Showing papers on "Hydrofluoric acid published in 1973"

Plasma synthesis of fluorocarbon films

Abstract: Fluorocarbon films were obtained by introducing perfluorobutene-2 into the afterglow region of an argon plasma. The plasma was generated electrodelessly using plates excited at 13.56 MHz at 70 watts of power. Film deposition rates between 250 A and 450 A per minute were obtained during typical operating conditions. The films were light yellow in color, adhered strongly to dry glass substrates, and exhibited liquid contact angles very similar to those reported for poly(tetrafluoroethylene) surfaces. The infrared spectrum of the film was quite similar to that obtained for Teflon. The freshly prepared film contained a high concentration of unpaired spins, and the ESR signal decayed slowly on standing in vacuum. The films could be removed from the glass substrates by immersion in dilute hydrofluoric acid or in brackish water.

Process for etching silicon wafers

Abstract: A METHOD FOR ETCHING SILICON WAFERS WITH IMPROVED CONTROL OF WAFER FLATNESS. WAFERS ARE INITIALLY ETCHED IN A HYDROFLUORIC ACID RICH ETCHANT CONTAINING NITRIC ACID AND ACETIC ACID, AND THEN ETCHED A SECOND TIME IN A NITRIC ACID RICH ETCHANT CONTAINING HYDROFLUORIC ACID AND ACETIC ACID.

Atomic absorption analysis of beryllium and vanadium in rocks

Abstract: 原子吸光分析法による岩石中のベリリウムおよびバナジウムの定量における試料処理, 共存成分の影響, 干渉の抑制などについて検討した.一般のケイ酸塩岩石および粘土, 長石中の0.5～50ppmのベリリウム, 5～500ppmのバナジウムは, 試料を過塩素酸, 硝酸, フッ化水素酸で分解し, 希塩酸で溶解して試料溶液とし, 標準溶液にアルミニウム, カルシウム, カリウムを添加して定量した.超塩基性岩, 石灰岩, けい石試料中のベリリウムは, アセチルアセトン-クロロホルム抽出を併用することにより0.04ppm程度まで定量できた.緑柱石中のベリリウムは試料を炭酸ナトリウムとホウ酸で融解したのち希塩酸で溶解し, 所要時間約15分で定量できた.バナジウムに対する共存成分の干渉を塩酸溶液, 硫酸溶液で検討した結果, 負の干渉は硫酸溶液で多く, 溶液の活量係数に関係があることがわかった.

Electron beam dissociation of fluorine

Abstract: A high‐energy pulsed electron beam has been used to dissociate fluorine molecules in fluorine, helium, CO2, and hydrogen chloride gaseous mixtures. By using a probe HF laser and monitoring the amount of ir absorption by hydrogen fluoride resulting from the rapid F + HCl → HF + Cl reaction in these mixtures, the fluorine atom concentration was determined. It was found that an upper limit of approximately three fluorine atoms is produced from each electron‐molecule ionizing collision.

Continuous process for obtaining aluminium fluoride by reacting fluosilicic acid with an aluminous material

Abstract: The present invention relates to a continuous process for preparing aluminium fluoride by reacting fluosilicic acid (substantially pure) obtained from superphosphate, phosphoric acid or hydrofluoric acid industries, having a maximum P2O5 content of 250 ppm and an aluminous material, preferably alumina or bauxite hydrate.

Studies on the cytogenetic and genetic effects of fluoride on barley. I. A comparative study of the effects of sodium fluoride and hydrofluoric acid on seedling root tips.

Abstract: The effects of sodium fluoride and hydrofluoric acid on barley were determined and compared following treatments of seedling root tips at three different concentrations (1 × 10−2M, 1 × 10−4M, 1 × 10−6M) and for six different durations (12, 24, 36, 48, 60, and 72 hr). Treatment with a 1 × 10−2M concentration of either sodium fluoride or hydrofluoric acid markedly slowed the rate of seedling growth. However, no inhibition of growth was observed following treatment with a 1 × −4M or a 1 × 10−6M concentration of either agent. Chromosomal aberrations were induced and mitosis was inhibited by each of the three different concentrations of both sodium fluoride and hydrofluoric acid. The sodium fluoride treatments induced a higher frequency of chromosomal aberrations than did the hydrofluoric acid treatments, possibly due to differences in pH and in the total available fluoride ions. These treatments produced bridges, fragments, chromosome gaps, binucleate cells and micronuclei.

