Form Of Tungsten Research Articles

The Effect of Air Injection for Formation of Radicals in Liquid Glow Discharge Plasma Electrolysis with K2SO4 Solution

Glow discharge is part of the phenomenon of plasma formation on the electrode side in contact with the electrolyte solution and begins with an electrolysis reaction with direct electric current. In this research, 0.02 M K2SO4 electrolyte was used, the anode in the form of tungsten and stainless steel for the cathode in a direct current plasma electrolysis reactor. The phenomenon of plasma formation is explained using a strong current and voltage characteristic curve. There are three plasma formation zones: the ohmic zone, the transition zone and the glow discharge plasma zone. Air injection affects the formation of glow discharge plasma and radicals. Without the injection of air, radicals formed only •OH, •H and •O with emission intensities of 20012 a.u, 10121 a.u and 10245 a.u. Air injection 0.8 L men-1 produced radicals •OH, •N, •N2*, •N2+, •H and •O with emission intensities of 30863a.u, 20139 a.u, 28540 a.u, 18023 a.u, 12547 a.u and 49800 a.u. Many radicals are generated when the plasma reaches stability. The plasma is dominated by H2O ionization, and the plasma is more stable if formed in the gas phase. Other results from this research at 0 L men-1, 0.2 L men-1, 0.4 L men-1 and 0.8 L men-1 stable plasma were formed at 675 V, 660 V, 650 V and 650 V. The plasma that can be seen from the bright light, the injection of air accelerates the formation of a gas envelope to reduce energy.

The Effect of Power on Nitrate Synthesis and The Emission Intensities of Reactive Species Using Anodic Plasma Electrolysis

Nitrates are used as fertilizer to fulfill nutrients for plants. Anodic plasma electrolysis technology can be an effective and environmentally friendly solution in nitrogen fixation into nitrate compounds. This research aimed to determine the effect of controlling voltage and power in nitrate synthesis using plasma electrolysis with air as the raw material injected at the anode. The material used is an electrolyte solution of 0.02 M K2SO4, the electrodes used are in the form of tungsten and stainless steel, and a nitrate reagent is used for the nitrate test. The results of the study showed that at 400 W, the optimal rate was 0.8 L men-1 with 1889 mg L-1 of nitrate formed. While at 500 W and 600 W, the optimal rate of 1 L men-1 with nitrate formed was 2213 mg L-1 and 2453 mg L-1. The emission intensities of reactive species N, N2*, N2+,•OH, •H, and •O at an optimal rate of 0.8 L men-1 400 W 700 V in 20139 au, 28540 au, 18023 au, 30863 au, 12547 au, 49800 au. The addition of air injection will increase the oxygen input into the plasma zone, which can produce reactive species •O and nitrogen produces reactive species N, N2*, N2+ forms NO. The formed NO compounds can be oxidized to NO2, and the reaction between NO2 and reactive species •OH forms nitrates.

Improving the Micro-Hardness of OHNS Die Steel by EDM Process Using Taguchi Approach

Electrical Discharge Machining (EDM) process is extensively used in tool and die making industry for accurate machining of internal profiles in hardened materials. Surface alloying by EDM process has emerged as a major research area in the field of non-traditional machining processes. As the dissolution of the tool electrode takes place during the process, the constituents of the electrode material may be deposited on the machined surface. Some additive powders in the dielectric medium may also form part of the plasma channel in the molten state and alloy with the recast layer under appropriate machining conditions. In this experimental work, Oil-Hardening Non-Shrinkable (OHNS type ‘O2’) die steel was machined with tungsten powder suspended in the dielectric medium. L9 orthogonal array of Taguchi approach to design of experiments was used for setting input process parameters. The machined surfaces were subjected to micro-hardness testing, SEM (Scanning Electron Microscopy) and XRD (X-ray Diffraction) analysis. The results show the presence of additional elements in the surface in the form of tungsten and tungsten carbide (WC) and improvement in micro-hardness by more than 100 %. Chemical composition of the machined surface was further checked on an optical emission spectrometer to verify the results.

