Papers by Keyword: Nanopowder

Abstract: Well dispersed Aluminum Nitride (AlN) nanopowder and AlN thin film were compared to observe their structural and luminescence properties. AlN thin films were deposited on silicon and copper substrates by RF magnetron sputtering. PL peaks analysis indicated the same pattern of emission peaks over different excitation wavelengths ranging from 200 nm to 300 nm for both the AlN nanopowder and thin film, nearly 100 -1000 times PL increment observed in AlN nanopowder. It is suggested that the reason for PL of AlN material is due to surface defects and impurities like oxygen-related point defects (O⁺_N), nitrogen vacancies (V_N), the transition from the donor level of V_N (nitrogen-vacancy) to the acceptor level of AlN (antisites defects), and various defect complexes (V^3-_Al – 3 O⁺_N) are responsible for the enhanced observed emission peaks. With well-defined emission curves, AlN Nanopowder and thin films are observed to be good substrate and insulator material for microelectronic circuits, Light Emitting Diodes, Laser Diodes, and in biomedical applications such as bioimaging and biosensors.

Abstract: The aim of the present research work was to prepare NiFe₂O₄ nanoparticles using standard wet chemical method namely sol-gel auto-combustion with a view to study them in heat transfer application. The prepared nanoparticles of NiFe₂O₄ were then applied to prepare nanofluid with deionised water as a base fluid. The characterization of the prepared NiFe₂O₄ nanopowder is done by X-ray diffractometer (XRD) technique. The XRD pattern was recorded at room temperature. The analysis of XRD pattern was carried by standard software suggests that prepared nickel ferrite nanopowder possess single phase cubic spinel structure. The lattice constant was obtained by using XRD data reasonably agree with the reported values. The mean size of the particle was estimated through XRD pattern, in which the most intense peak (311) was considered to obtain full width at half maxima (FWHM). The Scherrer formula was used to obtain average crystallite size which was found to be 33 nm. The surface morphology of the prepared NiFe₂O₄nanopowder was studied by means of scanning electron microscopy (SEM) technique. The average grain size determined by linear intercept method was found to be of the order of 40 nm. The SEM image shows formation of spherical grains with some agglomeration. The prepared nanofluid of nickel ferrite was used to estimate thermal conductivity. It was found that, the thermal conductivity of NiFe₂O₄nanofluid was increased compared to deionised water.

Abstract: The paper presents the results of research of influence of nanopowders of tungsten compounds obtained from hard-alloy waste on structure formation and kinetics of cement stone strength gain. The positive effect of additives on the mechanical and structural characteristics of the cement stone in the concentration range of 1...5 wt.% has been established.

Abstract: The paper presents the results of tests of HPC (high performance composites) samples consisting of aramid and glass fabrics modified by agglomerates of WC and WO₃ nanopowders. According to the test results, introduction of WC and WO₃ powders into the composite plate structure makes it more rigid and elastic, increasing its ability to dissipate energy.

Abstract: The impact of Fe, Co, Ni nano-additives on the density, microhardness and bending strength was investigated for several sintered pellets. Fe, Co, Ni nanopowders (NP) were prepared in the size range 67-94 nm using chemical metallurgy techniques. These powders (0.5 wt. %) were dispersed into three sets of micron powders: Co (+0.5 wt. % Co NP); Fe (+0.5 wt. % Fe NP); Fe+0.5wt. % C (+0.5 wt. % Co and 0.5 wt. % Ni NP). Mixtures were further mixed and processed using a magnetic mill and a turbulent mixer. Sintering was carried out using spark plasma sintering (SPS) as well as pressureless sintering (PS). The densities of sintered pellets were found to increase by 2.5-3% (SPS) and 3-5% (PS) in the presence of nano-additives; corresponding increases in microhardness and bending strength were determined to be 7.9-11.1% and 17.9-38.7%, respectively. These results are discussed in terms enhanced packing due to interparticle sliding and the filling of free spaces with the nanodisperse phase.

