Experimental Observation of the Temperature at the Liquid/Gas Interface

Experimental studies on measurements of the temperature profile in the vicinity of the evaporating distilled water layer were carried out. The temperature was measured with a chromel-alumel thermocouple, when it moves under the action of the precision actuator directed perpendicular to the evaporating layer. According to the experimental results the fluctuation in temperature of the air and liquid was found in the immediate vicinity of the liquid/gas interface. However, temperature jumps near the interface was not observed

Effect of precursor mass on product phase composition in plasma dynamic synthesis of tungsten carbide

An interest in WC[1-x] cubic tungsten carbide results from its catalytic properties similar to those of platinum group metals and the synergistic effect between WC[1-x] and Pt in reactions of hydrogen evolution and hydrogen oxidation. However, according to the phase diagram of the W–C system, the cubic phase WC[1-x] only exists in a narrow range of temperature stability (about 2798–3058 K), which makes it difficult for being obtained. To date, there are different methods for synthesizing tungsten carbide powder with a low content of cubic phase that complicates the study of WC[1-x] properties. A direct plasma dynamic synthesis is known as one of the promising methods to produce WC[1-x]. The aim of this work is to find the optimal amount of tungsten precursor to obtain cubic tungsten carbide with a high purity by plasma dynamic method. The synthesized products were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns showed that the main phase was cubic tungsten carbide with negligible content of hexagonal tungsten carbide W[2]C and pure tungsten W. According to a quantitative analysis of synthesized products, which were obtained using masses of initial tungsten equal to 1.0, 0.7, 0.6 and 0.5 gram, the yield of WC[1-x] phase was 84, 89, 95 and 92 wt%, respectively. The results of TEM displayed that the synthesized powders consist of crystallites, having the size less than 100 nm (WC[1-x]), and a carbon matrix. This carbon was not detected in XRD due to its presence as an amorphous phase