Structural, Mechanical And Tribological Properties Of Nanocomposite Ti_1-xAl_xN/MoN Self-lubricating Nanomultilayer Films Synthesized By Ion Plating

The focus of present research was to investigate the synthesis of Ti(1-x)AlxN/MoN nanomultilayer thin films using diverse Ti and Al composition to get optimum performance by means of cathodic multi-arc ion plating (CAIP) deposition system and also to analysis structural, mechanical and tribological properties. Extensive efforts also spend to examine structural, mechanical and tribological effects on bilayer period. (A) and rotation mode. To achieve the goal the systematical research is carried out in three experiments. The substrates used for the deposition in this project was; polished Si (100), cemented carbide and stain less steel.In 1st experiment; Ti0.33Al0.67N/MoN nanomultilayer coatings produced by CAIP system using 2-fold rotation technique to investigate mechanical, tribological and structural features also examined effects of substrate rotation speed (SRS) on them. Chemical composition of Ti, Al, Mo and N was examined by EDS, the ratio between Ti and Al is closed to design 1:2.The bilayer periods are in the range of 11-61 nm depending on rotation speed. The 3 round per minute (RPM) coating exhibits the smoothest surface (Rms=19 nm) and 1 RPM sample has highest hardness of 44 GPa. Nanohardness (H) and elastic modulus (E) reduced by increasing RPM. All mechanical features, for example; elastic modulus, nanohardness, smoothness of surface and coefficient of friction of nanomultilayered structure are higher in comparison with monolayer counterparts. Wear track and surface morphology experiments have also been analyzed.In 2nd experiment; TiAl and Mo targets in CAIP system are used to produce Ti0.70Al0.30N/MoN nanomultilayered structure through 1-fold rotation. Bilayer periods (A) of all multilayers was governed through substrate holder and their thickness were in the range of 21 to 124 nm. Nanomultilayer Ti0.70Al0.30N/MoN has MoN layers alternating with TiAIN layers, both layers are in nanocrystalline size. Chemical composition of Ti, Al, Mo and N were calculated by using EDS over all samples, the composition between Ti and Al is closed to design composition Ti0.70Al0.30N.The preferred crystalline orientation exhibited by nanomultilayer Ti0.70Al0.30N/MoN coatings were MoN (200), MoN (202), TiAIN (200), TiAIN (220). At bilayer period of 25 nm, where highest E and H were attributed. However, wear rate was reduced by decreasing bilayer thickness. On average, the cross-sectional scanning electron microscopy (SEM), nanoindentation measurements with atomic force microscopy (AFM) showed improved mechanical properties along the development with bilayer thickness of Ti0.70Al0.30N/MoN of nanomultilayered coatings, also with a dense microstructure and fine grains which reduced the surface roughness.Finally in 3rd experiment; thin films with a Tio.50Alo.50/MoN nanocomposite comprising of hard transition metal nitride alternate with self-lubricant to form a multilayer structure were synthesized by CAIP system. The bilayer period (A) of all of the nanomultilayer was organized by the turning speed of the substrate holder ranging from 22 to 104 nm. In present study the Ti & Al ratio has been sustained near to 1:1, to attain optimize characteristics of Ti0.50Al0.50N/MoN coatings. The preferred orientation of nanomultilayer Ti0.50Al0.50N/MoN thin films was MoN (200) and TiAIN (200). The nanohardness of nanocomposite were increased as the bilayer period decreased from 104 nm to 26 nm, further hardness decreased along bilayer period. The nanomultilayer having a bilayer thickness of 26 nm revealed high hardness of 37 GPa, whereas lowest wear rate (8.09E-7 mm3/N.m) is observed at A= 22 nm. Wear rate, roughness and coefficient of friction were decreased with decreasing bilayer period.