Acid-etching

Etching Acid solutions Alkaline solutions Organic compounds Low or high pH Dissolved metals Complexed metals Waste chemicals... 

Acid resist for etching Acid, battery Anise oil... 

Complex surface processes during HC1 etching (acidic dissolution of oxides, electrochemical oxidation) lead to the formation of a porous, chloride-containing iron oxide layer while nickel remains in the zero-valent state. Subsequent reduction, facilitated also by hydrogen atoms formed on nickel sites, results in an increased number of surface iron and nickel atoms and an enhanced catalytic activity. The larger concentration of atomic hydrogen on the surface and the presence of surface Ni are observations that are supported by the decreased selectivity of olefin formation. 

Etching acid usually refers to a solution of hydrofluoric acid which will attack any silicon-containing substrate like glass. 

Etching Acid and wire brushing, normally for local treatment, e.g. welds... 

Descaling of hot worked stainless steels can be accomplished by mechanical or by chemical cleaning, or by a combination of both methods. The surface can be cleaned by sand blasting, but unless it is machined after blasting, only nonmetallic blast material should be used in order to avoid contamination and a reduction of the corrosion resistance. Following blast cleaning stainless steels are usually acid pickled and washed with water. Common etching acids are ... 

Anticorrosion paints Etching acids Detergents Paint removers Solvents Tropical woods... 

Acid etching Acid cleaning is nsed to remove oxide including basic Mg and Zn oxides, Al-oxide and silicate left by the alkaUne cleaning as well as removal of intermetallic particles in the smface. 

Flourinated surfactants aie used as wetting agents in etch baths because of their low surface tension and stability in strong acids. Glass articles are polished and etched with solutions containing sulfuric acid, HF, and a fluorinated surfactant (e.g., tetraethylammonium perfluorooctanesulfonate or potassium perfluorooc-tanesulfonate). Fluorinated surfactants increase the speed of etching, acid polish-... 

By its nature etching is a self-contaminating process. During etching acids react with thin film material exposed on the wafer and remove this film from the surface to create a pattern in the film as defined by the way that the photoresists were laid down. This process can generate particles, inorganic colloids and reaction residues. 

Aqueous hydrogen fluoride is a weak acid (see above) and dissolves silica and silicates to form hexafluorosilicic acid hence glass is etched by the acid, which must be kept in polythene bottles. 

Before use, the marble chips are washed repeatedly with hot water, and then de-aerated by first etching them with concentrated hydrochloric acid and then boiling them with air-free water under reduced pressure. The chips are then rapidly transferred to the generator small chips should be used and the bulb... 

Fluorine and its compounds are used in producing uranium (from the hexafluoride) and more than 100 commercial fluorochemicals, including many well known high-temperature plastics. Hydrofluoric acid etches the glass of light bulbs, etc. Fluorochlorohydrocarbons are extensively used in air conditioning and refrigeration. 

The names fluorine and fluorospar are derived from the Latin fluere meaning flow or flux. In 1529 the use of fluorspar as a flux was described. In 1670 the etching of glass by acid-treated fluorspar was reported. Elemental fluorine was isolated by Moissan ia 1886 (7). 

Analytical Methods. Fluorite is readily identified by its crystal shape, usually simple cubes or interpenetrating twins, by its prominent octahedral cleavage, its relative softness, and the production of hydrogen fluoride when treated with sulfuric acid, evidenced by etching of glass. The presence of fluorite in ore specimens, or when associated with other fluorine-containing minerals, may be deterrnined by x-ray diffraction. 

The newly formed y-Mn02 actually coats the surfaces of the particles of the soHd phase the MnSO dissolves in the Hquid phase, along with the majority of the ore impurities. The effective surface area is expanded by the etching action of the sulfuric acid. Following the acid treatment step, the slurry is filtered and the cake is carefiiUy washed and dried at a controlled temperature. 

Alkaline solutions consisting of approximately 160 g/L NaAlnO and 60 g/L NaOH at 75°C and contact times in the range of 15 minutes, exhibit high etch rates for printed circuit boards (252,253). The resulting manganese residues can readily be removed by acid neutrali2ation. Addition of K", Rb", and Cs" as co-ions to an alkaline NaAlnO solution maintains etch rates of resin substrates comparable to solutions of higher NaAlnO concentrations (254). 

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