Applying Lead Dioxide Coatings to Metallic Titanium by Anodic Deposition

摘要

1,189,183. Anodic deposition of lead dioxide. BADISCHE ANILIN- & SODA-FABRIK A. G. Aug. 25, 1967 [Aug. 27, 1966], No.39237/67. Heading C7B. Coatings of PbO 2 are applied to Ti, e.g. as netting for an anode in the electro-chemical hydrodimerization of acrylonitrile to adipodinitrile, by anodic deposition from aqueous electrolytes containing a Pb(II) salt, e. g. Pb(ClO 3 ) 2 or Pb(NO 3 ) 2 , with the corresponding acid HClO 3 or HNO 3 , in a process wherein (a) the Ti is pretreated with an aqueous acid solution containing FSP-/SP ions, e.g. 10-100g/l as HF with or without NaF or KF, or NH 4 HF 2 with ammonium acetate, and/or (b) the electrolyte contains FSP-/SP ions e.g. 0À1-2g/l. Electrolysis is preferably effected at 40-90‹ C. and current densities of 1-10 amps/sq.dm. The cathode may be a brass netting coated with lead. When pretreating with HF solution, the Ti is preferably immersed in a concentrated solution of NaF prior to electrolysis. The Ti may be initially treated with aqueous NaOH solution, then degreased in C 2 H 2 Cl 4 and pickled with concentrated HCl prior to the above treatment. It is stated that it is known to electro-deposit PbO 2 on Ta from an acid Pb(NO 3 ) 2 solution. Alkaline baths are known containing sodium plumbite or lead tartrate. Specification 1,145,539 is referred to.