http://arthra.ugal.ro/handle/20.500.14043/26030 2026-04-05T17:28:04Z http://arthra.ugal.ro/handle/20.500.14043/26043 Thermal Decomposition of Hafnium Ethoxide-Mollecular Precursor for Hafnia Dielectric Thin Films Vâlcu (Herbei), Elena Emanuela; Mușat, Viorica; Leedham, Timothy The HfO2 thin-film is a very promising gate dielectric material for last generation transistors. The paper presents the thermal decomposition of hafnium ethoxide used as molecular precursor for obtaining hafnia thin films. The investigated molecular precursor is a mixture of Hf3O(OC2H5)10 and Hf4O(OC2H5)14 moisture sensitive amorphous powder. The thermal decomposition of hafnium ethoxide precursor was investigated by TG-DTG-DSC analysis from room temperature to 6000C in nitrogen atmosphere at 5K/min. The composition of gas products resulted during pyrolytic decomposition has been studied by Fourier Transformation Infrared Spectroscopy (FTIR) and Mass Spectroscopy (MS). In the gas products, hydrogen, methyl, ethyl, vinyl, hydroxyl groups, acetic aldehyde and acetylene were identified. From mass spectroscopy and FTIR data results that the loss of ethoxy groups from the molecular precursor occurs in the decomposition steps between 200 and 375oC. That suggests that in different steps, ligands from different coordination spheres are lost. The Annals of "Dunarea de Jos" University of Galati Fascicle IX Metallurgy and Materials Science N0. 3 – 2012, ISSN 1453 – 083X 2012-01-01T00:00:00Z http://arthra.ugal.ro/handle/20.500.14043/26042 Increase of Converter Life by Own Slag Coating Munteanu, Viorel; Drăgan, Viorel; Zorlescu, Dan This paper presents a method for the improvement of the lining life of the BOF converter by slag coating, under nitrogen pressure. Own slag coating of converter lining is put in practice after steel tapping. Dolomite blocks are used like standard wear converter lining. Nitrogen blowing for own slag coating is carried out by oxygen lance. After steel tapping without slag, the converter is tilt in blowing position and the oxygen lance is let down in the lowest position. The nitrogen is blown under 10-12 barr pressure and 450-500 Nm3/min rate, for 3 minutes. By this slag coating technology the performance of refractories has been improved from about 370 heats per campaign in reference year to about 800 heats per campaign at the end of two years of experiments, and therefore refractory consumption decreased from 5.25 kg/t under 3.00 kg/t and the cost of converter refractories decreased by 0.24 $/t. Another variant for improvement of the BOF converter lining life was the use of magnesia bricks for selective lining areas (trunion rings area and charging mouth). The own slag coating technology has been used also. In the case of this variant, the lining life of converter has been improved to about 800 heats per campaign at the end of two years of experiments and so the refractories consumption decreased under 2.45 kg/t. Because of the higher price of magnesia bricks and of the lower price of dolomite blocks, the cost for converter refractories has decreased only by 0.02$/t. The Annals of "Dunarea de Jos" University of Galati Fascicle IX Metallurgy and Materials Science N0. 3 – 2012, ISSN 1453 – 083X 2012-01-01T00:00:00Z http://arthra.ugal.ro/handle/20.500.14043/26041 Comparison of the Efficiency of Three Types of Solar Collectors Mocanu, Cătălin Bogdan; Panait, Tănase; Teodoru, Alexandrina; Tasma, Daniela Solar energy is one of the most abundant resources energy available in the world. Solar collectors have evolved in the last decades, but still they haven’t reached very high efficiencies. The collector efficiency is dependent on the temperature of the plate which in turn is dependent on the nature of the fluid flow inside tube, solar isolation, ambient temperature and top loss coefficient, the emissivity of the plate and glass cover. This paper presents the test results of three different solar collectors and compares their efficiency. The Annals of "Dunarea de Jos" University of Galati Fascicle IX Metallurgy and Materials Science N0. 3 – 2012, ISSN 1453 – 083X 2012-01-01T00:00:00Z http://arthra.ugal.ro/handle/20.500.14043/26040 Evaluation of the Sonic System Efficiency for Raw Water Treatment Cîrnu, Carmen; Bordei, Marian; Ciurea, Aurel Water pollution is defined as the change in the water composition that is harmful to human health, unsuitable for economic use or reactive and that can cause damage to the aquatic flora and fauna. In the appreciation of the World Health Organization, appreciation, approximately 2/3 of illnesses are due to polluted water, and the main pollutants come from industry. The paper presents an analysis of the technical systems used for raw water decanting with a view to making it drinkable. The Annals of "Dunarea de Jos" University of Galati Fascicle IX Metallurgy and Materials Science N0. 3 – 2012, ISSN 1453 – 083X 2012-01-01T00:00:00Z