Two University engineering professors, Jack Hudson and John Scully, have developed a new theory on how rust forms, the University announced Friday.
Their results contest previous theories concerning the development of metal corrosion and were published in the Aug. 20 issue of Science Magazine.
Scientists in the past have theorized that individual pits of corrosion on metal stabilize and grow independently, the study says.
The general theory developed by Hudson and Scully, along with several co-researchers at the Fritz-Haber Institute of the Max Planck Society in Germany, explains that high corrosion rates are caused not by the presence of individual pits of rust, but rather by the explosive growth in the number of metastable pits. Metastable pits are tiny rust seeds the size of a few micrometers which can develop on a metal surface.
All commonly used stainless steels, which are designed to be rust-resistant, can nevertheless undergo localized pitting corrosion, which then weakens the metal itself.
Researchers said their new theory shows the spread of rust to be similar to the epidemic spread of communicable disease. Each new corrosion pit increases the probability of new pits on metal in its vicinity.
The scientists also found that stainless steels can rust faster as environmental factors change.
According to the findings, corrosion from rust is estimated to cost United States industry three percent of the GNP annually.