Showing papers on "Hydrofluoric acid published in 2010"

Fluorine doped zinc oxide thin films deposited by chemical spray, starting from zinc pentanedionate and hydrofluoric acid: Effect of the aging time of the solution

Abstract: Fluorine doped zinc oxide thin films, ZnO:F, were deposited on sodocalcic glass substrates, starting from zinc pentanedionate and hydrofluoric acid, by the chemical spray technique. The effect of the aging time of the starting solution on the electrical, structural, morphological and optical characteristics of the ZnO thin films was studied. Uniform, adherent, and mirror-like films were deposited at different days. A high electrical resistivity, was found in the films deposited the first day. However, a decrease in the resistivity, until a minimum, in the order of 3 × 10−2 Ω cm was reached for films deposited after the starting solution was aged for twelve days. The films fit well with the hexagonal, wurtzite-type ZnO structure, with a (0 0 2) preferential growth. Variation in the grain size was observed as a consequence of the aging of the solution. An average crystallite size varied between 17.3 and 22.8 nm due to aging effect, and some variations in surface morphology were encountered. All the films are highly transparent in the near UV–vis range, with an average transmittance oscillating between 83% and 90%.

Extractors for estimating plant available silicon from potential silicon fertilizer sources

Abstract: Methods to quantify plant available silicon (Si) from Si-based slags for use as fertilizers are not well defined. Although it is possible to estimate total Si from a potential Si fertilizer source; this approach does not represent how much Si is available for uptake by the plant. In this study, Si was extracted from ten sources [Wollastonite W10; calcium silicate slag from the US; calcium silicate from Canada; magnesium silicate; Excellerator; silican gel; 00-00-12 + Si (liquid source) and three types of potassium silicate with different concentrations in the liquid form, K53; K120 and AgSilTM25] using each of the following seven methods: hydrochloric acid (HCl) plus hydrofluoric acid (HF) extraction, leaching column; sodium carbonate (Na2CO3–10 g L−1) + ammonium nitrate (NH4NO3–16 g L−1); citric acid (50 g dm−3 or 5%); hydrochloric acid (0.5 N); neutral ammonium citrate (NAC); and resin (Amberlite IRC-50, pK 6.1). All the Si-containing products were added to pots at rates equal to 600 kg ha−1 of Si based...

Digestion method and detection method for iron ore

Abstract: The invention provides a digestion method and a detection method for iron ore. The digestion method comprises the following steps: adding an iron ore sample in which hydrofluoric acid and nitric acid (or sulfuric acid) are mixed, then carrying out high-pressure closed microwave digestion to obtain a suspension; and heating the suspension in an unclosed system to secure the second digestion with residual nitric acid (or residual sulfuric acid) and added perchloric acid and hydrogen peroxide, thereby obtaining a solution which is digested fully. The detection method comprises the following steps: preparing a solution with the digested solution, and detecting the prepared solution by inductive coupling plasma atomic emission spectrometry, thereby obtaining content of each element of the iron ore sample. The invention has the advantages of high efficiency, high accuracy, and simple and fast process. Especially, the invention realizes accurate detection of key element content in iron ore, such as As, Pb, Zn, W, Sn, Ca, Mg, Cu, Co, Ni, Cr and Mo which affect product quality of iron and steel smelting and vanadium/titanium extraction.

Dynamics of porous silicon formation by etching in HF + V2O5 solutions

Abstract: Formation of porous silicon by etching of silicon wafers with vanadium pentoxide (V2O5) dissolved in hydrofluoric acid (HF) has been studied with infrared spectroscopy and electron microscopy. V2O5 creates in solution, which initiates the reaction by injecting holes into the silicon valence band. Much is known about the mechanism of etching that leads to flat Si surfaces; however, the transition to pore formation is not well understood. The rate of film growth depends linearly on the V2O5 concentration in aqueous solutions but has a nonlinear dependence on the formal HF concentration. Addition of ethanol greatly decreases the etch rate and changes the pore morphology from a mixture of {100} + {110} planes to predominantly {100} planes. A plot of thickness versus etch time evolves from a quadratic to a linear dependence, whereas the surface area depends linearly on the etch depth. These observations are consistent with a model in which pores with a uniform diameter nucleate randomly then lengthen linearly ...

