Platinum-tantalum alloys

Platinum alloys containing from 0 5 to 20 per cent, of tantalum are hard, withstand heat, as well as the action of adds and fused potassium hydrogen sulphate, and are more resistant to the action of aqua-regia than platinum.8 They possess the mechanical properties off platinum-iridium alloys and are less expensive the relative quantities, of tantalum and iridium required to produce the same hardness and mechanical resistance are stated to be 1 5. Platinum-tantalum alloys, hence have been recommended for various purposes in place of platinum or platinum-iridium. Tantalum can also be coated with platinum, andl can then be utilised in high-temperature work. ... 

Cesium does not alloy with or attack cobalt, iron, molybdenum, nickel, platinum, tantalum, or tungsten at temperatures up to 650°C (35). 

Gold can be used only in very small portions or very thin coatings because of its cost. Most of the applications for wliich it was used in the past have now been accomplished with tantalum at a much lower cost. A gold/ platinum/rhodium alloy is used in the manufacture of rayon-spinning jets in the production of rayon fibers. This alloy presents the combination of strength, corrosion resistance and abrasion resistance necessary to prevent changes in hole dimensions. 

The right-hand electrode consisted of a tantalum foil (attached to a Pt wire) coated with a platinum-iridium alloy. This alloy, containing 45% iridium, is used as a CI2 electrode because Pt is not fully appropriate since it is subject to corrosive attack by CI2 in the presence of HCl. Their results for the cell i are as follows 25°C eeiKO = 1.13596 V 30°C = 1.13309 V 40 C ... 

The aged solution is forced by a pump through a spinning jet or spinneret. This consists of a cap made of a chemically inert metal, such as tantalum or platinum or platinum-rhodium alloy, which contains a number of small holes usually between 0 05 and O-l mm in diameter (see Fig. 6.1). The spinning mixture is extruded through these holes into a medium which causes it to solidify or coagulate. 

Nitric acid reacts with all metals except gold, iridium, platinum, rhodium, tantalum, titanium, and certain alloys. It reacts violentiy with sodium and potassium to produce nitrogen. Most metals are converted iato nitrates arsenic, antimony, and tin form oxides. Chrome, iron, and aluminum readily dissolve ia dilute nitric acid but with concentrated acid form a metal oxide layer that passivates the metal, ie, prevents further reaction. 

Pla.tinum, Platinum plating has found appHcation in the production of platinised titanium, niobium, or tantalum anodes which are used as insoluble anodes in many other plating solutions (see Metalanodes). Plating solutions were often based on platinum "P" salt, which is diamminedinitroplatiniim (IT). A dinitroplatinite sulfate—sulfuric acid bath has been used to plate direcdy onto titanium (129). This bath contains 5 g/L of the platinum salt, pH adjusted to 2.0 with sulfuric acid. The bath is operated at 40°C at 10—100 A/m. Other baths based on chloroplatinic acid have been used in both acid and alkaline formulations the acid bath uses 20 g/L of the platinum salt and 300 g/L hydrochloric acid at 65° C and 10—200 A/m. The alkaline bath uses 10 g/L of the platinum salt, 60 g/L of ammonium phosphate and ammonium hydroxide to give a pH of 2.5—9.0. The alkaline bath can be plated directly onto nickel-base alloys acid baths require a gold strike on most metals. 

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 anodic behaviour of platinum and certain of its alloys is of considerable technical importance, since they can be employed under a wide range of conditions without appreciable corrosion, and often in circumstances where no other metal can be used. Their use industrially has recently been extended by applying them as thin coatings to a substrate of a passive metal such as tantalum or, more commonly nowadays, titanium, to reduce the cost. Platinised titanium anodes are discussed in detail in Section 11.3. 

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. 

In the time since 1994 a lot of materials, Stainless steel [6], Ni-base alloys [6-9], numerous high performance ceramic materials [7, 9-12] and metals like Titanium [13-14], Tantalum [15], Niobium [16], Gold [6] and Platinum [6] have been tested under SCWO typical conditions in the Institute for Technical Chemistry) laboratories. 

The DSA-type anodes are inert , coated anodes made of a valve metal (titanium, niobium, or tantalum) base coated with an electrochemically active coating. The active coating is made either of noble metals or of mixed metal oxides. Noble metals in active coatings are usually platinum or platinum alloys. Mixed metal-oxide coatings contain active oxides and inert oxides the active components are usually ruthenium dioxide (R.UO2) and iridium dioxide (IrC>2) and the inert components are mostly titanium dioxide (TiC>2) and other oxides such as tantalum... 

Conversely, very non-poisonous or inert metals are needed when artificial prostheses have to be introduced during surgery and so metals which, if dissolved, would give soft ions are chosen, e.g. gold, silver, tantalum, and platinum or their alloys. Because they give soft ions there is negligible tendency for those metals to give up electrons to form soft metal ion—hard solvent bonds (water is hard). 

The dimethylglyoxime method has been used for determination of Ni in foodstuffs [10], platinum-group metals [69], iron ores [70], niobium, tantalum, molybdenum, and tungsten [71], steel [72], sewage [73], and aluminium alloys [74]. Dimethylglyoxime in the presence of oxidant was used for determining Ni in foodstuff [75], sea-water [76], plants [77], steel [5], lead and antimony [78], copper alloys [79], zinc and cadmium [80], and tungsten and its... 

The aim of this contribution is to present data on the preparation of catalysts containing as embedding species a large family of eolloids such as colloids of ruthenium, platinum, or palladium-gold alloys and triflate derivatives such as lanthanum and silver triflate or tert-butyldimethylsilyltrifluoromethanesulfonate (BMSTM). Silica, zirconia and tantalum oxides were used as carrier. All these preparations considered the polymeric sol-gel route using as starting materials silicon, zirconium or tantalum alcoxides. 

Tantalum compounds (as Ta) Of low acute toxicity. Dusts mildly Irritating to the lungs. 5 mg/m (metal and oxide dusts, as Ta) 2500 mg/m (metal and oxide dusts, as Ta) Metal is a gray-black solid, platinum-white if polished. Odorless. Tantalum pentoxide is a colorless solid. Used in aerospace and other specialty alloys. 

In addition, ILs could also be used as both solvent and electrolyte for the electrodeposition of copper [35, 36], aluminum [37, 38], tantalum [4], platinum [39], silver [40, 41], gold [40-42], and silicon [43]. For example, Endres et al. have reported the electrodeposition of nanocrystalline metals and alloys, such as aluminum from ILs, which previously could not be electrodeposited from aqueous or organic solutions. This method enabled the synthesis of aluminum nanocrystals with average grain sizes of about 10 nm, Al-Mn alloys, as well as Fe and Pd nanocrystals [4] [as shown in Fig. 4.2). 

---