| (Ti-Al)N coatings were deposited on Cobalt-cemented tungsten carbide (WC.Co) tool inserts by an unbalanced inverted cylindrical magnetron sputtering system (AC ICM-10). Cylindrical titanium and aluminum targets separated by a cylindrical metal with 80 mm height were used for the deposition. The targets were sputtered in an argon and nitrogen gases with constant flow rates and with a radio frequency power of 5 kW at 0.27 Pa of working pressure. The tool insert positioned at a distance of 185 mm from the upper end of the deposition chamber and at the same horizontal distance from the chamber walls. Thin film coating was characterized by X-Ray Diffraction, Scanning Electron Microscopy, and Energy Dispersive X-Ray Spectroscopy and confirmed to be of the Ti-Al-N type. Machining tests were carried out on a quenched-tempered steel (Cr4.2Mo4) using a lathe turning machine with different cutting speeds and feed rate and depth of cut were kept constant. Uncoated and coated carbide tool inserts were subjected to the same cutting conditions and the tool orientation were kept constant during all machining tests. Work piece surface roughness and the resulting cutting forces were measured and reported for each machining trial. Present results show that the X-ray diffraction showed the presence of a (200) NaCl crystal structure of the deposited films. The coated inserts exhibit lower wear rate and longer lifetime than those uncoated with high and low cutting speeds. Also, the coated inserts show significantly lower surface roughness than the uncoated. |
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