Fluoride concentration effect on the anodic growth of self‐aligned oxide nanotube array on Ti6Al7Nb alloy

Abstract: The formation of nanotube oxide layers on Ti6Al7Nb alloy in H3PO4 acid solutions containing fluoride ions is presented here. Among several parameters influencing the quality of nanotubes formed anodically such as potential, time of anodizing, fluoride ions concentration and scan rate of polarization, in particular, the last two seem to be the most responsible for the structure and morphology of nanotubes. The effect of fluoride ions concentration on the morphology of nanotubes on the two-phase (α + β) Ti6Al7Nb implant alloy, has been evaluated in our work. The formation of nanotubes was performed by polarizing the Ti6Al7Nb alloy samples in 1 M H3PO4 containing 0.2%, 0.3% and 0.4% wt. Hydrofluoric acid (HF) to 20 V using scan rate 500 mV/s and then holding them at that potential for further 2 h in the same electrolyte. Nanotubes of diameter ranging from 50 to 80 nm, with thicker walls over β-phase grains than over α-phase grains, were obtained. During the formation process, which includes two stages–the first, potentiodynamic and the second, potentiostatic (20 V)–different electrochemical behavior was observed in electrolytes of various fluoride concentration. The clear relationship between the highest currents and the biggest diameter of nanotubes for 0.3% wt. HF containing electrolyte observed during the first stage of anodizing is explained with regard to electrochemical characteristics of alloying elements and transport of electrolyte anions in oxide layers. Copyright © 2010 John Wiley & Sons, Ltd.

Experiments on the Release of CMOS-Micromachined Metal Layers

Abstract: We present experimental results on the release of MEMS devices manufactured using the standard CMOS interconnection metal layers as structural elements and the insulating silicon dioxide as sacrificial layers. Experiments compare the release results of four different etching agents in a CMOS technology (hydrofluoric acid, ammonium fluoride, a mixture of acetic acid and ammonium fluoride, and hydrogen fluoride), describe various phenomena found during the etching process, and show the release results of multilayer structures.

Method for manufacturing semiconductor device

Abstract: In a method for manufacturing semiconductor device by forming a semiconductor film on a substrate and then releasing the semiconductor film to manufacture the semiconductor device, the efficiency of reuse of the substrate can be enhanced. An etching stopper layer (13), a release film (14), and a semiconductor film (20) is formed on a substrate (11) sequentially, after the semiconductor device is formed on the semiconductor film (20), a trench (21) is formed in the semiconductor film (20) and the release film (14) by using a first etching solution such as mixed solution of sulfuric and hydrogen peroxide, and then the release film (14) is removed by using a second etching solution such as hydrofluoric acid. The etching stopper layer (13) is harder to etch by first etching solution (mixed solution of sulfuric and hydrogen peroxide) compares to the semiconductor film (20) and the release film (14), and the semiconductor film (20) is harder to etch by second etching solution (hydrofluoric acid) compares to the release film (14).

Method for producing nano-wire array film of titanium dioxide

Abstract: The invention discloses a method for preparing a titanium dioxide nano-wire array film. The method comprises the following steps: mixing hydrofluoric acid, nitric acid and deionized water to prepare an acid wash; adding melamine and nitric acid into a hydrogen peroxide solution to obtain a reaction solution; washing the surface of a metal titanium plate by the acid wash to be immersed in the reaction solution to react for 60 to 72 hours at a temperature of between 60 and 90 DEG C; and washing the reacted titanium plate by the deionized water to be dried, and insulating the titanium plate for 1 to 2 hours at a temperature of between 350 and 550 DEG C. The method for preparing the titanium dioxide nano-wire array film does not need a template or a catalyst, and has the advantages of simpleness and feasibility, low cost, pure film, regular size arrangement, perfect crystallization, large specific surface area and firm combination with a substrate, and the titanium dioxide nano-wire arrayfilm has wide application in photocatalysis, photoelectrocatalysis, thin-film solar cell, gas sensor, cold cathode electronic emission and other fields.

