Acid etch operators

Hypothetical Qualitative Assessment—Acid Etch Operators... 

Most of these reservoirs have natural permeabilities below 10 mD, and the stimulation of their production is achieved through acid fracturing operations. Viscosified hydrochloric acid is pumped into wells at pressures larger than formation parting pressure. Irregular etching of the fracture walls by the acid is expected to create highly... 

Other rinsewater reuse opportunities are also available. Acid cleaning rinsewater effluent can be used as rinsewater for workpieces that have gone through a mild acid etch process. Effluent from a critical or final rinse operation, which is usually less contaminated than other rinse waters, can be used as influent for rinse operations that do not require high rinse efficiencies. Another option is using the same rinse tank to rinse parts after both acidic and alkaline baths. 

The waste acid used for the tests with Zr was the effluent from etching operations. The acid concentrations averaged 22 g/L HF and 400 g/L HNO3 with the Zr concentration averaging 45 g/L. Minor metal impurities in solution included Al, Be, Cr, Cu, Fe,... 

Bonding of aluminum comprises greater than 90% of the end uses for epoxy film adhesives. At least three major cleaning methods have been used chromic acid etch, phosphoric acid anodize and sulfuric acid anodize. Each process produces a different microstructure and chemical surface to which to bond. A corrosion-resistant epoxy primer is often used to protect the delicately etched surface during assembly operations. The adhesive must then bond to the primer and provide the myriad of intricate test strengths required by each aircraft producer, each aircraft, and each design. The tedious nature of optimizing each adhesive to meet each detailed specification becomes apparent and will not be further pursued in this discussion. 

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). 

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