Effects of nitrogen pressure and pulse bias voltage on the properties of Cr-N coatings deposited by arc ion plating

Cr-N coatings were deposited on 1Cr18Ni9Ti stainless steel in the pure N2 atmosphere by arc ion plating (AIP). The relationships between deposition parameters and coating properties were investigated. X-ray diffraction showed a phase transformation from CrN + Cr2N + Cr → CrN + Cr → CrN and the CrN preferred orientation changed from (200) to (220) as N2 pressure increased. Increasing bias voltage led to CrN preferred orientation changed from (200) to (220) and the formation of Cr2N. XPS results indicated that chemical composition of the coatings changed as N2 pressure increased but it changed little with bias voltage. The lower melting point of chromium nitride formed on target surface induced the increase of macroparticles and deposition rate with increasing N2 pressure; and bias voltage had an obvious effect on reducing macroparticles of the Cr-N coatings. Residual stresses were measured by substrate curvature technique, and the changing tendency coincided with the microhardness of the coatings.