Digestion method of soil metal elements

Abstract: The invention discloses a digestion method of soil metal elements. The method comprises the following steps: (1) weighing a soil sample; (2) preparing a mixed acid A which has a volume ratio of nitric acid to hydrofluoric acid to perchloric acid of 6-10:4-5:2; (3) preparing a mixed acid B which has a volume ratio of the hydrofluoric acid to perchloric acid of 8-10:1; (4) adding the mixed acid A to a digestion cup to decompose soil; (5) adding the mixed acid B to escape silicon; (6) removing acid: washing off acid globules suspending on the cup wall with 0.2-5% diluted hydrochloric acid or diluted nitric acid, controlling temperature of an electric heating plate at 110-130 DEG C and distilling to dryness; and (7) make constant volume: adding the diluted nitric acid to dissolve residue in the digestion cup, and adding the diluted nitric acid of the same concentration to the fixed volume for measurement. The method has high efficiency and improved safety. The method is applicable to measurement of metal elements such as Cu, Zn, Fe, Mn, Ca, Mg, Ni, Pb, Cd and the like in soil and produces accurate and reliable determination results.

Etch rate dependence on crystal orientation of lithium niobate

Abstract: This paper presents the etch rate of lithium niobate (LiNbO3) as a function of crystal orientation. Etching is a fundamental technology needed for the fabrication of new sensors, actuators, and other new devices. In this study, LiNbO3 spheres 30 mm in diameter were etched in hydrofluoric acid and a mixture of hydrofluoric and nitric acids at different temperatures and different times. The measured data of the etched sphere shape were processed and plotted, giving etch rate diagrams over the entire spheres. Based on the etch rate data obtained, the Wulff-Jaccodine method was used to predict the etched shape of 128°Y-cut and 155°Y-cut LiNbO3. The predicted etching profiles were compared with those obtained by experiments. A least-square polynomial fit for the data was also developed and was found to be useful in removing some of the variation in the measurements.

Competition between phosphates and fluorides at anodic formation of titania nanotubes on titanium

Abstract: The influence of phosphate (and its concentration) on the electrochemical properties of anodic porous oxide films formed on titanium surfaces in fluoride containing electrolyte was investigated by performing electrochemical measurements [potentiodynamic/potentiostatic polarization, open circuit potentia) (OCP), and capacitance measurements] foratitanium/oxide film/solution interface system in SBF solution. In previous work we demonstrated, that during anodizing titanium and titanium-based implant materials in 2 M phosphoric acid solution the highly bioactive phosphate gel-like layer can be formed over compact titania which can significantly stimulate apatite formation. In the present work, we report that anodizing titanium in the same solution with the addition of fluorides leads to formation of titanium oxide nanotubes rich in both phosphates and fluorideswhich makes the method highly suitable for additional promoting of apatite deposition intotitania nanotubes.To study the effect of phosphates concentration, layers of titania nanotubes were produced in electrolytes of different phosphoric acid concentration. Their behavior as the future coatings on titanium for biomaterial applications was characterized by capacitance tests in simulated body fluids and by Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) observations. Judging on the results of XPS analysis, the competition between fluorides and phosphates is observed during anodizing, and the higher concentration of the latter is responsible for higher bioactivity of nanotubes formed in 2M H 3 PO 4 + 0.4% wt hydrofluoric acid (HF).

