TUNGSTEN

Name: Tungsten (supposedly from the Proto-Norse/German Wolf Rahm “Wolf Drool”)

Symbol: W

Group: 6

Period: 6

Block: d

Category: Transition metals

Atomic number: 74

Atomic mass: 183.84 u

Electrons per shell: 2, 8, 18, 32, 12, 2

Electronegativity: 2.36

Density: 19.25 g/cc

Melting point: 3422ºC

Boiling point: 5930ºC

Thermal conductivity: 170 W (m·K)

Electrical conductivity: 2 × 10^7 S/m

Magnetic order: Paramagnetic

Ordinary state: Solid

States of Oxidation: +4, +6

Mohs Hardness: 7.5

Vickers Hardness: 3430 MPa

Brinell Hardness: 2570 MPa

Most stable isotopes: W-180 (0.12%), W-182 (26.50%), W-183 (14.31%), W-184 (30.64%), and W-186 (28.46%)

Discoverer: Juan José and Fausto Elhúyar, Spaniards (1783)

Tungsten, also known as Wolfram, is a transition metal from group 6 of the periodic table, renowned for its exceptional hardness, high density, and extremely elevated melting point, making it a strategic material in modern industry. Its discovery is deeply linked to the Nordic regions, particularly Sweden, where it is found in minerals like scheelite (CaWO₄) and wolframite ((Fe,Mn)WO₄), two tungstates that combine tungsten with calcium, iron, or manganese in the form of complex oxides. Historically, Sweden and the Scandinavian Peninsula have been associated not only with tungsten but also with many lanthanides, due to the rich mineralogy of the region, which has been a key center for research in chemistry and mineralogy since the 18th century.

The first scientific contact with tungsten occurred in 1781 when the renowned Swedish chemist Carl Wilhelm Scheele investigated scheelite, then known as "tungsten" (from the Swedish tung sten, meaning "heavy stone"). Scheele managed to obtain tungstic acid (H₂WO₄) from this mineral but could not isolate the metal in its pure form. Shortly thereafter, his compatriot Torbern Bergman, a prominent scientist of the time, conducted complementary studies and, together with Scheele, hypothesized that tungstic acid could be the key to discovering a new element. Although their efforts did not culminate in the isolation of the metal, they laid the groundwork for subsequent research by identifying the unique chemical properties of the mineral.

The definitive milestone in the discovery of tungsten occurred in 1783 when the Basque brothers Fausto and Juan José de Elhúyar, Spanish chemists trained in the European scientific tradition, successfully reduced tungstic acid using charcoal, obtaining the pure metal for the first time. This achievement, carried out at the Seminary of Vergara and supported by the Real Sociedad Bascongada de Amigos del País, marked a crucial moment in the history of chemistry. The Elhúyar brothers proposed the name "wolframio," derived from the term "wolfram" used by Bergman, which in turn referred to the mineral wolframite, whose etymology comes from the German wolf rahm ("wolf's soot" or "wolf's cream"), alluding to the foam that formed during its processing. However, in English-speaking countries and much of continental Europe, the name "tungsten" (from Swedish tungsten) became popular due to its association with scheelite, creating a duality in nomenclature that persists to this day, with "wolframio" as the official term recognized by the International Union of Pure and Applied Chemistry (IUPAC) and "tungsten" widely used in industrial and commercial contexts.

The discovery of tungsten by the Elhúyar brothers not only highlighted Spain's contribution to modern chemistry, along with other metals like platinum and vanadium, but also reflected the scientific spirit of the Enlightenment, characterized by international collaboration and experimental rigor. The importance of tungsten grew exponentially in the 20th century when its unique properties, such as its melting point of 3422 °C (the highest of all metals) and its density of 19.25 g/cm³, made it an essential material for industrial applications. From incandescent lamp filaments to high-strength alloys in cutting tools, turbines, and armor plating, tungsten is a pillar of modern metallurgy. Its extraction, mainly from scheelite and wolframite in countries like China, Russia, and Bolivia, satisfies the global demand for this strategic metal, whose versatility continues to drive advances in sectors such as aerospace, electronics, and defense.

