| Authors: | Barshilia, Harish C.; Acharya, Shashidhara; Ghosh, Moumita; Suresh, T. N.; Rajam, K. S.; Konchady, Manohar S.; Pai, Devdas M.; Sankar, Jagannathan. |
| Abstract: | Approx. 1.5-2.5 micro m thick nanocomposite coatings of TiAlCrYN were deposited using a four-cathode reactive unbalanced pulsed d.c. magnetron sputtering system from the sputtering of Ti, Al, Cr, and Y targets in Ar + N2 plasma. The TiAlCrYN nanocomposite coatings were deposited on various substrates such as high speed steel (HSS) drill bits, mild steel and silicon. TiAlCrYN coatings with almost similar mech. properties but with different Ti, Al, Cr and Y contents were prepd. to study their thermal stability and machining performance. The structural and mech. properties of the coatings were characterized using X-ray diffraction and nanoindentation technique, resp. The elemental compn., bonding structure, surface morphol. and cross-sectional data were studied using energy-dispersive X-ray anal., XPS and field-emission SEM, resp. Nanoscratch tests were performed to det. the adhesive strength of the coatings. The corrosion behavior of TiAlCrYN nanocomposite coatings on mild steel substrate was studied using potentiodynamic polarization in a 3.5% NaCl soln. Micro-Raman spectroscopy was used to characterize the structural changes as a result of heating of the nanocomposite coatings in air (600-1000 DegC). TiAlCrYN coatings prepd. at 17 at.% Ti, 13 at.% Al, 21 at.% Cr and 1 at.% Y exhibited thermal stability as high as 900 DegC in air (denoted as Sample 3). For the performance evaluation, the TiAlCrYN coated HSS drill bits were tested under accelerated machining conditions. With a drill speed of 800 rpm and a feed rate of 0.08 mm/rev the TiAlCrYN coated HSS drill bits (Sample 3) averaged 657 holes, while drilling a 12 mm thick 304 stainless steel plate under dry conditions, before failure. Whereas, the uncoated drill bits failed after drilling 50 holes under the same machining conditions. Results indicated that for the HSS drill bits coated with TiAlCrYN, the tool life increased by a factor of more than 12. [on SciFinder (R)] |