Preparation method of crystallized TiO2 nanotube array

Abstract: The invention discloses a preparation method of a crystallized TiO2 nanotube array. The specific steps are as follows: titanium pieces are placed into acetone to conduct ultrasonic cleaning for 30-40 minutes, after air-drying, the titanium pieces are placed into aqueous solution containing 25-28ml/L of concentrated sulfuric acid, 12-15ml/L of hydrofluoric acid and 50-65ml/L glacial acetic acid, conducting electrochemical polishing at 10-15v constant-current direct current under the room temperature for 8-20 minutes, then the polished titanium pieces are placed into ethylene glycol solution of ammonium fluoride with 0.05-1% of the bulking value concentration to conduct anodic oxidation, when conducting the anodic oxidation, the used negative pole is a platinum piece, the voltage is 60v and the reaction time is 8-12 hours, the obtained TiO2 nanotube array is placed into the water and insulation is conducted for 12-16 hours in a hydro-thermal reaction kettle with the temperature of 50 DEG C, and the crystallized TiO2 nanotube array is obtained. The preparation method has simple devices and low energy consumption, and is applicable to large-scale production; and simultaneously, the TiO2 nanotube array prepared by the method has a pure anatase phase.

Method for surface frosting of glass product

Abstract: Provided is a method for surface frosting of glass product, wherein a glass product is first immersed in a pre-treatment solution having a composition including water (H 2 O) 60-80 wt %, hydrofluoric acid (HF) 10-20 wt %, and nitric acid (HNO 3 ) 10-20 wt % for approximately 5 seconds to remove grease/oil and/or contamination from a surface of the glass product, then immersed in a frosting solution having a composition including nitric acid (HNO 3 ) 15-40 wt %, ammonium hydrofluoride (NH 4 HF 2 ) 30-60 wt %, hydrofluoric acid (HF) 0-10 wt %, water (H 2 O) 0-45 wt %, and hydrochloric acid (HCl) 0-1 wt % for approximately 1-5 minutes, and finally rinsed with water. As such, the surface of the glass product so treated forms a surface texture that provides smooth tactility of hand touch and shows an outer appearance of a scale like pattern formed on the surface of the glass product.

Method for preparing sample showing metallurgical structure of tantalum-tungsten alloy

Abstract: The invention discloses a method for preparing a sample showing a metallurgical structure of tantalum-tungsten alloy and belongs to the technical field of the preparation of metallographic samples. The method comprises the process steps of coarse grinding, washing, fine grinding, washing, polishing and etching, wherein in a formula of the cleaning liquid, a volume ratio of sulfuric acid to nitric acid to hydrofluoric acid to deionized water is 5:2:2:11; and in a formula of the etching liquid, a volume ratio of sulfuric acid to nitric acid to hydrofluoric acid to deionized water is 5:2:2:1. The method has simple process and easily prepares the metallurgical sample of the tantalum-tungsten alloy and obtains clear metallurgical photos of the tantalum-tungsten alloy.

Method for measuring contents of aluminum, calcium, barium, strontium, and phosphorus in silicon-calcium-barium alloy by ICP (inductively coupled plasma)

Abstract: The invention relates to the technical field of ferrous metallurgical analysis, in particular to a method for measuring contents of aluminum, calcium, barium, strontium, and phosphorus in silicon-calcium-barium alloy by ICP (inductively coupled plasma). The method comprises the following steps of: dissolving a sample with nitric acid and hydrofluoric acid, fuming with sulfuric acid, diluting to a certain volume, and introducing an atomized solution into an inductive coupling plasma atomic emission spectrometer to measure the intensity of a spectral line to be measured; and solving the concentration of elements corresponding to substances to be measured based on the measured spectral line intensity of known concentration standard substances. The method has the advantages of no pollution and capability of analyzing and determining the content of the calcium, the barium, the aluminum, the phosphorus and the strontium in the silicon-calcium-barium alloy and meanwhile, separating the barium and the strontium which can not be separated by a chemical analytical method.

