Preparation and Properties of Mo Coating on H13 Steel by Electro Spark Deposition Process

H13 steel is often damaged by wear, erosion, and thermal fatigue. It is one of the essential methods to improve the service life of H13 steel by preparing a coating on it. Due to the advantages of high melting point, good wear, and corrosion resistance of Mo, Mo coating was fabricated on H13 steel by electro spark deposition (ESD) process in this study. The influences of the depositing parameters (deposition power, discharge frequency, and specific deposition time) on the roughness of the coating, thickness, and properties were investigated in detail. The optimized depositing parameters were obtained by comparing roughness, thickness, and crack performance of the coating. The results show that the cross-section of the coating mainly consisted of strengthening zone and transition zone. Metallurgical bonding was formed between the coating and substrate. The Mo coating mainly consisted of Fe9.7Mo0.3, Fe-Cr, FeMo, and Fe2Mo cemented carbide phases, and an amorphous phase. The Mo coating had better microhardness, wear, and corrosion resistance than substrate, which could significantly improve the service life of the H13 steel.

Tribological Behaviour of Sputter Coated ZnO Thin Films

The tribological properties of ZnO thin film coated on an aluminium work piece by RF magnetron sputtering were studied as a function of deposition power, substrate coating temperature, heat treatment and rotation speed. The variation in the coefficient of friction of ZnO films produced under various levels of coating parameters and conditions were experimentally determined using a pin-on-disk tribometer. The results showed that with change in deposition conditions and heat treatment, there are significant microstructural changes in ZnO films, which affect the coefficient of friction. The hardness of the prepared films was also tested using a Vickers Hardness testing machine. There was a consistent and considerable decrease in the friction coefficient of the aluminium working piece after ZnO coating. It is found that the ZnO can be used as a low friction coating material for components working under oxidative and high temperature environments.

Effects of deposition parameters on properties of high resistance CrSi-based thin-film resistors

Cr is a metal with lower resistivity (as compared with Si) and positive temperature coefficient of resistance (TCR value) and Si is a semiconductive material with higher resistivity and negative TCR value. For that, the commercial-grade targets of 28 wt.% Cr-72 wt.% Si, 40 wt.% Cr-60 wt.% Si and 55 wt.% Cr-45 wt.% Si were used to deposit the thin-film materials using sputtering method at the same parameters, and their physical and electrical properties were measured and compared under different deposition powers. The crystallization and the surface morphology of the CrSi-based thin-film resistors were measured using X-ray diffraction (XRD) pattern and field emission scanning electron microscopy (FESEM). In order to find the effect of deposition power on the average atomic ratio of Cr and Si, the elemental ratios were also measured as a function of deposition power for different CrSi-based targets by FESEM equipped with Energy-Dispersive X-ray spectroscopy (EDX) for elemental Cr and Si. The effects of Cr concentration and deposition power on the sheet resistances, resistivity and TCR values of the deposited CrSi-based thin-film resistors were also well measured and compared, and the reasons to cause the variations of resistivity and TCR values were also investigated and discussed.

Effect of Deposition Power on the Thermoelectric Performance of Bismuth Telluride Prepared by RF Sputtering

In this work, we present a simple method to improve the thermoelectric performance of the RF sputtered bismuth telluride films by raising the power of deposition. The as-deposited samples synthesized under different powers were investigated and compared. It shows that the films prepared under relatively higher power conditions exhibit much higher electrical conductivity to result in a greater power factor accompanied with a minor drop in the Seebeck coefficients. A relationship is established between the improvement in thermoelectric performance and the decrease in crystallinity, which might also reduce the thermal conductivity. A maximum power factor of 5.65 × 10−4 W·m−1·K−2 at 470 K is obtained for the sample deposited under 50 W with its Seebeck coefficient being −105 μV/K. The temperature-dependent behaviors of the samples are also looked into and discussed. This work might offer an in-situ and cost-effective approach to improve the performance of thermoelectric materials.

Effect of RF Power on the Properties of Sputtered-CuS Thin Films for Photovoltaic Applications

Copper sulfide (CuS) thin films were deposited on a glass substrate at room temperature using the radio-frequency (RF) magnetron-sputtering method at RF powers in the range of 40–100 W, and the structural and optical properties of the CuS thin film were investigated. The CuS thin films fabricated at varying deposition powers all exhibited hexagonal crystalline structures and preferred growth orientation of the (110) plane. Raman spectra revealed a primary sharp and intense peak at the 474 cm−1 frequency, and a relatively wide peak was found at 265 cm−1 frequency. In the CuS thin film deposited at an RF power of 40 W, relatively small dense particles with small void spacing formed a smooth thin-film surface. As the power increased, it was observed that grain size and grain-boundary spacing increased in order. The binding energy peaks of Cu 2p3/2 and Cu 2p1/2 were observed at 932.1 and 952.0 eV, respectively. Regardless of deposition power, the difference in the Cu2+ state binding energies for all the CuS thin films was equivalent at 19.9 eV. We observed the binding energy peaks of S 2p3/2 and S 2p1/2 corresponding to the S2− state at 162.2 and 163.2 eV, respectively. The transmittance and band-gap energy in the visible spectral range showed decreasing trends as deposition power increased. For the CuS/tin sulfide (SnS) absorber-layer-based solar cell (glass/Mo/absorber(CuS/SnS)/cadmium sulfide (CdS)/intrinsic zinc oxide (i-ZnO)/indium tin oxide (ITO)/aluminum (Al)) with a stacked structure of SnS thin films on top of the CuS layer deposited at 100 W RF power, an open-circuit voltage (Voc) of 115 mA, short circuit current density (Jsc) of 9.81 mA/cm2, fill factor (FF) of 35%, and highest power conversion efficiency (PCE) of 0.39% were recorded.