Etching, hydrogenation

Materials used in this Study. The effect of spin casting on mechanical properties of polymers in the boundary regime to interactive interfaces was studied with the monodisperse homopolymer, polyethylene-copropylene (PEP) (Mw=374,000, Mw/Mnpolymer films, of varying thickness between 20-520 nm, were made by spin casting from toluene solution onto HF etched (hydrogen passivated) silicon wafer (42), The bulk radius of gyration Rg of the polymers was determined to be 24.3 nm. Film thicknesses were determined by ellipsometry (autoEl, Rudolph). The films were dried for approximately one week at room temperature under atmospheric pressure and intentionally left unarmealed prior to scanning. 

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. 

Veprek S and Sarott F A 1982 Electron-impact-induced anisotropic etching of silicon by hydrogen Plasma Chem. Plasma Proc. 2 233-46... 

Gillis H P, Choutov D A, Steiner P A IV, Piper J D, Crouch J H, Dove P M and Martin K P 1995 Low energy electron enhanced etching of Si(IOO) in hydrogen-helium DC plasma App/. Phys. Lett. 66 2475-7... 

Gillis H P, Choutov D A, Martin K P, Pearton S J and Abernathy C R 1996 Low energy electron enhanced etching of GaN/Si in hydrogen DC plasma J. Electrochem. Soc. 143 L251-4... 

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. 

HFin etching of pLUORINE COMPOUNDS, INORGANIC - HYDROGEN] (Vol 11)... 

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. 

Fig. 4. Examples of emission spectrometry as a diagnostic monitoring tool for plasma processing, (a) The removal of chlorine contamination from copper diode leads using a hydrogen—nitrogen plasma. Emissions are added together from several wavelengths, (b) The etching and eventual removal of a 50-p.m thick polyimide layer from an aluminum substrate, where (x ) and (° ) correspond to wavelengths (519.82 and 561.02 nm, respectively) for molecular CO2...

Etch Mechanisms. Most wet etches for the compound semiconductors employ oxidation of the semiconductor followed by dissolution of the oxide. For this reason, many wet etches contain the oxidant hydrogen peroxide, although nitric acid can also be used. One advantage of wet etching over dry is the absence of subsurface damage that is common with dry etching. Metal contacts placed on wet-etched surfaces exhibit more ideal characteristics than dry-etched surfaces. 

Boron carbide is resistant to most acids but is rapidly attacked by molten alkalies. It may be melted without decomposition in an atmosphere of carbon monoxide, but is slowly etched by hydrogen at 1200°C. It withstands metallic sodium fairly well at 500°C and steam at 300°C (8). 

Eor the cover-coat direct-on process, a ferric sulfate [10028-22-5] Ee2(S0 2> etch is included in the metal pretreatment for rapid metal removal. It is designed to remove ca 20 g/m (2 g/ft ) of iron from the sheet metal surface. Hydrogen peroxide [7722-84-1/, H2O2, is added intermittently to a 1% ferric sulfate solution to reoxidize ferrous sulfate [7720-78-7] EeSO, to ferric sulfate. 

Hydrogen fluoride Catalyst in some petroleum refining, etching glass, silicate extraction by-product in electrolytic production of aluminum Petroleum, primary metals, aluminum Strong irritant and corrosive action on all body tissue damage to citrus plants, effect on teeth and bones of cattle from eating plants... 

Hydrogen fluoride Glass Etching, becoming opaque... 

The atmospheric pollution prevailing in special industrial or laboratory locations may induce more severe corrosion, e.g. the vapours from concentrated hydrochloric or acetic acid will etch tin, and moist sulphur dioxide will produce a sulphide tarnish, as will hydrogen sulphide at temperatures above about 100°C. The halogens attack tin readily. The commonly used volatile corrosion inhibitors are without adverse action although the benefit derived from their use is doubtful. 

Containers of foodstuffs should not be unduly stained or etched and must not be perforated or allowed to become distended by pressure due to evolution of hydrogen, and the contents must not suffer unacceptable changes of colour or flavour. Long storage periods, e.g. two years, may be required. 

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