Molybdenum and Alloy Steel

Molybdenum is used efficiently and economically in alloy steel & iron to

-improve hardenability

-reduce temper embrittlement

-resist hydrogen attack & sulphide stress cracking

-increase elevated temperature strength

-improve weldability, especially in high strength low alloy steels (HSLA)

Molybdenum Added Into Steel

In the present section the focus is on grades and properties of Mo containing alloy steel and iron. End uses cover the whole world of engineered products for :

-Automotive, shipbuilding

-aircraft and aerospace

-Drilling, mining, processing

-Energy generation, including boilers, steam turbines and electricity generators

-Vessels, tanks, heat exchangers

-Chemical & Petrochemical processing

-Offshore; Oil Country Tubular Goods (OCTG)

In most cases molybdenum is needed to meet the high end of the application properties, which is accomplished with comparatively small molybdenum additions. In fact, with the exception of High Speed Steel and Maraging Steel the Mo content often ranges between 0.2 and 0.5% and rarely exceeds 1%.

Molybdenite Processing

In molybdenite processing, the molybdenite is first heated to a temperature of 700 °C (1,292 °F) and the sulfide is oxidized into molybdenum(VI) oxide by air:

2 MoS2 + 7 O2 → 2 MoO3 + 4 SO

The oxidized ore is then either heated to 1,100 °C (2,010 °F) to sublimate the oxide, or leached with ammonia, which reacts with the molybdenum(VI) oxide to form water-soluble molybdates:

MoO3 + 2 NH4OH → (NH4)2(MoO4) + H2O

Molybdenite

Copper, an impurity in molybdenite, is less soluble in ammonia. To completely remove it from the solution, it is precipitated with hydrogen sulfide.

Pure molybdenum is produced by reduction of the oxide with hydrogen, while the molybdenum for steel production is reduced by the aluminothermic reaction with addition of iron to produce ferromolybdenum. A common form of ferromolybdenum contains 60% molybdenum.

Molybdenum Biochemistry

The most important role of the molybdenum in living organisms is as a metal heteroatom at the active site in certain enzymes. In nitrogen fixation in certain bacteria, the nitrogenase enzyme, which is involved in the terminal step of reducing molecular nitrogen, usually contains molybdenum in the active site (though replacement of Mo with iron or vanadium is also known). The structure of the catalytic center of the enzyme is similar to that in iron-sulfur proteins: it incorporates a Fe4S3 and multiple MoFe3S3 clusters.

MoS2

In 2008, evidence was reported that a scarcity of molybdenum in the Earth's early oceans was a limiting factor for nearly two billion years in the further evolution of eukaryotic life (which includes all plants and animals) as eukaryotes cannot fix nitrogen, and must therefore acquire most of their oxidized nitrogen suitable for making organic nitrogen compounds, or the organics themselves (like proteins) from prokaryotic bacteria. The scarcity of molybdenum resulted from the relative lack of oxygen in the early ocean. Most molybdenum compounds have low solubility in water, but the molybdate ion MoO42− is soluble and forms when molybdenum-containing minerals are in contact with oxygen and water. Once oxygen made by early life appeared in seawater, it helped dissolve molybdenum into soluble molybdate from minerals on the sea bottom, making it available for the first time to nitrogen-fixing bacteria, and allowing them to provide more fixed usable nitrogen compounds for higher forms of life.

Molybdenum Parts

Although oxygen once promoted nitrogen fixation via making molybdenum available in water, it also directly poisons nitrogenase enzymes. Thus, in Earth's ancient history, after oxygen arrived in large quantities in Earth's air and water, organisms that continued to fix nitrogen in aerobic conditions were required to isolate and protect their nitrogen-fixing enzymes in heterocysts, or similar structures protecting them from too much oxygen. This structural isolation of nitrogen fixation reactions from oxygen in aerobic organisms continues to the present.

Molybdenum Rods

Though molybdenum forms compounds with various organic molecules, including carbohydrates and amino acids, it is transported throughout the human body as MoO42−.At least 50 molybdenum-containing enzymes were known by 2002, mostly in bacteria, and their number is increasing with every year; those enzymes include aldehyde oxidase, sulfite oxidase and xanthine oxi

  

TZM Bars

Molybdenum Bars

dase. In some animals, and in humans, the oxidation of xanthine to uric acid, a process of purine catabolism, is catalyzed by xanthine oxidase, a molybdenum-containing enzyme. The activity of xanthine oxidase is directly proportional to the amount of molybdenum in the body. However, an extremely high concentration of molybdenum reverses the trend and can act as an inhibitor in both purine catabolism and other processes. Molybdenum concentrations also affect protein synthesis, metabolism and growth.