Detection of SNM by delayed gamma rays from induced fission

The Pulsed Neutron Interrogation Test Assembly (PUNITA) is an experimental device for research in NDA methods and field applicable instrumentation for nuclear safeguards and security applications. PUNITA incorporates a standard 14-MeV (D-T) pulsed neutron generator inside a large graphite mantle. The generator target is surrounded by a thick tungsten filter with the purpose to increase the neutron output and to tailor the neutron energy spectrum . In this configuration a sample may be exposed to a relatively high average thermal neutron flux of about (2.2±0.1)×10 3 s −1 cm −2 at only 10% of the maximum target neutron emission . The sample cavity is large enough to allow variation of the experimental setup including the fissile sample, neutron and gamma detectors , and shielding materials. The response from SNM samples of different fissile material content was investigated with various field-applicable scintillation gamma detectors such as the 3×2 in. LaBr 3 detector. Shielding in the form of tungsten and cadmium was applied to the detector to improve the signal to background ratio. Gamma and neutron shields surrounding the samples were also tested for the purpose of simulating clandestine conduct. The energy spectra of delayed gamma rays were recorded in the range 100 keV–9 MeV. In addition time spectra of delayed gamma rays in the range 3.3–8 MeV were recorded in the time period of 10 ms–120 s after the 14-MeV neutron burst. The goal of the experiment was to optimize the sample/detector configuration including the energy range and time period for SNM detection. The results show, for example, that a 170 g sample of depleted uranium can be detected with the given setup in less than 3 min of investigation. Samples of higher enrichment or higher mass are detected in much shorter time.

Electroless deposition of ternary Ni–W–P alloys from sulphate and chloride based baths

The present investigation focuses on the preparation of ternary electroless Ni–W–P alloy deposits using sulphate (B1) and chloride (B2) based baths. The characteristics of the deposits were studied using XRD, SEM, XPS and atomic force microscopy (AFM) techniques. XRD patterns showed that the tungsten influences the structure and grain size of the deposits produced using B1 and B2 based baths. EDX analysis showed that a drastic reduction of phosphorus content owing to the addition of tungsten in both types of deposits. XPS studies showed that W content was approximately 2 at.-% and in the coatings deposited using B1 baths the elemental form of tungsten is twice that in the coatings deposited using B2 baths. From SEM analysis coarse nodular structure was found for the deposits obtained using B1 baths. It was also found from AFM images that the roughness values of ternary deposits using B2 baths were lower than those using B1 baths. Heat treatment at different temperatures on the deposits showed a higher increase in hardness in the coatings from B2 baths.

Importance of tungstate species for the transport of tungsten in hydrothermal solution: Case studies on major Japanese tungsten deposits.

Thermodynamic calculations on the stability relations among various tungsten species are performed in order to elucidate the possible form of tungsten during the transportation in hydrothermal solution, using the knowledge of the fluoride and chloride concentrations. Based on the fluorine contents in micas and topaz and the fluid inclusion data, it is calculated that HF/H2O and HC1/H2O fugacity ratios in the natural hydrothermal solutions responsible for major Japanese tungsten deposits at the Kaneuchi, Ohtani, Takatori, Fujigatani, Kiwada, and Kuga range from 10-3.15 to 10-5.91 and are less than 10-3.33, respectively. Pressure and temperature conditions for the formation of the studied deposits are summarized and calculated to be from 1 to 2 kbars, and from 300° to 600°C, respectively. Oxygen fugacities are assumed to be those defined by the C-CO-CO2 buffer as the most reducing condition encountered. Based on the pressure, temperature, f(O2), f(HF)/f(H2O), and f(HCl)/f(H2O) conditions evaluated for the studied deposits, thermodynamic calculations are performed to compare the stabilities of halogen-bearing species with those of tungstates. Calculated results show that H2WO4 may be a predominant species in the natural hydrothermal solutions responsible for the formation of major Japanese tungsten deposits.