Zirconium oxide aging

Unsatisfactory physicochemical stability of the sorbent. Titanium hydroxide is slightly soluble in seawater (0.1 mg/1 [165]) and also shows some degradation upon aging. Mixed titanium and zirconium oxide-type sorbents, known as thermoxides with much better stability [178, 179] were developed. 

Among the most important demands that are made for electrolytes on the basis of zirconium oxide is combination of high electrical conductivity with ageing stability in the range of operating temperatures (900-1000° C). 

Zirconium oxide closely resembles aluminium oxide or alumina. For a long time the latter effectively concealed the presence of the former. Nobody suspected an unknown element in zirconium minerals known as early as the Middle Ages. Thus, zirconium, one of the most abundant metals on Earth (0.02%) remained invisible up to the end of the 18th century. Today the mineral zircon is the main source of zirconium it occurs in two varieties hyacinth and jargoon. Already in old times hyacinth was known as a precious stone owing to its beautiful colours ranging from yellow-brown to smoky green. 

Yavorsky, P.J., Properties and High Temperature Alications of Zirconium Oxide. Ceramic Age 64-69 (June 1962). 

Analogously, hematite particles could be coated with zirconium hydrous oxide by aging zirconium sulfate solutions in the presence of cores, which required the... 

The improvement of the thermal stability of ceria by introduction of zirconium has been widely studied [8-10] and "estimated" by measuring the surface area of mixed oxides after high temperature thermal treatment. In the case of mixed oxides prepared by co-precipitation for example, an increase of the "preserved" surface area of aged oxides was observed even with the introduction of only 10 at.-% of... 

The cerium-zirconium mixed oxide (Ce/Zr = 64/36, atomic ratio) as well as the pure ceria samples (both without and with Pt) were obtained by a Rhone-Poulenc proprietary process. The purity of the cerium used was higher than 99.5%. For the study of the interaction between Pt and cerium-zirconium mixed oxides, a hexachloroplatinic solution was used as a source of Pt. The OH groups on the surface of the mixed oxides were exchanged by PtCle ions in water. The material obtained was dried in an oven at 120°C and calcined in a muffle furnace at 500°C. For aged catalysts, the calcination was performed at 900°C for 6 hours. The Pt loading was 0.5% (weight %). 

By impregnating y-Al203 with cerium/zirconium citrate solutions and subsequent calcination nanostructured CemZri.n,02 mixed oxides supported on AI2O3 are obtained, which feature remarkably high oxygen stor e even after a calcination at 1373 K for 24 h. Mutual thermal stabilisation between alumina and solid solutions has been observed, which prevents formation of a-alumina and sintering effects after a severe ageing. 

Kaneko et al. employed a coprecipitation method, which involved a base-catalyzed procedure that precipitated irregular particles of zirconia-sihca mixed oxides. Specifically, a zirconium salt (zirconyl chloride octahy-drate) was added to an acidified solution of sodium metasilicate ennehydrate. The solution was made alkaline (pH 7-9) to allow the precipitation of the mixed oxide gel. The gel was aged for 10 hr, collected by filtration and washed to remove residual chloride ions. The gel was dried at 110°C and then ground to an appropriate mesh size. The resulting precipitate was regarded as an intimate mixture of silica and metal oxide gel (in this case, zirconia). The silica... 

Insolubilization. Insolubilization of compounds within textiles parallels the history of humanity the direct dyeing techniques for cotton were highly advanced in the Bronze Age. With the exception of fiber-reactive dyes discussed earlier, other cotton dyes, ie, vat and sulfur, are insolubilized within the fiber after an oxidization step. Insoluble metal oxides have been used to flameproof cotton, and zirconium compounds have been insolubilized on cotton to render the fabric microbial resistant (135) or mildew resistant (136) via a mineral dyeing process (see Textile Finishing). 

With regard to the zirconium-niobium alloy, it appears that its corrosion rate is not much affected by irradiation, but it is very dependent on the local chemistry and can be accelerated by oxidizing conditions. The corrosion rate is also dependent on heat treatment condition, and good resistance is shown by material aged for 72 hours at 500°C. With such material and with suitable chemical control, it is expected that, as with Zircaloy-2, there will be no problem due to loss of section and the important consideration is that of hydrogen absorption and its consequent effect on mechanical properties. 

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