Modulated pulse power sputtered chromium coatings

Cr coatings were deposited using continuous dc magnetron sputtering (dcMS) and modulated pulse power sputtering (MPP) techniques in a closed field unbalanced magnetron sputtering system at equivalent average target powers. It was found that MPP sputtering exhibited higher deposition rates than in dcMS when the average target power density was above 14 W cm− 2 for the Cr coating depositions. Plasma diagnostics confirmed a significant increase in the numbers of both target material (Cr) and gas (Ar) ions in the MPP plasma as compared to the dc plasma. The substrate peak current densities measured in the MPP depositions (104–324 mA cm− 2) have been increased by over a factor of 50 to those in the dcMS conditions (2–5.5 mA cm− 2). The enhanced ion flux bombardment from the highly ionized MPP plasma led to the formation of denser microstructure and finer grain size in the MPP Cr coatings than in the dcMS Cr coatings. In addition, MPP sputtered Cr coatings exhibited improved hardness and adhesion.