PRESSURE DEPENDENCE OF FLAME ZONE SIZE OF SINGLE ALUMINIUM PARTICLES

Mathematical modeling of geometric dimensions and thermodynamic parameters of flame around single aluminium under combustion in the 79 % Ar + 21 % O2 atmosphere was implemented. The modeling was carried out on the basis of summarizing of experimental data and results of thermodynamic analysis. The dependencies of temperature and oxidizer (oxygen) concentration on the flame boundary and pressure of surrounding medium on particle size were determined. Also relation of flame radius with particle radius was established. The calculations was realized according to model of diffusion mode combustion with taking into account quasistationarity and thermodynamic equilibrium of processes, from the assumption of spherical symmetry of the flame. The flame boundary, oxidizer concentration and temperature on the boundary are determined on the basis of condition of predetermined completeness of aluminium transformation into ultrafine oxide Al2O3. The relative size of flame zone is established to decrease from 4.5 to 6.8 when surrounding medium pressure changes from 0.1 to 6 MPa. The relative size of flame zone and oxidizer concentration on the flame boundary increase as the particle burn out. As the particle radius decreases the part of radiative heat exchange decreases in total balance of it’s energy. And the part of radiative heat exchange does not exceed 8 % for industrial aluminium powders with particles diameter less than 50 m. The surrounding medium pressure influences on values of parameters calculated essentially with the exception of part of radiation heat flow.

Photodegradation of Methylene Green in the Presence of Polypropylene Microfiber Material

Degradation of toxicants in photocatalytic reactor is studied. To an array of data on the photochemical properties of Methylene Green (MG) when exposed to UV radiation in photoreactors was obtained. Based on the analysis of the results obtained, conclusions can be drawn about the relationship between the structure of pollutants, their initial concentration, oxidizer concentration, etc., with the efficiency of utilization, and schemes for photochemical processes was constructed. The role of polypropylene microfiber materials (PMM) in the degradation of MG under UV irradiation was studied.

Forensic Analysis of Inorganic Anions from Post–Blast Pyrotechnic Residues

Increase bombing activities in recent years have raised much awareness amongst forensic scientists of the importance of post–blast investigation. Analysis of post blast bomb residues is useful in identification of explosives and establishing link to its origin. The use of pyrotechnic in homemade explosives has emerged as a new threat to society. In this study, pre and post–blast inorganic anions from pyrotechnic residues were analyzed using ion chromatography with conductivity detection. Inorganic anions were separated using Metrosep A SUPP 5 anion column with NaHCO3 – Na2CO3 eluent. Eight anions (fluoride, chloride, nitrite, chlorate, nitrate, phosphate, sulfate and thiocyanate) were successfully separated within 40 min. Good linearity of calibration graph and LOD ranged from 4.8 to 21.0 ppb were achieved. Chemical anionic constituents of the fireworks were found to differ from each other. However, they were found to be common in nitrate and chlorate as oxidizer. Ratio of oxidizer was also found to be much higher than other anions. Post–blast samples showed drastic reduction in oxidizer concentration.

Surfactant Mediated Slurry Formulations for Ge CMP Applications

ABSTRACTIn this study, slurry formulations in the presence of self-assembled surfactant structures were investigated for Ge/SiO2 CMP applications in the absence and presence of oxidizers. Both anionic (sodium dodecyl sulfate-SDS) and cationic (cetyl trimethyl ammonium bromide-C12TAB) micelles were used in the slurry formulations as a function of pH and oxidizer concentration. CMP performances of Ge and SiO2 wafers were evaluated in terms of material removal rates, selectivity and surface quality. The material removal rate responses were also assessed through AFM wear rate tests to obtain a faster response for preliminary analyses. The surfactant adsorption characteristics were studied through surface wettability responses of the Ge and SiO2 wafers through contact angle measurements. It was observed that the self-assembled surfactant structures can help obtain selectivity on the silica/germanium system at low concentrations of the oxidizer in the slurry.

Study on Chemical Mechanical Polishing Technology of Copper

Chemical mechanical polishing (CMP) of copper films in alkaline slurries was investigated. In the copper CMP, the slurry was made by adding colloidal silica abrasive to de-ionized water.The organic alkali was added to adjust the pH, H2O2 was used as an oxidizer.The effects of varying polishing temperature, polishing pressure, slurry flow rate, organic alkali concentration and oxidizer concentration on removal rate were investigated in order to determine the optimum conditions for those parameters. It is shown the chemical composition of the slurry was 2%~3% oxidizer concentration, 3% organic alkali concentration and proper amount surfactant is reasonable. The solid concentration of the polishing slurry was fixed at 20% by weight. The removal rate of copper could reach 700nm/min and the surface roughness after CMP was 0.49nm.