Process for purifying and condensing reaction gases in the production of hydrofluoric acid

Abstract: The present invention relates to a process for recovering hydrogen fluoride from the gaseous reaction product of a metal fluoride with sulfuric acid by washing the gaseous product in a first stage with concentrated sulfuric acid and thereby cooling the gas to a temperature of about 60 DEG to 130 DEG C, cooling said gas by indirect heat exchange with water to a temperature of about 30 DEG to 50 DEG C in a second stage and in a third stage by direct heat exchange with pure hydrofluoric acid to a temperature of about 20 DEG to 25 DEG C, condensing hydrogen fluoride in the cooled gaseous product of the third stage in at least two additional stages and recovering condensed hydrogen fluoride.

The reduction of uranium hexafluoride by hydrogen at room temperature

Abstract: The reaction between uranium hexafluoride and hydrogen is catalyzed by hydrogen fluoride, especially in the presence of platinum metal. The catalyzed reaction has an observable rate at room temperature. The reaction provides the basis for the preparation of BETA -uranium pentafluoride on a laboratory scale. (auth)

Surface preparation process for recoating of used coated metallic electrodes

Abstract: A surface preparation process for use in recoating of used metallic electrodes coated with one or more platinum group metals, one or more iron group metals, or chemical compounds thereof, which comprises using said metallic electrode(s) as anode(s) and passing a current between said metallic electrode(s) and a steel cathode(s) in an aqueous solution of sulfuric acid, nitric acid, perchloric acid, salts thereof, chlorates or persulfates, or a mixture solution thereof, and then dipping said metallic electrode(s) into an aqueous solution of hydrofluoric acid or hydrochloric acid.

Process of producing hydrogen fluoride from fluosilicic acid

Abstract: Hydrofluoric acid is prepared from fluosilicic acid (FSA) by feeding aqueous fluosilicic acid into a reactor where it is mixed with monoethylene or propylene glycol or diethylene glycol, in sufficient quantity to provide a (HF/FSA + H2O) ratio of from about 4 to about 6, at a temperature which will vaporize substantially all the SiF4. The glycol is then sent to a still where the HF and small amounts of water are stripped. The aqueous HF is passed to a still from which anhydrous HF is recovered and aqueous HF may be recycled to the reactor.

Composition for chemical milling refractory metals

Abstract: This application describes a composition and a process of chemically milling refractory metals and their alloys. The composition comprises a combination of nitric acid, hydrofluoric acid, and phosphoric acid, and preferably includes a derivative of carbonic acid, such as carbamide. The composition is particularly useful in the chemical milling of beta titanium, alpha beta titanium, and alpha titanium alloys. Use of the composition of this invention results in reduced tolerances in the chemically milled article and also reduced hydrogen absorption in the titanium part which is chemically milled.

Recovery of hydrofluoric acid from aqueous fluosilicic acid

Abstract: Recovery of hydrofluoric acid from aqueous fluosilicic acid by treating said aqueous fluosilicic acid at a temperature of from 100° to 300°C. and under a pressure of from 3 to 80 atmospheres and separating resulting hydrogen fluoride containing aqueous phase and silicon tetrafluoride containing gaseous phase and optionally hydrolyzing the silicon tetrafluoride containing gaseous phase in aqueous medium and recycling the aqueous fluosilicic acid to the process as starting material.

Replacement of platinum vessels with a pressure device for acid dissolution in the rapid analysis of glass by atomic-absorption spectroscopy

Abstract: The rapid analysis of glass is made possible by replacing the crucibles in which time-consuming fusion is carried out by a device for quantitative acid dissolution under pressure and subsequent atomic-absorption spectroscopic determinations of the elements.The sample is decomposed by hydrofluoric acid at 105 °C in a decomposition vessel consisting of a crucible-shaped stainless-steel container fitted with a removable PTFE crucible and a stainless-steel screw-cap with a PTFE disc inserted in the metal body. Subsequent addition of boric acid forms the analysis matrix of fluoroboric acid-boric acid for the atomic-absorption determinations of silica, alumina, iron, titanium, magnesium, calcium, sodium and potassium.This procedure obviates the use of platinum vessels, prevents losses of constituents due to alloying, reduction and volatilisation, does not introduce extraneous cations, and is reliable, simple and rapid to perform.

