Titanium-palladium alloy

Ruthenium alloyed to platinum, palladium, titanium and molybdenum have many apphcations. It is an effective hardening element for platinum and palladium. Such alloys have high resistance to corrosion and oxidation and are used to make electrical contacts for resistance to severe wear. Ruthenium-palladium alloys are used in jewelry, decorations, and dental work. Addition of 0.1% ruthenium markedly improves corrosion resistance of titanium. Ruthenium alloys make tips for fountain pen nibs, instrument pivots, and electrical goods. Ruthenium catalysts are used in selective hydrogenation of carbonyl groups to convert aldehydes and ketones to alcohols. 

Alloying to modify the overpotential of the metal surface for H2 evolution or O2 absorption can help control corrosion, although it is not always obvious whether these cathodic processes should be suppressed (i0 lowered) or stimulated to produce the desired corrosion resistance. In the case of titanium (see Section 16.6), for example, palladium was alloyed in to catalyze H2 evolution and to force the metal into a passive condition. 

Cocco et al. [54] discuss the preparation of metallic glass, while copper-titanium, aluminum-titanium, and palladium-titanium systems in particular are prepared under a controlled atmosphere with hydrogen and argon. Components of Nb-Ni and Nb-Y have also been described [55]. Amorphous Ni-Ti alloys have been prepared by Schwarz et al. [56], while Ni-Ga, Ni-Ge, Ni-In, and Ni-Sn has been synthesized in supersaturated solid solutions [57]. Fe, Co, Ni-Ta-alloys are described by Lee and Yang [58], while FeSi2 doped with Co or Al for thermoelectric material is also mentioned [59]. 

R.E. Buxbaum, R. Subramanian, J.H. Park, and D L. Smith, Hydrogen Transport and Embrittlement for Palladium Coated Vanadium-Chromium-Titanium Alloys, Journal of Nuclear Material, Part A, 233-237, 1996, pp.510-512. 

The methods described in detail in Section 36.2, or only mentioned, have been used as follows for spectrophotometric determination of palladium the thio-Michler s ketone — in silver, copper, and anodic slime [32], in catalysts [31] with thiosemicarbazide derivatives — in water [44] and alloys [46] with palladium-carbon powder — with a-benzilmonoxime [48] with PAR — in catalysts and ores [58] with thiazolylazo derivatives — in Ni-Al catalysts [63] with 5-Br-PADAP — in titanium alloys with pyridylazo derivatives - in nickel alloys [68] with sulphonitrophenol - in silver alloys [70] with Arsenazo III — in iron and meteorites and with Palladiazo — in catalysts, minerals, silica gel, and calcium carbonate [78]. 

Because of the high activity of palladium in electrocatalysis, palladium-based alloys, which contain one or more platinum-group metals along with titanium as well as boron and/or silicon, have been thoroughly investigated. 

Buxbaum, R. E, Subramanian, R, Park, J. H, Smith, D. L. Hydrogen transport and embrittlement for palladium coated vanadium-chromium-titanium alloys. J Nucl Mater. 1996 233-237 510-2. 

In the patent by Hill, an aUoy of titanium containing 13 wt%vanadium, 11 wt% chromium and 3 wt% aluminum was developed as a hydrogen transport membrane material [12]. In this alloy, the crystal structure of titanium, which is normally hexagonal below 1153 K (880 °C), is stabilized in its high-temperature body centered cubic allotropic form. The body centered cubic crystal lattice is preferred for hydrogen transport. This titanium alloy was found to have hydrogen permeability superior to that of pure palladium in the range 300-450 °C (573-723 K)... 

The trap theory is supported by experimental results for iron-titanium alloys in which the density of reversible and irreversible traps was varied [67]. Increasing the density of reversible traps, for example, was found to decrease the susceptibility to intergranular cracking, as described above. Reversible traps in the form of PdAl precipitates likewise appear to play an important role in suppressing intergranular cracking of a palladium-modified... 

Filler Metals. Braze filler metals initially used for brazing titanium and its alloys were silver with additions of lithium, copper, aluminum, or tin. Most of these brazed filler metals were used in low-temperature applications (540 to 600 °C, or 1000 to 1100 °F). Commercial braze filler metals (see Table 6), including silver-palladium, titanium-nickel, tita-nium-nickel-copper, and titanium-zirco-nium-beiyUium, are now available that can be used in the 870 to 925 °C (1600 and... 

The effect of oxygen on the strength decreases with rising temperature and nearly disappears at 400°C. Between the titanium alloys, the palladium alloy behaves in a similar way as the unalloyed metal, as far as the influence of oxygen on the physical properties is concerned. On the contrary, for the high tensile alloys of TiA16V4 type, the strength mainly results from the martensitic transformation which takes place (2). 

The corrosion behaviour of amorphous alloys has received particular attention since the extraordinarily high corrosion resistance of amorphous iron-chromium-metalloid alloys was reported. The majority of amorphous ferrous alloys contain large amounts of metalloids. The corrosion rate of amorphous iron-metalloid alloys decreases with the addition of most second metallic elements such as titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, copper, ruthenium, rhodium, palladium, iridium and platinum . The addition of chromium is particularly effective. For instance amorphous Fe-8Cr-13P-7C alloy passivates spontaneously even in 2 N HCl at ambient temperature ". (The number denoting the concentration of an alloy element in the amorphous alloy formulae is the atomic percent unless otherwise stated.)... 

The addition of beryllium and silicon to nickel-palladium alloys gives very good high-temperature brazes, especially for alloys containing aluminium and titanium. 

The method is more useful with titanium, and the effect of alloying titanium with a small amount of palladium is described in Section 5.4. The use of platinum in the prevention of hydrogen embrittlement in tantalum. 

The addition of a more passive metal to a less passive metal normally increases the ease of passivation and lowers the Flade potential, as in the alloying of iron and chromium in 10 wt. % sulphuric acid (Table 10.31) . Tramp copper levels in carbon steels have been found to reduce the corrosion in sulphuric acid. Similarly 0 -1 palladium in titanium was beneficial in pro-... 

Alloying with palladium (0.15 per cent) significantly improves the corrosion resistance, particularly to HC1. Titanium is being increasingly used for heat exchangers, for both shell and tube, and plate exchangers replacing cupro-nickel for use with sea water. 

The fuels are finely powdered metals (2.0-10.0 g) among which titanium, zirconium, manganese, tungsten, molybdenum and antimony are very common. Sometimes, non-metal powders such as boron and silicon (for fast burning delays), binary alloy powders such as ferrosilicon, zirconium-nickel, aluminum-palladium and metal compounds such as antimony sulfide, calcium silicide etc. are also used. 

Figure 16.11 Passive titanium-0.2% palladium alloy in aqueous acid. Here, io refers to catalyzed H2 evolution.

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