Pre-treatment of titanium

Elliot JC (1994) Structure and chemistry of the apatites and other calcitrm orthophosphates. Stndies in Inorganic Chemistry 18. Elsevier Science, Amsterdam Elllingsen JE (1995) Pre-treatment of titanium implants with fluoride improves their retention in bone. J Mater Sci Mater in Med 6 749-753... 

Anodic treatment may also be considered when bonding other metals. Examples inclnde the anodizing of magnesium in ammonium bifluoride solution, the anodic etching of stainless steel in nitric acid and anodizing of titanium in sodium hydroxide or chromic acid (see Pre-treatment of titanium). Alternative anodizing of copper can prodnce a Microflbrous surface (see Pre-treatment of copper). 

Pre-treatment of titanium G W CRITCHLOW Survey of important types of pre-treatment and comparisons of bond durability... 

Coating life in moist atmospheres is also influenced by the effects of moisture on the substrate-coating interface, and marked improvements in life have been claimed by the use of moisture-protective pre-treatments of the substrate. Niederhauser et al ° studied a wide range of metals and titanium nitride, titanium carbide and chromium carbide as pre-treatments. The material was sputter-deposited on a steel substrate, and then sulphided by introducing hydrogen sulphide into the sputtering chamber in order to improve molybdenum disulphide adhesion. They found a marked improvement in life, particularly with a rhodium or palladium interlayer, but the actual degree of improvement is confused because they also used co-sputtered PTFE, and this is discussed further in Section 10.6. 

Sierka RA and Bryant CW. Enhancement of biotreatment effluent quaUty by illuminated titanium dioxide and membrane pre-treatment of the kraft extraction waste stream and by increased chlorine dioxide substitution. Wat. Set Tech. 1994 29(5-6) 209-218. 

Susceptibility to aqueous cracking occurs to different degrees. Some alloys will break in moist air in the pre-cracked conditions, others require immersion in distilled water, while others require immersion in water containing appreciable amounts of dissolved halide. Different heat treatments may produce these different levels of susceptibility in one alloy. The Ti-8AI-1 Mo-1 V alloy, for example, will fail in laboratory air in the step-cooled condition, but requires immersion in distilled water in the mill-annealed condition and in 0.6 m KCl in the duplex annealed condition. Heat treatment of titanium alloys produces a variety of phase structures, morphology and composition, and the effects upon stress-corrosion susceptibility are complex. Generally, processes increasing the yield stress low A, c and A iscc> while... 

On the other hand, the provision of vast numbers of minute nuclei assists the phosphate coating reaction to start at a multitude of centres, resulting in a finely crystalline coating. This effect can be obtained chemically by a predip in a solution of sodium phosphate containing minutely dispersed traces of titanium or zirconium salts or in weak solution of oxalic acid. This type of pre-dip entirely eliminates any coarsening effect due to previous treatment in strong alkalis or acids. 

Many paints require vigorous pre-treatment before the matrix can be destroyed. Even after considerable oxidation it may be necessary to filter off titanium dioxide. Some paints are, however, more amenable to acid dissolution. Eider [147] reported that it was possible to determine barium, cadmium, calcium, cobalt, lead, magnesium, manganese, mercury, tin, zinc and zirconium in vinyl additives and paint (1 g) by dissolution in hot concentrated nitric acid (10 ml). The mixture was filtered and made up to 100 ml. Liquid samples were again dissolved in MIBK (lg in 100 ml). Air/ acetylene and nitrous oxide/acetylene flames were used to complete the analysis as appropriate. Porter [148] reported losses of lead during the dry ashing of alkyd and latex paints and therefore recommended dissolution in either nitric/perchloric acids or nitric acid alone. 

Industrial grades of pure titanium have relatively low tensile strength in comparison to alpha-beta stabilized alloys such as Ti6A14V. Therefore, the majority of industrial uses for titanium incorporate the alpha-beta alloys and as such these are the focus of most adhesion studies.As with other metals, there is a large range of pre-treatments available for titanium and its alloys, as indicated in Table 1. 

Table 1. Summary of the main pre-treatment processes for titanium...

In many industrial applications, for example, in Aerospace applications and defence sectors, the titanium alloy could be exposed to hot-wet or hot-dry environments, and consequently, studies have focussed on identification of the best performing pre-treatment for particular environmental conditions and stress states. 

The a — 0 transformation has a large hysteresis in hydrogenated titanium alloys, and different thermal treatments change their phase content. Various degrees of metastability due to hysteresis are implicit for the alloys after different thermal treatments. Metastable phases undergo transformation to a more equilibrium state during deformation, which can effect the flow of the alloy. Below we consider the effect of the thermal pre-strain treatment on ductility on the strength of the Ti-6A1-2Zr-1.5V-lMo-rH alloys. ... 

Photo-initiated AOPs are subdivided into VUV and UV oxidation that are operated in a homogeneous phase, and in photocatalysis (Fig. 5-15). The latter can be conducted in a homogeneous aqueous phase (photo-enhanced Fenton reaction) or in a heterogeneous aqueous or gaseous phase (titanium dioxide and certain other metal oxide catalysts). These techniques apply UV-A lamps or solar UV/VIS radiation and they are in pre-pilot or pilot status. According to Mukhetjee and Ray (1999) the development of a viable and practical reactor system for water treatment with heterogeneous photocatalysis on industrial scales has not yet been successfully achieved. This is mainly related to difficulties with the efficient distribution of electromagnetic radiation (UV/VIS) to the phase of the nominal catalyst. 

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