On production of nanocrystalline ternary nitride coatings via magnetron sputtering
- Publication Type:
- Journal Article
- Materials Science Forum, 2003, 426-432 (3), pp. 2473 - 2478
- Issue Date:
Magnetron sputtering was employed to produce high performance nanocrystalline ternary (Ti,Al)N coatings. Two important deposition parameters, namely the nitrogen deposition pressure and the substrate bias voltage, which affect the energies of the depositing atoms and molecules approaching the substrate, were used as the controlling variables in the process. Nanocrystalline structures were found to develop at an optimum bias condition with low deposition pressures. With increasing substrate bias voltage, the compositions of the coatings were almost unchanged but refinement of the coating structure occurred. Densified coatings with a nanograin size of 90 nm developed at a bias voltage of -100 V. With further increase of the bias voltage, a coarser coating structure developed. On the other hand, an increase in the nitrogen deposition pressure also affected the formation of the nanocrystalline coatings. As the nitrogen pressure was increased beyond 0.4 mTorr, coarser coating structures were formed, thus restricting the production of the nanocrystalline coatings at higher nitrogen pressures. The nanocrystalline nitride coatings generally contained a densified structure with improved surface roughness and properties. Microhardness measurements conducted at low loads showed that the nanocrystalline coatings generally had much higher hardness.
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