FORMATION OF LEAD DIOXIDE ON LEAD AND ITS ALLOYS IN AQUOUS CHLORIDE MEDIUM

摘要

1423093 Electro-depositing PbO 2 ; cathodic protection COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH 13 Feb 1974 6588/74 Headings C7B and C7E PbO 2 coated Pb or Pb alloy for cathodic protection is formed by anodically polarizing the Pb or Pb alloy, with a solid PbO 2 microelectrode fitted to its surface, in aqueous NaCl or synthetic sea-water e.g. containing 0.5 to 3% W/VNaCl. The Pb alloy may contain 6% Sb or 1% Ag. The cathode may be of mild steel. The anode current density may be 0.5 to 6A/dmSP2/SP. The ratio of area of Pb (alloy) to PbO 2 microelectrode may vary from 10 to 600. The PbO 2 microelectrode may be prepared by electrodepositing PbO 2 from aqueous Pb(N03)2 - Cu(NO 3 ) 2 bath on graphite, steel or Ni substrate, removing the deposit and, if necessary, abrading and/or grinding to desired size and shape, or electro-depositing on masked substrate exposing that portion which equals the size and shape of the microelectrode, and fitting the microelectrode into drilled holes in the Pb or Pb alloy.