In animals and plants a tricyclic compound called molybdopterin (which, despite the name, contains no molybdenum) is reacted with molybdate to form a complete molybdenum-containing cofactor called molybdenum cofactor. Save for the phylogenetically-ancient molybdenum nitrogenases discussed above, which fix nitrogen in some bacteria and cyanobacteria, all molybdenum-using enzymes so far identified in nature use the molybdenum cofactor. Molybdenum enzymes in plants and animals catalyze the oxidation and sometimes reduction of certain small molecules, as part of the regulation of nitrogen, sulfur and carbon cycles.

Synthetic Sapphire Applications

Along with zirconium and aluminium oxynitride, synthetic sapphire is used for shatter resistant windows in armored vehicles and various military body armor suits, in association with composites.

A common use of synthetic sapphire is in sapphire optical windows. The key benefits of sapphire windows are:

- Very wide optical transmission band from UV to near-infrared, (0.15-5.5 µm)  

-Significantly stronger than other optical materials or standard glass windows

- The hardest natural substance next to diamond

- Highly resistant to scratching and abrasion (9 Mohs scale)

- Extremely high melt temperature (2030°C)

 -Totally unaffected by all chemicals except some very hot caustics

Blue Sapphire

Sapphire glass windows (although being crystalline) are made from pure sapphire boules that have been grown in an application specific crystal orientation, typically along the optical axis, the c-axis, for standard optical windows for minimum birefringence. The boules are sliced up into the desired window thickness and finally polished to the desired surface finish. Sapphire optical windows can be polished to a wide range surface finishes due to its crystal structure and it hardness. The surface finishes of Optical Windows are normally called out by the Scratch-Dig specifications in accordance with the globally adopted MIL-O-13830 specification.

Synthetic Sapphire Applications

Sapphire glass windows are used in high pressure chambers for spectroscopy, crystals in various watches, and windows in grocery store barcode scanners since the material's exceptional hardness and toughness makes it very resistant to scratching.

Cermax xenon arc lamp with synthetic sapphire output window One type of xenon arc lamp (originally called the "Cermax" its first brand name), which is now known generically as the "ceramic body xenon lamp", uses sapphire crystal output windows that tolerate higher thermal loads – and thus higher output powers when compared with conventional Xe lamps with pure silica window.

Molybdenum Properties

Molybdenum

1. Molybdenum Physical properties

In its pure form, molybdenum is a silvery-grey metal with a Mohs hardness of 5.5. It has a melting point of 2,623 °C (4,753 °F); of the naturally occurring elements, only tantalum, osmium, rhenium, tungsten, and carbon have higher melting points.Weak oxidation of molybdenum starts at 300 °C. It has one of the lowest coefficients of thermal expansion among commercially used metals.The tensile strength of molybdenum wires increases about 3 times, from about 10 to 30 GPa, when their diameter decreases from ~50–100 nm to 10 nm.

2. Molybdenum Compounds and chemistry

Molybdenum is a transition metal with an electronegativity of 2.16 on the Pauling scale and a standard atomic weight of 95.96 g/mol.It does not visibly react with oxygen or water at room temperature, and the bulk oxidation occurs at temperatures above 600 °C, resulting in molybdenum trioxide:

2 Mo + 3 O2 → 2 MoO3

The trioxide is volatile and sublimates at high temperatures. This prevents formation of a continuous protective oxide layer, which would stop the bulk oxidation of metal.Molybdenum has several oxidation states, the most stable being +4 and +6 (bolded in the table). The chemistry and the compounds show more similarity to those of tungsten than that of chromium. An example is the instability of molybdenum(III) and tungsten(III) compounds as compared with the stability of the chromium(III) compounds. The highest oxidation state is common in the molybdenum(VI) oxide (MoO3), whereas the normal sulfur compound is molybdenum disulfide MoS2.

Molybdenum(VI) oxide is soluble in strong alkaline water, forming molybdates (MoO42−). Molybdates are weaker oxidants than chromates, but they show a similar tendency to form complex oxyanions by condensation at lower pH values, such as [Mo7O24]6− and [Mo8O26]4−. Polymolybdates can incorporate other ions into their structure, forming polyoxometalates.The dark-blue phosphorus-containing heteropolymolybdate P[Mo12O40]3− is used for the spectroscopic detection of phosphorus.[16] The broad range of oxidation states of molybdenum is reflected in various molybdenum chlorides:

Molybdenum(II) chloride MoCl2 (yellow solid)

Molybdenum(III) chloride MoCl3 (dark red solid)

Molybdenum(IV) chloride MoCl4 (black solid)

Molybdenum(V) chloride MoCl5 (dark green solid)

Molybdenum(VI) chloride MoCl6 (brown solid)

The structure of the MoCl2 is composed of Mo6Cl84+ clusters with four chloride ions to compensate the charge.

