Showing papers on "Hydrofluoric acid published in 1986"
TL;DR: In this article, the optimum operating conditions for diffusion dialysis were studied for the recovery of nitric acid and hydrofluoric acid from mixed solutions containing these acids and ferric ions.
104 citations
TL;DR: In this paper, a cross sectional transmission electron microscopy revealed that the stain films retain the crystallinity of the substrate but contain networks of pores on the scale of several hundred angstroms.
53 citations
TL;DR: Only Ta, Sb, Re, and Tc are well extracted with either polyurethane foam or dicyclohexano-18-crown-6 in dichloro-ethane under the conditions investigated.
20 citations
TL;DR: In this article, the standard enthalpy of formation (ΔHf0298 = −424.58±0.47 kcal mol−1; −1776.43±1.97 kJ moP−1) was determined.
16 citations
Patent•
09 Jul 1986
TL;DR: In this article, the authors proposed to reduce the content of impurities to a ppb level by adding fluorine to hydrofluoric acid wherein the compd. of at least one nonmetallic element selected from a group of boron, silicon, phosphorus, sulfur and chlorine is dissolved as the impurities.
Abstract: PURPOSE:To reduce the content of impurities to a ppb level by adding fluorine to hydrofluoric acid wherein the compd. of at least one nonmetallic element among boron, silicon, phosphorus, sulfur and chlorine is dissolved as the impurities, allowing the impurities to react with the fluorine and then distilling the acid. CONSTITUTION:Fluorine is added to hydrofluoric acid wherein the compd. of at least one nonmetallic element selected from a group of boron, silicon, phosphorus, sulfur and chlorine is dissolved and allowed to react with the compd. The acid is then distilled. By such a method, almost all the impurities can be easily concentrated and obtained in the initial fraction as the distillate. Fluorine is charged into the reaction system in the form of gaseous fluorine, a mixture of an inert gas and fluorine or the soln. of gaseous fluorine in an inert liq. such as hydrofluoric acid. The reaction of the impurities with gaseous fluorine is preferably carried out at -20-+20 deg.C and at atmospheric pressure.
11 citations
TL;DR: In this paper, the trace antimony in river water was determined by hydride-generation atomic absorption spectrometry, where the water was concentrated after the addition of mineral acids.
Abstract: Trace antimony in river water was determined by hydride-generation atomic absorption spectrometry. The water was concentrated after the addition of mineral acids. Siliceous residues deposited during the concentration were solubilized with hydrofluoric acid and expelled by evaporation in the presence of sulfuric acid. After chelating resin separation, the effluent was acidified with sulfuric acid to ionize the hydrolyzed antimony. The accuracy checked with a biological standard reference material was satisfactory when the insoluble residues in the material were treated with hydrofluoric acid after acid digestion. Antimony contents in the water ranged between 0.1 and 0.9ng ml-1.
10 citations
TL;DR: In this article, a simple and fast analytical method for complex Ni-based and Co-based heat-resistant alloys has been developed by inductively coupled plasma/atomic emission spectrometry (ICP-AES).
Abstract: A simple and fast analytical method for complex Ni-based and Co-based heat-resistant alloys has been developed by inductively coupled plasma/atomic emission spectrometry (ICP-AES). Heat-resistant alloys of widely varying composition are dissolved in a mixture of hydrofluoric acid and nitric acid. A demountable hydrofluoric acid-resistant sample introduction system was used in which the surface of polytetrafluoroethylene (PTFE) parts was treated with metallic Na to improve the wetting property of the PTFE. Synthetic standard solutions are used for the calibration. Major and minor alloying elements are determined. The calibration curve method and internal standard method are compared. The internal standard method used two spectrometers and Mg as an internal standard element.
9 citations
8 citations
Patent•
05 Jul 1986
TL;DR: In this article, a high strength Ni alloy having satisfactory resistance to corrosion by nonoxidizing acids by adding specified percentages of Cr, Mo, Al, Ti, Fe, C, Nb and Ta to Ni is presented.
