At present, there are two coating materials have bright prospects in application. One is artificial diamond PCD coating, which American scientists invent a method for producing nano-diamond immediately under 1.01×10Pa and decreases the production cost of traditional diamond coating. The other is cubic boron carbide CBN coating, its hardness only lower than diamond, which has similar structure with diamond and hardness reach 60Gpa.

Owing to the unique structure and high coherent of nonmaterial, shows a variety of features such as surface effect, size effect, super plasticity and so on. Although tungsten carbide and ceramics have great hardness and toughness, they are all belonging to brittle materials. Especially ceramic materials have been hampered in application because of its own high brittleness.
















Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Among these kinds of new technology, surface coating is the most direct, which applies a harder layer on basis for enhancing the anti-abrasion and erosion wear. So the mechanical property will be improved and reduce the abrasion. Apply surface coating to nozzle process, which is unfamiliar in domestic, but it had some applications abroad already. After coating, the roughness of internal surface of the nozzle is remarkably decreasing, which improves the precision and extends the lifespan. For instance, coating on the substrate of tungsten carbide or pottery by 10-30mm diamond film will make the material physical and chemical properties are close to the natural diamond. And improve the lifespan up to 3-10 times compared to un-coating material.



















Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Although most of the world wide production of tungsten comes from the mineral wolframite, Scheelite is especially abundant in the US and provides the United States with most of its supply. The word "Tungsten" was probably first used by A. F. Cronstedt in 1755, who applied it to the mineral subsequently known as "Scheelite," which is the natural form of calcium tungstate.

C. C. Leonhard named this mineral Scheelite in 1821 in recognition of the discovery made by K. W. Scheele, in 1781. He believed that the mineral was a compound of lime and a previously unknown acid, which he called "Tungstic Acid. Tungsten was first isolated from tungstic aci in 1783 by the de Elhuyar brothers. Before Scheele made his discovery, the mineral was generally regarded as containing tin.

The word tungsten denotes a substance of high density and is derived from the Swedish language, "tung," meaning heavy, and "sten," meaning stone. The metal is known as tungsten in some countries and as wolfram in others, including Sweden, the country of origin of the name tungsten. The chemical symbol W, which is universally used to denote tungsten, suggests that wolfram was formerly the more generally accepted name for the element. In Britain the mineral wolframite is also known as wolfram.



 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

The element is resistant to ordinary acids and aqua regia but dissolves in a mixture of hydrofluoric and nitric acids. It forms compounds with carbon, chlorine, oxygen, sulfur, and some other elements. It forms tungstic acid (H2WO4), or wolframic acid, which is the basis of a series of salts called tungstates, or wolframates.

Tungsten metal is used extensively for filaments for light bulbs and electronic tubes. Carboloy, stellite, and tungsten steels are of importance in industry because they retain their hardness and strength at high temperatures. Tungsten is usually added to steel in the form of ferrotungsten, obtained by the reduction of ferrous tungstate in an electric furnace.

Tungsten carbide is used in place of diamond for dies and as an abrasive. Sodium wolframate is used in the fireproofing of fabrics, in the weighting of silk, and as a mordant in dyeing. Tungsten does not occur uncombined in nature. Large deposits of its ores are found in various parts of the world. The trioxide occurs in nature as the mineral wolfram ochre. Scheelite and wolframite are the chief wolframate minerals. Tungsten is usually prepared from the trioxide by reduction with hydrogen or carbon.



 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Uses of Scheelite:

Scheelite is an important source of tungsten,which is a strategically important metal. Scheelite is rarely cut as gemstones. But it is considered as a rare mineral specimen by collectors and good specimens can command very high prices.

Since Scheelite is a primary ore of tungsten we will add some information about tungsten. Tungsten is a very hard, silver-white to steel-gray metal with a body-centered cubic crystalline structure. In its chemical properties it resembles molybdenum.

It is sometimes called wolfram, and it's chemical symbol "W" is taken from this name. When naming compounds of tungsten, use of the name wolfram as a root is preferred. Tungsten is one of the most dense metals and has a higher melting point than any other metal. It melts at about 3,410 deg C and boils around 5,660 deg C. Pure tungsten is ductile, and wires made of it, even those of very small diameter, have a very high tensile strength. 



