Basic Knowledge of Refractory Metal Tantalum

Tantalum Overview

Tantalum is part of the refractory metal group and it has good physical and chemical properties.

Tantalum has high hardness that can reach 6-6.5. Its melting point is as high as 2996 ° C, only after carbon, tungsten, rhenium and osmium. Tantalum is malleable and can be drawn into a thin foil. Its coefficient of thermal expansion is very small, and it only expands by 6.6 parts per million per degree Celsius. In addition, it has a strong toughness and is superior to copper.

Refractory Metal tantalum
Refractory Metal Tantalum

Tantalum does not react with hydrochloric acid, concentrated nitric acid and “aqua regia” under both cold and hot conditions. And tantalum is only corroded by concentrated sulfuric acid at temperatures above 150 °C. Tantalum can be considered one of the most chemically stable metals at temperatures below 150 °C. It is also highly resistant to corrosion because of the formation of a stable tantalum pentoxide (Ta2O5) protective layer on its surface.

Tantalum Application

Tantalum can be used to manufacture evaporation vessels, as well as tubes, rectifiers, and electrolytic capacitors. Tantalum forms a stable anodized film in an acidic electrolyte. The electrolytic capacitor made of tantalum has the advantages of large capacity, small size and good reliability. Tantalum capacitors are the most important use of tantalum, around 2/3 of the full use of tantalum. Tantalum is also the material for making electron-emitting tubes and high-power tube parts. Anti-corrosion equipment made by Tantalum is used in the chemical industry such as strong acid, bromine and ammonia producing industries. The metal tantalum can be used as a structural material for the combustion chamber of an aircraft engine. Tantalum is easy to form and can be used as support accessories, heat shields, heaters and heat sinks in high temperature vacuum furnaces. Tantalum can also be used as orthopedic and surgical materials. Tantalum sputtering targets and tantalum evaporation materials are important coating materials in physical vapor deposition.

tantalum capacitor
tantalum capacitor

High Purity Tantalum Preparation

The chemical inertness and relatively low price of tantalum make it a good alternative to platinum.  However, high-purity tantalum is not easy to get because it is always found together with niobium in the mineral groups of tantalite, columbite, and coltan. To get high purity tantalum, here are several methods.

1 Tantalum powder can be obtained by metal thermal reduction (sodium thermal reduction) method. The potassium fluotantalate is reduced with sodium metal under an inert atmosphere: K2TaF7 + 5Na-→Ta+5NaF+2KF. The reaction was carried out in a stainless steel tank, and the reaction was quickly completed when the temperature was heated to 900 °C. The powder prepared by this method has irregular grain shape and fine particle size, and is suitable for making tantalum capacitors.

2 The tantalum powder can also be obtained by molten salt electrolysis: a molten salt of a mixture of potassium fluoroantimonate, potassium fluoride and potassium chloride is used as an electrolyte, and tantalum pentoxide (Ta2O5) is dissolved therein and electrolyzed at 750 °C. This method can obtain a bismuth powder having a purity of 99.8 to 99.9%.

3 Tantalum can also be obtained by carbothermal reduction of Ta2O5. The reduction is generally carried out in two steps: first, a mixture of a certain ratio of Ta2O5 and carbon is made into tantalum carbide (TaC) at 1800 to 2000 ° C in a hydrogen atmosphere. Then, TaC and Ta2O5 are prepared into a mixture in a certain ratio, and reduced to tantalum in a vacuum.

4 Tantalum can also be obtained by thermal decomposition or hydrogen reduction of chloride. The dense metal crucible can be prepared by vacuum arc, electron beam, plasma beam melting or powder metallurgy.

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Multiple Applications of Silver

Medical uses of silver

Silver is used in many medical applications due to its antibacterial properties. Most medical devices, such as bandages, wound cleansers, catheters, pacemakers, valves and feeding tubes, that comes into contact with the body contain silver. The hospital also uses silver in air ducts to prevent certain conditions, such as Legionnaires Disease.

