Showing papers on "Hydrofluoric acid published in 1970"

ISOTOPE SEPARATION WITH THE cw HYDROGEN FLUORIDE LASER

Abstract: A cw hydrogen fluoride laser has been used successfully to separate deuterium from hydrogen by specific photocatalysis of the reaction of methanol with bromine. The strong absorption of H3COH was demonstrated for the HF laser lines P1(5), P1(6), and P1(7) while no absorption by deutero‐methanol of the HF beam was observed. Excitation of H2COH by the absorbed beam increased the rate of H3COH removal by reaction with bromine. Irradiation, at 90 W for 60 sec, with the cw hydrogen fluoride laser of a 1 : 1 H3COH : D3COD gas mixture in the presence of bromine produced isotope enrichment to greater than 95% D3COD.

Specific ion electrode in the determination of urinary fluoride.

Abstract: THE introduction of a fluoride sensitive specific electrode1 has greatly simplified the determination of fluoride iou and recently its use has been proposed for the determination of urinary fluoride2–5. This article draws attention to an interesting and important anomaly which has been observed in using the electrode for the routine screening of workers engaged in the manufacture of hydrofluoric acid.

Recovery of uranium from an organic extractant by back extraction with h3po4 or hf

Abstract: A PROCESS FOR THE RECOVERY OF URANIUM VALUES FROM URANIUM CARRYING EXTRACTS CONTAINING A DIALKYLPHOSPHORIC ACID AND A TRIALKYLPHOSPHINE OXIDE DISSOLVED IN AN ORGANIC SOLVENT IS DESCRIBED. THE PROCESS INVOLVES LIQUIDLIQUID EXTRACTION OF THE EXTRACTANTS WITH AN AQUEOUS SOLUTION CONTAINING DIVALENT IRON AND A COMPLEXING AGENT WHICH MAY BE EITHER PHOSPHORIC ACID, HYDROFLUORIC ACID OR MIXTURES THEREOF.

Process for demineralization of water

Abstract: The invention described herein is a process for the purification of carbon. That process provides for the treatment of carbon with hydrofluoric acid, or a mixture of hydrofluoric acid and nitric acid, followed in each case by treatment with hot aqueous hydrochloric acid. The carbon thus purified is notably effective for use as electrode material in a demineralization cell, i.e., one used for the demineralization of water.

Method and material for etching semiconductor bodies

Abstract: AN ETCHANT FOR UNIFORMLY ETCHING BODIES OF SILICON OR GERMANIUM WHICH PROVIDES AN ETCHED SURFACE WHICH IS FREE FROM PITS AND PEAKS. THE BODY IS ETCHED BY IMMERSING A SURFACE OF THE BODY IN A MIXTURE OF HYDROFLUORIC ACID, NITRIC ACID, ACETIC ACID AND EITHER SODIUM CHLORITE OR SODIUM NITRITE AND BUBBLING A GAS INTO THE ETCHANT SO THAT AT LEAST SOME OF THE GAS BUBBLES IMPINGE ON THE SURFACE OF THE BODY.

The Activity Coefficients of Hydrofluoric Acid in Water from 0 to 35 °C.

Abstract: The mean stoichiometric activity coefficients of hydrofluoric acid in aqueous solutions have been calculated from measurements of electrolytic conductivity, the electromotive forces of galvanic cells without liquid junction, and the freezing-point depression. Values obtained from freezing-point depressions were converted to values for 25 °C using known values of the heats of dilution and apparent molal heat capacities of aqueous solutions of hydrofluoric acid of various concentrations. It is also shown that values for the concentrations of the various ionic species in hydrofluoric acid, namely, H+, F-, HF 2 ¯ , and HF depend on the functions used to represent the ionic activity coefficients whereas values of the mean activity, a H + a F - , are independent of such functions. Values of the pH of various concentrations of hydrofluoric acid are given for temperatures of 0 to 35 °C; these, likewise, are nearly independent of activity-coefficient function used to obtain values for the ionic concentrations.

Process for chemical nickel plating of aluminum and its alloys

Abstract: ALUMINUM AND ITS ALLOYS CAN BE ELECTROLESSLY PLATED BY FIRST DEGREASING AND CLEANING THE ALUMINUM SURFACE, ETCHING THE DEGREASED AND CLEANED SURFACE WITH HYDROFLUORIC ACID FOLLOWED BY IMMERSING THE BASE OR SURFACE IN AN ACIDIC ELECTROLESS PLATING SOLUTION CONTAINING NICKEL IONS, HYPOPHOSPHITE IONS, FLUOBORATE AND/OR SULFAMATE IONS, GLYCOLATE IONS AND A SMALL AMOUNT OF FLUORIDE IONS. THE PH OF THE SOLUTION IS WITHIN THERANGE OF 5.3 TO 7.

An Internal Sample Container for Hydrofluoric Acid Solution Calorimetry

Abstract: An improved sample container for a solution calorimeter is described. The container is an integral part of the stirrer assembly so that the sample can be thermally equilibrated with the solvent before dissolution, and is constructed of polytetrafluoroethylene (Teflon) for use in hydrofluoric acid. This design eliminates the "sensible heat" correction and other sources of systematic error. Because the container permits rapid mechanical mixing of the sample in the solvent, relatively coarse size fractions (<325 mesh) can be used in silicate-solution calorimetry.

Method of electroplating readily oxidizable metals

Abstract: IN A METHOD OF ELECTROPLATING READILY OXIDIZABLE METALS AND ALLOYS, AN ARTICLE TO BE PLATED IS FIRST PICKED WITH A MIXTURE OF NITRIC ACID AND HYDROFLUORIC ACID OR A MIXTURE OF BORIC ACID AND HYDROFLUORIC ACID, IMMEDIATELY WASHED WITH AN ANHYROUS ORGANIC SOLVENT, DRIED BY AN INERT GAS OR UNDER VACUUM, DIPPED IN A PLATING BATH WITHOUT BEING EXPOSED TO THE ATMOSPHERE AND THEN AFTER A SHORT TIME ELECTROLYTICALLY PLATED.

