Iridium-osmium alloy

Iridosmine = Iridium osmium alloy Fe-Cordierite = Sekaninaite Iserine (Nigrine) = Ilmenite + Rutile Isoplatinocopper = Hongshiite Isostannite = Kesterite-Ferrokesterite Jade = Jadeite (Nephrite)... 

Orthite = Allanite Orthose = Orthoclase Osmiridium = Iridium-osmium alloy Outremer = Ultramarine (Lazurite)... 

Iridosmine is not a compound, but an alloy of iridium, osmium, and a small amount of platinum that is used to make fine-pointed surgical instruments and needles and to form the fine tips of fountain pens. It is used worldwide to make weights because it resists oxidation better than any other alloyed metals. 

Two different kinds of metals are found in chondrites. Small nuggets composed of highly refractory siderophile elements (iridium, osmium, ruthenium, molybdenum, tungsten, rhenium) occur within CAIs. These refractory alloys are predicted to condense at temperatures above 1600 from a gas of solar composition. Except for tungsten, they are also the expected residues of CAI oxidation. 

Platinum is one member of a family of six elements, called the platinum metals, which almost always occur together, Before the discovery of the sister elements, the term platinum was applied to an alloy with Pt as the dominant metal, a practice that persists to some degree even today. The major properties of the platinum metals are given in Table 1 See also Iridium Osmium Palladium Rhodium and Ruthenium. 

Steel appears to form valuable alloys with a very small proportion of some other metals. With a little silicon and aluminum, it yields a metal equal to the Indian wootz and with small quantities of silver, platinum, rhodium, palladium, and even iridium and osmium, alloys of prodigious hardness and toughness are obtained. part of silver is sufficient to effect a marked improvement. 

High Temperature Properties. There are marked differences in the abihty of PGMs to resist high temperature oxidation. Many technological appHcations, particularly in the form of platinum-based alloys, arise from the resistance of platinum, rhodium, and iridium to oxidation at high temperatures. Osmium and mthenium are not used in oxidation-resistant appHcations owing to the formation of volatile oxides. High temperature oxidation behavior is summarized in Table 4. 

Ruthenium, iridium and osmium Baths based on the complex anion (NRu2Clg(H20)2) are best for ruthenium electrodeposition. Being strongly acid, however, they attack the Ni-Fe or Co-Fe-V alloys used in reed switches. Reacting the complex with oxalic acid gives a solution from which ruthenium can be deposited at neutral pH. To maintain stability, it is necessary to operate the bath with an ion-selective membrane between the electrodes . 

Plutonium-noble metal compounds have both technological and theoretical importance. Modeling of nuclear fuel interactions with refractory containers and extension of alloy bonding theories to include actinides require accurate thermodynamic properties of these materials. Plutonium was shown to react with noble metals such as platinum, rhodium, iridium, ruthenium, and osmium to form highly stable intermetallics. 

Because of- the similarity in the backscattering properties of platinum and iridium, we were not able to distinguish between neighboring platinum and iridium atoms in the analysis of the EXAFS associated with either component of platinum-iridium alloys or clusters. In this respect, the situation is very different from that for systems like ruthenium-copper, osmium-copper, or rhodium-copper. Therefore, we concentrated on the determination of interatomic distances. To obtain accurate values of interatomic distances, it is necessary to have precise information on phase shifts. For the platinum-iridium system, there is no problem in this regard, since the phase shifts of platinum and iridium are not very different. Hence the uncertainty in the phase shift of a platinum-iridium atom pair is very small. 

Iridium occurs in small amounts in native platinum or platinum metal alloys. Iridium and osmium together constitute osmiridium, which is resistant to chemical attack and is a byproduct of platinum extraction. 

Osmium occurs in nature, always associated with other platinum group metals. It usually is found in lesser abundance than other noble metals. Its most important mineral is osmiridium (or iridosmine), a naturaUy occurring mineral alloyed with iridium. 

When recovered from the mineral osmiridium, the mineral is fused with zinc to convert it into a zinc alloy. The alloy is then treated with hydrochloric acid to dissolve the zinc away leaving a finely divided material. This finely divided sohd then is fused with sodium peroxide and caustic soda to convert osmium and ruthenium into their water-soluble sodium salts, sodium osmate and sodium iridate, respectively. While osmium is fully converted to osmate salt, most ruthemium and a small part of iridium are converted to ruthenate and iridate, respectively. The fused mass is leached with water to separate metals from sohd residues. 

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