Papers by Author: Wan Qi Qiu

Abstract: The microstructure and crystallographic characteristics of diamond film deposited with the chemical vapor deposition method was investigated using transmission electron microscopy (TEM). It is found that fivefold twin center does not always behave as growth nuclei of diamond grain. For those behaving as growth nuclei, there are a large amount of defects in every block of fivefold twin. However, for those not behaving as growth nuclei, two blocks of fivefold twin contain large quantities of defects, the other three are nearly clear. High resolution TEM analysis shows stacking faults coexist with microtwins in the two vast-defects-contained blocks. The effect of the mismatch angle (7.5°) in fivefold twins on microtwins, and the coexistence mechanism of both stacking faults and microtwins are also discussed.

Abstract: Arc ion plating(AIP) has higher deposition rates, whereas macro-particles (MPs) make the film properties decreasing. In this paper, AIP with or without magnetic filter (MF or AIP) and composition of AIP followed with magnetic filter (MFAIP) were designed to deposit TiN films on silicon (Si) and high-speed steel(HSS), respectively. Scanning electron microscope (SEM), nanoindentation and microscratch tests were investigated. SEM showed that both the MF and the MFAIP films had a superfine layer among the columnar crystals grown vertically against substrate surface. However, the columnar crystals of MF films were leptosomatic and well-orientational, while MFAIP ones were coarse and short, and even ragged in size and orientation. Nanoindentation test results showed the highest hardness for MF films and the lowest one for AIP films. A new parameter Scratch Crack Propagation Resistance (CPRs) was introduced to evaluate the film adhesion properties in a scratch test. MF films had the highest adhesion. AIP films were most susceptible to failure as the CPRs was the lowest, although the Lc1 was higher than MFAIP ones. It was proposed that the MPs were effectively removed with the MF, and the MF layers were superfine to improve the properties of the films.