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Molybdenum and tungsten in sapphire crystal growth industry

Molybdenum

With its unique mechanical and chemical properties, molybdenum is an outstanding material that can meet the most exacting requirements. Because molybdenum possesses a very high melting point, a low coefficient of thermal expansion and a high level of thermal conductivity, it is used in many different industries. Molybdenum is a genuine all-rounder. We use this material, for example, to produce ribbons and wires for the lighting industry, semiconductor base plates for power electronics, glass melting electrodes, hot zones for high-temperature furnaces and sputtering targets for coating solar cells and flat screens.

Molybdenum fine wire
Molybdenum fine wire
Molybdenum hot zone
Hot zone
Molybdenum glass melting electrode
Glass melting electrode
Molybdenum base plate
Molybdenum base plate
Properties of molybdenum
Atomic number42
CAS number7439-98-7
Atomic mass95.94
Melting point2620°C
Boiling point5560°C
Atomic volume0.0153 [nm3]
Density at 20 °C10.2 [g/cm3]
Crystal structurebody-centred cubic
Lattice constant0.3147 [nm]
Abundance in the Earth's crust1.2 [g/t]
Applications
Applications
Molybdenum-alloys
Alloys
Molybdenum properties
Properties
Natural occurrence and preparation
Occurrence
Powder metallurgy
Powder-
metallurgy

Guaranteed purity

!!Auf unsere Qualität können Sie sich verlassen. Wir produzieren unsere Molybdänprodukte vom Metalloxid bis zum fertigen Produkt selbst. Als Ausgangsmaterial verwenden wir nur reinstes Molybdänoxid. So garantieren wir Ihnen für unser Molybdän eine Reinheit von 99,97 % (metallische Reinheit ohne W). Der restliche Anteil setzt sich aus folgenden Elementen zusammen:!!

ElementTypical value max. [μg/g]Guaranteed value max. [μg/g]
Al110
Cr320
Cu220
Fe520
K620
Ni110
Si220
W169300
C1330
H010
N510
O640
Cd15
Hg*01
Pb05


*Initial value

The presence of Cr (VI) and organic impurities can be excluded definitely because of the production process (multiple heat treatment at temperatures above 1 000 °C in H2-atmosphere)

Applications

The industrial applications for our molybdenum are as varied as its properties. We briefly present three of these below:

High purity and excellent creep resistance

Our molybdenum is exceptionally pure, withstands very high temperatures and is nevertheless still easy to machine. For example,to produce crucibles for all the conventionally employed processes in the field of sapphire growth. Thanks to their exceptional purity, these have proved their worth as optimized melting and solidification vessels.

High dimensional stability and excellent corrosion resistance

Our stirrers homogenize all types of glass melt. To do this, they must withstand extreme temperatures and aggressive glass melts. Molybdenum makes it possible. With its excellent dimensional stability and corrosion resistance against metal and glass melts, our material ensures optimum stirring coupled with long product service lives.

High thermal conductivity and low thermal expansion

High power densities and the flow of electricity through power diodes and transistors generate heat. Thanks to its good thermal conductivity and thermal expansion properties that are adapted to the relevant semiconductor material, molybdenum and its alloys are the perfect substrate for power electronics. When used as a base plate, molybdenum reliably dissipates heat.

Pure molybdenum - or maybe an alloy?

We prepare our molybdenum to perform perfectly in every application. We can determine the following properties through the addition of various alloys:

  • Physical properties (e.g. melting point, vapor pressure, density, electrical conductivity, thermal conductivity, thermal expansion, heat capacity)
  • Mechanical properties (e.g. strength, fracture behavior, creep resistance, ductility)
  • Chemical properties (corrosion resistance, etchability)
  • Machinability (e.g. cutting processes, formability, weldability)
  • Recrystallization behavior (recrystallization temperature, embrittlement, aging effects)

And there's more: By using our own customized manufacturing processes, we can modulate various other properties of molybdenum across a wide range of values. The result: Molybdenum alloys with different ranges of properties which are precisely engineered to meet the requirements of each individual application.

