Guoqiang Lin

Macro-particle reduction mechanism in biased arc ion plating of TiN

The mechanism of macro-particles (MPs) contamination in arc ion plating is investigated on TiN films under different biases. The effect of the biases is analyzed from the viewpoint of plasma physics. It is shown that the negatively charged MPs are affected by the biases through a repulsive force from the negatively biased substrate. They are more easily charged by electrons under pulsed biases because they repeatedly move in and out of the oscillating plasma sheath. In d.c. bias modes, the plasma sheath is stable and its charging effect is weak. Thus the repulsive force from the substrate under the pulsed biases is higher than that under the d.c. ones, and therefore, MPs are significantly reduced.

Preparation of TiN films by arc ion plating using dc and pulsed biases

TiN hard coatings were prepared by arc ion plating with both direct current (dc) and pulsed biases. An extensive investigation was undertaken to determine the effects of the substrate temperature on the mechanical properties and the microstructures of films. The results show that the substrate temperature is decreased evidently when a pulsed bias instead of a dc one is employed. At the same time, the microstructures and the properties are also improved. A low-temperature arc ion plating can be realized by using pulsed biases.

Experiments and theoretical explanation of droplet elimination phenomenon in pulsed-bias arc deposition

TiN films on stainless steel have been synthesized by arc deposition with dc and pulsed biases. We show that at the same bias (−300 V), coarse particles on the film surface are significantly decreased both in size and in amount if the bias is pulsed. In order to clarify the related process, we have analyzed, using orthogonal design, the influences from different working parameters. We show that the parameters related to the pulsed bias such as magnitude and duty cycle have important effects on the size distribution of the particles. According to our theoretical calculations based on plasma sheath and dust plasma theories, the origin of the droplet elimination lies in enhanced repulsion of the negatively charged droplets in pulsed plasma.

Influence of Nitrogen Flow Rate on the Microstructure and Properties of N and Me （Me=Cr,Zr） Co-doped Diamond-like Carbon Films

In this paper, Me ( Me =Cr, Zr) and N co-doped diamond like carbon (DLC- Me N) composite films were prepared on cemented carbide substrates by pulsed bias arc ion plating. The effect of nitrogen flow rates on the microstructure and properties of the films were investigated by X-ray photoelectron spectroscopy (XPS), Raman spectra, grazing incident X-ray diffraction (GIXRD), high resolution transmission electron microscopy (HRTEM) and nano-indentation. Raman, GIXRD and HRTEM results show that the deposited films are nanocomposite films with Me N nanocrystalline phase embedded within DLC amorphous matrix, which are vital for the mechanical properties of the films. The nitrogen flow rate has significant effect on the compositions and structures and hence on the hardness and elastic modulus of the films, and increasing nitrogen flow rate decreases drastically the hardness and elastic modulus of the films.

Influence of deposition parameters on the microstructure and properties of nitrogen-doped diamondlike carbon films

CNx films were prepared on cemented carbide substrates by a pulsed bias arc ion-plating method with two graphite targets and using N2/Ar mixture gases. The effects of the deposition parameters, such as substrate negative-bias voltage, duty cycle, and nitrogen flow rate, on the structures and properties of CNx films were investigated using Raman spectra and nanoindentation. The properties of CNx films are closely related to the film structures. For CNx films deposited at a different bias voltage, the CNx film deposited at a bias voltage of −300 V had the highest hardness. The ID/IG ratio and G peak position decreased and then increased with increasing bias voltage, and the minimum values, which correspond to the highest sp3 content, were obtained at a bias voltage of −300 V. For the CNx films deposited at different duty cycles, the hardness and elastic modulus decreased with increasing duty cycle. For the CNx films deposited at different nitrogen flow rates, the results show that first the ID/IG ratio decr...

Plasma load characteristics of pulsed-bias arc ion plating

In a pulsed-bias arc ion plating system, the load voltage and current in the substrate circuit manifest oscillation behaviors. A simple analogous electrical circuit model is then constructed, which consists of a pair of capacitor and resistor connected in parallel. The output of the analogous circuit reproduces the oscillation profiles measured from experiments. Finally, plasma sheath theory is used to explain the capacitance characteristic of the plasma load.

Structure and properties of ZrN doped diamondlike carbon films prepared by pulsed bias arc ion plating

ZrN doped diamondlike carbon composite films with different compositions were deposited on cemented carbide substrates at different nitrogen flow rates by pulsed bias arc ion plating. Scanning electron microscopy results show that the film surfaces were all uniform, smooth, and dense. X-ray photoelectron spectroscopy reveal the C contents are more than 60%, the N content increases, and the Zr content decreases with increasing nitrogen flow rate. The Raman spectra indicated that the deposited films were diamondlike carbon. X-ray diffraction results suggested that a ZrN crystalline phase was also present in the films. The hardness and elastic modulus were closely related to the composition and structure of the films and decrease with increasing nitrogen flow rates, principally due to the increase in the sp2 content and the decrease in the ZrN crystalline phase.

Influence of Nitrogen Vacancy Concentration on Mechanical and Electrical Properties of Rocksalt Zirconium Nitride Films

To study the influence of the nitrogen vacancy (VN) on mechanical and electrical properties of zirconium nitride deeply, ZrNx films with different VN concentrations were synthesized on the Si (111) substrates by enhanced magnetic filtering arc ion plating. The morphologies, microstructures, residual stresses, compositions, chemical states, mechanical and electrical properties of the as-deposited films were characterized by field-emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, Nanoindenter and Hall effect measurements. The results showed that ZrNx films exhibited rocksalt single-phase structure within a VN concentration ranging from 26 to 5%. The preferred orientation, thickness, grain size and residual stress of the ZrNx films kept constant at different VN concentrations. Both the nanohardness and elastic modulus first increased and then decreased with the decrease in VN concentration, reaching the peaks around 16%. And the electric conductivity of the ZrNx films showed a similar tendency with nanohardness. The underlying atomic-scale mechanisms of VN concentration-dependent hardness and electric conductivity enhancements were discussed and attributed to the different electronic band structures, rather than conventional meso-scale factors, such as preferred orientation, grain size and residual stress.