Hydrofluoric acid, etching

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. 

Fig. 22. XPS Si2p spectra (a) before and (b) after hydrofluoric acid etching.

For maximum resistance to heat and environment. ASTM D 2651 hydrochloric, orthophosphoric, hydrofluoric acid etch... 

D. J. Monk, D. S. Soane, and R. T. Howe, Hydrofluoric acid etching of silicon dioxide sacrificial... 

Kulkarni, A. Mukherjee, D. Mukherjee, D. Gill, W.N. Reprocessing hydrofluoric acid etching solutions by reverse osmosis. Chem. Eng. Com-mun. 1994, 129, 53-68. 

Waldron K, Lee MR, Parsons I (1994) The microstmctures of perthitic alkali feldspars revealed by hydrofluoric acid etching. Contrib Mineral Petrol 116 360-364 Walker FDL (1990) Ion microprobe study of intragrain micropermeability in alkali feldspars. Contrib Mineral Petrol 106 124-128... 

Acetic acid Ammonium bifluoride Ammonium fluoborate Fluoboric acid Nitric acid etchant, semiconductor prod. glass Hydrofluoric acid etching... 

Nitric-hydrofluoric acid etch Adequate Poor... 

Zhang X, Tu KN, Xie YH, Tung CH (2006) High aspeet ratio nickel structures fabrieated by eleetroehemieal replication of hydrofluoric acid etched silieon. Eleetroehem Solid State Lett 9(9) C150-C152... 

Material-specific etching recipes exist for a variety of ceramics based on oxides, nitrides, and carbides. Highly concentrated acids or molten salts are often used as etchants, although basic etchants are also used in some cases. Hydrofluoric acid etching is usually performed on aluminum oxide materials containing Si02. Etching... 

Figure10.13 Fabrication stepsofan MEMS-type methanol steam reformer by hydrofluoric acid etching [144].

The surface pretreatment for titanium is the well-known nitric hydrofluoric acid etching by a sodium bifluoric solution (see ASTM D2651 01). Some proprietary deviations from this basic treatment are taken by manufacturers. For example, hold release mechanism brackets in titanium alloy (Ti6Al4V) are used for mounting on antenna reflectors as parts of pyrotechnic mechanisms in order to deploy the reflectors in orbit before entering in operation (see Fig. 45.19). 

Tethered alkoxyamines were also obtained in situ following a two-step procedure. First, 3-(trimethoxysilyl)propyl methacrylate (TSPMA) was attached to the surface. Then, the methacrylate function was allowed to react, under heating, with AIBN in the presence of TEMPO to afford the corresponding alkoxyamines. From this alkoxyamine-coated silicon, PS and poly(2-hydroxyethyl methacrylate) (HEMA) were then successfully prepared [20]. The novelty of this report is that micropatteming of the silicon surface was controlled by a combination of SI-NMP and Sl-ATRP. The ATRP initiator was covalently immobilized via UV-induced hydrosilylation of 4-vinylbenzyl chloride (VBC) with the (hydrofluoric acid-etched) hydrogen-terminated silicon (Si-H) microdomains to produce a micropattemed and Si-C bonded VBC monolayer. 

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