 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Crystal Description of Scheelite :

Scheelite forms perfect tetragonal dipyramidal crystals that look very much like octahedrons. The crystals may also be truncated with minor pyramids, on the top and/or bottom points of the crystal. Which show Scheelite's true form. Scheelite may also be found in massive and granular form.

Other minerals that form crystals similar to Scheelite include wardite, anatase and powellite. Powellite, CaMoO4, is isostructural with Scheelite which is why it forms similar crystals. The two minerals form a series in which the tungsten of Scheelite is substituted by the molybdenum of Powellite. Powellite fluoresces a yellow color while Scheelite fluoresces a bright blue under short wave ultraviolet light. Of course since molybdenum can substitute for tungsten, some Scheelite specimens will show a yellow fluorescence.

Scheelite crystals can be mistaken as octahedron crystals. So fluorite with it's perfect octahedral cleavage and fluorescence. Can be mistaken for the brownish orange Scheelite. Massive Scheelite has often been mistaken for massive quartz, but then the fluorescence of Scheelite is a dead giveaway.

 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Scheelite Distinguishing Characteristics:

The fluorescence may be confusing especially when it becomes whitish or yellow from molybdenum substitution, but the high gravity differentiates it from fluorescent fluorite, and the crystals are so common that they will often be seen.

Specimens from worldwide localities show little difference in their color of fluorescence. Unlike other minerals, Scheelite is a "self-activated" mineral. Its fluorescence is due to the mineral itself, rather than some chance chemical impurity. The characteristic blue to bluish white fluorescence of this species is a valuable property in prospecting for Scheelite deposits at night. Old mines have even been reopened when mine shafts were examined with ultraviolet lamps.

Scheelite crystals can be mistaken as octahedron crystals. So fluorite with it's perfect octahedral cleavage and fluorescence. Can be mistaken for the brownish orange Scheelite. Massive Scheelite has often been mistaken for massive quartz, but then the fluorescence of Scheelite is a dead giveaway. 

 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Occurrence, Localities and Origins:

Occurs in connection with the tin deposits of Bohemia, Saxony and Cornwall; in quantity in New South Wales and Queensland. Found in the United States at Trumbull, Connecticut; at the Atolia District near Randsburg, San Bernardino County, California; near Mill City Pershing County, Nevada; near Dragoon, Cohise County, Arizona; in Lake County, Colorado; near Gage, New Mexico, where it occurs with pyrite and galena in a vein cutting limestone, and in the placer gravels at Nome, Alaska. High perfection orange scheelite crystals suitable for mineral collectors are being mined in China.

Production. Scheelite has been mined in quantity in Idaho, Alaska, California, Nevada, Arizona, and New Mexico, as a source of tungsten, but most of this element has heretofore been produced from other compounds, mainly wolframite. For some years it was produced in large quantity near Bishop, Inyo Co., California.

Scheelite is a subordinate ore of tungsten, with wolframite furnishing the greater amount on a worldwide basis. In the US, Scheelite has been the more important source of the metal. Tungsten is used principally in the manufacture of tool steel, various steel alloys and electric furnaces. It is also employed as the filaments in electric-light bulbs, in the manufacture of sodium tungstate which is used for fireproofing cloth, as a mordant in dyeing, and for a number of other minor purposes.

 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Composition, Structure and Associated Minerals:

Scheelite is found in granite pegmatites, contact metamorphic deposits, and high temperature veins. In these veins, it occurs usually with quartz in crystalline rocks associated with cassiterite, topaz, fluorite, apatite, molybdenite, wolframite, and many other metallic compounds. Found at times with gold. As a contact metamorphic product in altered limestone intruded by granite it is associated with typical scarn minerals like garnet and epidote. It is probably in all cases deposited from hot solutions. Sometimes found as crystals, but usually occurs reniform, with a columnar structure; also massive and granular.

Identification and Diagnostics

Scheelite is distinguished from limestone, which its massive forms closely resemble, by its higher specific gravity and the absence of effervescence with HCl. From quartz it is distinguished by its softness and from barite by greater hardness and higher specific gravity. Nearly all scheelite fluoresces under short wave ultra violet light. This can make for a fast method of finding scheelite specimens.



 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn