Georgia Tech scientists have developed a new method to make lumber thermally insulated, fungal-resistant and nearly impervious to water.
The new process involves applying a protective coating of metal oxide that is only a few atoms thick throughout the entire cellular structure of the wood.
This process, known as Atomic Layer Deposition (ALD), is already frequently used in manufacturing microelectronics for computers and cell phones.
Conventional pressure treating involves putting lumber inside a pressurized watertight tank and forcing chemicals into the boards.
This has been widely used for more than a century to help stave off the fungus that causes wood rot in wet environments.
Georgia Tech’s new process is performed in an airtight chamber – just like any other pressure treatment. However, the chamber is set at low pressures to help the gas molecules permeate the entire wood structure.
“It was really important that this coating be applied throughout the interior of the wood and not just on the surface,” says assistant professor Mark Losego.
“Wood has pores that are about the width of a human hair or a little smaller, and we used these holes as our pathways for the gases to travel throughout the wood’s structure.”
As the gas molecules travel down those pathways, they react with the pore’s surfaces to deposit a conformal, atomic-scale coating of metal oxide throughout the interior of the wood.
The result is a new type of wood that can shed water off its surface and resist absorbing water even when submerged.
In their experiments, the researchers took finished pine 2x4s and cut them into one-inch pieces.
They then infused the lumber with three different kinds of metal oxides: titanium oxide, aluminum oxide and zinc oxide.
Of the three, titanium oxide performed the best by helping the wood absorb the least amount of water.
In addition to being hydrophobic, lumber treated with the new vapor process also resists the mold that eventually leads to rot.
Another benefit is that the vapor-treated wood is far less thermally conductive than untreated wood.
Image and content: Georgia Tech via Eurekalert