Chromium oxide hydroxide

H. Asteman, J.E. Svenson, L.G. Johnson, M. NoreU, Indication of chromium oxide hydroxide evaporation during oxidation of 304 L at 873 K in the presence of 10% water vapor, Oxid. Met. 52 (1999) 95-111. 

Degenhardt, J., McQuillan, A.J. (1999) Mechanism of oxalate ion adsorption on chromium oxide-hydroxide from pH dependance and time evolution of ATR-IR spectra, Chem, Phys. Lett Vol. 31,179-184,0009-2614. 

E.J. Opila, N.S. Jacobson, D.L. Myers, and E.H. Copland, Predicting oxide stability in high-temperature water vapor, Journal of the Minerals, Metals, and Materials Society 58 22-28, 2006 I. Kvernes, M. Oliveira, and P. Kofstad, High temperature oxidation of Fe-13Cr xAl alloys in air/water vapor mixtures, Corrosion Science 17 237-52, 1977 H. Asteman, J.-E. Svensson, M. Norrell, and L.-G. Johansson, Influence of water vapor and flow rate on the high-temperature oxidation of 304L Effect of chromium oxide hydroxide evaporation. Oxidation of Metals 54 11-26,2000 J.M. Rakowski and B.A. Pint, Observations on the effect of water vapor on the elevated temperature oxidation of austenitic stainless steel foil. Proceedings of Corrosion 2000, NACE Paper 00-517, NACE International, Houston, Texas, 2000 E. Essuman, G.H. Meier, J. Zurek, M. Hansel, and W.J. Quadakkers, The effect of water vapor on selective oxidation of Fe-Cr Alloys, Oxidation of Metals 69 143-162,2008 E.J. Opda, Oxidation and volatilization of silica formers in water vapor. Journal of the American Ceramic Society 86(8) 1238-1248,2003. 

Chromium Oxides hydroxides Chromium oxide hydrate... 

Chromium oxide hydroxide Chromium oxide hydroxide Chromium oxide hydroxide Chromium aluminium oxide... 

Asteman H, Svensson J-E, Norell M and Johansson L-G (2000), Influence of Water Vapor and Flow Rate on the High-Temperature Oxidation of 304L Effect of Chromium Oxide Hydroxide Evaporation, Oxid Met, 54, 11-26. 

Cr2 03 - 112 0, of indefinite composition occurs. This compound is commonly misnamed as chromic or chromium (ITT) hydroxide [1308-14-1], Cr(OH)2. A tme hydroxide, chromium (ITT) hydroxide trihydrate [41646-40-6], Cr(OH)2 3H20, does exist and is prepared by the slow addition of alkaU hydroxide to a cold aqueous solution of hexaaquachromium(III) ion (40). The fresh precipitate is amphoteric and dissolves in acid or in excess of hydroxide to form the metastable Cr(OH). This ion decomposes upon heating to give the hydrous chromium (ITT) oxide. However, if the precipitate is allowed to age, it resists dissolution in excess hydroxide. 

Chromium hydroxide green is a more bluish and brilliant green than chromium oxide greens. It is quite transparent, and has good strength and excellent stabiUty. It is used in eye makeup and soap. 

Chromoxyd, n. chromium oxide, specif, chromic oxide, chromium(III) oxide. -farbe, /. chrome oxide color, -hydrat, n. chromium hydroxide, specif, chromic hydroxide, chro-mium(III) hydroxide, -natron, n. sodium chromite. -salz, n. chromic salt, chro-mium(III) oxide-... 

Electrobalances suitable for thermogravimetry are readily adapted for measurements of magnetic susceptibility [333—336] by the Faraday method, with or without variable temperature [337] and data processing facilities [338]. This approach has been particularly valuable in determinations of the changes in oxidation states which occur during the decompositions of iron, cobalt and chromium oxides and hydroxides [339] and during the formation of ferrites [340]. The method requires higher concentrations of ions than those needed in Mossbauer spectroscopy, but the apparatus, techniques and interpretation of observations are often simpler. 

The chromium oxides were prepared according to the following procedure [6-8]. Chromium oxide resulted from the dehydration of chromium hydroxide obtained by the addition of an ammonia solution (5M) to a solution of chromium nitrate (0.5M) The final pH was equal to 7.5 and the hydroxide formed was kept constantly stired and heated at 80°C for 1 h so as to obtain complete precipitation. This solid was filtered and washed three times with hot distilled water and dried for 16 h in an oven at 90°C. It was then submitted to a dynamic thermal treatment under nitrogen at 380°C for 8 h. The chromium oxide formed was cooled down under the same vector gas. 