Abstract: PURPOSE:To obtain a high strength Ni alloy having satisfactory resistance to corrosion by nonoxidizing acids by adding specified percentages of Cr, Mo, Al, Ti, Fe, C, Nb and Ta to Ni. CONSTITUTION:An Ni alloy consisting of, by weight, 4-16% Cr, 9-20% Mo, 0.2-2% Al, 0.5-4% Ti, <=10% Fe, <=0.1% C, <=6% Nb and/or <=12% Ta (Ti+1/2Nb+1/4Ta=2-5%) and the balance Ni with impurities is manufactured. The Ni alloy has high strength and satisfactory resistance to corrosion by nonoxidizing acids such as sulfuric acid, hydrochloric acid and hydrofluoric acid.
8 citations
Patent•
12 Mar 1986
TL;DR: In this article, an etching soln for an Al-Si film is composed of phosphoric acid, nitric acid, acid, acetic acid, hydrofluoric acid and water in 350:140:70:1.5:30 volume ratio.
Abstract: PURPOSE: To produce a composition etching an Al-Si film in a single etching stage by blending phosphoric acid with nitric acid, acetic acid, hydrofluoric acid and water in a specified ratio. CONSTITUTION: An etching soln. composition for an Al-Si film is composed of phosphoric acid, nitric acid, acetic acid, hydrofluoric acid and water in 350:140:70:1.5:30 volume ratio. When the composition is used, an Al-Si electrode and Al-Si wiring can be formed by a simple etching method without requiring any expensive equipment. COPYRIGHT: (C)1987,JPO&Japio
Patent•
30 Oct 1986
TL;DR: In this paper, a resist film contg. silicon (Si) is first treated with hydrofluoric acid or the acidic soln. essentially consisting thereof and is then treated with the stripping liquid consisting of the org. solvent at the time of finely working the resist film by dry etching, then stripping said film.
Abstract: PURPOSE:To permit thorough stripping of a resist film contg. Si from a high- polymer film by treating the resist film with hydrofluoric acid or acidic soln. essentially consisting thereof before treating the resist film with a stripping liquid consisting of an ordinary org. solvent. CONSTITUTION:The resist film contg. silicon (Si) is first treated with hydrofluoric acid or the acidic soln. essentially consisting thereof and is then treated with the stripping liquid consisting of the org. solvent at the time of finely working the resist film by dry etching, then stripping said film. The hydrofluoric acid, soln. mixture composed of hydrofluoric acid and ammonium fluoride, soln. mixture composed of hydrofluoric acid, ammonium fluoride and acetic acid, etc., are used as the acidic soln. The thorough stripping away of the resist film contg. Si from the high-polymer film and the formation of the precise pattern are thereby permitted.
TL;DR: In this article, the determination of silicon, phosphorus and arsenic in siliceous materials based on the formation of their heteropolymolybdates was performed by distillation from phosphorus and the remainder of the sample.
Abstract: Hydrofluoric distillation has been applied to the determination of silicon, phosphorus and arsenic in siliceous materials based on the formation of their heteropolymolybdates. Silicon and arsenic are separated by distillation from phosphorus and the remainder of the sample. Arsenic is determined spectrophotometrically, in the presence of silicon, by controlling the hydrofluoric acid concentration. Afterwards, the sum of silicon plus arsenic is determined gravimetrically with quinoline. Phosphorus is determined in the residue by either of the two methods.
Patent•
22 Jul 1986TL;DR: In this article, a process for etching zirconium metallic articles using an aqueous bath of hydrofluoric acid and nitric acid is described, where the active acid and water contents of the bath are determined by measurement of the dissolved zirconsium content of the water bath.
Abstract: A process for etching zirconium metallic articles using an aqueous bath of hydrofluoric acid and nitric acid wherein the active hydrofluoric and nitric acid contents of the bath are determined by measurement of the dissolved zirconium content of the bath, and the bath is replenished in acid to give substantially the active hydrofluoric acid concentration and ratio to nitric acid, without removal of dissolved zirconium from the bath, to increase the bath etching life.
Patent•
23 Apr 1986
TL;DR: In this paper, the recovered substance contg. platinum group metals or their oxides and the oxides of a base metal is added to hydrofluoric acid, and the mixture is heated to 40-60 deg.
