Etching acidic

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. 

Figure 7.7 Svirface striations and shallow grooves on a carbon steel case coupling. Acid etched the metal along microstructural irregularities producing the grooves. Compare to Fig. 7.8. (Magnification 7.5x.)...

While polymeric surfaces with relatively high surface energies (e.g. polyimides, ABS, polycarbonate, polyamides) can be adhered to readily without surface treatment, low surface energy polymers such as olefins, silicones, and fluoropolymers require surface treatments to increase the surface energy. Various oxidation techniques (such as flame, corona, plasma treatment, or chromic acid etching) allow strong bonds to be obtained to such polymers. 

Processing details for the optimized FPL etching procedure, other chromic-sulfuric acid etches and the P2 etch are summarized in Table 1 [2,62J. 

Fig. 28. Pho.sphoric acid etched A606 steel surfaces showing normal heavy smut formation [54].

Fig. 29. Phosphoric acid etched A606. steel surface showing smut-free, smooth-walled crevice morphology [54].

Fig. 30. Phosphoric acid etched A.314 steel surface showing extensive etching along martensite boundaries. This alloy contains the same constituents as A606, but has been given a different heat treatment 54. ...

Surface treatment of the composite can have a significant effect on adhesion. Surface treatment enhances one or more of the mechanisms described previously. Wu et al. [15] studied the effects of surface treatment on adhesive bonding for AS-4/APC-2 laminates. They found that the greatest bond strength was achieved from acid etching and plasma etching the composite surface. Table 1 summarizes the various surface treatments that were evaluated. 

Chromic-sulfuric acid etch Coupling agent 30.27 21.29 0.708 0.105 0.091 0.108... 

Surface preparation of the core foil was originally simple acid etching. As the importance of durable surface treatments became known, a more stable chemical conversion coating with an organic primer-like coating became standard. Still, water ingression into honeycomb structure continued to cause the occasional... 

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