Preparation method of anatase single crystal TiO2 with large active surface

Abstract: A preparation method of anatase single crystal TiO2 with a large active surface is characterized by dissolving titanium powder in the mixed solution of hydrofluoric acid and hydrogen peroxide to conduct hydrothermal reaction at the temperature of 150-200 DEG C. After the reaction, the reaction product is washed until the pH value thereof reaches about 7 and is finally dried in a drying oven.

Potassium fluotitanate preparation technology and preparation device thereof

Abstract: The invention discloses a potassium fluotitanate preparation technology and a preparation device thereof. The preparation technology comprises the steps of: A, adding ilmenite powder into a reactor, and adding purified hydrofluoric acid and a peroxide solution for full infiltration to prepare fluotitanic acid; B, adding the potassium chloride solution after the fluotitanic acid is cooled so as to generate potassium fluotitanate precipitation; and C, adding the potassium carbonate solution into a novel reaction system consisting of filtrates, removing the Fe element by forming Fe(OH)3 flocks, and recovering the potassium chloride and potassium fluoride solutions. In the reaction system of the invention, Fe2 + in the ilmenite powder are all oxidized into Fe3 + by adding an appropriate amount of peroxide, and then an appropriate amount of K2CO3 solution is added to remove and recycle the Fe3+ in the mode of Fe (OH) 3 precipitate; and an reaction device is reasonably improved so as to fully condense and recycle the hydrofluoric acid in the reaction system, and the whole reaction system can basically realize 'zero emission' of pollutants.

Method for preparing dense fluoride ceramic films on magnesium surface and magnesium alloy surface

Abstract: The invention relates to a method for preparing dense fluoride ceramic films on a magnesium surface and a magnesium alloy surface and belongs to the technical field of metal surface treatment The method comprises the following steps of: chemically passivating a magnesium alloy; preparing a single-pulse ceramic film; and preparing a double-pulse ceramic film In a chemically passivating process, solution such as hydrofluoric acid, phosphoric acid, hydrogen fluoride amine and the like are used; the preparations of the single-pulse ceramic film and the double-pulse ceramic film are mainly performed in a fluoride electrolyte-containing system, wherein potassium fluoride (sodium) is taken as a main salt; phosphate is taken as an additive; and citrate or tartrate is taken as a main stabilizing agent The fluoride ceramic film obtained by the method is complete and dense, has high hardness, is firmly combined with a substrate, can be separately used as a protective layer and can be prepared into a composite surface functional layer which has higher corrosion resistance, higher wearing resistance and high hardness after subsequent processing treatment The overall process of the method has the advantages of simple flow, low equipment cost, environment friendliness and the like

Influence of laser microfabrication on silicon electrochemical behavior in HF solution

Abstract: Influence of direct laser writing with femtosecond pulses on electrochemical etching of n-type low conductivity (>1,000 Ωcm) silicon is demonstrated. It has been shown that thermal 1-µm-thick SiO2 layer on silicon surface can be used as a protective layer in the electrochemical etching process. It has been found that laser ablation changes not only the surface morphology and structure of silicon samples but also the character of their anodic etching in aqueous solution of hydrofluoric acid. Formation of microvoids and caverns of irregular shape has been observed at the laser-ablated sites. It is proposed that the change of silicon conductivity from n- to p-type takes place at the laser fabricated regions. Processes of Si anodic oxidation and electrochemical etching are discussed.

