Aluminum Etching Bath

Aluminum etching takes place in the NaOH bath. Dissolution rate of aluminum during NaOH etch can be determined [5]. From the AFM scans, surfaces of the aluminum are roughened slightly during the 15 s bath time. 

Hot water seal is a heated water bath (heated to approximately 180°F) used to seal the surface coating on formed aluminum that has been anodized and coated. In establishing an effluent allowance for this operation, the hot water seal shall be classified as a cleaning or etching rinse. 

All waveforms were collected using a custom-built, asymmetric, capacitively coupled (13.56MHz), reactive-ion etching apparatus. A circulating bath maintains the aluminum powered electrode temper cure at 24.0 0.5°C. The apparatus is equipped with a He-Ne laser, A-632.8nm) interferometer as depicted in Figure 4. The laser beam was aimed at the substrate surface at an angle of 10° off the normal. Laser intensity was measured by a photodiode whose... 

The anodizing process consists of 1) trim forming, 2) cleaning, 3) anodic electrolysis usually in sulfuric acid and, 4) sealing in an aqueous bath. Each of these steps are important, for example, the anodized oxide layer must be controlled to provide an optimum thickness. Sealing the anodized layer is also very important and must be complete. Corrosion problems associated with anodized aluminum trim include etching of the oxide film (known as "blush and bloom ) and pitting of the aluminum. 

I. Aluminum turnings (27 parts) are covered in a round-bottom flask with 276 parts of anhydrous ethanol. Then HgClg (0.2 part) and a trace of iodine are added to start the reaction. The evolution of hydrogen usually begins after a few seconds. If it fails to occur, the flask may be carefully heated on a water bath. If necessary, the aluminum should be slightly etched with dilute NaOH before use and then rinsed with alcohol. 

For tensile shear tests, aluminum alloy LY-12-CZ and cold rolled steel pieces of 0.5mm x 20mm x 60mm were used. The aluminum was etched in a K2Cr20. -H2SO bath, and the... 

Fatigue tests were conducted at 100 Hz and a stress ratio 0.1. Aluminum alloy LY-12-CZ panels of 5mm x 30mm x 100mm etched in a K2Cr20 -H2SO bath were used for the... 

Two anodizing surface pretreatments imposed after the acid etching of aluminum have proved to be the best surface for obtaining longest-durability aluminum joints. The pretreatments are referred to based on the type of acid predominant in the respective anodizing baths,... 

Etching (chemical milling) Etching in a sodium hydroxide solution to prepare the aluminum for anodizing by chemically removing a thin layer of aluminum. This alkaline bath gives the aluminum surface a matte appearance. 

Figure 5.43 Sequential steps through which a part is submitted by being dipped in baths in order to clean, etch, anodize, and seal an aluminum part being anodized.

Fluorinated surfactants improve the efficient life of alkali baths used in etching of aluminum. In mild-steel etching, the effect of the fluorinated surfactant on the etching process depends on the structure of the surfactant. For example, Atsurf F-21 has given the best mist reduction and Atsurf F-35 the best surface. Fluorinated surfactants are also used for etching plastic preplates. 

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