Abstract: The article analyses the influence of SiO₂ and Al₂O₃ nanopowders on properties of ceramics consisting of fly ash from thermal power plants, glass waste, and clay binder. Based on studies of physical and mechanical properties of the obtained ceramics (ultimate compressive strength, ultimate three-point bending strength, wear resistance, and water absorption), the paper shows the positive influence of the nanoadditives. The optimal number of SiO₂ and Al₂O₃ nanopowders in the formulation is 0.5 wt. % that has the strongest effect on ultimate compressive strength and water absorption of the fly ash ceramics samples. The direction of further research on improving the properties of ceramic products is an application of the Al₂O₃ nanopowder as more perspective nanoadditive using clay dispersant.

Abstract: The present study describes the impact of various protective process agents on chip forming processes. The research was conducted on NiCr20TiAl and 34NiCrMoV14-5 nickel-chromium alloys. New lubricant-cooling process agents with carbon nanopowder additives are studied. The optimal composition of the nanopowder additive and its effect during alloy cutting is examined. Experiments reveal the dependence of shrinkage ratio on cutting speed and various protective process agents. The values of H50 microhardness are also defined when cutting these alloys using protective process agents. Experimental studies found the positive effect of developed agents with nanopowder additives on the processes of NiCr20TiAl and 34NiCrMoV14-5 alloys chip formation.

Abstract: Studies of a powder used as a modifier obtained from solid-alloy waste, such as tungsten carbide (drill balls), are presented. Dispersion, particle morphology and phase analysis of the powder were studied. The powder obtained from solid-alloy waste is a phase – it is tungsten carbide WC, it consists of nanoobjects of various shapes (nanoparticles, nanoplastics) up to 100 nm in size, with a slight presence of agglomerates up to 250 nm in size. The influence of tungsten carbide nanopowder as a modifier on the mechanical properties (strength and hardness) of PK70D3 iron-based powder structural steel has been studied. For the study, two different modes of preparation of powder alloy have been used with the use of one-stage and two-stage sintering. The influence of additive nanopowder of tungsten carbide on the mechanical properties of structural alloy powder based on iron PK70D3 has been defined: strength increases by more than 23% (in single-stage sintering), by more than 28% (in double-sintering), hardness decreases by more than 6% in single-stage sintering and increases by more than 26% with two stages of sintering, compared to the initial alloy. It has been shown that samples, obtained using double sintering with a tungsten nanopowder modifier (2.5%), have higher values of strength (more than 80%) and hardness (more than 13%), compared to modified samples, obtained by single-stage sintering technology. Thus, the modification of a 2.5 % nanoprobe of tungsten carbide, a widely used structural powder alloy based on iron PC70D3 allows for a significant change in mechanical properties. The use of powder alloys in double sintering technology provides the material hardness and the strength increase.

Abstract: This paper emphasises the effect of the surfactant in the PMEDM process. The preparation of nanofluid is done by mixing and sonicating thoroughly into the deionised water is discussed. The effect of varying the graphene nanopowder concentration into the dielectric is also discussed. Also, the effect of surfactant SDS and CTAB in the machining process is elaborated at 0.1 and 0.2g per 800ml concentration. MRR improved by 21.27% and roughness by 18.91% at 0.2g and 8µs, 2A and 50V in 800ml deionised water. SDS provide better MRR and low roughness compared to CTAB at higher peak current and higher pulse on time Simultaneously, the addition of surfactant into the dielectric medium reduces the performance of the EDM process. The MRR varies from 21mg/min at 0g graphene to 45mg/min at 0.2g and then 31.81mg/min at 0.2g with 0.1g SDS, 43mg/min at 0.2g SDS, 28.33mg/min at 0.1g CTAB and 30mg/min at 0.2g CTAB. Debris size also varies with the input parameters.

Abstract: The paper presents the study results of the selective laser melting process of the Ti-6Al-4V alloy and nanosized powder TiC composition. The results of the particles morphology study of resulting powder composition after blending are presented. The microstructure and mechanical characteristics of the obtained composite material were studied. Study of microstructures using optical and electron microscopes were conducted.