Method for preparing hydrogen fluoride from flousper powder and sulfuric acid

Abstract: The invention discloses a method for preparing hydrogen fluoride from flousper powder and sulfuric acid. The method comprises the following specific steps of: adding solution of sulfuric acid and the flousper powder into a reactor with a stirrer respectively, wherein the molar ratio of calcium fluoride to the sulfuric acid is 1:3-1:30, the granularity of the flousper powder is 280 to 1,220 meshes, and the reaction temperature is controlled to between 90 and 300 DEG C; generating hydrogen fluoride gas and calcium sulfate solid after the reaction; purifying, condensing and rectifying the hydrogen fluoride gas to obtain anhydrous hydrogen fluoride, or purifying and absorbing the hydrogen fluoride gas to obtain hydrofluoric acid; transferring the calcium sulfate solid and the sulfuric acid toa filtering system from the reactor to perform solid-liquid separation; returning the separated solution of sulfuric acid to the reactor; and washing and drying the calcium sulfate solid separated from the sulfuric acid to form a by-product. The method has the advantages of simple equipment, high reaction efficiency, low cost and easy industrialized production.

Method for preparing silicon tetrafluoride from quartz sand

Abstract: The invention discloses a method for preparing silicon tetrafluoride by quartz sand, which comprises the following steps: taking 1000-1100 parts by weight of sulfuric acid with the concentration of 96-98% by mass percent and 560-575 parts by weight of hydrofluoric acid with the concentration of 50-52% by mass percent to be premixed together and absorbed, after the premixing and the absorption, obtaining the hydrofluoric acid with the concentration of 11-24% and the sulfuric acid with the concentration of 80-85%, and then obtaining a mixture A; taking 200-220 parts by weight and 150-200 meshes of silica powder and 500-550 parts by weight of the sulfuric acid with the concentration of 80-85% in mass percent to be premixed together, and obtaining a mixture B; adding the mixture A and the mixture B orderly into a reactor, stirring to react, and after 10-120 min of reaction with the reaction temperature of 60-80 DEG C, obtaining silicon tetrafluoride gas; and guiding the silicon tetrafluoride gas into a cooler by a honeycomb duct to be cooled and then enter a gasholder through a pipeline. The invention not only overcomes the high cost problem, but also achieves the reuse of reaction exhaust liquor and sizing agent, has no influence on environmental protection, and greatly reduces the energy consumption.

Method for measuring content of Al, Ti and Ca in low-carbon silicon iron

Abstract: The invention relates to a method for measuring the content of Al, Ti and Ca in low-carbon silicon iron, which comprises the following steps: dissolving a sample through a nitric acid and a hydrofluoric acid, after fuming the sample through a perchloric acid, adding a proper amount of hydrochloric acid, and heating to dissolve a salt; diluting to a certain volume with water; introducing atomization solution into an inductively coupled plasma atomic emission spectrometer; measuring the intensity of a spectral line to be tested; and calculating the concentration of a corresponding element of the substance to be tested according to the intensity of the spectral line which is measured by the standard substance at known concentration. The method has the advantages of capacity of quickly and accurately analyzing the content of Al, Ti and Ca in the low-carbon silicon iron and no pollution.

Wet-chemical systems and methods for producing black silicon substrates

Abstract: A wet-chemical method of producing a black silicon substrate. The method comprising soaking single crystalline silicon wafers in a predetermined volume of a diluted inorganic compound solution. The substrate is combined with an etchant solution that forms a uniform noble metal nanoparticle induced Black Etch of the silicon wafer, resulting in a nanoparticle that is kinetically stabilized. The method comprising combining with an etchant solution having equal volumes acetonitrile/acetic acid : hydrofluoric acid : hydrogen peroxide.

The FTIR studies on the structural and electrical properties of SnO2:F films as a function of hydrofluoric acid concentration

Abstract: The fluorine doped tin oxide films were prepared using hydrofluoric acid as the fluorine precursor. The effect of hydrofluoric acid concentration on the film orientation, morphology and electrical parameters were discussed. The FTIR indicates that the fluorine ions prefer to substitute the oxygen ions in the group of O-Sn-O. While beyond a certain doping level, fluorine ions start to occupy interstitial sites, which has a negative effect on carrier concentration. The FTIR also shows the increase of the disorder of SnO2 films with increasing fluorine doping. The main scattering centers of carriers are the impurity ions