Technique for masking silicon nitride during phosphoric acid etching

Abstract: A technique for passivating silicon nitride to phosphoric acid etchants during the formation of semiconductor devices is disclosed. The technique consists of exposing a silicon nitride surface to a diffusion source consisting of either a boron or phosphorous containing source material. The silicon nitride surface is exposed to the diffusion source, at a temperature ranging from 750-1,140* C, for a period of time sufficient to form a diffused source-rich layer of silicon nitride having the desired depth. The source-rich film is then oxidized in a wet oxygen or steam ambient, at a temperature ranging from 8501,100* C, for a period of time sufficient to form a passivating film. The passivating film is immune from attack by phosphoric acid but can be etched with hydrofluoric acid.

The action of phosphoric acid on glass

Abstract: Phosphoric acid attacks glass at temperatures of 200°C and above, at first etching the surface uniformly and producing a moderate increase in strength. After longer treatment the glass becomes coated with a layer of silicon phosphate which renders it resistant to hydrofluoric acid, but its mechanical strength is reduced because of crystalline inclusions in the surface. Under a microscope the crystalline deposits closely resemble marine barnacles in shape. The rate of reaction of glass with phosphoric acidsof increasing degrees of polymerisation has been measured.

Etchant for selectively etching patterns in thin silicon dioxide layers and method of preparing such an etchant

Abstract: This disclosure is directed to an aqueous etching composition for silicon dioxide based on ammonium fluoride and hydrofluoric acid to which an arsenic or thallium salt has been added and to a method of etching layers of silicon dioxide by means of said etching composition.

Search for alkanes of 15 to 30 carbon atom length.

Abstract: A 50-gram sample of lunar fines was subjected to stepwise extraction in a mixture of benzene and methanol while intact, after being pulverized, and after being digested in hydrofluoric acid. None of these three extracts contained detectable quantities of C15 to C30 alkanes. No C15 to C30 alkane was present in this lunar sample at a concentration exceeding I part per billion by weight.

Method of the continuous production of hydrofluoric acid

Abstract: A method for the continuous production of hydrofluoric acid by the purification and condensation of the hot reaction gases created by the reaction between fluorspar and sulphuric acid, comprising leading the hot reaction gases, already freed from dust, to a scrubbing and stripping column where recycled washing acid absorbs heat and impurities, and from which the gases strip at the same time hydrogen fluoride. The still hot gases are then led to a scrubbing section, employing first impure hydrofluoric acid and then pure hydrofluoric acid, which absorbs further impurities in exchange for which pure hydrogen fluoride is stripped. The cooled gases go then to a fractional condensation stage, where substantial amounts of hydrofluoric acid of industrial purity are collected and volatile impurities, with some hydrogen fluoride are bled off to conventional absorption with fresh sulphuric acid, which HF-laden gas is then led to the scrubbing and stripping column where it absorbs heat and further impurities and from which the hot incoming reaction gases strip hydrogen fluoride. The hot washing acid then continuously overflows to the mixing tank and supplies the acid required for the continuous reaction producing the hydrofluoric reaction gases.

Method of etching materials capable of being etched with hydrofluoric acid

Abstract: A METHOD FOR ETCHING THE OXIDES OF SILICON AND OTHER MATERIAL CAPABLE OF BEING ETCHED WITH AQUEOUS HYDROFLUORIC ACID IS DESCRIBED. THE MATERIAL TO BE ETCHED IS TREATED WITH AN ETCHING SOLUTION COMPRISING (A) AN ETCHANT HAVING THE GENERAL FORMUL R4NHX+1FY+2, WHEREIN X AND Y MAY BE 0 TO 1, AND X AND Y ARE EQUAL, AND WHEREIN R MAY BE A HYDROGEN RADICAL OR AN ORGANIC RADICAL REPRESENTED AS CNH2N+1 WHEREIN N IS AN INTEGER FROM 1 TO 10, AND (B) A SUITABLE SOLVENT FOR THE ETCHANT.

Electroless nickel plating on glass

Abstract: AN ADHERENT COATING OF ELECTROLESS NICKEL PLATE ON GLASS IS OBTAINED USING AN ACIDIC ELECTROLESS PLATING SOLUTION HAVING A PH WITHIN THE RANGE OF ABOUT 5.0 TO 7, WHICH SOLUTION CONTAINS BORATE IONS, FLUORIDE IONS AND AN ION OF AN ORGANIC HYDROXYCARBOXYLIC ACID SUCH AS GLYCOLATE ION. THE USE OF A HYDROFLUORIC ACID ETHCH PRIOR TO PLATING FURTHER IMPROVES ADHESION.

Process for the manufacture of perfluoralkylsulphonyl fluorides

Abstract: IN WHICH R1, R2, R3, R4, R5 and R6 independently of one another denote hydrogen or a C1-C6-alkyl group, in hydrofluoric acid. Process for manufacturing perfluoralkylsulphonyl fluorides which consists in electrolyzing cyclic unsaturated sulphones of the formula

Heats of formation of gibbsite and light element double oxides

Abstract: : The heat of formation of gibbsite, from alpha-alumina and water, has been redetermined by solution calorimetry in hydrofluoric acid at 75C. A value of - 13.3 plus or minus 0.6kcal was found. The heats of combination of selected light element double oxides have also been determined by solution calorimetry in hydrofluoric acid at 75C. In the case of the double oxides that contained alumina, gibbsite was used as a reference compound. (Author)