Papers by Keyword: Aluminum Hydroxide

Abstract: To improve the flame retardant and smoke suppression performance of fire retardant coatings. Aluminum hydroxide (ATH) and montmorillonite (MMT) were used as reinforced fillers to prepare intumescent fire-retardant coatings. The results showed that when ATH and MMT were combined with a mass ratio of 9:2, the flame retardant and smoke suppression performance was best. The maximum temperature on the back decreased by 47.1 °C, the heat release rate (HRR) decreased by 15.9%, the total smoke production (TSP) decreased by 23.5%, the peak carbon dioxide yield (PCDY) decreased by 39.4%, the maximum carbon residue was 50.59%. The main reason is that ATH reacts with phosphoric acid to form Al(H₂PO₄)₃, which binds each component together to increase the carbon residue. At high temperatures, ATH generates a large number of Mg-O-P and Si-O-P bonds and the mesh structure of MMT synergistically improves the thermal stability of the coating and absorbs flue gas particles. The oxides decomposed by ATH adhere to the surface of MMT and migrate to the surface of the charcoal layer to form a protective layer, which enhances the flame-retardant and smoke-suppressant properties of the coating. In this study, ATH/MMT was used as the flame retardant filler, and the optimal addition amount of ATH/MMT was obtained for the preparation of intumescent fire retardant coatings, which provides a theoretical basis for the selection of reinforcing fillers.

Abstract: The primary barrier to hydrogen production through the aluminum-water reaction is the oxide layer which forms on the exterior surface of the aluminum. In this work, the passivation was minimized by optimizing the concentration of sodium hydroxide solution (0.3 - 0.5 M) promoted by NaAlO₂ at room temperature reaction conditions. The aluminum used is waste aluminum foil AA1235 chips having dimensions of 20 mm x 30 mm. The results showed that the hydrogen production rate increases as the NaOH solution concentration increases. The higher the solution’s pH, the shorter the hydrolysis process of the alumina layer, hence the hydrogen production is faster. Adding NaAlO₂ as a promoter could increase the hydrogen production rate compared to sole NaOH, i.e., 11.162 ml/minute and 9.86 ml/minute, respectively. This increase occurred significantly during the fast reaction stage. It indicates that the solution containing NaOH and NaAlO₂ work synergistically whereby NaOH can accelerate the reaction rate in the aluminum core and NaAlO₂ functions as the booster for producing Al(OH)₃.

Abstract: The paper presents the results of differential scanning calorimetry, powder thermogravimetry, scanning electron microscopy, and X-ray phase analysis of ceramics made of powder obtained by chemical dispersion of B95 alloy. The process of obtaining a new ceramic material is briefly described. The mechanism of formation of the microstructure observed is described using the results obtained.

Abstract: Intumescent fire-retardant coatings based on epoxy resins, compared to traditional fire-retardant compositions, have improved performance properties – high strength, chemical and atmospheric resistance, adhesion to many materials. However, unmodified epoxy polymers are combustible and to obtain IFR based on them, flame retardants and mineral fillers are added to their composition. Intumescent systems for flame retardant coatings based on epoxy oligomers (non-halogen-containing) usually consist of ammonium or ammophos polyphosphate as an acidic agent and a wide range of fillers, both inert and gaseous, or which are an additional source of carbon. Each component of the fire-retardant intimate coating in different ways affects the processes of coke formation, which determines the requirements for their choice. Thus, the aim of this work is to conduct experimental studies of the dependence of the characteristics of the expanded coke layer on the composition of the intumescent epoxyamine composition. The results of experimental studies of the effect of ammonium polyphosphate and binary mixtures of ammonium polyphosphate (APP) with aluminum hydroxide (AH), sodium tetraborate decahydrate (STD), titanium oxide TiO₂ (TO), pentaerythritol (P), aerosil (A) and expandable graphite are presented (EG) on the multiplicity of expanding and weight loss of epoxy compositions at study temperatures of 350, 400 and 450°C. Studies have shown that the production of intumescent flame retardant coatings based on epoxy oligomers is possible provided they are filled with ammonium polyphosphate in an amount of more than 20 mass parts. The most effective in terms of expanding are additives titanium oxide and aluminum hydroxide in an amount of 20 mass parts, which allows to obtain intumescent fire-retardant coatings with a linear coefficient of expanding 30-32 and 24-27, respectively, throughout the range of temperatures. The obtained data are useful in the development of fire-retardant coatings based on epoxy oligomers.

