The influence of magnetic solenoid filtration on the property of (Ti–Al)N coatings deposited in a cathodic arc deposition system

The magnetic solenoid filtration techniques (both d.c. and a.c. modes) are employed in the present study for elimination of macroparticles present in the coatings deposited by the cathodic arc deposition system. The influence of the magnetic filtration technique on the property of (Ti-Al)N coatings is investigated. Properties of the coatings evaluated in terms of surface roughness, coating thickness, chemical composition and high temperature oxidation resistance are compared with the base line data derived from coatings prepared from a conventional cathodic arc deposition system. The surface smoothness of the resultant coating is considerably improved by the magnetic solenoid filtration technique, with some sacrifice in coating thickness. The a.c. magnetic solenoid filtration technique is observed to deliver the best combination result of coating thickness and surface smoothness. The relative contents of aluminum, titanium and nitrogen in the coatings are also observed to vary with the mode of solenoid filtration techniques employed, i.e. a.c., d.c. or no solenoid applied. The variation of aluminum content in (Ti–Al)N coatings also demonstrates its effect in the property of high temperature oxidation resistance. Ironically, (Ti–Al)N coatings deposited by the conventional cathodic arc system performed best in terms of oxidation resistance due to the retention of Al element in the coating.