Silver for textiles

The thermal and biological properties of silver make it an ideal choice for the commercial textile industry. Silver is used in the anti-microbial properties of high-end sportswear to inhibit the growth of bacteria that can cause odors. Traditionally, silver and gold threads have been woven into clothing.


Silver for food and water

Silver will play an important role in the food industry in the next decade. The US Food and Drug Administration has approved the addition of silver to bottled water to help kill bacteria, which opened the door for major municipalities to use white water for clean water at local communities, cities and state levels. Silver tip cutting tools are used for meat processing. It is also used in the processing of milk, cheese making and baking.

Silver superconductor

Another important use of silver is as a superconductor, mainly for large industrial and military electric motors. For a while, silver was used as a strategic reserve for military applications.

Other applications of silver

In addition to the above aspects, silver has many other uses. Silver is used as a wood preservative. Silver sputtering targets and silver evaporating materials are used for vacuum coating. The silver coating plays a key role in the solar power industry. Solar cells coated with silver absorb light and convert it into electricity.


From the perspective of industrial applications, the future of silver is indeed very obvious. Many industrial applications will continue to use silver, and many new applications for silver will continue to grow at a significant rate.

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Molybdenum Application for Metallurgy

Molybdenum, a silvery-grey metal, does not seem to be as popular as tit anium, aluminum, and platinum. But it is actually a very widely used metal in our life. Today, we will introduce the application of molybdenum in metallurgy.

Molybdenum in Metallurgy

Steel Metallurgy

The main use of molybdenum for metallurgy is to produce various types of steel and alloys. The addition of molybdenum (mainly in the form of ferromolybdenum, molybdenum oxide, and calcium molybdate) to a range of steels such as structural steel, spring steel, bearing steel, tool steel, stainless steel, and magnetic steel can significantly improve the properties of steel.


Molybdenum improves the hardenability, toughness and heat strength of steel and prevents temper brittleness. It also improves the corrosion resistance of steel to certain media so that it does not pit. In addition, adding molybdenum into the cast iron enhances the strength and wear resistance of the cast iron.

Nonferrous Metallurgy

In non-ferrous metal alloys, molybdenum can be alloyed with metals such as nickel, cobalt, ruthenium, aluminum, and titanium. These molybdenum alloys are used in the electronics, electrical industry, and machinery industries to make filament and tube parts for light bulbs; they can also be used to make parts such as electromagnetic contacts, gas engine blades, valve protection, and electric furnace resistance.

nickel molybdenum alloy
Nickel Molybdenum Alloy

Molybdenum can improve the heat resistance and corrosion resistance of non-ferrous alloys and is an important element of nonferrous metallurgy.

Metal Processing

Molybdenum and its alloys can be used in a variety of molds, cores, perforated bars, tool holders and chill plates for metalworking.


Tools made of molybdenum can improve the processing speed and feed rate of metal processing, reduce the wear and deformation of metal parts, and thus extend the service life of the workpiece. These tools can also be used to machine large-sized parts and improve the accuracy of the workpiece.

Resistance welding electrodes made of molybdenum can be used for electronic brazing and welding of copper, brass and other materials with high thermal conductivity.

The molybdenum tip has a long service life and does not contaminate the workpiece, so it is suitable for processing electronic products.

Molybdenum can be used to make test dies for steel samples, which is very durable.

In addition, some metals require high temperature treatment in hydrogen, inert gas or vacuum, and molybdenum boats are ideal containers for holding such metals.

Molybdenum Boat
Molybdenum Boat

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Who discovered Iridium? | History of Metal


Iridium, a very hard, brittle, silvery-white transition metal of the platinum group, is the second-densest metal (after osmium) with a density of 22.56 g/cm3 as defined by experimental X-ray crystallography.