Name of materialChemical composition (percentage by weight)
Mo (pure) >!!99,97 % Mo!!
TZM!!0,5 % Ti / 0,08 % Zr / 0,01 - 0,04 % C!!
MHC!!1,2 % Hf / 0,05 - 0,12 % C!!
Mo-Lanthanoxid (ML)ML!!0,3 % La2O3!!
MLR (R = Recrystallized)!!0,7 % La2O3!!
MLS (S = Stress relieved)!!0,7 % La2O3!!
MoILQ (ILQ = Incandescent Lamp Quality)

0,03 % La2O3

Mo-YttriumoxidMY!!0,47 % Y2O3 / 0,08 % Ce2O3!!
MoReMoRe5!!5,0 % Re!!
MoRe41!!41,0 % Re!!
MoWMW20!!20,0 % W!!
MW30!!30,0 % W!!
MW50!!50,0 % W!!
MoCuMoCu30!!30,0 % Cu!!
MoCu15!!15,0 % Cu!!
MoZrO2MZ17!!1,7 % ZrO2!!
MoNbMoNb10!!9,71 % Nb!!
MoTaMT11!!10,75 % Ta!!

TZM (Titanium-Zirconium-Molybdenum)

We transform our molybdenum into TZM by using small quantities of tiny, extremely fine carbides. TZM is stronger than pure molybdenum and possesses a higher recrystallization temperature and better creep resistance. TZM is used in high-temperature applications involving demanding mechanical loads, for example in forging tools or as rotating anodes in X-ray tubes. The recommended temperatures of use are between 700 and 1 400 °C.

MHC (Molybdenum-Hafnium-Carbon)

MHC is a particle-reinforced molybdenum-based alloy which contains both hafnium and carbon. Thanks to the uniformly distributed, extremely fine carbides, the material benefits from outstanding heat and creep resistance and, at 1 550 °C, the maximum recommended temperature of use is 150 °C higher than that of TZM. MHC is used in metal forming applications, for example. When used in extrusion dies, it is able to withstand extreme thermal and mechanical loads.

ML (Molybdenum-Lanthanum Oxide)

Small quantities of lanthanum oxide particles (0.3 or 0.7 percent) give the molybdenum a so-called stacked fiber structure. This special microstructure is stable at up to 2 000°C. Molybdenum-lanthanum oxide is therefore also creep-resistant even under extreme conditions of use. We mostly machine these alloys to produce furnace components such as stranded and other wires, sintering and annealing boats or evaporator coils. In the lighting industry, molybdenum-lanthanum oxide is used, for example, for retaining and feed wires.

MoILQ (Molybdenum-ILQ)

MoILQ is a microdoped molybdenum alloy with a lanthanum oxide content of only 0.03 percent by weight which has been specially developed for use in the lighting industry. Thanks to its specially adapted dopant content, its recrystallization temperature is higher than that of pure molybdenum. After recrystallization, its microstructure is also more fine-grained than in the case of pure molybdenum. Compared to our ML material, MoILQ is more suitable for forming and therefore easier to process. MoILQ is used for the core and support wires in the manufacture of filaments for incandescent and halogen lamps.

MY (Molybdenum-Yttrium-Cerium Oxide)

Our MY is a particle-reinforced molybdenum alloy that contains 0.47 percent yttrium oxide by weight and 0.08 percent cerium oxide by weight. We developed MY specially for use in the lighting industry. MY adheres well to quartz glass, is easy to weld and provides better resistance to oxidation than pure molybdenum. MY is primarily used in conductive ESS ribbons and in evaporation boats for applications in the field of coating technology.

MoW (Molybdenum-Tungsten)

!!Die Hochtemperatureigenschaften und Korrosionsbeständigkeit unseres Molybdäns verbessern Wolfram. MoW-Werkstoffe werden mit unterschiedlichen Zusammensetzungen von MW20 mit 20 Gewichtsprozent W bis MW50 mit 50 Gewichtsprozent W vorzugsweise für die Herstellung von Zink und für Rührwerkzeuge in der Glasindustrie eingesetzt. Außerdem fertigen wir aus unseren MoW-Legierungen Sputtertargets für die Beschichtung von Flachbildschirmen. MoW-Schichten zeigen ein verbessertes Ätzverhalten in der Herstellung von Dünnfilmtransistoren.!!

