Finely divided oxide

Briquets of mixed, finely divided oxide and carbon are heated to 1275—1400°C in a refractory container. The minimum pressure is about 40 Pa (0.3 mm Hg) for reduction at 1400°C. Lower pressures or higher temperatures cause excessive volatilisation of chromium. The result is a high purity, low interstitial product. 

Fretting or fretting corrosion may be defined as that form of damage which occurs at the interface of two closely fitting surfaces when they are subject to slight relative oscillatory slip. The surfaces are often badly pitted and finely divided oxide detritus is formed. 

The oxide (prepared at 300°C) bums in air above 200°C, while the finely divided oxide prepared by reduction may be pyrophoric at ambient temperature [1]. That prepared by thermal decomposition under vacuum of iron(II) oxalate is also pyrophoric [2],... 

The finely divided oxide prepared at low temperature is pyrophoric when heated in air, and bums brilliantly. 

It is noted that finely divided oxides as in the case of membrane structure can be rapidly dissolved in HF, hot concentrated sulfuric acid, ammonium fluoride, and concentrated hydrochloric acid, especially when under pressure. 

Finely divided oxide may be obtained by pyrolysis of cadmium salts of carboxylic acids, such as cadmium formate or oxalate ... 

Reaction with amorphous silicon at 900°C, catalyzed by steam produces cadmium orthosilicate, Cd2Si04. The same product also is obtained by reaction with sdica. Finely divided oxide reacts with dimethyl sulfate forming cadmium sulfate. Cadmium oxide, upon rapid heating with oxides of many other metals, such as iron, molybdenum, tungsten, titanium, tantalum, niobium, antimony, and arsenic, forms mixed oxides. For example, rapid heating with ferric oxide at 750°C produces cadmium ferrite, CdFe204 ... 

Use of a non-expl primer, such as consisting of a mixt of finely divided red P 10 to 35% and a finely divided oxidizer ( such as Pb dioxide or Ba or Sr nitrate)... 

CA 50, 11019 (1956) (Each grain of a blend consisting of a finely divided oxidizer and a solid fuel of a composite proplnt is coated with... 

In this article (Part I) we have comprehensively reviewed the structural implications of the vibrational spectroscopic results from the adsorption of ethene and the higher alkenes on different metal surfaces. Alkenes were chosen for first review because the spectra of their adsorbed species have been investigated in most detail. It was to be expected that principles elucidated during their analysis would be applicable elsewhere. The emphasis has been on an exploration of the structures of the temperature-dependent chemisorbed species on different metal surfaces. Particular attention has been directed to the spectra obtained on finely divided (oxide-supported) metal catalysts as these have not been the subject of review for a long time. An opportunity has, however, also been taken to update an earlier review of the single-crystal results from adsorbed hydrocarbons by one of us (N.S.) (7 7). Similar reviews of the fewer spectra from other families of adsorbed hydrocarbons, i.e., the alkynes, the alkanes (acyclic and cyclic), and aromatic hydrocarbons, will be presented in Part II. 

Iron(II) Oxide. Finely divided oxide incandesces in HN03.34... 

Finely divided oxidizers dispersed in fuel matrix. 

Entropy evaluations from published cryothermal data on the lanthanide (III) oxides are summarized in Table II with an indication of the lowest temperature of the measurements and the estimated magnetic entropy increments below this temperature. Their original assignment of crystalline field levels from thermal data still appears to be in good accord with recent findings e.g., 17). Unfortunately, measurements on these substances were made only down to about 8°K. because the finely divided oxide samples tend to absorb the helium gas utilized to enhance thermal equilibration between sample and calorimeter. 

During electrochemical deposition of metal oxides, metal hydroxides and metals, current are passed between an anode and cathode in a cell containing weakly alkaline electrolyte. The anion of the electrolyte is such that it does not form an insoluble salt with the metal anode. Metal ions issuing from the metal anode make contact with hydroxyl ions in solution and form finely divided oxides or hydroxides. The oxides or hydroxides are removed and chemically reduced to finely divided metal particles. The voltage necessary for carrying out the oxidation of the metal to metal ions is reduced through the use of an electrode as cathode, thereby reducing the cost of the process. 

The thermal decompositions of iron(II) carboxylates have been studied together with investigations of the electrical properties of the finely divided oxide product (y -FcjOj) which is potentially of commercial value in magnetic recording media [138]. 

The best catalytic films are produced when the finely divided oxides have been calcined to an intermediate degree. In the case of alumina, a desirable material is one which has been partially calcined to a hydrated form containing between 5 and 20 wt. % of chemically combined water. When the film is made from materials which are fully hydrated, it tends to be soft and easily removed by erosion. When fully dehydrated materials are used, the film is flaky and brittle. 

Synthesis of molecular sieves with T sites isomorphously substituted by other elements is frequently accompanied by the formation of more or less oxidic extraframework species as by-products (see Sect. 4.1.2.2). In this section the intended preparation of finely divided oxides or oxide clusters within the voids of the framework will be discussed. 

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