Silicon removal from incinerator ash by reaction with NOF.3HF

Abstract: Incinerator ash containing silicon is contacted with nitrosyl fluoride trihydrogen fluoride (NOF.3HF) converting silicon present to silicon tetrafluoride (SiF4) gas, thereby minimizing formation of gelatinous silica polymer in subsequent treatment of the ash to recover plutonium, americium, and the like.

Removal of phosphate compounds from fluoride containing solutions

Abstract: A process for removing phosphate compounds such as phosphoric anhydride (P2O5) from fluoride containing solutions such as dilute hydrofluoric acid (HF) or fluosilicic acid (H2SiF6) is disclosed. This process involves the precipitation of aluminum phosphate (AlPO4) from the acidic fluoride containing solutions. The precipitation is brought about by the addition of an aluminum salt such as aluminum fluoride (AlF3), aluminum chloride hydrate (AlCl3.6H2O), aluminum nitrate (Al(NO3)3.9H2O), aluminum sulfate (Al(SO4)3.13-1/2H2O), aluminum ammonium sulfate (Al2(SO4)3.(NH4)2SO4.24H2O) and triammonium aluminum hexafluoride ((NH4)3AlF6). The pH is then adjusted to at least about 3 and the phosphoric anhydride is removed by precipitation.

Producing concentrated hydrofluoric acid substantially free from impurities using polyether and polyol absorbents and nitrogen flushing gas

Abstract: A dilute or impure hydrofluoric acid in the form of a gaseous or liquid mixture is treated with an at least partially selectively absorptive organic solvent, and the solvent with the solutes is passed in counter-current relation in a stripping column with an inert gas which drives off the impurities and the water, after which the purified acid is separated from the solvent, chosen to have preferred selectivity for HF over the impurities and water, the inert gas also suppressing polymeric reactions in the organic solvent for which the latent tendency to be catalyzed by HF or impurities is more pronounced during stripping.

A radioreagent method of analysis of boron in sub-microgram range

Abstract: A radioreagent method for the determination of boron in submicrogram range is described. This method is based on the reaction of boric acid with hydrofluoric acid labeled with18F and the measurement of the activity of the product, HBF4*, which is isolated by complexation with methylene blue and extraction with 1,2-dichloroethane. The 0.51 Mev gamma ray activity resulting from18F of an aliquot of the extract is found to be proportional to the amount of boron in the sample. It was found that at least 0.1 μg of boron can be measured by this method with an accuracy of about 5% error. The short-lived nature of18F makes it necessary that the analysis be performed as soon as the isotope is available. The sample to be analyzed should be freed from hydrofluoric acid as well as other species which form precipitate or complexes with Hf. The method was applied successfully to the analysis of one of the Netional Bureau of Standards reference samples.

Fluorinated tertiary amino ethers

Abstract: Tetrafluoro-ethylene can be added to monoamines having oxyethyl or oxypropyl groups in aprotic polar solvents in the presence of alkali metals. The new monoamines obtained having the radicals tetrafluoro-ethyloxy-ethyl or tetrafluoro-ethyl-oxy-propyl are electrolyzed in anhydrous hydrofluoric acid, thus forming new monoamines in which all or nearly all hydrogen atoms of the starting compounds are replaced by fluorine.

5-methyl-peri-acenaphthindenone-prepn by reacting - acetoacetyl fluoride with acenaphthene in hydrofluoric acid medium

Abstract: 5-Methyl-peri-acenaphthindenone-7 (I) is prepd. by reaction of acetoacetyl fluoride, produced in situ by reaction of diketone with HF, with acenaphthene in >=90% HF at -10 degrees to 120 degrees C. Good yields e.g. 80% are obtd. compared with 23% by previous methods, and reaction temp. is conveniently low. (I) is used in vat dye prodn. and is an inter. for pigment dyes.

Method for reclaiming glass articles

Abstract: An aqueous solution containing hydrofluoric acid and tannic acid was found useful as a glass cleaning composition in reclaiming clean glass panel from a defective panel rejected during manufacture of a phospor screen for color picture tube. The composition is superior to conventional compositions not only in cleaning efficiency but also in operational safety because of lower hydrofluoric acid concentration and lower treating temperature.

Synthesis of chloro-and fluorophenylethynylsilanes

Abstract: 1. Either a partial or a total replacement of the chlorine atoms attached to silicon is possible when organochlorosilanes are reacted with phenylethynylmagnesium bromide. The analogous reaction of the organofluorosilanes proceeds in higher yields. 2. Some phenylacetylenic fluorosilanes were obtained by reacting the corresponding chlorosilanes with hydrofluoric acid.