摘要:
Finely divided, homogeneous and easily sintered superconducting powders of at least one rare earth element, e.g., yttrium and/or lanthanum, at least one alkaline earth metal, e.g., barium, calcium and/or strontium, and at least one transition metal, e.g., copper, nickel, manganese, cobalt and/or iron, and oxygen, are produced by (a) intimately admixing a sol of a rare earth element and an aqueous solution of at least one alkaline earth metal nitrate and of at least one nitrate of a transition metal, with the pH of the resulting mixture being adjusted to a value such that said nitrates remain solubilized therein; (b) drying the resulting mixture; (c) calcining the dried product; and, optionally; (d) grinding the calcined material.
摘要:
Finely divided, homogeneous and easily sintered superconducting powders of at least one rare earth element, e.g., yttrium and/or lanthanum, at least one alkaline earth metal, e.g., barium, calcium and/or strontium, and at least one transition metal, e.g., copper, nickel, manganese, cobalt and/or iron, and oxygen, are produced by (a) solubilizing, in water, the nitrates and/or acetates of at least one rare earth element, at least one alkaline earth metal, and at least one transition metal; (b) atomizing such solution to dryness; (c) calcining the dried product; and, optionally; (d) grinding the calcined material.
摘要:
A catalyst support and process for preparing same are provided wherein a metal substrate is coated with a layer of adherent alumina with a layer of chromium interposed between the alumina catalyst support and the metal substrate. The catalyst supports of the invention are especially useful in catalytic converters for the purification and control of exhaust gas emissions from internal combustion engines by the active catalyst oxidation/reduction of carbon monoxide, unburned hydrocarbons and nitrogen oxides.
摘要:
A novel anhydrous sodium tripolyphosphate, well adapted as an additive for foodstuffs and detergent compositions, has an Na/P ratio of essentially 1.667.+-.0.01, an apparent density of from 0.5 to 1.1, a mean agglomerate size of less than 100 microns, a phase I content ranging from 15 to 6% by weight, is devoid of insoluble fraction, and displays zero solidification or caking in a quiescent solvent medium.
摘要:
A process for treating a rock essentially constituted by calcium aluminophosphate, comprising the treatment of the ground rock with a concentrated sulfuric acid in stoichiometric excess with respect to calcium and aluminum, at a temperature of above about 120.degree. C., for a time between a few minutes and about 5 hours, followed by controlled water take-up. Subsequently, a residue containing substantially all the calcium and the aluminum of the rock and a solution of the acids serving to digest a tricalciumphosphate charge are separated. The process is particularly suitable for the treatment of Thies phosphate ore.
摘要:
Highly concentrated, aqueous colloidal dispersions of a cerium (IV) compound, adapted for the impregnation of catalyst supports, are prepared by reacting an aqueous solution of a cerium (IV) salt with a base, to precipitate a certain cerium hydroxynitrate, separating and washing said precipitate, and then dispersing the washed precipitate in an aqueous acid medium.
摘要:
Morphologically improved ceric oxide particulates have a BET specific surface, measured after calcination at a temperature of from 350.degree. to 450.degree. C., of at least 100 m.sup.2 /g, a total pore volume of at least 0.3 cm.sup.3 /g, and the pores of which having a mean diameter larger than 50 .ANG.. The improved ceric oxide particulates are prepared by reacting a cerium salt with a strong base in the presence of carboxylate ions, or a cerium carboxylate with a strong base; separating the precipitate of true cerium hydroxide thus produced; and washing, heat-treating, and calcining such precipitate.
摘要:
Finely divided powders of alkaline earth metal titanates, well suited for the fabrication of, e.g., ceramic resistors and condensers, are facilely prepared by (i) admixing a solution of an alkaline earth metal nitrate with a titanium sol having a pH ranging from 0.8 to 2.5 and which comprises elementary crystallites of TiO.sub.2 having particle sizes ranging from 10 to 100 .ANG., agglomerated into submicronic masses having particle sizes ranging from 200 to 1000 .ANG., (ii) next drying the suspension which results, (iii) calcining said dried suspension at a temperature ranging from 700.degree. to 1300.degree. C. for from 30 minutes to 24 hours, under a NO.sub.x partial pressure decreasing from 1 to 0, and then (iv) optionally grinding the powder resulting from said step (iii).
摘要:
A novel anhydrous sodium tripolyphosphate, well adapted for detergency applications, has an X-ray diffraction pattern essentially characterizing a phase I sodium tripolyphosphate; a viscosity, in aqueous medium, characterizing a phase II sodium tripolyphosphate; a rate of hydration characterizing a phase I sodium tripolyphosphate; and which exhibits an ROH at 1 minute of greater than about 90.degree. C.