Depending on the country, one name or the other is used. In Spain, the Netherlands, Poland, and Germany, among others, "Wolframio" ("Wolfram") is used. "Tungsten" is more popular in the United States, Central and South American countries, Canada, the United Kingdom, Ireland, Australia, among others. Ironically, in Sweden, Norway, Denmark, and Finland, the element is known as Volfram or Volframi (depending on the specific language). There is no precise consensus dictating which of the two should be employed. Under normal circumstances, anyone with minimal knowledge of metallurgy knows that this metal has two names.

The origin of "Tungsten" comes from Swedish, "Tung" means heavy, ponderous, and "Sten", stone, hence Tung + Sten would translate to "Heavy Stone". This refers to scheelite, which is denser than the vast majority of common minerals (6 g/cc).

"Wolfram" comes from German (or Norse) and, supposedly, alludes to a theory in which a demonic spirit or something similar in the form of a Wolf converted the "good mineral" containing Tin (cassiterite) into a useless one (at that time, of course) that, as happens in the case of Cobalt and Nickel, tormented miners by playing a practical joke on them. Wolfram would mean "Wolf's saliva" or "Wolf's spittle," something I find hard to believe, but well, I don't make (nor am I interested in making or rewriting) the rules.

Tungsten is a refractory metal with atomic number 74, belonging to the group of refractory metals. It is quite famous among these and stands out for its wide range of possibilities. It can be said that, among the scarce metals, it is by far the most popular.

In its pure state, it is silvery with a "tinned" tint very similar to that of Tin. Very pure and polished, it is bright, but it easily dulls over time due to the formation of a surface oxide that makes it more grayish, similar to Iron. It is very hard (second only to Chromium with 7.5 Mohs) and dense (almost as dense as Gold). It has the highest melting point of all chemical elements (since Carbon does not melt but sublimes) and also the highest boiling point, very close to Rhenium among metals (some place Rhenium first).

It is extremely robust, rigid, and when very pure, sufficiently ductile to form very thin wires with it, which is impossible with similar metals. It is affordable compared to other metals of its nature, and we can find it in multiple applications that exploit its hardness, heat resistance, and to a lesser extent, chemical inertia. It is indispensable in the armaments and aerospace industries, and it forms part of almost all important Nickel, Cobalt, or Nickel-Cobalt superalloys. A siderophile element (erroneously classified as Lithophile by Goldschmidt), it can be found accompanying ferrous metals as a byproduct of these, or also Manganese and Calcium. It is relatively easy to obtain, although the method involves several steps. As with most refractory metals, it is not necessary to obtain the pure metal to alloy it; instead, purified tungsten oxide (typically the yellow trioxide, WO3) is added to molten steel, where oxygen is released with coke, and the metal then alloys with Iron. Tungsten plays a dominant role in the steel industry and is, in many ways, one of the most important industrial metals.

Tungsten has been, is, and will be synonymous with superlative qualities. It has the highest tensile strength modulus (resistance to fracture by elongation) of all pure chemical elements, as well as the highest melting point among metals (and all elements if we consider that Carbon does not properly melt, but sublimes from solid to gas). It possesses the second highest compressive strength modulus among all elements, surpassed only by Osmium. The hardness of Tungsten is legendary, although not as high as that of Chromium (8.5 vs. 7.5 Mohs for Tungsten), but being more difficult to fracture than Chromium, it is (incorrectly) considered the "hardest" element. Nevertheless, Tungsten surpasses Chromium in its role as a hardener in Steel, among other things, because the Carbide it forms (typically binary, of formula WC) is much better than those formed by Chromium. These Carbides are the most thermodynamically stable among all existing metal-Carbon combinations (refractory) and are therefore the most expensive and widely used.

Metallic Tungsten is very robust and withstands mechanical stress well, but if a sufficiently strong, dry impact is applied, the metal responds as a typically brittle one would, cracking instead of denting, as is the case with malleable metals like Copper, Nickel, and precious metals used in jewelry.

Tungsten has the lowest coefficient of thermal expansion of all metals and elements in general.

It is also a very good thermal and electrical conductor. In its case, this is notable, given that normally refractory, hard metals are not usually good conductors of either heat or electricity (one of the reasons why Tungsten was chosen to manufacture the filaments of old light bulbs is its high electrical conductivity).