Abstract: Nowadays, the fire behavior of polymer composite materials is a concern in automotive applications. Due to the flammability of this type of compounds, the present study focused on analyzing the influence of the flame retardants of aluminum hydroxide and magnesium hydroxide on the flammability index. A DOE was carried out using a complete factorial design using two categorical variables (type of resin and type of retardant at two levels) and one quantitative variable (volumetric percentage of the retarder for 3 levels). Twelve combinations of composite material were manually conformed maintaining the general volumetric fraction (30% reinforcement, 70% polymer matrix). Percentages of retardants (3.6 and 9%) were part of the volumetric composition of the matrix. The performance and evaluation of the flammability test was carried out under ISO 3795: 1989 and FMVSS 302. In addition, the average temperature inside the test chamber was measured to observe its behavior during combustion. The results showed that the flammability index was significantly reduced with the use of polyester resin with retarder aluminum hydroxide at any percentage and the highest temperature inside the chamber was produced by the combustion of the epoxy resin with 9% retardant of flame.

Abstract: The known designs of tank for precipitation of aluminum hydroxide from sodium aluminate solution, used in the production of alumina are considered, and the improvement of the design of the precipitator with mechanical mixing is proposed, which allows to intensify the process of precipitation and to avoid strong caustic module of the solution changes.

Abstract: The pottery of Ratchaburi is very famous especially dragon jar which was fired by using dragon kiln. The kiln was made of unfired clay bricks, which its properties including high refractoriness, low thermal shrinkage and durable are desired. Aluminum hydroxide is an interesting material for improving brick’s properties, providing high active alumina (gamma-alumina) content after decomposition, high melting point and also reasonable cost. The study evaluated the effect of an additive, Al (OH)₃, on the fried properties of refractory clay brick. In this study, four difference proportions of Al (OH)₃ to clay , including 0:100, 25:75, 49:51 and 76:24 were studied. The specimens of 5x5x5 cm³ were formed by hand molding, then were fired at 1200, 1300 and 1400°C. The properties including refractoriness, volume shrinkage, strength, bulk density, water absorption, and slaking time were investigated. The samples of 25:75 ratio of Al (OH)₃ to clay, which was fired at 1300°C exhibited high in refractoriness, low volume shrinkage of 5% and relatively low density of 1.69 g/cm³ as compared to those of 1400°C fired. Moreover, the moderate water adsorption of 15 % and useable compressive strength of 12.4 MPa was also observed. As a result, these properties suitable for using in firebox of dragon kiln of Ratchaburi province.

Abstract: The paper gives the experimental data on physicochemical and sorption properties of aluminum hydroxides produced by electric spark dispersion of aluminum metal in water and electric explosion of an aluminum conductor in argon and further interaction with water. By comparing the phase composition, specific surface area, porosity, and functional dependence of the exchange capacity of products on the solution pH, we proved the influence of preparation conditions on the properties of the said products.

Abstract: High alumina foam ceramics products with low density, high specific surface area, low thermal conductivity, corrosion resistance and other excellent physical and chemical properties are suitable for chemical, metallurgy and other related fields ^[1-4]. Alumina foam ceramics that compression strength increased by 200%, was prepared by Rizwan Ahmad through impregnation process using foamed rubber ^[5]. However foamed rubber was expensive and could be decomposed creating poisonous gases at high temperature. Zhou l z ^[6] prepared mullite porous ceramics with high strength by gel-casting method. Gel-casting is an effective method for preparation of ceramics products with large size and complicated shape. Fiber reinforced dense ceramics composite materials with excellent performance have been studied widely ^[7-10], it is also an important issue to adequately investigate the reinforcement of porous ceramics with fiber.

Abstract: Mg-Al-Fe ternary layered double hydroxides (LDHs) were synthesized based on Red mud by a calcination-rehydration method, and characterized using X-ray diffraction (XRD). The flame-retardant properties of EVA/LDHs (EVA, ethylene-vinyl acetate) composites were studied via cone calorimeter test (CCT), smoke density test (SDT), and Thermogravimetric analysis (TGA). The CCTs data indicate that heat release rates (HRR) of EVA/LDHs composites decrease in comparison with that of EVA, EVA/Red mud, EVA/ATH and EVA/MH composites. The SDT results show that LDHs is helpful to smoke suppression. The TGA show that LDHs-containing EVA2 has higher thermal stability at high temperatures than the other samples.