Smithson Tennant

Smithson TennantIridium was discovered together with osmium in1803 by English chemist Smithson Tennant in London. When crude platinum was dissolved in dilute aqua regia (a mixture of nitric and hydrochloric acids), it left behind a black residue. Because of the black color, it was initially thought to be graphite. By treating it alternately with alkalis and acids, Tennant was able to separate it into two new elements. These he announced at the Royal Institution in London, naming one iridium (comeing from the Latin word ‘iris’, meaning rainbow) because many of its salts were so colorful; and the other osmium (derived from osme, the Greek word for smell) because it had a curious odor.


Name Iridium
Symbol Ir
Color silvery-white
CAS number 7439-88-5
Melting point 2446°C, 4435°F, 2719 K
Boiling point 4428°C, 8002°F, 4701 K
Density (g cm−3) 22.5622


Iridium is a rare, hard, lustrous, brittle, very dense platinum-like metal. Chemically it is almost as unreactive as gold. It is the most corrosion-resistant metal known and it resists attack by any acid. Iridium is generally credited with being the second densest element (after osmium) based on measured density, although calculations involving the space lattices of the elements show that iridium is denser.


Due to its good corrosion-resistance, it is used of as a hardening agent for special alloy or to form an alloy with osmium, which is used for bearing compass and tipping pens.

Iridium Application

Iridium is used in making Iridium crucibles and other equipment that is used at high temperatures. Iridium sputtering target is a coating material to produce Iridium film, which is used as protective film or heavy-duty electrical contacts. In addition, Iridium was used in making the international standard kilogram, which is an alloy of 90% platinum and 10% iridium.

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Reference: “Iridium.” Chemicool Periodic Table. 17 Oct. 2012. Web. 3/21/2019 <>.

Who Discovered Yttrium? | Metal History

Yttrium is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a “rare-earth element“. Yttrium was discovered as early as the 18th century, but it has not been widely used until the last few decades in chemistry, physics, computer technology, film coating, medicine and other fields.

Yttrium History

In 1787, while the Swedish chemist Carl Axel Arrhenius exploring a quarry near Ytterby, a small town near Sweden’s capital city, Stockholm, he discovered an unusual black rock. He thought that he had discovered a new mineral, and sent some specimens to Johan Gadolin, a Finnish mineralogist, for analysis.

During the analysis, Gadolin isolated the yttrium from the mineral. The mineral was later named gadolinite in Gadolin’s honor, and Yttrium was named Ytterby from where the mineral was discovered.

In 1843, a Swedish chemist named Carl Gustaf Mosander studied yttrium samples and discovered three oxides, which were called yttria, erbia and terbia at that time. Currently, they are known as yttrium oxide (white), terbium oxide (yellow), and erbium oxide (rose-colored). A fourth oxide, ytterbium oxide, was identified in 1878.

Yttrium, a transition metal

In the Periodic Table of Elements, yttrium is considered one of the transition metals (yellow in the pic). Other more well-known transition metal elements include gold, silver and iron. The transition metals are the metallic elements that serve as a bridge, or transition, between the two sides of the table. They tend to be strong but pliable, therefore, some of these metals are widely used for wires. Yttrium wires and rods are used in electronics and solar energy. Yttrium is also used in lasers, ceramics, camera lenses, sputtering targets and dozens of other items.

Periodic Table
Periodic Table

Yttrium, a rare earth metal

Yttrium is also one of the seventeen rare-earth elements. The rare-earth elements include yttrium, scandium and 15 lanthanides. They have become indispensible in the manufacturing of cell phones and other technology. Despite their name, rare-earth elements are rather plentiful around the world. Yttrium can be found in most of the rare earth minerals, but has never been discovered in the Earth’s crust as a freestanding element.

Yttrium Properties

Atomic number 38
Atomic symbol Y
Atomic mass 88.906
Melting point 2,772 Fahrenheit (1,522 Celsius)
Boiling point 6,053 F (3,345 C)
Density 4.47 grams per cubic centimeter
State at room temperature Solid

Yttrium Applications

Yttrium metal is used as:

A deoxidizer for vanadium and other non-ferrous metals.

A nebulizer for nodular cast iron.

A catalyst for ethylene polymerization.