Likewise, Tungsten is extremely resistant to deformation by heat. While other metals begin to wrinkle at a certain temperature (long before even reaching temperatures close to the melting point), Tungsten remains rigid well past 2000ºC, without dilating. The problem is that long before even reaching 1000ºC, the metal begins to oxidize very rapidly; after all, it is neither a noble nor a precious metal (something similar occurs with Tantalum and Rhenium).

Another interesting characteristic of Tungsten is that it is highly resistant to liquid mercury (which spontaneously forms amalgams with most metals).

Tungsten cannot be considered a base metal as it does not act as such; the vast majority of the time it is used as an alloying agent, never as a base, except for rare exceptions where it is found sintered, again, without acting as a metal proper.

In connection with this, it is important to note that the "metallic" Tungsten that is usually sold, for example, in the form of tubes for highly heat-resistant conduits or general parts used as nuclear shielding, is not strictly single-phase metallic Tungsten, but rather granules of the metal compacted under high pressure and heat, which are finally agglomerated with the use of a second metal in small doses that acts as a cement. This process is also followed for Carbides, Nitrides, Borides, and Oxides.

Only Tungsten melted by an electron beam (laser) can be considered truly metallic Tungsten, since in this case the atoms form proper long chains instead of a cemented solution, like a composite.

Naturally, 100% metallic Tungsten melted in one piece is very expensive and has no uses since normally the sintered version is used for everything. The problem is that Tungsten formed by sintering does not have the same properties as a single-piece melt (a costly process since the melting point is over 3000ºC and is only achieved in small doses by electron beam), so many of the "official" values for Tungsten, such as its Vickers hardness, Brinell hardness, elastic modulus, among others, might not be accurate, or at least, they would be better in the molten state than in the sintered state.

Molten Tungsten is sold to collectors in the form of "nuggets" obtained by the aforementioned electron beam melting process, which achieves a temperature sufficient to melt the metal, condense it, and form small spheroid "tear-shaped" nuggets (like small balls) of the pure metal. Beyond this, using it in this way has no major relevance.

Robust, rigid, hard, the champion of refractories, dense and durable, strong. Tungsten, like other refractory metals and Osmium and Iridium, presents a unique crystalline structure in which atoms are so strongly bonded to each other that they form chains stable enough to remain unaltered up to more than 3000ºC in an inert atmosphere. 

The corrosion resistance of Tungsten, also known as Wolfram, a transition metal from group 6 of the periodic table, is one of its most complex characteristics and, in certain aspects, a significant limitation compared to other transition metals like chromium or molybdenum. Although tungsten is known for its exceptional hardness, high density, and record melting point of 3422 °C, its behavior against corrosive agents reveals a chemically selective nature. Under ambient conditions, tungsten shows remarkable inertia to both dilute and concentrated acids at room temperature, making it resistant to immediate attack by common acids such as hydrochloric (HCl), sulfuric (H₂SO₄), and nitric (HNO₃). However, this resistance is only superficial, as over time, even at low temperatures, these acids slowly attack the metal's surface, forming oxides or soluble compounds that compromise its integrity. When heat is applied, the reaction significantly accelerates, becoming irreversible and leading to more pronounced corrosion, especially in oxidizing acids like nitric and sulfuric, where tungsten loses its chemical stability.

Alkaline bases represent an even greater challenge for Tungsten, particularly under high-temperature conditions. Hot solutions of sodium hydroxide (NaOH) or potassium hydroxide (KOH) rapidly dissolve the metal, forming soluble tungstates such as Na₂WO₄, which limits its use in alkaline environments, such as certain industrial chemical processes. Furthermore, tungsten is one of the few metals that experiences hydrogen embrittlement at elevated temperatures, a phenomenon in which atomic hydrogen diffuses into the metal's crystal structure, reducing its ductility and compromising its mechanical quality. This susceptibility to hydrogen is especially problematic during the manufacturing of pure metallic tungsten or its alloys, as it can affect the structural integrity of components intended for high-strength applications, such as cutting tools or incandescent lamp filaments.

