Cobalt

Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt in the Earth's crust is found only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.

Cobalt-based blue pigments (cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was later thought by alchemists to be due to the known metal bismuth. Miners had long used the name kobold ore (German for goblin ore) for some of the blue-pigment producing minerals; they were so named because they were poor in known metals, and gave poisonous arsenic-containing fumes upon smelting. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the kobold.

Today, some cobalt is produced specifically from various metallic-lustered ores, for example cobaltite (CoAsS), but the main source of the element is as a by-product of copper and nickel mining. The copper belt in the Democratic Republic of the Congo, Central African Republic and Zambia yields most of the cobalt mined worldwide.

Ring

Ring may refer to:

Arts and entertainment

Film

Games

Literature

Music

Science and technology

Astronomy

Wedding ring

A wedding ring or wedding band is a ring, often but not always made of metal, indicating the wearer is married. Depending on the local culture, the ring is usually worn on the base of the right or the left ring finger. The custom of wearing such a ring has spread widely beyond its origin in Europe. In the United States, wedding rings were originally worn only by wives, but during the 20th century they became customary for both husbands and wives. Wedding rings are a tradition that goes back many centuries, having been manifested in the wedding customs of many nations and religious groups. They come in many forms, most traditionally a ring made of gold or some other precious metal. Many people wear their wedding rings day and night, causing an indentation in the skin that remains visible even when the ring is taken off. Another indication of their cultural importance is that wedding rings are among the few items permitted to be worn by otherwise restrictive rules for prison inmates and visitors.

Tungsten carbide

Tungsten carbide (chemical formula: WC) is a chemical compound (specifically, a carbide) containing equal parts of tungsten and carbon atoms. In its most basic form, tungsten carbide is a fine gray powder, but it can be pressed and formed into shapes for use in industrial machinery, cutting tools, abrasives, armor-piercing rounds, other tools and instruments, and jewelry.

Tungsten carbide is approximately two times stiffer than steel, with a Young's modulus of approximately 530–700 GPa (77,000 to 102,000 ksi), and is double the density of steel—nearly midway between that of lead and gold. It is comparable with corundum (α-Al
2O
3) in hardness and can only be polished and finished with abrasives of superior hardness such as cubic boron nitride and diamond powder, wheels, and compounds.

Naming

Historically referred to as Wolfram Wolf Rahm, wolframite ore discovered by Peter Woulfe was then later carburized and cemented with a binder creating a composite now called "Cemented Tungsten Carbide". Tungsten is Swedish for 'heavy stone'.

Carbon-fiber-reinforced polymer

Carbon-fiber–reinforced polymer, carbon-fiber–reinforced plastic or carbon-fiber–reinforced thermoplastic (CFRP, CRP, CFRTP or often simply carbon fiber, or even carbon), is an extremely strong and light fiber-reinforced plastic which contains carbon fibers. The spelling 'fibre' is common in British Commonwealth countries.

CFRPs can be expensive to produce but are commonly used wherever high strength-to-weight ratio and rigidity are required, such as aerospace, automotive and civil engineering, sports goods and an increasing number of other consumer and technical applications.

The binding polymer is often a thermoset resin such as epoxy, but other thermoset or thermoplastic polymers, such as polyester, vinyl ester or nylon, are sometimes used. The composite may contain other fibers, such as an aramid (e.g. Kevlar, Twaron), aluminium, ultra-high-molecular-weight polyethylene (UHMWPE) or glass fibers, as well as carbon fiber. The properties of the final CFRP product can also be affected by the type of additives introduced to the binding matrix (the resin). The most frequent additive is silica, but other additives such as rubber and carbon nanotubes can be used. The material is also referred to as graphite-reinforced polymer or graphite fiber-reinforced polymer (GFRP is less common, as it clashes with glass-(fiber)-reinforced polymer). In product advertisements, it is sometimes referred to simply as graphite fiber for short.