Адгезия на границе раздела Ta(Mo)/NiTi

The atomic and electronic structure of the Ме(110)/NiTi(110) and TiO2(100)/Me(110) interfaces, where Me = Ta, Mo was investigated by the projected augmented-waves method within the density functional theory. It has been shown that the formation of intermediate oxide layers at the metal–alloy interface leads to adhesion decrease.

Antimony production by carbothermic reduction of stibnite in the presence of lime

Experimental work on the carbothermic reduction of Sb2S3 in the presence of lime was carried out in the temperature range of 973 to 1123 K to produce antimony in an environmentally friendly manner. The results demonstrated the technical feasibility of producing antimony by this method without producing SO2 gas. Complete conversion of Sb2S3 was obtained at 1023 K in about 1000 seconds and at 1123 K in less than 250 seconds using stibnite-carbon-lime mixtures with molar ratios Sb2S3:CaO:C = 1:3:3. It was found that the reduction proceeds through the formation of an intermediate oxide SbO2, which is subsequently reduced by CO(g) to yield antimony metal and CaS. The kinetics of the Sb2S3 reduction was analyzed by using the equation ln(1-X) = -kt. The activation energy was 233 kJ mol-1 in the temperature range of 973 to 1123 K. This value would correspond to an antimony catalyzed carbon oxidation by CO2.

Intermediate Oxide Layers for Direct Bonding of Copper (DBC) to Aluminum Nitride Ceramic Substrates

DBC is a process where copper foils are bonded to ceramic substrates for manufacturing hybrid electronic circuits and packages with high power-handling capabilities. For aluminum nitride (AlN) ceramics, a heat-treatment is required to grow an oxide layer to promote the bonding with copper. The oxidation treatment, however, must be conducted in special conditions to avoid the occurrence of severe cracking. In this work, an alternative method is proposed to form an intermediate oxide layers for DBC to AlN substrates. By this method, eutectic powder mixtures (CuO-CaO and CuO-Al2O3 systems) were applied to dense AlN substrates and then heat-treated at 1200 °C for 1 h in air. Different types of AlN ceramics sintered between 1650 and 1700 °C for 4 h in nitrogen atmosphere with additives of the system Y2O3-CaO-SrO-Li2O were investigated. The prepared oxide layers (thickness of ~25 m) presented good microstructural joining with the AlN substrates (characterized by SEM and EDS analysis), and did not affect significantly the thermal conductivity in the working temperature range of electronic devices (~100 to 50 W/m.K determined by laser flash method between 100 and 200 °C) compared to the AlN substrates.

Electroless Plated Pd/GaAs Schottky Diode and its Application to Hydrogen Detection

In this study, the dependence of Pd/GaAs Schottky diode on the electroless plating (EP) variable is systematically studied. Both alkaline and acidic formulas for electroless Pd depositions are employed for investigations. The correlation between Pd gain size and the manipulation of plating bath composition is constructed. Experimental results show that the performances of Pd/GaAs Schottky diode, electric rectification and hydrogen detection, are largely governed by the Pd grain size. Furthermore, without the interference of sodium ion, the acidic-plated Pd/GaAs diode with intermediate oxide layer exhibits the excellent hydrogen sensing performances from 15 ppm to 1.0 % H2/air.