More Than a Temporary Corrosion Covering: Chemically Bonded Phosphate Ceramics
Photo courtesy of EonCoat LLC.
Chemically bonded phosphate ceramics create a passivation layer that stops corrosion,
protected by a tough ceramic outer layer.
by Del Williams, Contributing Writer
Corrosion of steel, aluminum and other structural metals erodes the safety and financial stability of industries and countries alike. Fighting corrosion in ships, tanks, planes
and equipment costs the Pentagon $22.9 billion a year. Corrosion costs advanced industrialized nations about 3. 5 percent of
GDP to replace damaged material and components, plus a similar amount due to lost production, environmental impact, disrupted transportation, injuries and fatalities.
While traditional corrosion protection has relied mostly on
short-lived physically-bonded coverings of substrate surfaces, a
new category of chemically bonded phosphate ceramics (CBPCs)
can create a long-lived passivation layer that stops corrosion.
This is further protected by a tough ceramic outer layer.
paint is scratched, chipped, or breached and corrosion promoters enter the gap between the substrate and polymer coating. Then the coating can act like a greenhouse—trapping
water, oxygen and other corrosion promoters—allowing corrosion to spread.
Placing sacrificial, reactive elements next to steel that will corrode first, such as zinc and galvanized coatings, is another strategy. This works until the sacrificial elements are used up and
recoating must be done, usually after a few years.
Cathodic protection, where a negative voltage is imposed on
steel, can limit corrosion on pipelines or other stationary, continuous metal structures where voltage can be attached. But this
can fail if it’s not properly insulated and voltage goes to ground.
For assets that demand long-term corrosion protection, stainless steel alloys work. But with stainless steel costing up to six
times more than mild steel, this option is often cost prohibitive.
The limits of traditional corrosion protection
For generations, polymer paints have acted as a physical barrier
to keep corrosion promoters such as salt water and oxygen
away from steel and aluminum substrates. This works until the
A new approach to corrosion protection
Ideally, engineers, facility managers and industrial paint contractors would want the long-term corrosion-resistance of a stainless
steel part with the lower cost of coating application. A new category
www.coatingsworld.com
September 2011