Abstract: PURPOSE:To recover platinum group metals easily and efficiently by heating the recovered substance contg. platinum group metals or their oxides and the oxides of a base metal with hydrofluoric acid to dissolve the oxides of the base metal in the hydrofluoric acid. CONSTITUTION:The recovered substance contg. platinum group metals or their oxides and the oxides of a base metal is added to hydrofluoric acid, and the mixture is heated to 40-60 deg.C. The oxides of the base metal dissolve in the hydrofluoric acid, but the platinum group metals or their oxides do not dissolve in it. By filtering this hydrofluoric acid soln. through activated carbon, the platinum group metals or their oxides can be recovered by separation.
TL;DR: In this article, the impact of these insoluble reaction products on the etching surfaces can cause strength degradation, which can be characterized by scanning electron microscopy, wet chemical, X-ray diffraction, and surface area analyses.
Abstract: During etching of soda-lime glass in hydrofluoric acid solutions, insoluble reaction products can collect in the acid solution or deposit on the glass surface. In this study it is shown that impact of these insoluble reaction products on the etching surfaces can cause strength degradation. The insoluble reaction products are characterized by scanning electron microscopy, wet chemical, X-ray diffraction, and surface area analyses.
Patent•
12 Dec 1986
TL;DR: In this paper, a mixture of mixed soln. of nitric acid and hydrofluoric acid is used to uniformize and freshen coloring which arises from anodic oxidation coatings.
Abstract: PURPOSE:To uniformize and freshen coloring which arises from anodic oxidation coatings by subjecting the valve metal to a pre-treatment by a mixed soln. of nitric acid with hydrofluoric acid at a specific concn. or in addition to this, further subjecting said valve metal to a pre-treatment by a dilute sulfuric acid and dilute hydrofluoric acid. CONSTITUTION:The valve metal having coarse crystal grains is subjected to the pre-treatment by the aq. mixed soln. of nitric acid and hydrofluoric acid contg. 1-10wt% hydrofluoric acid and 2-20wt% nitric acid; or before subjecting to said pre-treatment, the valve metal is treated successively by the dilute sulfuric acid and dilute hydrofluoric acid to preferentially subject grain boundaries to etching. The valve metal such as Ti, Ta and Zr (alloy) subjected to the above-mentioned treatments is then subjected to an anodic oxidation.
Patent•
01 Dec 1986
TL;DR: A process for recovering titanium dioxide, useful as a white pigment, from ilmenite-type ores comprises digesting the ore with hydrofluoric acid to produce a fluoride salt-containing solution, treating the fluoride salt containing solution with an alkali metal salt (preferably KCl) to precipitate alkaline metal fluotitanate, and then treating the precipitate with a base to produce hydrated titanium dioxide and alkali-metal fluoride, subjecting the alkali metals fluoride to electrodialytic water splitting to produce base and hydro-fluoric
Abstract: A process for recovering titanium dioxide, useful as a white pigment, from ilmenite-type ores comprises digesting the ore with hydrofluoric acid to produce a fluoride salt-containing solution, treating the fluoride salt-containing solution with an alkali metal salt (preferably KCl) to precipitate alkali metal fluotitanate, treating the precipitate with a base to produce hydrated titanium dioxide and alkali metal fluoride, subjecting the alkali metal fluoride to electrodialytic water splitting to produce base and hydrofluoric acid, employing a portion of the base in the precipitate treating step and recycling a portion of the hydrofluoric acid to the digesting step. The hydrated titanium dioxide can be calcined to produce titanium dioxide.
Patent•
12 Aug 1986
TL;DR: In this paper, the authors proposed a method to produce potassium 6-fluorophosphate in high workability and efficiency, by reacting hydrofluoric acid or anhydrous hydric acid with a potassium compound of phosphoric acid, which is preferably potassium dihydrogen phosphate or potassium polyphosphate.
Abstract: PURPOSE: To produce potassium 6-fluorophosphate in high workability and efficiency, by reacting hydrofluoric acid or anhydrous hydrofluoric acid with a potassium compound of phosphoric acid. CONSTITUTION: Hydrofluoric acid or anhydrous hydrofluoric acid is made to react with a potassium compound of phosphoric acid. The potassium compound of phosphoric acid is preferably potassium dihydrogen phosphate or potassium polyphosphate. The hydrofluoric acid used in the above process has a hydrogen fluoride (HF) concentration of about 60W97wt% and the anhydrous hydrofluoric acid has a hydrogen fluoride (HF) concentration of about ≥97wt%. The above reaction is preferably carried out at ≤50°C. COPYRIGHT: (C)1988,JPO&Japio
Patent•
26 Nov 1986
TL;DR: In this article, the oxide scale on the surface of stainless steel is removed by cracking the scale and subjecting the steel to electrolytic treatment in an aqueous neutral salt soln.
