Properties of coated tools for improved performances

The degradation of materials, connected to ageing and wear, can be limited by suitable treatments aimed at the increase of surface properties Among the surface modification techniques thermal spraying processes allow a lot of advantages improving the performance and extending the life of materials and components. The convenience for the substitution of nodular cast iron with coated steel for the manufacture of rolls to be employed in a rod mill plant was studied by means of disk on disk wear tests on plain carbon samples coated with the fuse and spray technology, using 7 different type of nickel or cobalt based powders, comparing their wear resistance with the behaviour of nodular cast iron specimens. On the basis of the wear tests, the most promising coating materials were applied to steel rolls and their behaviour and duration on a rod rolling plant were compared with those of nodular cast iron rolls. The rolls coated with nickel based alloy admixed with WC-Co powder reached the best performance, with a duration about 40 % higher than the cast iron ones.