MoRe (Molybdenum-Rhenium)

Small quantities of rhenium make molybdenum ductile even below room temperature. Molybdenum-rhenium (MoRe) is primarily used for thermocouple wires in the standard compositions MoRe5 and MoRe41 as well as in applications where a high level of ductility is important.

MoCu (Molybdenum-Copper)

Molybdenum-copper (MoCu) is a composite material which contains up to 30 percent copper by weight. This composite combines the high thermal conductivity of copper and the low thermal expansion of molybdenum. Our MoCu is perfect for the manufacture of passive cooling elements (heat sinks and heat spreaders) in electronic components. Due to their low weight, molybdenum-copper composites are particularly suitable for this type of application where every gram counts: In the automotive industry they are used as carrier plates for the IGBT modules that act as inverters in electric drives.

MoZrO2 (molybdenum-zirconium oxide)

 

!!Glasschmelzelektroden müssen aggressiven Glasschmelzen und sehr hohen Temperaturen standhalten. Durch die Zugabe von 1,7 Gewichtsprozent Zirkoniumoxid haben wir Molybdän Eigenschaften verliehen, die speziell für die Glasindustrie interessant sind. MoZrO2 hat eine höhere Korrosionsbeständigkeit gegenüber Glasschmelzen und eine höhere Hochtemperaturfestigkeit und Kriechbeständigkeit als reines Molybdän.!!

Our molybdenum sputtering targets are used to produce thin functional layers for flat screens. In the case of touch panels, in particular, a high level of corrosion resistance is essential. We therefore add the alloy element niobium to our all-round star, molybdenum, in order to achieve a particularly high level of corrosion resistance. You want to combine high corrosion resistance and easy structuring of the sputtered layer? Then we recommend our MoTa alloy.

A good all-rounder. Material properties of molybdenum.

Molybdenum belongs to the group of refractory metals. Refractory metals are metals that have a higher melting point than platinum (1 772°C). In refractory metals, the energy binding the individual atoms together is particularly high. Refractory metals have a high melting point coupled with a low vapor pressure, high modulus of elasticity and high thermal stability. Refractory metals are also typically characterized by a low coefficient of thermal expansion and relatively high density. The fact that molybdenum belongs to the same group as tungsten in the periodic table means that it has a similar atomic structure and chemical properties. The excellent thermal conductivity of both molybdenum and tungsten is also of particular interest. However, molybdenum is easily deformable even at quite low temperatures and is therefore simpler to work than tungsten.

Molybdenum is a genuine all-rounder with a very well-balanced range of properties:

Properties
Atomic number42
Atomic mass95.94
Melting point2 620 °C / 2 893 K
Boiling point5 560 °C / 5 833 K
Atomic volume1,53 · 10-29[m3]

Vapor pressure

at 1 800 °C1 · 10-4 [Pa]
at 2 200 °C5 · 10-2 [Pa]
Density at 20 °C (293 K)10.2 [g/cm3]
Crystal structurebody-centred cubic
Lattice constant3,147 · 10-10[m]

Hardness at 20 °C (293 K)

stress-relief annealed>220 [HV10]
recrystallized160 - 180 [HV10]
Modulus of elasticity at 20 °C (293 K)320 [GPa]
Poisson number0,31
Coefficient of linear thermal expansion at 20 °C (293 K)5,2 · 10-6[m/(m·K)]
Thermal conductivity at 20 °C (293 K)142 [W/(m ·K)]
Specific heat at 20 °C (293 K)0,254 [J/(g·K)]
Electrical conductivity at 20 °C (293 K)17,9 · 106[1/(Ω·m)]
Specific electrical resistance at 20 °C (293 K)0,056 [(Ω·mm2)/m]

Sound speed at 20 °C (293 K)