Despite these limitations, Tungsten exhibits good corrosion resistance in fresh and salt water, making it suitable for certain applications in aquatic environments, such as components in marine systems or structures exposed to humidity. In hydrochloric acid, tungsten shows moderate resistance, especially in low concentrations and at room temperature, but its stability decreases significantly in the presence of oxidizing acids like nitric or sulfuric, where the formation of surface oxides fails to effectively protect the metal. These chemical characteristics restrict the use of tungsten in chemically aggressive environments, but its exceptional mechanical and thermal resistance compensates for this in applications where corrosion is not the primary factor. For example, tungsten is widely used in high-strength alloys for cutting tools, welding electrodes, and armor plating in the aerospace and defense industries, as well as in filaments for lamps and X-ray tubes, where its stability at high temperatures is more critical than its corrosion resistance. The global production of tungsten, mainly from minerals such as scheelite and wolframite in countries like China, Russia, and Bolivia, continues to grow to meet the demand for these specialized applications.

Tungsten is the most important and famous transition metal of period 6, surpassed only by Platinum and, of course, Gold.

Tungsten has many uses, but the vast majority can be summarized by considering its properties in its pure state and those it imparts to the alloys in which it is added.

In a binary Iron-Tungsten alloy in the absence of Carbon, Tungsten would significantly increase the rigidity and hardness of Iron, but even 0.10% Carbon completely alters the result, not to mention contents between 0.90% and 1.10% Carbon convert the mixture into a very hard, rigid, and more heat-resistant alloy. It is also more resistant to wear and to the loss of hardening obtained by heat treatment. Tungsten is 100% soluble in Iron at any volume and can be added to Steel (of any type, including Stainless) as an oxide without having to go through the costly procedure of purification and obtaining the pure or high-purity metal (>99.9%).

In Steels, Tungsten is used in quantities between 2% and up to 20%. The higher the content (and provided that the amount of Carbon is around 1% by mass), the greater the hardness and rigidity achieved, at the cost of a loss of ductility and malleability. High-Tungsten Steels are so rigid that working them with a hammer is virtually impossible, even for machines, let alone for the arm of the best blacksmith who already struggles with a Carbon Steel of close to 1% without considering the addition of Tungsten.

With Tungsten, and if Carbon is present at 1% (or around 1%), this metal "steals" Carbon atoms from Iron, forming intergranular Tungsten Carbide which greatly increases the hardness and rigidity that Iron manages to retain, since it is tough enough to achieve a non-brittle alloy that nevertheless requires heat treatment to prevent embrittlement. Tungsten-Steel combinations are used only when a very high mixture of hardness and heat resistance is required, as Tungsten itself is not an inexpensive metal.

Recently, Tungsten has been replaced by percentages of Chromium, Vanadium, and especially Molybdenum, which seek to lower the cost of the final alloy. The main group of Tungsten Steels is HSS (High Speed Steel), although its use has declined in favor of Tungsten Carbide (without Iron/Steel), which is much harder (9 Mohs vs. 7-7.5 Mohs for ultra-hard HSS Steel) and is often simply called "Carbide," something I do not recommend as it can be confused with the other most used Carbide, Silicon Carbide.

Tungsten improves the corrosion resistance of Steels, but not as much as Chromium and Molybdenum. The reason is that in one gram of Tungsten there are billions fewer atoms than in one gram of Molybdenum and even fewer than Chromium. It is never used for this purpose; it is considered an additional beneficial effect but not specifically used for it.

The role of Tungsten in Nickel alloys (Superalloys) and to a lesser extent, though also notably, in Cobalt alloys (e.g., some grades of Stellite, Vitallium). In this sense, Tungsten is primarily used to improve dimensional stability (rigidity) by preventing thermal expansion at high temperatures, with or without Carbon.

The most important compound of the metal is as famous as Tungsten itself. It has been used since before World War II and is the most "familiar" form of the element in the sense that normally the Tungsten purchased is actually the Carbide, which does not have the same properties as the pure metal, as is logical.

Since I have already described the compound and its uses previously in the Carbides section (see Carbon section), it forms easily; it is not necessary to add the pure metal and then make it react with Carbon; instead, the Oxide (typically WO3) is directly added in the presence of carbon saturation. I say saturation because the percentages of Carbon must be sufficiently high, either as coke or any other form of carbon supply, for the Oxygen to be completely released, forming CO2. When Oxygen is removed, Tungsten's high affinity causes it to absorb Carbon and finally form the Carbide without any major inconvenience other than the cost of resources needed to carry out the reaction, which involves high temperatures = more fuel burned.

