It is well known that a metallic vessel such as an iron vessel containing water having electrolytes dissolved therein as, for example, seawater, corrodes gradually, and in order to prevent the corrosion of such a vessel, an electric means is used, which is called "electric prevention for corrosion". The electric prevention for corrosion is also called "cathodic protection". In such electric prevention, a metallic vessel is used as a cathode and carbon, magnetite or a platinum-coated-titanium electrode is used as an anode, and a D.C. voltage is applied to the electrodes. In this case, an electrode which is used as an anode is required to have good corrosion resistance. In addition to this, in order to prevent the corrosion of "iron vessel for heating water", or "iron water heater" by the cathodic protection method, an electrode which is used as an anode is required to have good thermal shock resistance as well as good corrosion resistance because heating and cooling are repeated in the water heater.
It has been ground that the carbon electrode is characterized by poor corrosion resistance, and the magnetite electrode is characterized by poor corrosion resistance and thermal shock resistance. The platinum-coated-titanium electrode is excellent in electric conductivity and thermal shock resistance but it has low resistance for ripple current.
It is an object of the present invention to provide an electrode which is excellent in thermal shock resistance as well as the corrosion resistance and further, has a lower resistivity.
USPTO Backgrounds
USPTO Backgrounds