The mixed chromium and nickel (5% and 10% Ni atomic) catalysts were prepared by dehydration of mixed chromium and nickel hydroxides prepared by adding an ammonia solution to a solution of chromium and nickel nitrate in order to maintain a pH = 7 1. The final pH was equal to 7.S. The hydroxyde treatment was the same as the one already described for chromium oxide. 

The electrochemical behavior of thin-film oxide-hydroxide electrodes containing chromium, nickel and cobalt compounds was investigated. Experimental results have shown that such compounds can be successfully used as active cathodic materials in a number of emerging primary and secondary battery applications. 

Hitachi Cable Ltd. (35) has claimed that dehydrogenation catalysts, exemplified by chromium oxide—zinc oxide, iron oxide, zinc oxide, and aluminum oxide—manganese oxide inhibit drip and reduce flammability of a polyolefin mainly flame retarded with ATH or magnesium hydroxide. Proprietary grades of ATH and Mg(OH)2 are on the market which contain small amounts of other metal oxides to increase char, possibly by this mechanism. 

Preparation of Potassium Chromate. (Perform one experiment on each table.) Melt a mixture of 1 g of potassium carbonate, 1 gof potassium hydroxide, and 2 g of potassium nitrate in an iron crucible by heating with the flame of a burner. While stirring the melt with an iron wire, introduce 1 g of finely comminuted chromite or -0.8 g of chromium oxide into the crucible. Roast the mixture for 5-10 minutes on a blowpipe. Treat the cooled melt with water. Filter the solution and evaporate it until a crystalline film appears. What is the composition of the formed crystals Why was potassium carbonate introduced into the reaction Write the equation of the reaction. 

Oxides and oxide -hydroxides Iron oxide pigments Chromium oxide pigments Mixed metal oxide pigments chromium oxide cob chromium oxide hydrate green alt green and b lue iron oxide red iron oxide orange chromium rutile orange iron oxide yellow nickel rutile yellow, chromium rutile yellow iron oxide brown zinc iron spinell, Mn-Fe-brown... 

The pigment properties of chromium oxides can be modified by precipitation of hydroxides (e.g., of titanium or aluminum), and subsequent calcining. This treatment changes the color to yellow-green, and decreases the flocculation tendency [3.54], Aftertreatment with organic compounds (e.g., alkoxylated alkylsulfon-amides) is also used [3.55]. 

Process wastewater may contain small amounts of unreacted chromates recovery is uneconomical. Prior to release into drainage systems, the chromates in these wastewater streams must be reduced (e.g., with S02 or NaHSOj) and precipitated as chromium hydroxide [3.60]. In Germany, for example, the minimum requirements for wastewater in the production of chromium oxide pigments are specified in [3.61]. 

The copper chromium oxide (Cu/Cr = 1) has been prepared by coprecipitation of copper and chromium nitrates with ammonium hydroxide, followed by thermal decomposition in flowing nitrogen up to the final temperature (370"C), according to a previously described method (8). The apparatus and the catalytic procedure have also been described elsewhere in case of gas phase reactions (5) and liquid phase reactions (7). 

The bromine atom of chromium pentaphenyl bromide is also replaced by the hydroxyl group when the compound is shaken in chloroform solution with an aqueous suspension of silver oxide. The other products present in the crude bromide remain dissolved in the chloroform, but since silver oxide seems to exert an oxidising action a mixture of bases results, and not pure chromium pentaphenyl hydroxide as might be anticipated. 

Chromium tetraphenyl iodide in methyl alcohol or moist chloroform is treated with silver oxide, or the iodide is subjected to electrolysis, using an alcohol solution with a platinum or mercury cathode and a rotating silver anode. One molecule of wTater is removed by drying over calcium chloride. The base forms orange-coloured plates, M.pt. 104° to 105° C. when placed in a bath previously heated to 95° C. It dissolves readily in water or alcohols, is sparingly soluble in chloroform, insoluble in benzene or ether. Measurements of its conductivity in aqueous solution show that it is comparable in strength with the alkali hydroxides, whilst comparative tests in methyl alcohol solution show that it is a stronger base than chromium pentaphenyl hydroxide. It may readily be converted into the chloride, bromide and iodide. 

In contrast to the amphoteric Cr(OH)3, chromium(II) hydroxide is a typical basic hydroxide. It dissolves in acid, but not in excess base. Conversely, the chromium(VI) compound, Cr02(0H)2, is a strong acid (chromic acid, H2Cr04). Recall from Section 15.15 that acid strength increases with increasing polarity of the O-H bonds, which increases, in turn, with increasing oxidation number of the chromium atom. 

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