Effects of Salt Corrosion on the Adhesion of Brass Plated Steel Cord to Rubber

Abstract

Abstract Adhesion loss caused by salt corrosion is proposed to occur by the following process: 1) During a salt corrosion test, the NaCl solution rises in the cavity located at the steel-cord center. 2) An electrochemical oxygen concentration cell is formed. 3) OH− is produced by the reduction of oxygen. 4) An increase of the NaOH concentration causes the reverse of ion tendency between brass and steel. 5) Dezincification and dissolution of brass take place in the brass plating. The same process also occurs in the corrosion of a bare brass plated steel cord immersed in NaCl solution. Compounds containing cobalt stearate and a compound free from cobalt show adhesion deterioration by the process described above. Many other cobalt salts suppress the corrosion of brass in NaCl solution. At the same time, the underlying steel changes to become ignoble compared with brass, leading to the production of a large amount of rust. In view of the above considerations, it is desirable to remove the cavity located at the steel-cord center in order to suppress the steel-cord corrosion. Use of an open type of steel cord is useful in this respect.