Longitudinal wave6 250 [m/s]
Transverse wave3 350 [m/s]
Electron work function4,39 [eV]
Capture cross-section for thermal neutrons2,7 · 10-27[m2]

We are able to influence the properties of our molybdenum and its alloys by varying the type and quantity of alloy elements that we add as well as by using tailor-made production processes. The carbides that we specifically include in our TZM and MHC materials modulate the mechanical properties of molybdenum across all temperature ranges. In particular, oxides increase the recrystallization temperature and creep resistance of the molybdenum. Rhenium makes molybdenum ductile even at room temperature. Copper increases the thermal conductivity without having any serious effects on the coefficient of expansion.

Evaporation rates of refractory metals
Evaporation rates of refractory metals
Vapour pressure of refractory metals
Vapour pressure of refractory metals
Linear thermal expansion coefficient of Mo, TZM and MLR
Linear thermal expansion coefficient of Mo, TZM
and MLR depending on the temperature
Thermal conductivity of Mo, TZM and MLR
!!Wärmeleitfähigkeit von Mo, TZM und MLR!!
depending on the temperature
Specific heat
Specific heat
Specific electrical resistance
Specific electrical resistance

Molybdenum alloys compared to pure molybdenum

TZMMHCMLMoILQ
Alloy components (percentage by weight)0,5 % Ti
0,08 % Zr
0,01 - 0,04 % C
!!1,2 % Hf
0,05 - 0,12 % C!!
0,3 % La2O3
0,7 % La2O3
0,03 % La2O3
Thermal conductivity--
Stability at room temperature++
Stability at high temperatures/ Creep resistance++(<1 400 °C)
+ (>1 400 °C)
++(<1 500 °C)
+ (>1 500 °C)
+(<1 400 °C)
++ (>1 400 °C)
+
Recrystallization temperature++++++
Ductility after HT use+++++
Weldability++++
MYMoWMoReMoCu
Alloy components (percentage by weight)0,47 % Y2O3
0,08 % Ce2O3
20 - 50 % W5 / 41 % Re15 / 30 % Cu
Thermal conductivity~--++
Stability at room temperature~++-
Stability at high temperatures/ Creep resistance+++-
Recrystallization temperature+++-
Ductility after HT use+~+++
Weldability+~++-

~ comparable with pure Mo + higher than pure Mo ++ much higher than pure Mo - lower than pure Mo -- much lower than pure Mo

Thermophysical properties

Refractory metals are typically characterized by a low coefficient of thermal expansion and relatively high density. The same is true of molybdenum. This material is also characterized by a high level of thermal conductivity and low electrical specific resistance. Molybdenum atoms are strongly bonded and the element has a higher modulus of elasticity than many other metals. The thermophysical properties of molybdenum change with temperature.

Thermal expansion of molybdenum
Linear thermal expansion of molybdenum and tungsten
specific heats of molybdenum and tungsten
Specific heats of molybdenum and tungsten
Emissivity molybdenum

!!Die Abbildung fasst die in der Literatur zugänglichen temperaturabhängigen Emissivitätswerte für Molybdän - dargestellt als rotes Streuband - zusammen. Experimentell an Plansee-Proben in typischen Lieferzuständen bestimmte Emissivitätswerte liegen am oberen Ende des Streubandes.!!

The specific electrical resistivity of a material is the multiplicative inverse of its electrical conductivity. The lower the value of the specific electrical resistivity of a material, the better is its conduct current. The specific electrical resistivity is measured in Ωmm²/m. Metals show very different specific electrical resistivities. An example: silver 0.016 Ωmm²/m; titanium 0.8 Ωmm²/m. The temperature, alloying elements, impurities and defects of the respective material strongly influence the specific electrical resistivity. Our high performance materials molybdenum and tungsten show a very low specific electrical resistivity: appr. 0.05 Ωmm²/m at room temperature and even less then 0,5 Ωmm²/m at a temperature of 1,500°C. Therefore our metals are best suitable for the use as contact and coating materials. As molybdenum and tungsten have a cubic crystal lattice, the specific electrical resistivity shows the same value in all crystallographic orientations.

