Aluminum with metal oxides

Lightfast chrome yellow pigments that are coated with metal oxides (e.g., of aluminum, titanium, manganese) are produced by Du Pont [3.135]. 

Violante, A., Ricciardella, M., Del Gaudio, S. and Pigna, M. (2006) Coprecipitation of arsenate with metal oxides nature, mineralogy, and reactivity of aluminum precipitates. Environmental Science and Technology, 40(16), 4961-67. 

Barium reacts with metal oxides and hydroxides in soil and is subsequently adsorbed onto soil particulates (Hem 1959 Rai et al. 1984). Adsorption onto metal oxides in soils and sediments probably acts as a control over the concentration of barium in natural waters (Bodek et al. 1988). Under typical environmental conditions, barium displaces other adsorbed alkaline earth metals from MnO2, SiO2, and TiO2 (Rai et al. 1984). However, barium is displaced from Al203 by other alkaline earth metals (Rai et al. 1984). The ionic radius of the barium ion in its typical valence state (Ba+) makes isomorphous substitution possible only with strontium and generally not with the other members of the alkaline earth elements (Kirkpatrick 1978). Among the other elements that occur with barium in nature, substitution is common only with potassium but not with the smaller ions of sodium, iron, manganese, aluminum, and silicon (Kirkpatrick 1978). 

More than one boride phase can be formed with most metals, and in many cases a continuous series of solid solutions may be formed. Several methods have been used for the relatively large-scale preparation of metal borides. One that is commonly used is carbon reduction of boric oxide and the appropriate metal oxide at temperatures up to 2000 °C. Fused salt electrolysis of borax or boric oxide and a metal oxide at 700 1000 °C have also been used. Small-scale methods available include direct reaction of the elements at temperatures above 1000 °C and the reaction of elemental boron with metal oxides at temperatures approaching 2000 °C. One commercial use of borides is in titanium boride-aluminum nitride crucibles or boats for evaporation of aluminum by resistance heating in the aluminizing process, and for rare earth hexaborides as electronic cathodes. Borides have also been used in sliding electrical contacts and as cathodes in HaU cells for aluminum processing. 

Lightfast chrome yellow pigments that are coated with metal oxides (e.g., of aluminum, titanium, manganese) are produced by DuPont [3.119]. A chrome yellow that is coated with large amounts of silicate and alumina and which shows improved stability to temperature, light, and chemicals is also produced by DuPont [3.120]. 

A different technique was used by Durand Keklikian and Partch [16] to generate particles with a surface coating. Previously, a more volatile substance was coated on a less volatile particle. For their case, oil droplets coated with metal oxide were generated. This was accomplished by nebulizing solutions of titanium or aluminum alkoxides in oil. Hydrolysis of the alkoxide to the oxide occurred in the presence of water vapor, forming a solid shell encapsulating the oil droplet. 

Many consumers view the color of lipstick as the most important characteristic of this product. The colors and dyes of lipsticks are generally regulated within the United States and include many water-insoluble (oil-soluble) products, such as brilliant blue, erythrosine, amaranth, rhodamine, tartrazine, dibromofluorescein, and tetrabromofluorescein (bluish-red com-pound). The dyes must be water insoluble otherwise, the color would quickly fade or be removed in a short time by the consumer through the movement of the saliva-soaked tongue across the lips. Water-soluble dyes such as green or blue food dyes may be used to provide lipstick coloration, but they are usually first laked or combined with metal oxides such as aluminum hydroxide [A1(OH3)] to form an insoluble precipitate that is then suspended in the oil base of the lipstick. 

Mixed Co-Al and Zn-Al hydroxide surface precipitates can also form on aluminum-bearing metal oxides and phyllosilicates (Towle et al., 1997 Thompson et al., 1999a,b Ford and Sparks, 2000). This is not surprising, as Co " ", Zir+, and NP+ all have radii similar to AP+, enhancing substitution in the mineral structure and formation of a coprecipitate. However, surface precipitates have not been observed with Pb2+, as Pb-+ is too large to substitute for AP+ in mineral structures (Sparks, 2002, 2005). 

Another kind of nanocomposite is the energetic nanocomposite, generally as a hybrid sol-gel with a sihca base, which, when combined with metal oxides and nanoscale aluminum powder, can form superthermite materials [10,11]. 

Hagaman et al. (2012) studied interaction of benzoic acid with metal oxides using solid-state O NMR spectroscopy. Complexes formed by dry benzoic acid with mesoporous silica and nonporous titania and alumina were analyzed. Chemical reactions with silica were not observed, but the behavior of benzoic acid on silica was a function of the water content. The acid was characterized by high mobility as evidenced by a liquid-like, Lorentzian NMR resonance. Excess benzoic acid remained as the crystalline hydrogen-bonded dimer. Benzoic acid reacted with titania and alumina surfaces in equilibrium with air to form the corresponding titanium and aluminum benzoates. In both materials, the oxygen of the O-labeled acid was bound to the metal, showing the bond... 

Compare the metallic valences of sodium, magnesium, and aluminum with their oxidation numbers in their principal compounds. 

In the early days of the railway, rails were welded with the molten iron formed in this reaction. The combination of powdered aluminum and a metal oxide has been used as a rocket fuel and evidence has been obtained to indicate that after the disaster the Germans replaced the aluminum by bronze which does not react with metal oxides. Thus, the bad reputation hydrogen has had as a result of the accident is undeserved and the resulting limiting use of the airship was due to faulty chemistry and could have been avoided. 

Aluminum-containing propellants deflver less than the calculated impulse because of two-phase flow losses in the nozzle caused by aluminum oxide particles. Combustion of the aluminum must occur in the residence time in the chamber to meet impulse expectations. As the residence time increases, the unbumed metal decreases, and the specific impulse increases. The soHd reaction products also show a velocity lag during nozzle expansion, and may fail to attain thermal equiUbrium with the gas exhaust. An overall efficiency loss of 5 to 8% from theoretical may result from these phenomena. However, these losses are more than offset by the increase in energy produced by metal oxidation (85—87). 

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