Added in small quantities to reduce the grain size in chromium, molybdenum, etc., as well as to strengthen aluminum and magnesium alloys.

Yttrium sputtering target for film coating.

Yttrium compounds have the following uses:

Yttrium oxide is used to produce yttrium iron garnets.

Yttrium oxide is used in ceramic and glass formulations.

Yttrium oxide is widely used for making compounds such as YVO4europium and YVO4europium phosphors in television tubes.

Yttrium iron (Y3Fe5O12), yttrium aluminium (Y3Al5O12) and yttrium gadolinium garnets possess interesting magnetic properties.

Yttrium iron garnets are extremely efficient transmitters and transducers of acoustic energy.

Yttrium aluminum garnet has a hardness of 8.5 and is finding application as a gemstone.

Yttrium oxide sputtering target is used for film coating.

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How was Chromium discovered? | Metal History

Chromium Discovery

In 1766, the German scientist Johann Gottlob Lehmann analyzed a Siberian ore and determined that it contained lead, which was classified as Siberian red lead.

Louis Nicolas Vauquelin
Louis Nicolas Vauquelin


In 1797, a bright red ore was found in the Siberian gold mine. The French chemist Louis Nicolas Vauquelin boiled the mineral with potassium carbonate, and got the lead carbonate and a yellow potassium salt solution of chromic acid. He added a high-mercury salt solution to the yellow solution, and a beautiful red solution appeared; the lead salt solution was added, and a yellowish precipitate appeared; when stannous chloride was added, the solution turned into a crisp green color. He thought that he had found a new metal, which was exactly chromium. The method produces metal chromium.

Chromium can produce beautiful multi-colored compounds: metallic chromium is silvery, chromium sulfate is green, magnesium chromate is yellow, potassium dichromate is orange, chromic is scarlet, and chromium oxide is green, chrome tanning is blue-violet, lead chromate is yellow…Thus Chromium got its name from the Greek word chroma, meaning color, and the chemical symbol is Cr.

Multiple colors of Chromium compounds
Multiple colors of Chromium compounds

Chromium Applications

Chromium was initially used as a pigment. At present, nearly all chromium is commercially extracted from chromite, also known as iron chromium oxide (FeCr2O4).

Chromium was considered to be a component of plants and animals in 1948. It was found to be biologically active in 1954. In 1957, chromium was identified as an essential trace element for animal nutrition. Chromium can act as an enhancer of insulin, affecting the metabolism of sugars, proteins, fats and nucleic acids through insulin.

As a metal element, chromium also has high industrial value. Chromium is widely used in metallurgy, chemical, cast iron, refractory and high-end technology industries.

Chromium Coating
Chromium Coating

Chromium sputtering target is an excellent film coating material applied for decorative coating, tool coating, semiconductor coating and so on.

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A Summary of the Titanium Alloy Properties

SAM®Titanium is a new type of metal. Its properties are related to the content of other impurities, such as carbon, nitrogen, hydrogen and oxygen. The purest titanium iodide has an impurity content of less than 0.1%, but it has low strength and high plasticity.

The general properties of 99.5% industrial pure titanium are as follow:

Stanford Advanced Materials
density ρ 4.5g/cm3
melting point 1725°C
thermal conductivity λ 15.24W/(mK)
tensile strength σb 539MPa
elongation δ 25%
section shrinkage ratio ψ 25%
elastic modulus E 1.078×105 MPa
hardness HB 195

(1) High specific strength

The density of titanium alloy is generally about 4.5g/cm3 (only 60% of steel), but the strength of pure titanium is close to that of normal steel. And some high-strength titanium alloys have higher strength than many alloy structural steels. Therefore, the specific strength (strength/density) of titanium alloy is much larger than that of other metal structural materials. It can be used to produce parts and components with high unit strength, good rigidity and lightweight. At present, titanium alloys are used for aircraft engine components, skeletons, skins, fasteners and landing gear.