Specific electrical resistance of molybdenum and tungsten
Specific electrical resistance of molybdenum and tungsten
Thermal conductivity of molybdenum and tungsten as a function of temperature
Thermal conductivity molybdenum and tungsten
depending on the temperature

Mechanical properties

Due to its high melting point of 2 620 °C, molybdenum retains its strength and creep resistance even at high temperatures. The strength of molybdenum increases even further the more the material is cold-worked. In contrast to that of other metals, the ductility of molybdenum materials also increases with increasing cold working. We add rhenium as an alloy element to increase the ductility of molybdenum and to reduce its brittle-ductile transition temperature. We also use titanium, zirconium, hafnium, carbon and oxides of rare earths as alloy components to add to our molybdenum. Compared to other metals, the modulus of elasticity of molybdenum and its alloys is very high due to the strong bonds between the molybdenum atoms. This means that we are able to create a variety of materials with very specific ranges of properties.

Modulus of elasticity of molybdenum
Modulus of elasticity of molybdenum plotted against
the testing temperature compared to our other
!!hochschmelzenden Metallen Wolfram, Chrom, Tantal und Niob.!!
Typical 0.2 % proof stress for Mo and TZM sheet material in stress-relieved or
Typical 0.2 % proof stress for Mo and TZM
sheet material in stress-relieved or
recrystallized condition (2 mm sheet thickness)
Typical tensile strength
!!Typische Zugfestigkeit für Mo- und TZM- Blechmaterial im!!
!!spannungsarmgeglühten bzw. rekristallisierten Zustand (Blechstärke 2 mm)!!
Comparison of the steady - state creep rate
Comparison of the steady - state creep rate of Mo, TZM and MLR
sheet material at 1100 °C
Comparison of the steady - state creep rate of Mo, TZM and MLR sheet material at 1450 and 1800 °C
Comparison of the steady - state creep rate of Mo, TZM and MLR
sheet material at 1450 and 1800 °C

Description of the sample material for the creep tests

MaterialTesting temperature [°C]Material thickness [mm]Heat treatment before the test
Mo11001.51200 °C / 1h
14502.01500 °C / 1h
18006.01800 °C / 1h
TZM11001.51200 °C / 1h
14501.51500 °C / 1h
18003.51800 °C / 1h
MLR11001.51700 °C / 3h
14501.01700 °C / 3h
18001.01700 °C / 3h
Typical 0.2 % proof stress for Mo
!!Typische 0,2% Dehngrenzwerte für Mo-, TZM- und MHC-Stab-!!
!!material (Durchmesser 25 mm; spannungsarmgeglühter Zustand)!!
Typical ultimate tensile strength for Mo- and TZM sheet material
!!Typische Zugfestigkeit für Mo-, TZM- und MHC-Stabmaterial!!
(diameter 25 mm; stress relieved condition)
Hardness values for Mo, TZM and MHC rod material (25 mm diameter,
!!spannungsarmgeglühter Zustand) in Abhängigkeit der Temperatur!!
Optical micrograph of a Mo sheet
Optical micrograph of a
!!Mo-Bleches (spannungsarmgeglüht)!!
Optical micrograph of a Mo sheet
Optical micrograph of a
Mo sheet (recrystallized)
Optical micrograph of a MLR sheet metal
Optical micrograph of a MLR sheet metal

Brittle-to-ductile transition temperature

If molybdenum is heated above a certain temperature then it loses its brittleness and becomes ductile. This temperature that is required to bring about the transition from brittleness to ductility is known as the brittle-to-ductile transition temperature. It depends on various factors including the chemical composition and level of cold working of the metal.

The ductility and fracture toughness of molybdenum materials decrease as the recrystallization level increases. This means that the recrystallization temperature is a decisive factor. Above the recrystallization temperature, the structure of the material changes. This restructuring of the grain reduces the strength and hardness of molybdenum and increases the likelihood of fractures. Demanding forming processes such as rolling, swaging or drawing are necessary in order to restore the initial structure. The recrystallization temperature is highly dependent on the level of cold working of the molybdenum and on its chemical composition, and in particular its dopant content. The table below summarizes the typical recrystallization temperatures of basic molybdenum materials.