Tungsten Carbide, also known as "Widia" from German or simply "Carbide" (the latter also applies to Silicon Carbide), is used for drill bits, sandpaper, and abrasives in general. It is a grayish "steely" powder that is milled to reduce the grain size, to such an extent that these become observable only under a microscope. Once reduced in size, they are cemented with a binder such as Cobalt or Nickel to form the final piece.

Cobalt is used for Widia parts that are more heat-resistant and exhibit greater rigidity and hardness. Widia grades with Cobalt are among the most rigid and compact materials in the world, withstanding high Gigapascal indices under pressure.

Nickel is typically used in tougher (but less rigid) mixtures, more resistant to corrosion, in combination with Chromium-Molybdenum to improve resistance to chemical attack.

Tungsten carbide has become a fashionable choice for use as a material in so-called alternative jewelry, and more specifically, in the manufacture of wedding band type rings.

Much has been said and debated about the properties of this material (erroneously called metal or alloy). While some claim that a ring made of tungsten carbide could withstand the heat of the Sun's surface, others claim it is in fact a mere brittle composite, easy to pulverize. In this section, we will once and for all clear up doubts about this material. What is it made of? How is it manufactured? Is it true that it is "indestructible"? And most importantly, in my opinion, is it really worth its cost?

I will start by saying that tungsten carbide itself is an extremely hard (9.5 Mohs) grayish powder that is synthesized from the chemical combination of the elements tungsten and carbon at high temperatures.

It is neither a metal nor a ceramic, but a combination of these two; that is, a cermet.

In its pure state, it is a very hard, brittle, and corrosion-resistant powder, it melts at high temperatures (around 2800 °C) and has been used since before the 20th century as a starting material for the manufacture of cutting tools that exploit its main virtue: hardness.

It wasn't until the 1980s that the possibility of using it in the field of jewelry began to be explored, although its popularity definitively exploded in the first decade of this century.

But, if it's a powder, how do they shape it into a ring?

What you see when you look at a tungsten carbide ring is actually a sintered composite. It is not in any case the aforementioned powder, but the latter shaped (agglomerated) thanks to a ferrous metal that acts as "glue" between the carbide particles. In the jewelry industry, nickel is usually used in preference to cobalt, as the former is much tougher and more corrosion-resistant than the latter. Actually, a tungsten carbide ring is a mixture of the powder that gives it its name and a metal or alloy of the latter that reinforce its ductility (which is minimal in any case) and serve as a base, as already mentioned.

The reason it has a smooth and solid finish (free of pores) is due to a very elaborate and complex process in which the intrusion of chemical agents such as oxygen, nitrogen, or hydrogen is not tolerable.

Tungsten was and continues to be used in military applications for the manufacture of all kinds of devices, among which ultra-hard, high-density ammunition stands out, typically reserved for large-caliber projectiles since its use in smaller calibers does not offset the difference with Lead and hardened Steel. Normally, as the diameter of the projectile increases, Lead is also abandoned in favor of Steel. This is due, among other things, to the fact that Lead is too dense in its high-purity state (rarely used pure, instead doped with Antimony) and soft (it would expand even before exiting the barrel due to friction). Steel is doped with Tungsten because it increases the rigidity, hardness, and density (although it does not reach that of Lead) in projectiles for Tanks, submarines, battleships, et cetera, and to a lesser extent, aerial fighters.

The second main use of Tungsten is as a hardener in Steels for armor plating, initially in German Panzers and then applied to more combat vehicles, not necessarily ground-based. The improvement in resistance to projectile impacts, in turn, sacrifices vehicle mobility (due to the increase in overall weight). Heat resistance in this context is not as relevant as in other contexts.

One of the things rarely mentioned about Tungsten Steel as the warhead of tank projectiles is that the preferred material was not this, but depleted uranium, which is not only denser than any Tungsten alloy, but unlike them, is pyrophoric; it ignites upon impact. This causes the opposing vehicle to suffer an explosion accompanied by fire, which is more dangerous than a non-flammable projectile.

