, but degradation is much worse as temperatures rise. Even common heaters containing stainless steel sheaths, used in humidity chambers at 90°F, are susceptible to degradation by moisture. At right, moisture-exposed heaters show rapid degradation after only one year of use.

 

Most recently, efforts to prevent moisture attack have shifted to advanced materials used or processed at high temperatures (>500°C). Advanced thermally-stable hermetic packaging designs are needed to accommodate new form factors such as those found in flexible electronics. Presently-used encapsulation films are either not sufficiently transparent or they degrade readily in sunlight, as with polymeric or inorganic-organic hybrid films. 

 

Susceptibility to moisture is a lot more severe at even higher temperatures (>900°C) faced by many advanced ceramics, refractories, thermal spray ceramic coatings, and ceramic matrix composites.  Due to the inherent open porosity of these bulk materials, the degradation occurs throughout the bulk with rapid deterioration of its mechanical and/or thermal properties. 

 

Cerablak™ Passivation Against Moisture
Cerablak® UTF can be deposited on polymeric surfaces to provide a transparent, ultra-thin inorganic surface which is not degraded by solvents or chemicals, is UV stable, and provides a barrier to water vapor. Water vapor transmission (WVTR) measurements show a reduction in water vapor transport of four orders of magnitude when a Cerablak® coating is applied—all with less than 100nm of Cerablak® film!

 

Cerablak® HTS can seal a wide range of composite structures with the ability to infiltrate porosity under 100 nanometers in diameter due to favorable formulation characteristics. The barrier film is deposited uniformly throughout the internal pore network without adding much weight (typically <2%) and has little or no detrimental impact on thermal or physical properties. Conversely, enhancements in mechanical properties are observed in most cases.