Like chromium and some other transition metals, molybdenum is able to form quadruple bonds, such as in Mo2(CH3COO)4. This compound can be transformed into Mo2Cl84−, which also has a quadruple bond.

The oxidation state 0 is possible with carbon monoxide as ligand, such as in molybdenum hexacarbonyl, Mo(CO)6.

Advanced Tungsten Molybdenum Sapphire Furnace

The GT Advanced Technologies advanced tungsten molybdenum sapphire furnace  is the ideal platform for producing high-quality, large-area sapphire substrates for markets that demand the highest grade sapphire material such as high brightness LEDs and other specialty industrial markets. Based on 40 years of proven sapphire production and crystalline growth process technology, the tungsten molybdenum sapphire furnace combines a highly automated, low risk operating environment capable of producing consistently uniform sapphire boules that yield high quality material for a lower cost of ownership.

Tungsten Molybdenum Sapphire Furnace

Advantages
-Fast A-axis, bottom-up growth producing high quality, low stress sapphire material.
-Short cycle times <18 days for 100 Kg boule*.
-Annual production capacity >100,000 TIE per furnace.
-Scalable architecture offers investment protection.
-Based on 40 years of proven sapphire material production.
-Flexibility in crucible geometry and charge size to meet wide range of customer requirements.
-Highly automated growth process with no moving parts for low cost, low risk operations.
-Easy seeding process.

The sapphire material produced in the tungsten molybdenum sapphire furnace is grown in a low thermal gradient, low stress environment that consistently produces high quality material ideally suited for high brightness HB LED applications and other specialty industrial markets. The tungsten molybdenum sapphire furnace provides a low-risk path to high volume sapphire production and a high return on your investment.

Molybdenum Sheet

Standard: ASTM B386
Material: Mo >99.95%
Density: >10.2g/cc

Molybdenum sheet is made of the material of molybdenum, so that molybdenum sheet owns the properties of molybdenum. Molybdenum sheet can stand extreme temperatures and keep its strength and stiffness at high temperatures. Molybdenum sheet also has good thermal conductivity and lower thermal expansion. It can provide excellent corrosion resistance that is similar to tungsten sheet. Our molybdenum products are widely used in aviation, aerospace, nuclear high-temperature furnace, glass, ceramic, crystal production, medical, illumination and vacuum sputtering etc. molybdenum sheet, suitable for light, electric vacuum device and electric semiconductor device.

Molybdenum Sheets

Molybdenum sheet is processed to obtain maximum ductility for applications involving bending, spinning, drawing or stamping. It is this objective that also gives the impression of molybdenum sheet special advantages. If the customer designates their specific application, we can supply the best material suited for their use, to meet their requirements of product-molybdenum sheet. It is this objective that also gives the impression of molybdenum sheet special advantages. If the customer designates their specific application, we can supply the best material suited for their use, to meet their requirements of product-molybdenum sheet.

Application:
Molybdenum sheet is used for making electric light source parts, components of electric vacuum and electric power semiconductor. It is also used for producing molybdenum boats, heat shield and heat bodies in high temperature furnace.

Molybdenum Crucible

-Standard: GB/T 17992-1999                                 

-Impurity content: <=0.03%

-Mo Content: >=99.95%

-Density: >9.8 g/cm3

-Working temperature: >1100°C

-Content Technique Density Size

-Mo >=99.95% Forging >=10.1g/cm3 (10-130mm) dia. x (10-2mm)

-Mo >=99.95% Sintering >=9.8g/cm3 (100-500mm) dia. x (50-700mm)

Molybdenum Crucibles

Most molybdenum crucible is produced by sintering pure molybdenum. The reason to use pure molybdenum as raw material is to prevent other metals melting in the molybdenum crucible from mingling impurities. Because molybdenum crucible has high-temperature resistance, low pollution and other excellent properties, molybdenum crucible is widely used in various industries. According to the required diameter, thickness, tilt angle, we can produce a various shapes and sizes of molybdenum crucible to meet your need.

Molybdenum crucible is a very important and essential tool in many industries. Molybdenum crucible can be used in smelting and rare earth metallurgy, mechanism process, electronics, artificial crystals, coating technology industries, such as: crystal materials, the sapphire growth, vacuum coating production, quartz glass melting furnace, smelting furnace and silicon crystal furnace and so on.