Titanium Aeroplane Engine
Titanium Aeroplane Engine

(2) High-temperature strength

Titanium alloys can be used in higher temperature environments than aluminum alloys. Titanium alloys can retain the required strength and maintain long-term operation at the temperatures between 450 and 500 °C. While the specific strength of the aluminum alloy is significantly reduced when the temperature reaches 150 ° C.

(3) Good corrosion resistance

Titanium alloy can work in the moist atmosphere and seawater medium with good corrosion resistance, which is much better than stainless steel. It is especially resistant to pitting, acid etching and stress corrosion. In addition, titanium also has excellent corrosion resistance to alkali, chloride, chlorine organic substances, nitric acid, sulfuric acid, and the like. The fly in the ointment is that titanium has poor corrosion resistance to reducing oxygen and chromium salt media. For more information about the corrosion resistance of titanium, please read this passage Does titanium never corrode?

Titanium Ship
Titanium Ship

(4) Good low-temperature performance

Titanium alloys retain their mechanical properties at low and ultra-low temperatures. Titanium alloys with good low-temperature properties and extremely low interstitial elements. For instance, TA7 can retain a certain degree of plasticity at -253 °C. Therefore, the titanium alloy is also an important low-temperature structural material.

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The Self-Healing Ability of Cerium Coating (Chromium Substitute)

In recent years, several research efforts are targeted on the utilization of rare earth elements, especially on cerium thin film coatings. Cerium is a soft, ductile and silvery-white metal that tarnishes when exposed to air, and it so soft that can be cut with a knife. Cerium has no biological role and is not very toxic. Many surface treatments, like sol-gel, chemical vapor deposition (CVD) and physical vapor deposition (PVD) technique, based on the use of cerium and cerium compounds have been investigated because of their low toxicity. In other words, consumption or inhalation of those compounds is not considered harmful to health.

Cerium compound physical vapor deposition permits to improve corrosion protection performance of the surface it is deposited on. The composition of the films has an impact on the corrosion properties of the cerium-based layer. In general, the coatings obtained by PVD are composed of Ce compound in trivalent or tetravalent states. The ratio between these 2 oxidization states is strongly depending on the oxidizing ability of the medium. However, no clear correlation between the Ce oxidation state and corrosion properties was found nowadays.

cerium film
cerium film

What’s more, these cerium coatings have an active mechanism similar to that observed for chromate coatings that they both have the amazing self-healing ability when damage occurs. Chromate coatings have the self-healing properties because of the presence of unreacted Cr6+ ions that are able to migrate to the exposed metal (for example a scratch) and can be further reduced to create a Cr3+ based compound that seals the scratch or the defect. However, the chromate compounds are extremely toxic and carcinogenic. Since cerium is not toxic, it is a perfect substitute for chromate. When it comes to cerium, the contact between a CeO2 film and solution induces the formation of Ce(OH)22+ ions. The existence of oxidizable metal would reduce these ions into Ce3+. Then the precipitation of trivalent cerium oxide occurs; it can be enhanced by the local increase of alkalinity. Therefore, this precipitated oxide seals the film and decreases the corrosion rate of metal. Since cerium is not toxic, it is a perfect substitute for chromate.

In conclusion, cerium is good, but some people would concern their price. Is rare earth element—Cerium—very expensive? The answer is not, actually Cerium is one of the least expensive rare earths and is the major component of “mischmetal”. So don’t care too much about the price.

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Related Blog: How was cerium discovered? | History of Cerium

Molybdenum Target Mammography Detection

Breast cancer, one of the major causes of deaths among women, affects about 12% of women around the world. According to research surveys, the smaller the breast cancer is when it is detected, the less the possibility of death. This requires that women should go over the medical body check regularly to decrease the risk of breast cancer. At present, molybdenum target mammography is considered the recommended breast screening examinations for women’s breast cancer.

What is the Breast Cancer?

Breast cancer is caused by the development of malignant cells in the breast. It is a sign of breast cancer when cells in the breast begin to grow out of control, and these cells usually result in forming a tumor.

