G. Pajonk et H. Bubert, Influence of pickling high alloyed CrNi-steels and nickel base alloys withcitric acid on the composition of their tarnish oxides, MIKROCH ACT, 133(1-4), 2000, pp. 289-293
Extra-ordinary mechanical features and high corrosion resistance are essent
ial qualities of CrNi-steels and nickel base alloys. The corrosion resistan
ce of these materials fundamentally depends on their surface conditions. Ta
rnish colours and welding scale, formed during thermal treatment or joining
, are removed by pickling components made of these alloys with sulphuric ac
id, nitric acid and hydrofluoric acid as well. By this kind of surface refi
nement several million tons per annum of aggressive waste waters are produc
ed, that cause high environmental risks and not acceptable employee endange
rings. Therefore, a project was promoted by the DECHEMA e.V. to replace hyd
rofluoric acid by organic complexing agents. The related surface analytical
examinations are reported in this publication.