Method of chemically cleaning the surface of articles of zirconium or hafnium or alloys thereof and of applying adherent electrophates to zirconium or hafnium surfaces or to the surfaces of alloys of these metals

摘要

In a method of cleaning the surface of articles of Zr or Hf, or alloys of Zr or Hf, the article is first physically cleaned, e.g. by sand-blasting, and then immersed in an aqueous solution containing NH4F and HF in a molar ratio of 1,2-3 for 10-240 seconds at a temperature of 70 DEG -120 DEG F. The solution may contain 0,25-1 per cent. of an aliphatic amine of formula CnH2n + 1 NH2. Where 12sEnsE18, when the said molar ratio may be 1-3 and the quantities of NH4F and HF are preferably 0,44-1,32 and 0,44-0,88 moles/litre respectively. A surface prepared in this way is stated to be particularly suitable for receiving an electroplated metallic coating.