Abstract: PURPOSE:To remove oxide scale on the surface of stainless steel in a short time by cracking the scale, subjecting the steel to electrolytic treatment in an aqueous neutral salt soln, and immersing the steel in an aqueous sulfuric acid soln and an aqueous mixed acid soln contg nitric acid and hydrofluoric acid in succession CONSTITUTION:Oxide scale on the surface of Cr or Cr-Ni stainless steel is cracked or broken by bending, stretching, shot blasting or other method, and the steel is subjected to electrolytic treatment in an aqueous soln of a neutral salt such as Na2SO4 The steel is then immersed in an aqueous sulfuric acid soln having 100-300g/l concn of sulfuric acid at 70-95 degC, and it is further immersed in an aqueous mixed acid soln contg 150g/l nitric acid and 30g/l hydrofluoric acid The oxide scale on the surface of the stainless steel is dissolved and removed in a short time
Patent•
27 Mar 1986TL;DR: In this article, the authors described a process for preparing 4,4'-diacylbiphenyl characterized in that biphenyl is brought into contact with an acylating agent in liquid hydrofluoric acid at a temperature greater than or equal to 50 degrees C, in the presence of boron trifluoride in such an amount that the absolute pressure of BORON trifluride in the reaction chamber is at least one bar.
Abstract: 1. Process for preparing 4,4'-diacylbiphenyl characterized in that biphenyl is brought into contact with an acylating agent in liquid hydrofluoric acid at a temperature greater than or equal to 50 degrees C, in the presence of boron trifluoride in such an amount that the absolute pressure of boron trifluoride in the reaction chamber is at least one bar.
Patent•
15 May 1986
TL;DR: In this paper, an oscillating plate mounted on the sidewall of a treating tank was used for the removal of fine particles from the surface of a silicon substrate by the so-called wedge effect.
Abstract: PURPOSE:To obtain the surface of a silicon substrate, whereon fine particles little stick, by a method wherein a treatment is performed on the silicon substrate using hydrofluoric acid or dilute hydrofluoric acid, and after that, the silicon substrate is dipped in hydrogen peroxide-containing organic alkaline solution of the specific liquid temperature using ultrasonic waves of the specific frequency at the same time and is cried. CONSTITUTION:A silicon substrate 1 is dipped in a treating tank 3 filled up with hydrogen peroxide-containing organic alkaline solution 2 to be performed a treatment. Ultrasonic waves of a frequency of 500kHz or more are applied to the direction parallel to the substrate 1 by an oscillating plate 4 mounted on the sidewall of this treating tank 3. The directivity of the ultrasonic waves is strong at the frequency in this extent and the particle acceleration by oscillation is also large. At this time, the solution 2 is diffused between the silicon substrate 1 and fine particles by a so-called wedge effect, and at the same time, the fine particles are made to liberate from the surface of the silicon substrate by the gentle etching action of the organic alkali in the solution. The liquid temperature of the organic alkaline solution used for the treatment is maintained at 50 deg.C or more by a heater 7.
Patent•
03 Jun 1986
TL;DR: In this paper, the authors proposed to produce high-purity silica at a low cost by adding ammonia to a liquid produced by extracting chaff with an HF solution, filtering the decomposed ammonium hexafluorosilicate and SiO 2, adding a strong acid to the filtrate and recycling the mixture to the reaction system.
