Papers by Keyword: Aluminium Powder

Abstract: Today, the development of aluminium industry is highly dynamic. Aluminium production rightly takes top positions in the global metal market. Unique properties of aluminium mean that it is widely used in various industries. The construction industry is no exception – here, aluminium is actively used as a gassing agent for production of steam-cured aerated concrete, which is produced by mixing Portland cement, sand, water and aluminium fine powder or aluminium paste. The main disadvantage of aluminium fine powder is its high degree of dusting: at certain air concentration levels, this becomes fire-and explosion-prone. This is the reason the producers add complex organic additives into their aluminium fine powder: to ensure lower dusting levels and produce an aluminium paste, which is safer to use. This work focuses on obtaining an aluminium paste with sufficient share of organic additives to ensure the efficient performance of aluminium paste as a gassing agent in the production of steam-cured aerated concrete. A number of tests were carried out on mixing aluminium fine powder with various organic additives (fatty additive; wetting agent and gassing kinetics stabiliser; dedusting agent) in different ratios. The paper analyses the quality of distribution of organic additives inside the finished product and studies the relevant gassing kinetics.

Abstract: In this activity, customized panels for the CS deposition have been produced and aluminium has been deposited using air as a carrier gas. The custom-made panels were made with different matrix thicknesses on the surface in order to point out the influence of the fibres in the deposition and to study the feasibility and the growth of the coating. The polymer chosen for the matrix is polypropylene, widely used in the automotive sector, while for the reinforcements glass fibres have been used. Different process parameters have been examined in order to point out the influence of temperature, stand-off distance and pressure chosen, on the compaction and densification of the coating produced. In addition, morphological investigations were performed to further characterize the coatings deposited. It has been noticed that aluminium powders can be effectively deposited on polypropylene panels, leading to significantly better results when the thickness of the matrix is ​​sufficient to prevent the powders bouncing elastically on the fibres, while benefiting from the stiffening effect of the latter.

Abstract: High porosity in porous concretes contributes to benefits in terms of lightweight, high water permeability, and superior insulation properties in the concretes. Nevertheless, excessive porosity can lead to diminished compressive strength. This study, therefore, aimed at fabricating porous concretes with porosity and compressive strength in the range suitable for practical applications. Since addition of aluminium powder is a well-known technique for porosity production, this study also assessed effects of aluminium addition on properties of porous concretes. Relationships among concentrations of aluminium, porosity, and compressive strength of the specimens were examined. Microstructural analysis from scanning electron microscope (SEM) images and compressive strength testing according to ASTM C109 revealed that the specimens with 0.15 wt% Al demonstrated porosity and compressive strength were in an acceptable range. Additionally, porosity production and specimen strengthening were discussed with respect to chemical compositions.

Abstract: Aluminium-Matrix-Nanoparticle-Composites were produced by ball milling of micro scale Aluminium powder with various nanoscales ceramic powders like Silicon Carbide, Alumina and Boron Nitride with subsequent consolidation by hot extruding. The composites were investigated by amplitude dependent damping tests, tensile tests at elevated temperatures, hardness measurements, imaging methods and electric conductivity tests. All tested samples were machined out of hot extruded rods. The Amplitude dependent damping of bending samples was determined by measuring the strain dependent logarithmic decrement of free decaying vibrations of bending beams at room temperature. These tests were done after successive step by step isochronal heat treatments. Some samples show substantial improvement of the mechanical properties due to dispersion hardening or grain refinement. It can be concluded that the results are mainly influenced by dislocation effects like Orowan-effect, work-hardening, grain-size-hardening, recrystallization, and creation of dislocations at ceramic particles due to thermal mismatch. Moreover some results can be attributed to fatigue during mechanical cycling namely crack nucleation, crack growth and fraction. The electric conductivity was measured indirectly by permeability tests with a digital hysteresis recording devise. The results show the low influence of nano-particle dispersion hardening to conductivity in comparison of work-hardening.

Abstract: The paper studies the impact of gaseous water on the stability of micron aluminum powders in time at room temperature using the method of gravimetric analysis. The stability was studied using methods of thermal analysis during heating up to 1200 °С in air. The composition of products was analyzed using X-ray diffraction analysis. It was found out that the stability of micron aluminum powders depends on partial pressure of water vapor: the increase of pressure results in decreased stability of powders. The work gives recommendations for storing micron aluminum powders.

Abstract: The aim of this study is to determine the effect of different types of pore-forming agent and sintering temperature on the pore size of ceramics. The porous ceramic material was developed by mixing of alumina, zeolite and calcium oxide (CaO) as the main materials and ethylene glycol as the binder. Meanwhile, two types of pore-forming agent were used, i.e., yeast and a mixture of aluminium powder and expandable polymeric spheres (EPS). The content of pore-forming agent was at 10 wt% of the mixture and the samples were shaped by using plaster of paris mould. After being dried, the samples were sintered at temperature range of 1000 up to 1500 °C for two hours. Microstructural analysis and pores size measurement were performed to determine the effect of pore-forming agent and sintering temperature on the ceramic. The result showed that yeast yielded larger pore sizes in the porous ceramic upon being sintered at 1400 °C for two hours, which were up to 402 μm. Therefore, yeast has the potential to be utilized as pore-forming agent in development of filter and wall insulation material.