Noble metals are primarily gold, silver and platinum. They are not subject to corrosion and oxidation, and this distinguishes them from other metals. Their stocks are small, but their products are truly unique. Platinum metals such as palladium, ruthenium, iridium, rhodium and osmium are also noble. Platinum metal is characterized by heat resistance, ductility, corrosion resistance, reflectivity and emission ability, as well as thermal and electrical conductivity and high magnetic characteristics. These unique physical and chemical properties are possessed not only by the metals themselves, but also by their compounds and materials based on them: alloys, catalysts, powders, coatings, and oxide films. They are indispensable in the chemical and oil refining industries, electronics, electrical engineering, nuclear and rocket technology, and instrument making. These metals provide guaranteed reliability in the work of computing, as well as measuring and control devices and instruments.
All precious metals have the most important qualities that are necessary for the manufacture of various jewelry. These are their properties such as softness, ductility, ductility, and the ability to alloy with other metals. Due to the high cost, they began to be called precious.
The most expensive precious metal is gold. It is the only metal of all that has a bright yellow color in its purest form. If it is polished, then its luster will increase significantly. Gold is not subject to oxidation in air, is resistant to moisture. Due to its most valuable property - chemical resistance, gold from the entire group of metals is recognized as the most noble. In jewelry, pure gold forms the basis of precious alloys.
Many prefer noble metals of white color, mainly in jewelry. Such metal is silver. In addition to jewelry, silver was used for the manufacture of cutlery, dishes. Silver is easily machined. This metal has ductility, ductility, ductility. Also, it is characterized by high reflectivity, thermal and electrical conductivity. A significant part of the silver mined is used in electronics, instrumentation, for minting coins, covering mirrors, and in photography. Recently, the scope of this metal is constantly expanding. Silver is not very resistant to moisture. It takes on a dark shade.
Also, noble metals include platinum in their list - heavy and refractory metal. In nature, there is no pure platinum. It is presented in the form of a natural alloy with other noble metals, such as palladium, ruthenium, rhodium, osmium, iridium. Platinum is characterized by higher hardness than gold and silver. It is not subject to chemical effects. Platinum high-grade alloy is widely used in jewelry manufacturing.
The platinum group includes palladium. Its chemical properties are lower than platinum. It has a beautiful, almost white color. Palladium is the lightest, flexible, fusible and ductile of platinum group metals. It can easily roll and stretch into the wire. Palladium does not fade and is highly polishable. It is contained in low-grade gold to increase its anti-corrosion properties.
The group of platinum metals includes rhodium, resembling aluminum with its bluish-white color. This metal is hard, brittle. It has a high reflectivity. Rhodium is considered a chemically resistant metal. This metal is resistant to oxygen, chlorine, sulfur, phosphorus. The chemical and physical properties of rhodium are used to coat gold and silver products.
Ruthenium is a refractory metal. It possesses fragility and hardness, just like rhodium. This metal has found its application in instrumentation; it is present in small quantities in platinum alloys.
One of the platinum group metals is iridium, whose characteristic is similar to that of ruthenium and rhodium. Of all the metals, it is one of the most chemically stable. It is actively used in the chemical industry.
The last representative of platinum metals is osmium. It is not subject to mechanical processing, insoluble in acids. Osmium is introduced into alloys to increase their chemical stability and hardness.