MaterialTemperature [°C] for 100 % recrystallization (annealing time: 1 hour)
Deformation level = 90 %Deformation level = 99.99 %
Mo (pure)1100-
TZM1400-
MHC1550-
ML13002000
MoILQ12001400
MY11001350
MoRe411300-
MoW301200-

!!Bei der mechanischen Bearbeitung von Molybdän und generell von Refraktärmetallen ist die Kenntnis über die speziellen Eigenschaften dieser Materialgruppe unumgänglich. Die spanlose Formgebung wie Biegen oder Abkanten muss über der Spröd-Duktil-Übergangstemperatur erfolgen, damit das Blech zuverlässig rissfrei verformbar ist. Je dicker das Blech, desto höhere Temperaturen sind notwendig, um es rissfrei zu formen. Auch Schneiden und Stanzen von Molybdän sind gut möglich, wenn das Werkzeug geschärft ist und die Anwärmtemperatur richtig eingestellt ist. Auch die spanabhebende Bearbeitung ist mit sehr robusten und starken Maschinen kein Problem. Bei speziellen Fragen rund um das Thema mechanische Bearbeitung von Refraktärmetallen stehen wir Ihnen mit unserer langjährigen Erfahrung sehr gerne zur Verfügung.!!

Chemical resistance

!!Die gute chemische Beständigkeit von Molybdän und seinen Legierungen wird in der chemischen Industrie und in der Glasindustrie besonders geschätzt. Bei einer Luftfeuchtigkeit von unter 60 % ist Molybdän korrosionsbeständig. Erst bei höherer Luftfeuchtigkeit bilden sich Anlauffarben aus. In alkalischen und oxidierenden Flüssigkeiten wird Molybdän bei Temperaturen über 100 °C unbeständig. Für die Anwendung von Molybdän in oxidierenden Gasen und Elementen über 250 °C haben wir zum Schutz vor Oxidation eine Schutzschicht namens Sibor® entwickelt. Glasschmelzen, Wasserstoff, Stickstoff, Edelgase, Metallschmelzen und Oxidkeramiken greifen Molybdän auch bei sehr hohen Temperaturen nicht oder im Vergleich zu anderen metallischen Werkstoffen weniger an.!!

!!Nachstehende Tabelle zeigt das Korrosionsverhalten von Molybdän. Die Angaben beziehen sich, wenn nicht gesondert vermerkt, auf reine, nicht mit Sauerstoff vermengte Lösungen. Fremde, chemisch aktive Substanzen in kleinsten Konzentrationen können das Korrosionsverhalten stark beeinflussen. Sie haben Fragen zu komplexen Korrosionsthemen? Wir stehen Ihnen mit unserer Erfahrung und unserem eigenen Korrosionslabor sehr gerne zur Verfügung.!!

Corrosion resistance of molybdenum
WaterCold and warm water < 80 °C (353 K)resistant
Hot water > 80 °C (353 K)not resistant
Hot water with nitrogen gassing or inhibitorresistant
Inorganic acidsHydrofluoric acid < 100 °C (373 K)resistant
Nitrohydrochloric acid, cold and warmnot resistant
Orthophosphoric acid up to 270 °C (543 K)resistant
Nitric acid, cold and warmnot resistant
Hydrochloric acid, cold and warmresistant
Sulfuric acid < 70 % up to 190 °C (463 K)resistant
Chromosulfuric acidnot resistant
LyesAmmonia solutionresistant
Potassium hydroxide (KOH < 50 %) up to 100 °C (373 K)resistant
Potassium hydroxide (KOH > 50 %)not resistant
Sodium hydroxide (NaOH < 50 %) up to 100 °C (373 K)resistant
Sodium hydroxide (NaOH > 50 %)not resistant
Sodium hypochlorite solution, cold and warmnot resistant
Organic acidsFormic acid 20 °C (293 K)resistant
Acetic acid up to 100 °C (373 K)resistant
Conc. lactic acid 20 °C (293 K)resistant
Oxalic acid 20 °C (293 K)resistant
Tartaric acid 20°C (293 K)resistant
Non-metalsBoron up to 1 600 °C (1 873 K)resistant
Carbon up to 1 100 °C (1 373 K)resistant
Phosphorous up to 800 °C (1 073 K)resistant
Sulfur up to 440 °C (713 K)resistant
Silicon up to 600 °C (873 K)resistant
Fluorine 20 °C (293 K)not resistant
Chlorine up to 250 °C (523 K)resistant
Bromine up to 450 °C (723 K)resistant
Iodine up to 450 °C (723 K)resistant
Glass melts*Up to 1 700 °C (1 973 K)resistant

