The Rate and Mechanism of Dissolution of Purest Aluminum in Hydrofluoric Acid

Abstract

Pure aluminum (99.99%) dissolves in hydrofluoric acid with a rate comparable to that of titanium in the same acid. The rate of dissolution, V (mm3/cm 2 min of hydrogen), in 0.1-6N hydrofluoric acid is in agreement with the empirical equation V = 28 + 275N, and for 6-1ON with V = 20.44N ~.~. Recrystallized Muminum showed the same rates within the error limits (• Of the noble metal salts added to the acid, only nickel and gold increased the dissolution rate; deposits obtained from other salt solutions did not adhere to the surface of the dissolving aluminum. Ammonium fluoride and ammonium chloride additions to the acid decreased the dissolution rate (passivation) because a salt film was formed on the aluminum surface. The potential of aluminum in 2N hydrofluoric acid was -1.22 v, indicating that the extent or thickness of protective surface films was negligible. The dissolution rate of aluminum in sulfuric acid, phosphoric acid, and other acids can be increased considerably by addition of water-soluble fluorides. The behavior of aluminum in hydrofluoric acid, as well as in hydrochloric acid, could be explained qualitatively using the concept of local currents in a manner similar to that proposed earlier.

Effect of Chemical Surface Texturing on the Superhydrophobic Behavior of Micro–Nano-Roughened AA6082 Surfaces

“…Meanwhile, the impurities in the neighborhood of these defects could also magnify the chemical etching reaction. The dissolution phenomena in the aluminum induced by hydrofluoric acid starts after a relatively high immersion time (30–50 min) [ 77 ]. According to Straumanis et al [ 77 ], the addition of a small quantity of hydrofluoric acid to other acids allows the electrochemical dissolution of the alloy to be promoted.…”

“…The dissolution phenomena in the aluminum induced by hydrofluoric acid starts after a relatively high immersion time (30–50 min) [ 77 ]. According to Straumanis et al [ 77 ], the addition of a small quantity of hydrofluoric acid to other acids allows the electrochemical dissolution of the alloy to be promoted. In addition, HF acid reacts with Si-rich precipitates, favoring a selective dissolution in its neighboring area, thus influencing the large corrosion phenomena induced by a HCl acid solution.…”

“…Meanwhile, the impurities in the neighborhood of these defects could also magnify the chemical etching reaction. The dissolution phenomena in the aluminum induced by hydrofluoric acid starts after a relatively high immersion time (30-50 min) [77].…”

“…According to Straumanis et al [77], the addition of a small quantity of hydrofluoric acid to other acids allows the electrochemical dissolution of the alloy to be promoted.…”

Quantification and micron‐scale imaging of spatial distribution of trace beryllium in shrapnel fragments and metallurgic samples with correlative fluorescence detection method and secondary ion mass spectrometry (SIMS)

“…The same happened as we gradually increased the concentration of ABF to 10%. It has been reported that although aluminum reacts with and is extracted in hydrofluoric acid (HF), however, addition of ammonium salts result in formation of a surface coating which resist further action by the acid (Straumanis & Wang, ). Since binding of beryllium is sensitive to pH and reaches a maximum at above pH12, we decided to use dilute hydrofluoric acid to break down the aluminum matrix and solubilize the constituents.…”