Formation of porous anodic films on Ti–Si alloys in hot phosphate-glycerol electrolyte

Abstract

Porous anodic films, with pore size of ~10 nm, have been developed by anodizing of magnetron sputtered Ti-25 at% Si alloy at constant formation voltages in glycerol electrolyte containing dibasic potassium phosphate at 433 K. The films, of amorphous structure, contain titanium and silicon species, as units of TiO 2 and SiO 2 , throughout the film thicknesses, with negligible amounts of phosphorus species. The silicon is enriched in the film relative to the composition of the alloy, the level of enrichment suggesting that anion migration is increased in comparison with amorphous film growth at ambient temperature. In contrast to the behaviour of the alloy, essentially barrier films were formed on commercially pure titanium in the glycerol electrolyte, when a main anodic reaction was generation of oxygen, which was probably promoted by the development of anatase.

Formation of porous anodic titanium oxide films in hot phosphate/glycerol electrolyte

“…The formation of crystalline oxide induces gas generation during anodizing [22][23][24], such that the efficiency of film growth is reduced.…”

“…The anodic film formed on titanium in such an electrolyte was relatively thin (only ~300 nm) [20], and the efficiency for film formation was low due to gas evolution [22]. The gas evolution is associated with the development of crystalline oxide in growing anodic titanium oxide [23,24].…”

Growth of porous anodic alumina films in hot phosphate–glycerol electrolyte

“…Keywords: porous anodic alumina, organic electrolyte, growth mechanism, TEM, GDOES [19][20][21]. In the present study, the growth of porous anodic alumina films has been investigated in K 2 HPO 4 -glycerol electrolyte at 433 K using field emission gun scanning electron microscopy (FEG-SEM), 5 transmission electron microscopy (TEM) and glow discharge optical emission spectroscopy (GDOES).…”

“…Recently, it has been found that porous anodic oxide films are formed in phosphate-glycerol electrolyte at an elevated temperature of 433 K. In this electrolyte, porous films may be developed on a range of valve metals, including aluminium [17], niobium [18], tantalum [17] and titanium [19][20][21]. In the present study, the growth of porous anodic alumina films has been investigated in K 2 HPO 4 -glycerol electrolyte at 433 K using field emission gun scanning electron microscopy (FEG-SEM), 5 transmission electron microscopy (TEM) and glow discharge optical emission spectroscopy (GDOES).…”

“…Using a niobium oxide outer layer to suppress chemical dissolution resulted in films that were about 1.2 times the thickness of the consumed aluminium for an electrolyte containing 0.25 mass% water. The expansion suggests possible contribution of field-assisted flow of film material in growth of the porous anodic film.Keywords: porous anodic alumina, organic electrolyte, growth mechanism, TEM, GDOES [19][20][21]. In the present study, the growth of porous anodic alumina films has been investigated in K 2 HPO 4 -glycerol electrolyte at 433 K using field emission gun scanning electron microscopy (FEG-SEM), 5 transmission electron microscopy (TEM) and glow discharge optical emission spectroscopy (GDOES).…”