Preparation And Properties Of Nc-TiN/a-Si₃N₄ Nanocomposite Films

1. Preparation and Mechanical Behavior of nc-TiN/a-Si₃N₄ Nanocomposite Filmsnc-TiN/a-Si₃N₄ nanocomposite films with different content of Si (at%) were deposited on (400) silicon substrate by ion beam sputtering (IBS) combined with filtered cathodic arc (FCA) plasma spraying. The composition and microstructure of nc-TiN/a-Si₃N₄ nanocomposite films were analyzed by means of atomic force microscopy (AFM), X-ray Photoelectron spectroscopy (XPS), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). Their mechanical properties were evaluated using a nanoindenter and UMT-2 multi-functional friction and wear test rig. It has been found that Si and Ti in the nanocomposite films exist in the form of amorphous silicon nitride (a-Si₃N₄) and nanoscale titanium nitride (nc-TiN), respectively, and TiN is dominated by preferential orientation along (200) plane. The nanocomposite film containing 10.9%Si has the maximum hardness of 25.6 GPa as well as minimum friction coefficient and wear rate.2. Effect of Bias Voltage on Structure and Mechanical Behavior of nc- TiN/a-Si₃N₄ Nanocomposite Filmsnc-TiN/a-Si₃N₄ nanocomposite films were deposited on (400) silicon substrate by ion beam sputtering (IBS) combined with filtered cathodic arc (FCA) plasma spraying under different bias voltage. The effect of the bias on the composition, microstructure and mechanical properties of the nanocomposite films was investigated. It has been found that the bias voltage has a great impact on the deposition rate of the films. Si content (at%) of the films initially increases but later decreases with the increase of the bias voltage, and it reaches the maximum under a bias voltage of -100 V. When the negative bias increases from 0 V to -300 V, the preferred orientation of TiN along (200) plane is transferred to the one along (111) plane; and TiN is completely transformed to amorphous under a bias voltage of -300 V. Besides, the hardness of the nanocomposite films reaches the maximum of 46 GPa under a bias voltage of -100 V at which the films consist of more compact and uniform columnar crystal than those prepared under other bias voltage. Moreover, the adhesion of the nanocomposite films reaches the maximum and its O content (at%) reaches the minimum also under a bias voltage of -100 V. 3. Preparation and Mechanical Behavior of nc-TiN/a-Si₃N₄ Nanocomposite Gradient Filmsnc-TiN/a-Si₃N₄ nanocomposite gradient films with different layer distinction were deposited on (400) silicon substrate by ion beam sputtering (IBS) combined with filtered cathodic arc (FCA) plasma spraying. The morphology and structure of resultant nc-TiN/a-Si₃N₄ nanocomposite gradient films were analyzed by means of AFM and XRD. Their mechanical properties were evaluated using a nanoindenter and UMT-2 multi-functional friction and wear test rig. It has been found that superhard phenomenon exists in the nanocomposite gradient films. When the layer distinction increases from -15 nm to 15 nm, the nanohardness increases initially but later on deceases. Under 10 nm layer distinction, the nanohardness of the nanocomposite gradient films reaches the maximum (62 GPa). In the meantime, layer distinction also has significant effects on the micro-mechanical properties and friction and wear behavior of the gradient films. Namely, the adhesion substrate, friction coefficient, and wear rate of the nanocomposite gradient films increase with increasing layer distinction; but they are decreased with further increase of layer distinction. In one word, the nanocomposite gradient film with 0 nm of layer distinction possesses the best comprehensive properties.