Untitled

Corrosion behavior of hybrid coatings: Electroless Ni–Cu–P and sputtered TiN

“…The XRD diagram at the highest bias of −150 V indicated a lower degree of (111) texture orientation and a larger share of crystallites with (200) axis of orientation. This effect of a high negative bias on TiN structure has been formerly observed [1,4].…”

“…Their arrangement is more faulted at the interface region with the amorphous Ni-Cu-P and their density in Ti seems greater. Ti film thickness is above 200 nm, to prevent high compressive stress in thinner layers at higher bias voltages, as found in [4]. The gradual alignment of columns is extended over a film thickness of more than 200 nm.…”

“…The thin (0.01-0.2 µm) Ti sub-layer improves the adherence of TiN to the substrate. It has been found that keeping Ti interlayers thin and the bias voltage low, within the range of − 50 V-0 V, the compressive residual stress remained within the range of 184-255 kg/mm 2 (1.8-2.5 GPa), though it increased with an increasing negative potential value [4]. This is greater by about 2 orders of magnitude than the usual residual stresses in galvanic coatings.…”

“…An extremely large compressive residual stress of 6 GPa was found even in a 0.1-μm thick TiN film [3]. The dependency of the residual stress in TiN/Ti/steel has been studied as a function of the Ti coating thickness and substrate bias [4]. The thin (0.01-0.2 µm) Ti sub-layer improves the adherence of TiN to the substrate.…”