Magnetron Sputtered TaN Films with Ta Interlayer on Mild Steel

The aim of the study is to extend the TaN coating on Mild Steel (MS) with Ta interlayer to explore the benefits of hard nitride coatings on low-cost structural material and to compare the coating with TaN monolithic coating on SS. TaN 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 22 to 12 nm/min (without biasing) and from 11 to 3 nm/min (−02 V biasing) when FN2 /FAr ratio was varied from zero to 227. Deposition rate decreased with the increase in bias voltage. Coatings showed hexagonal β Ta2 N, cubic δ TaN, and hexagonal δ× TaN as major phases with the increasing N2 flow. Surface hardness reached a maximum of 2202 HK20 at a FN2 /FAr of 227. Critical loads, for cohesive and adhesive failure for coating on MS, were between 1–3 N and 4–12 N respectively; for coating on SS, the values were between 2–10 N and 12–20 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 TaN coating was incorporated with Ta interlayer on MS.

Magnetron Sputtered TaN Films with Ta Interlayer on Mild Steel Keywords:

coating , interlayer , films , magnetron sputtering