Abstract: PURPOSE: To produce high-purity silica at a low cost, by adding ammonia to a liquid produced by extracting chaff with an HF solution, filtering the decomposed NH 4 F and SiO 2 to obtain high-purity silica, adding a strong acid to the filtrate and recycling the mixture to the reaction system. CONSTITUTION: (1) Chaff is treated with a solution of hydrofluoric acid (HF) to extract the existing silicon compound in the form of hexafluorosilicic acid (H 2 SiF 6 ). (2) The extract is added with ammonia and decomposed via ammonium hexafluorosilicate [(NH 4 ) 2 SiF 6 ] into ammonium fluoride (NH 4 F) and silica (SiO 2 ). (3) Silica precipitated as amorphous powder is separated by filtration, washed with water and dried to obtain a high-purity silica. (4) The filtrate containing ammonium fluoride is added with a strong acid to form hydrogen fluoride, which is recycled to the step (1). The strong acid used in the above process is preferably sulfuric acid. COPYRIGHT: (C)1987,JPO&Japio
TL;DR: In this article, a lower limit of 10 18 phosphorus atoms cm −3 can be determined by sectioning intervals of 30-50 nm, and the depth of silicon is measured by determining the silicon content in the etching solution by conventional inductively-coupled plasma atomic emission spectrometry.
Patent•
10 Mar 1986
Patent•
06 Mar 1986
TL;DR: In this paper, organic acid solutions, characterised in that, instead of hydrochloric acid, they contain hydrofluoric acid, in order by this means to dissolve so-called "mineralisations" and/or other silicic-acid-containing reaction products in drinking water wells.
Abstract: The invention relates to organic acid solutions, characterised in that, instead of hydrochloric acid, they contain hydrofluoric acid, in order by this means to dissolve so-called "mineralisations" and/or other silicic-acid-containing reaction products in drinking water wells, which is not possible with the acid combinations used hitherto. This is associated with the avoidance of a reducing agent or oxidising agent which have previously been required to dissolve manganese oxide (MnO2), in which case it should be noted that, when reducing agents are used, the COD and BOD5 in the reaction waters subsequently pumped out, that is waste waters after regeneration (from wells), is extraordinarily high. When gravel washing machines made of stainless steel are used, pitting corrosion and stress-crack corrosion do not occur, which cannot be avoided when hydrochloric acid is used. There is no problem in neutralising, during well development, any unconsumed hydrofluoric acid via a simple calcium compound (CaO, Ca(OH)2 etc.), absolutely harmless calcium fluoride precipitating out.
Patent•
25 Sep 1986TL;DR: A process for the preparation of trifluoromethylanilines is described in this article, where a para-trihalomethyl benzene isocyanate or carbamyl halide is prepared in liquid hydrofluoric acid.
Abstract: A process for the preparation of trifluoromethylanilines. Hydrolysis and exchange fluorination of a para-trihalomethyl benzene isocyanate or carbamyl halide are carried out in liquid hydrofluoric acid.
TL;DR: In this article, the enthalpies of solution in hydrofluoric acid of metakaolinites, obtained by thermal dehydroxylation of kaolinite in the temperature range 450-950°C, have been measured calorimetrically.
Patent•
IBM1
TL;DR: In this article, an etchant composition and method for the resistivity specific etching of doped silicon films which overlie intrinsic or lightly doped crystal regions is presented, which leaves no silicon residue.
Abstract: The present invention provides an etchant composition and method for the resistivity specific etching of doped silicon films which overlie intrinsic or lightly doped crystal regions. The etchant comprises hydrofluoric acid, nitric acid, and acetic acid, the molecular ratio of nitric acid to hydrofluoric acid being greater than 2,0 and the mole percentage of nitric acid being greater than 14 mole %. The etchant leaves no silicon residue and provides for controlled etching with an etch stop at the lightly doped or intrinsic region. The method comprises the steps of:
providing an etch mask overlying the silicon layer;
immersing the doped silicon on the crystal surface in the etchant; and
etching portions of the doped silicon layer exposed through the mask in the solution until the exposed doped silicon is removed and the underlying surface is clear and specular.
TL;DR: In this paper, high transparent and highly conducting films of SnO2:F were prepared by chemical vapour deposition technique and the results showed that the films had high carrier concentration and high mobility.
Abstract: Highly transparent and highly conducting films of SnO2:F were prepared by chemical vapour deposition technique. The films prepared at 350°C substrate temperature and 2·5 lit. min−1 flow rate of oxygen showed maximum figure of merit. The optimum doping concentration of fluorine was 1·02 wt%. The Hall experiment showed that the films prepared at optimum conditions had high carrier concentration and high mobility.