Etching action

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. 

Steel, unless adequately protected with a film of oil subsequent to rolling mill operations, has a tendency to form surface rust rather quickly. This rust on the surface of the metal prevents proper conversion coating. A traditional method of removing rust is an acid applied by power spray equipment. The spraying action cleans both by physical impingement and the etching action of the acid. The power spray action is followed by a brush scrub, which further removes soil loosened by the acid. The brush scrub is followed by a strong alkaline spray wash, which removes all traces of the acid and neutralizes the surface.1-5... 

Tetra-Etch and Fluoro-Etch, Action Technologies, Inc., Pittston, PA. 

Because the wax resisted the etching action of the acid, materials behaving as such within the field of lithography have since then been called resists. 

In plasma etchers, specific radicals are selected from the mix of the species generated within the chamber to effect the etching action. For the specific case of species generated from CF4 gas within a plasma chamber, for example, the fluorine radical (F) is selected by means of an appropriately configured perforated aluminum shield or other contraption that blocks the other species from reaching the wafer. In this way, etching of the wafer proceeds only by the reaction of the fluorine radical. Substrates such as silicon, silicon dioxide, and silicon nitride are readily etched by this technique. ... 

Chemical/mechanical polishing (CMP) may also be used. In this case an abrasive is used together with a chemical (usually either an acid or a caustic solution) that will produce an etching action. CMP is actually very complex and still not fully understood. Final CMP may involve an abrasive that is softer than the materials being polished. 

Pure glycerin has a limited smooth etching action on zinc and is quite satisfactory as hydraulic fluid in door stops. Similarly, glycerin-alcohol mixtures are practically inert to zinc, provided the mixture is pure and free of water. Water or low grade glycerin may cause some pitting. 

A problem common to etching printed boards is not having the entire area etch clean at the same time. This occurs when etch action is more rapid at the edges of printed areas than in a broad expanse of copper. If very fine patterns and lines are required, the result can be loss of the pattern due to undercutting, especially when the board is left in the etcher until all the field copper has etched away. Modern etchers with reduced pooling of etchant have reduced this problem. 

CALCIUM HYDROXIDE. CaCOH) . In laboratory tests, calcium hydroxide solutions have rapid etching action on aluminum alloys which quickly subsides as the result of the formation of protective Films on the aluminum surface. See also Ref (1) p. 128. (2) p. 133, (3) p. 72. (4) p. 47. 

TRICHLORETHYLENE - CARBON TETRACHLORIDE In short periods of exposure necessary for degreasing prior to electropiating, neither trichiorethylene nor carbon tetrachioride will have any visible effect on zinc alloy die castings. Dry carbon tetrachloride has no visible effect on continued exposure of much longer duration. Dry trichiorethylene over a period of four months shows a very slight etching action. 

Physical etching uses beams of ions, electrons, or photons to bombard on the material surface. The ions are accelerated in an electric field and bombarded on the surface of a target. The ions knock out the atoms from the substrate surface due to the high kinetic energy, that is, the etching action takes place due to the physical action of the incident ion flux. 

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