(19)

(11)

EP 0 349 601 A1

(12)

(43) Date of publication: 10.01.1990 Bulletin 1990/02 (21) Application number: 88907512.0 (22) Date of filing: 19.07.1988

(51) International Patent Classification (IPC):  C22B 21/ 00( . ) C25C 3/ 00( . ) (86) International application number: PCT/US1988/002374 (87) International publication number: WO 1989/006291 (13.07.1989 Gazette 1989/15)

(84) Designated Contracting States: BE CH DE FR GB IT LI LU NL SE (30) Priority: 28.12.1987 US 19870138391 24.05.1988 US 19880197889 (71) Applicant: ALUMINUM COMPANY OF AMERICA Pittsburgh, PA 15219 (US)

(72) Inventors: STEWART, Donald, L., Jr. Greensburg, PA 15601 (US) VAN LINDEN, Jan, H., L. Allison Park, PA 15101 (US) LACAMERA, Alfred, F. Trafford, PA 15085 (US) PIERCE, Thomas, V. Delmont, PA 15626 (US) PARKHILL, James, O. Tarentum, PA 15084 (US) URBANIC, John, M. Pittsburgh, PA 15235 (US) HORNACK, Thomas, R. Lower Burrell, PA 15068 (US) (74) Representative: Baillie, Iain Cameron, et al  c/o Ladas & Parry Altheimer Eck 2 D-80331 München D-80331 München (DE)