Plasma way to obtain ultrafine iron and aluminum oxides

The paper deals with two plasma-chemical synthesis installations based on alternating cur-rent plasma torches with power up to 30 kW, which can be used for production of ultrafine (nanosized) oxide and carbide materials. Some results obtained during experimental studies on the production of ultrafine powders of metal oxides (iron and aluminum) are presented.

Analysis of Phase Composition and Properties of Composite Nickel-Phosphoric Coatings Using Wear-Resistant and Antifriction Modifying Agents

The possibility of introduction of antifriction and wear-resistant modifying agents into the matrix of a composite nickel-phosphorus coating to obtain effective composite coatings, is considered. The analysis of the possible influence of modifying additives in the form of ultrafine powders on the tribological properties of the developed coatings, is carried out.

Ultrafine beta-FeOOH and Fe3O4 obtained by precipitation method: comparative study of electrical and electrochemical properties

In this work, ultrafine powders of b-FeOOH and Fe3O4 have been obtained by the precipitation method. The values of the specific surface area for materials b-FeOOH and Fe3O4 are 101 and 135 m2/h. Frequency dependences of specific electrical conductivity have been obtained in the temperature range of 20-150 oC. It has been found that the materials show a superlinear dependence (SPL). In addition, the crossover energies from dc to JPL and from JPL to SPL have been calculated: Edc = 0.55eV, Ep1 = 0.51eB, Ep2 = 0.16eB and Edc = 0.22 eV, Ep1 = 0.21eB, Ep2 = 0.1 eB. Potentiodynamic studies have been performed at a scan rate from 1 mV/s to 50 mV/s. The b-FeOOH electrode material showed a specific capacitance value of 80 F/g at a scan rate of 1 mV/s, while the specific capacitance of the Fe3O4 material reached 32 F/g. Galvanostatic measurements have been done for discharge currents of 0.05 A/g, 0.1 A/g - 0.25 A/g. b-FeOOH sample is characterized by the maximum specific energy value of 8 W h/kg at the value of specific power equal to 20 W/kg, and Fe3O4 material is characterized by the maximum specific energy of about 3.5 W h/kg.

Temperature Dependent Up-Conversion Luminescence Properties of Er3+ Doped KNN Ultrafine Powders Prepared by Pulsed Laser Ablation in Liquid

Er3+ doped potassium sodium niobate (KNN: Er) ultrafine powders have been prepared by pulsed laser ablation in water. X-ray diffraction (XRD) pattern of the sample demonstrated that the as-synthesized powders were crystalized in orthorhombic phase. Scanning electron microscopy (SEM) and transmittance electron microscopy (TEM) images exhibited that the morphology of ultrafine powders are cube-like. Under the excitation of 980 nm laser, the sample exhibits green emission, which is originated from the transition of thermal coupled energy levels (2H11/2, 4S3/2) to ground state level 4I15/2. Temperature dependent up-conversion emission intensity associated with thermal quenching of total green emission band and the fluorescence intensity ratio (FIR) between two sub-emission bands related to population of thermal coupled energy levels are investigated for temperature sensing in the temperature range of 300 K to 480 K. The temperature sensing performances related to different technique were discussed. A maximum relative sensitivity reaches 1.01% K-1 at 464 K for emission intensity thermometry and that is 0.84% K-1 at 374 K for FIR thermometry technique. All these results show that KNN: Er ultrafine phosphors prepared via pulsed laser ablation in water have prospect for non-contact temperature sensing.