During World War II, both Spain (northwest region, Galicia and Asturias to a lesser extent) and especially Portugal (Europe's largest reserves) saw German delegations initiate a short-lived local market (which would last the war) in which it has been said locally that "they came to buy this (referring to Tungsten minerals) at the price of Gold," which is not literal, of course. It was expensive, but not that expensive.

The Germans were the first to realize the effects of Tungsten in Steel, so they began buying it from anyone who had mines of this metal, which was indispensable for the development of the war. Currently, Tungsten continues to be used for armament purposes (to the extent that its metal has risen in price) and has been progressively withdrawn from the civilian market (non-military applications such as drill bits, abrasives, et cetera) while it was published that Molybdenum Steels "were superior," which is false and is a cover-up to hide the real reason for the progressive withdrawal of the metal, not because it is dangerous to sell (not at all) but because the more Tungsten is placed in civilian hands, the less there will be for the military industry. Sometimes it's so simple to understand that my head hurts reading what I normally have to read.

Tungsten, also known as Wolfram, stands out as an exceptional material for anti-nuclear shielding due to its extraordinary density of 19.25 g/cm³, one of the highest among metals, comparable to that of gold and uranium. This high density is derived from tungsten's compact crystalline structure, where tungsten (W) atoms are arranged in a body-centered cubic lattice with extremely strong W–W bonds repeated billions of times in just one gram of the metal. This atomic configuration creates a high-density nuclear "net" that acts as a highly effective barrier against various forms of ionizing radiation, including fast neutrons, alpha particles (positively charged helium nuclei), and, to a lesser extent, gamma rays, which are high-energy photons. Tungsten's ability to attenuate these radiations makes it a strategic material in applications where radiation protection is critical, such as in nuclear reactors, medical radiotherapy facilities, and shielding systems in the aerospace and defense industries.

The effectiveness of Tungsten as anti-nuclear shielding lies in its high atomic density and its high atomic number (Z=74), which allow it to interact efficiently with charged particles and high-energy radiation. Fast neutrons, which are uncharged particles, are absorbed or scattered by the dense tungsten nuclei, reducing their energy and minimizing their penetration capability. Alpha particles, due to their positive charge and large mass, are easily stopped by tungsten's dense atomic lattice, which blocks their passage over very short distances. In the case of gamma rays, which require high-density and thick materials for attenuation, tungsten offers a more compact solution than traditional materials like lead, as its higher density allows for the same protection with a smaller volume. This is particularly advantageous in applications where space and weight are constraints, such as in satellites, spacecraft, or containers for radioactive materials.

Unlike other shielding materials, such as lead, which is softer and less resistant to high temperatures, Tungsten combines its radiation attenuation capability with outstanding mechanical and thermal resistance, thanks to its melting point of 3422 °C, the highest of all metals. This property allows tungsten to maintain its structural integrity in extreme environments, such as the interiors of nuclear reactors or systems exposed to radiation in space. Additionally, tungsten is less toxic than lead, making it a safer alternative for medical applications, such as shields in computed tomography equipment or radiotherapy. However, its high density and production cost, derived from its extraction from minerals like scheelite (CaWO₄) and wolframite ((Fe,Mn)WO₄) in countries like China, Russia, and Bolivia, can limit its use in large-scale applications. Despite these limitations, the unique combination of density, strength, and shielding capability of tungsten solidifies it as an indispensable material in protection against nuclear radiation, contributing to safety in critical sectors such as nuclear energy, medicine, and space exploration.

Tungsten is used as weight in elite applications as a replacement for Lead (ballast) because it is denser even in smaller volumes. This is very practical, for example, in motorsports competitions, where weight is distributed more evenly in smaller volume spaces. As a rule, the same car cannot be considered in an equal state of competitiveness if one driver weighs 10 kilograms more than another in the same team or on the grid in general. This amount, which may not seem like much (10 kilograms, more or less), becomes very important in elite cars or rather single-seaters such as Formula 1 or IndyCar where ballast is added when the sum of the driver's and vehicle's weight does not meet the minimum.

In inert gas welders, Tungsten alloyed with Thoria (ThO2) is very effective as it exhibits extreme heat resistance.

In a state of high purity, Tungsten is used to manufacture carriers such as tubes or containers for corrosive gases, corrosive chemical substances, et cetera, whenever the need for a heat-resistant material is sought.