Magnetron Sputtered NbN Films with Nb Interlayer on Mild Steel

[摘要] The aim of the study is to extend the NbN coating on MS with Nb interlayer to explore the benefits of hard nitride coatings on low-cost structural material and to compare the coating with NbN monolithic coating on SS. NbN on MS and SS was deposited by reactive d.c. magnetron sputtering at various N2/Ar flow ratios and substrate bias. Deposition rate decreased from 20 to 10 nm/min (without biasing) and from 16 to 8 nm/min (−50 V biasing) whenFN2/FArratio was varied from zero to 70%. Deposition rate decreased with the increase in bias voltage. Coatings showed hexagonalβNb2N, cubicδNbN, and hexagonalδ′ NbN as major phases with the increasing N2flow. Surface hardness reached a maximum of 2040 HK25at aFN2/FArof 20%. Critical loads, for cohesive and adhesive failure for coating on MS, were between 6–8 N and 9–12 N respectively; for coating on SS, the values were between 7–15 N and 12–25 N respectively. Duplex coatings were studied for hardness by Knoop microindentation, adhesion by scratch tester, and corrosion by potentiodynamic polarization technique. Hardness, adhesion, and corrosion resistance all improved when NbN coating was incorporated with Nb interlayer on MS.

[学科分类] 材料工程