Investigation of magnetron sputtered titanium–nickel–nitride thin films for use as mould coatings

Titanium–nickel–nitride coatings (Ti–Ni–N) were prepared by unbalanced magnetron sputtering with a pulsed DC discharge at the targets. The amount of nickel in the coatings ranged from 8 to 32 at.% and the nitrogen-to-titanium ratio was less than 1. Polished samples of steel (X42Cr13) were used as substrates, both shims and moulding inserts. Plastic universal hardness was between 7 and 21 GPa. Cross-section SEM images reveal a slightly columnar structure with a very smooth surface.The inserts were used in moulding experiments with polymethylmethacrylate (PMMA). They revealed a remarkable performance. No delamination of the coating was observed. The only wear detectable was some abrasion occurring at the dome-shaped top of the columns of the coating. This results in a decrease of the average roughness Ra and even better surface smoothness of the moulded PMMA parts.