Tungsten Molybdenum Sapphires Treatments

Tungsten molybdenum sapphires may be treated by several methods to enhance and improve their clarity and color.It is common practice to heat natural sapphires to improve or enhance color. This is done by heating the sapphires in furnaces to temperatures between 500 and 1800 °C for several hours, or by heating in a nitrogen-deficient atmosphere oven for seven days or more. Upon heating, the stone becomes more blue in color, but loses some of the rutile inclusions (silk). 

When high temperatures are used, the stone loses all silk (inclusions) and it becomes clear under magnification. The inclusions in natural stones are easily seen with a jeweler's loupe. Evidence of sapphire and other gemstones being subjected to heating goes back at least to Roman times. Un-heated natural stones are somewhat rare and will often be sold accompanied by a certificate from an independent gemological laboratory attesting to "no evidence of heat treatment".

Tungsten Molybdenum Sapphires

 Yogo sapphires sometimes do not need heat treating because their cornflower blue coloring is uniform and deep, they are generally free of the characteristic inclusions, and they have high uniform clarity. When Intergem Limited began marketing the Yogo in the 1980s as the world's only guaranteed untreated sapphire, heat treatment was not commonly disclosed; by 1982 the heat treatment became a major issue. At that time, 95% of all the world's sapphires were being heated to enhance their natural color. Intergem's marketing of guaranteed untreated Yogos set them against many in the gem industry. This issue appeared as a front page story in the Wall Street Journal on August 29, 1984 in an article by Bill Richards, Carats and Schticks: Sapphire Marketer Upsets The Gem Industry.

Tungsten Molybdenum Sapphires

Diffusion treatments are used to add impurities to the sapphire to enhance color. Typically beryllium is diffused into a sapphire under very high heat, just below the melting point of the sapphire. Initially (c. 2000) orange sapphires were created, although now the process has been advanced and many colors of sapphire are often treated with beryllium. The colored layer can be removed when stones chip or are repolished or refaceted, depending on the depth of the impurity layer. Treated padparadschas may be very difficult to detect, and many stones are certified by gemological labs (e.g., Gubelin, SSEF, AGTA).

Tungsten Molybdenum Sapphire

Tungsten molybdenum sapphire  is a gemstone variety of the mineral corundum, an aluminium oxide (α-Al2O3). Trace amounts of other elements such as iron, titanium, chromium, copper, or magnesium can give corundum blue, yellow, purple, orange, or a greenish color. Chromium impurities in corundum yield a pink or red tint, the latter being called a ruby.

Tungsten Molybdenum Sapphire

Commonly, sapphires are worn in jewelry. Sapphires may be found naturally, by searching through certain sediments (due to their resistance to being eroded compared to softer stones) or rock formations. They also may be manufactured for industrial or decorative purposes in large crystal boules. Because of the remarkable hardness of sapphires, 9 on the Mohs scale (and of aluminium oxide in general), sapphires are used in some non-ornamental applications, including infrared optical components, such as in scientific instruments; high-durability windows; wristwatch crystals and movement bearings; and very thin electronic wafers, which are used as the insulating substrates of very special-purpose solid-state electronics (most of which are integrated circuits

Color in gemstones breaks down into three components: hue, saturation, and tone. Hue is most commonly understood as the "color" of the gemstone. Saturation refers to the vividness or brightness or "colorfulness" of the color, and tone is the lightness to darkness of the color. Blue sapphire exists in various mixtures of its primary (blue) and secondary hues, various tonal levels (shades) and at various levels of saturation (vividness).

Tungsten Molybdenum Sapphire

Blue sapphires are evaluated based upon the purity of their primary hue. Purple, violet, and green are the most common secondary hues found in blue sapphires. Violet and purple can contribute to the overall beauty of the color, while green is considered to be distinctly negative. Blue sapphires with up to 15% violet or purple are generally said to be of fine quality. Blue sapphires with any amount of green as a secondary hue are not considered to be fine quality. Gray is the normal saturation modifier or mask found in blue sapphires. Gray reduces the saturation or brightness of the hue and therefore, has a distinctly negative effect.

The color of fine blue sapphires may be described as a vivid medium dark violet to purplish blue where the primary blue hue is at least 85% and the secondary hue no more than 15%, without the least admixture of a green secondary hue or a gray mask..

The 423-carat (85 g) Logan sapphire in the National Museum of Natural History, in Washington, D.C., is one of the largest faceted gem-quality blue sapphires in existence.