Palladium alloying element

Platinum, as an alloying element, is used in many dental casting golds (Tables 6 and 7) to improve hardness and elastic qualities. Platinum in combination with palladium and iridium has limited use for dental pins and wires. 

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 disappearance of the paramagnetism of palladium-silver alloys (rich in Pd) when the ratio (H + Ag)/Pd = 0.6 (24) illustrates that the effect of both these alloying" elements in palladium is additive and each one contributes essentially in the same way to the change of magnetic susceptibility of palladium. 

When rhodium is combined with platinum and palladium, the elements together form the internal metals of automobile catalytic converters, which convert hot unburned hydrocarbon exhaust gases to less harmful CO and H O. Similar alloys are used to manufacture high-temperature products such as electric coils for metal refining furnaces and high-temperature spark plugs. 

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. 

US Patent 6,183,542 was issued in 2001 for a palladium membrane process. This process provides an apparatus that can handle high flow rates of gas, per unit area of membrane, while using a minimal amount of hydrogen-permeable material. This is accomplished by using stainless steel mesh elements to reinforce the thin-walled, palladium or palladium alloy membranes. This process also provides the ability to withstand large pressure gradients in opposite directions and thus will make it easier to clean membranes that have been clogged with contaminants. 

Alloying elements exert a very important influence upon the occlusion of hydrogen by palladium. The absorptive power of commercial palladium is from 10 to 20 per cent, less than that of the pure metal, a fact that is attributed to the presence of small quantities of platinum and ruthenium.6... 

Corrosive reaction streams. In some application environments, the reactive or corrosive nature of one or more of the reaction components in a membrane reactor can pose a great technical challenge to the selection as well as the design of the membrane element Feed streams often contain some Impurities that may significantly affect the performance of the membrane. Therefore, attention should also be paid to the response of the selected membrane material to certain impurities in the reactant or product streams. Care should be taken to pretreat the feed streams to remove the key contaminants as far as the membrane is concerned in these cases. For example, palladium alloy membranes can not withstand sulfur- or carbon-containing compounds at a temperature higher than, say, 500 C [Kamcyama et al., 1981]. Even at lOO C, the rate of hydrogen absorption (and, therefore, permeation) in a pure palladium disk is... 

Other potential temperature variations or cycling may also occur as a result of feed or control disturbances. Thus it is important to ensure that the temperature of the system is in control so that no damage is done to the membrane, catalyst or other system components. It is well known, for example, that [Ktlladium can become embriuled under hydrogen-rich conditions particularly at a temperature near 300 or so. Some remedy in the case of palladium is to introduce certain metal such as silver as the alloying element. 

The most usable binary palladium alloy disclosed up to now is that of palladium with 25 at.% silver. Some other metals of groups IB, IV, and VIII of the periodical table and the rare earth elements have been studied as a second component of palladium alloys for hydrogen separation. Table 2 [6] lists the hydrogen permeabilities of miscellaneous binary palladium alloys at 623 K as compared with that of palladium. 

The so-called white gold alloys were introduced to resemble platinum when that metal was prohibitive in price, and their use in jewellery has been very successful. The earliest white gold contained. gold, nickel and zinc. Gold-palladium alloys are easier to work and with 20 per cent of the latter element are completely white, but the high price of palladium militates against their use except in the most expensive jewellery. Green, blue and purple alloys are also easily made by addition of cadmium, iron and aluminium respectively. 

The first catalytic converters used mainly platinum, but palladium is now the predominant catalyst metal. Sixty percent of the palladium manufactured worldwide is used in catalytic converters. Other uses are as the electrodes in MLCCs and other electronic components, and a small amount is used in jewelry (for example, an alloying element in white gold). 

After 5 minutes of reaction time in each case, the solution was centrifuged and washed with DI water three times. A few drops of washed solutions were placed on sample holders in each case and left to dry under ambient conditions. The dried sanq>les were either coated by evaporation of gold-palladium alloy or sputter coated with gold and they were further characterised by Field Emission-Scanning Electron Microscope (FE-SEM) for product morphology, which was also equipped with an Energy Dispersive Spectroscopy (EDS) facility for elemental analysis. In the control experiments without using the protein, no silica precipitation was observed even over a 24 hour period, as was described previously [13]. 

Ruthenium is a hard, white metal. It does not tarnish at room temperature and is not attacked by acids, not even aqua regia. If potassium chlorate is added, however, the reaction is explosive. Ruthenium is used as an alloying element for platinum and palladium, making these metals harder by soluhon hardening. Such alloys have a high resistance to wear and are used in the manufacture of tips for fountain-pen nibs. A content of 0.1% Ru in titanium improves the corrosion resistance of this metal. Stable anodes for chlorine production are made of titanium, coated with ruthenium. A new technique for improved storage capacity on hard disks uses ruthenium. 

Ruthenium is used as an alloying element for platinum and palladium, making these metals harder by solution hardening. A content of 0.1% Ru in titanium improves the corrosion resistance of this metal. Stable anodes for chlorine production are made of titanium, coated with ruthenium. 

The crevice corrosion resistance can be improved by alloying titanium with elements such as nickel, molybdenum, or palladium. Consequently, grade 12 and the titanium-palladium alloys are more resistant to crevice corrosion than unalloyed titanium. 

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