Noble Metals

The corrosion resistance of the noble metals is considered excellent although there are some discrepancies in corrosion testing results of these materials. A practical upper limit on the uniform corrosion rates of noble metals is generally set at about 2 mils/yr due to their high costs. Some of the corrosion rates in various environments may extend higher than this “acceptable” limit as will be discussed. The high cost of the noble metals limits their use in functional devices to small scale applications such as electrical contacts due to their good conductivity and corrosion resistant linings where the combination of their properties make them cost effective.