Breast Cancer
Breast Cancer


Breast cancer itself is not a fatal disease because the breast is not an indispensable organ for maintaining human life. However, if the malignant cells spread to other important parts of the human body, such as the heart, the liver, and kidney, breast cancer may lead to death.

Breast cancer occurs almost entirely in women, but men can get breast cancer, too. And it is closely related to age—only 5% of all breast cancers occurring in women under 40 years old.

What is Molybdenum target mammography?

Molybdenum target, or molybdenum sputtering target, is known as the materials in physical vapor deposition for film coating.

Molybdenum target mammography is another important application of Molybdenum target. It is a non-invasive method to test breast diseases such as breast mass and calcification. From the viewpoint of techniques, it is a digital imaging technology that combines traditional radiology technology with modern computer technology that transforms the X-ray image into a digital image that can be quantized. Molybdenum target mammography enables radiologists to find suspicious malignant lesions in mammography easier. Thus, it has been used as a routine examination to reduce the risk of breast cancer.

Molybdenum target mammography
Molybdenum Target Mammography

Why is Molybdenum target mammography beneficial?

Molybdenum target mammography is currently the primary choice for the diagnosis of breast disease. It is an easy and non-invasive method of examination which can accurately reflect the condition of the entire breast. What’s more, it can be used to observe the breast disease caused by various factors and the results are relatively reliable. With the help of Molybdenum inspection, some precancerous lesions can be found and can be followed up for observation. So it is beneficial for women’s health.

Above information is from SAM Sputter Target, a global sputtering targets manufacturer specialized in Molybdenum target.

How was Molybdenum discovered? | History of Molybdenum

The brief history of the discovery of molybdenum

Although molybdenum was discovered in the late 18th century, it was used early before its discovery. For example, in the 14th century, Japan used a molybdenum-containing steel to make a saber. In the 16th century, molybdenite was used as graphite because it was similar to the appearance and properties of lead, galena, and graphite. At that time, Europeans referred to these kinds of molybdenum-containing ore as “molybdenite”.

Bengt Andersson Qvist
Bengt Andersson Qvist

In 1754, the Swedish chemist Bengt Andersson Qvist tested the molybdenite and found that it did not contain lead, so he believed that molybdenite and galena were not the same substance.

In 1778, the Swedish chemist Carl Wilhelm Scheele found that nitric acid did not react with graphite. While nitric acid reacted with molybdenite and produced a white powder, which was boiled together with an alkali solution to crystallize a salt. He believes that this white powder is a kind of metal oxide. After heating with charcoal, no metal is obtained; and when it is heated together with sulfur, the original molybdenite is obtained, so he believes that molybdenite should be an unknown mineral.

Peter Jacob Hjelm

Inspired by Scheler, in 1781, the Swedish chemist Peter Jacob Hjelm used a “carbon reduction method” to separate a new metal from the white powder and named the metal “Molybdenum”.

Molybdenum industry development

Since molybdenum is easily oxidized and has high brittleness, molybdenum smelting and processing are limited. Molybdenum was not able to be machined in the early period, so it is impossible to apply molybdenum to industrial production on a large scale. At that time, only a few molybdenum compounds were used.

In 1891, France’s Schneider Schneider took the lead in the production of molybdenum-containing armor plates using molybdenum as an alloying element. It was found to have superior properties, and the density of molybdenum was only half that of tungsten. Molybdenum gradually replaced tungsten as an alloying element of steel. The application of the molybdenum industry was started.

At the end of the 19th century, it was found that the properties of molybdenum steel were similar to those of tungsten steel of the same composition after the addition of molybdenum in steel. In 1900, the production process of ferromolybdenum was developed. The special properties of molybdenum steel to meet the needs of gun steel materials were also discovered. This made the production of molybdenum steel rapidly developed in 1910. Since then, molybdenum has become an important component of various structural steels that are resistant to heat and corrosion and has also become an important component of non-ferrous metals — nickel and chromium alloys.

This history column aims at introducing the history of different metal elements. If you are a metal lover or history lover, you can follow our website. For previous posts of metal history, you can look them up in the “history” category.

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