Qiulong Chen

Mechanism of hydrogen desorption during palladium brush-plating

Abstract Continuous Pd deposits were fabricated by brush-plating. The morphologies of the Pd deposits were characterized by atom force microscopy (AFM). No micro-cracks were found in the deposits. The deposits were made up of spherical nano-clusters. Analyses of the morphology of Pd deposits brush-plated with different anode sliding speeds indicated that the H 2 bubbles desorbed from the deposits by two modes, passive and active, respectively. For the first mode, H 2 bubbles are removed by the anode movement. For the second mode, H 2 bubbles escape from the deposits actively. As a result, pores were avoided in the Pd deposit by brush-plating. A deposit self-repairing mechanism in Pd brush-plating is proposed.

Mechanism of enhanced adhesion between hydrogenated amorphous carbon films and tungsten preimplanted steel substrates

Hydrogenated amorphous carbon (a-C:H) films have good mechanical properties but poor adhesion on substrates such as tool steels thereby limiting their applications. Film adhesion can be improved by conducting tungsten preimplantation into the steel substrates before deposition of the carbon film. The enhancement mechanism is investigated in this study by depositing the films on W plasma-preimplanted (20kV, 5×1017ionscm−2) and untreated steel substrates using mixed acetylene and argon plasmas with different flow rate ratios by means of plasma immersion ion implantation and deposition. Preimplantation creates a graded WC interface that mitigates diffusion of the dissociated carbon atoms on the surface. Compared to the films deposited on untreated steel substrates, the ones deposited on the W-implanted steel substrates exhibit improved adhesion strength, especially for the lower acetylene to argon flow rate ratios. Tungsten preimplantation is critical to the successful fabrication of a-C:H films on steel sub...

Experimental and numerical evaluations of adhesion strength and stress in TiN films deposited on ti-implanted aluminum

Titanium ions were implanted into aluminum substrates at 40kV prior to magnetron sputtering deposition of the Ti interlayer and TiN film using our custom-designed multifunctional ion implanter without breaking vacuum. An 82-nm-thick modified layer was formed between the TiN film and the substrate. The characteristics of the implanted samples were compared to those of TiN∕Al and TiN∕Ti∕Al samples that were not preimplanted. Based on our scratch tests, the critical loading Lc of the TiN∕Ti∕Ti-implanted Al sample was significantly improved compared to the unimplanted TiN∕Al and TiN∕Ti∕Al samples. Finite element analysis was conducted to simulate the scratch process to help reveal the stress distributions in the vicinity of the interlayer. The results show that the stress around the interface is largely reduced in the TiN∕Ti∕Ti-implanted Al sample. Consequently, the mechanical properties such as resistance to loadings are enhanced.

Preparation of CuInSe2 film with electrodeposition

CuInSe2(CIS) films directly electrodeposited on sputtered Mo-glass, sprayed SnO2-glass substrates had been accomplished at room temperature in the potentiostatic mode from a bath containing CuCl, InCl3(DOT)4H2O and SeO2. The acidity of bath was adjusted to 1PH. Energy dispersive spectrometry, atomic force microscopy (AFM), x- ray diffraction and hot-probe method was utilized to characterize the CIS films. The key factor for preparing single-phase CuInSe2 is the proportion of CuCl, InCl3(DOT)4H2O and SeO2. The CIS films are nearly stoichiometry of CuInSe2 and polycrystalline on Mo- glass. The Cu excess films are p-type semiconductor, and the In excess films n-type. The deposition potential obviously affects the surface morphology of CIS films. AFM results had indicated that the CIS films on Mo-glass grow in layer and on SnO2 glass in island.