The British Petroleum Company, P.l.c.

Richard A Cayless

Prem Sagar Thukral

David A Pippard

Leonard B Hazell

The naturally occurring metal oxide layer in contact with a metal in the bulk state is treated with a solution of a salt of yttrium or the lanthanide metals. The treatment is applied in order to increase the adhesive strength of bonds between the metal and subsequently applied adhesives and to enhance the durability of such bonds in aqueous environments. The concentration of the applied solution is preferably in the range 10.sup.-2 to 10.sup.-6 M. Yttrium or samarium nitrate is the preferred salt. The treatment is preferably used in conjunction with epoxy resin adhesives.

Process for the treatment of a metal oxide layer, a process for bonding

A method of inhibiting corrosion of a metal surface comprises applying to the metal surface an organic solvent in which is dissolved a phosphate monoester of a hydroxyalkyl acrylate or a hydroxyalkyl alkylacrylate which phosphate monoester has the general formula; ##STR1## where R.sub.1 is hydrogen, a methyl group or an ethyl group R.sub.2 is an alkyl group having from 2 to 10 carbon atoms and

Surface treatment of metal

A method of producing a corrosion inhibitor formed of particles of an inorganic oxide having corrosion inhibiting anions chemically bound to the particles comprising contacting the inorganic oxide with an aqueous solution containing corrosion inhibiting anions at a temperature of from 50.degree. to 95.degree. C. and at a pH sufficiently low to initiate ion-exchange and maintaining the pH at this low level by the addition to the solution of further anions or a compound forming such anions in solution. Preferably the corrosion inhibiting anions are molybdate anions. The particles may be incorporated into protective coatings in amounts up to 80% wt based on dry film weight giving coatings with up to 12% wt of anions.

Method of producing corrosion inhibitors

Corrosion inhibiting particles comprise an inorganic oxide which is silica or alumina, having corrosion inhibiting cations, particularly calcium or zinc cations, chemically bound to the particles. They may be prepared by contacting a silica or alumina containing hydroxyl groups with an alkaline solution containing the cations, at ambient temperature. The corrosion inhibiting particles may be incorporated into protective coatings, e.g. paints based on epoxy resins, alkyd resins, vinyl resins or chlorinated rubbers, in amounts up to 80% wt based on dry film weight, giving coatings with up to 7.2% wt corrosion inhibiting cations. Release of the cations is by ion exchange with other cations, e.g. the alkali metal cations of sea water, and does not, as is normal with corrosion inhibiting coatings, depend on the water solubility of the corrosion inhibitor.

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London, United Kingdom

Richard A Cayless