* Excluding glasses containing oxidants (e.g. lead glass)

Corrosion resistance against gases
Ammonia gas resistant at
< 1000 °C
Air and oxygen resistant at < 400 °C
Noble gasesno reactionNitrogenno reaction
Carbon dioxide resistant at
< 1200 °C
Hydrogenno reaction
Carbon monoxide resistant at
< 1400 °C
Water vapor resistant at
< 700 °C
Hydrocarbons resistant at < 1100 °C

Please note that in atmospheres containing oxygen, in particular, a high level of oxidation occurs at temperatures over 400 °C. With special coatings such as Sibor®, we prevent the oxidation of molybdenum.

Corrosion resistance against ceramic furnace construction materials
Aluminum oxide resistant at < 1 900 °CMagnesium oxide resistant at < 1 600 °C
Beryllium oxide resistant at < 1 900 °CSilicon carbide resistant at < 1 300 °C
Graphite resistant at < 1 100 °CZirconium oxide resistant at < 1 900 °C
Magnesite bricks resistant at < 1 600 °C

The addition of up to 30 percent by weight of tungsten as an alloy component significantly improves the corrosion resistance of molybdenum, for example in zinc.

Corrosion resistance against metal melts
Aluminum resistant at
< 700 °C
Sodium resistant at < 1 030 °C
Berylliumnot resistantNickelnot resistant
Lead resistant at < 1100 °CPlutonium resistant at < 900 °C
Oxygen-containing lead resistant at
< 500 °C
Mercury resistant at < 600 °C
Caesium resistant at < 870 °CRubidium resistant at
< 1000 °C
Ironnot resistantScandiumnot resistant
Gallium resistant at < 300 °CRare earths resistant at < 1100 °C
Potassium resistant at
< 1200 °C
Silverresistant
Copper resistant at < 1300 °CUraniumnot resistant
GoldresistantBismuth resistant at
< 1400 °C
Lithium resistant at
< 1400 °C
Zinc resistant at < 400 °C
Magnesium resistant at
< 1000 °C
Tin resistant at < 550 °C

Natural occurrence and preparation

!!Molybdän ist schon seit dem 3. Jahrhundert v. Chr. bekannt. Der Begriff Molybdaena stand damals jedoch für Grafit und Bleiglanz, der mit dem Molybdänglanz (natürliches Vorkommen) verwechselt wurde. Erst im 17. Jahrhundert erkannte man, dass Molybdaena kein Blei enthält, und 1778 gelang es Carl Wilhelm Scheele, mithilfe von Salpetersäure, weißes Molybdänoxid (MoO3) herzustellen. Scheele nannte den weißen Niederschlag "Terra molybdaenae" (Molybdänerde). Im Jahr 1781 gelang es Peter Jakob Hjelm erstmals, Molybdänoxid zu reduzieren. Das Resultat: Metallisches Molybdän. Das chemische Symbol und genaueres Wissen über die chemischen Eigenschaften von Molybdän verdanken wir Jöns Jakob Berzelius. Die erste Fertigung von reinem Molybdän gelang erst Anfang des 20. Jahrhunderts durch Reduktion von Molybdäntrioxid (MoO3) mit Wasserstoff. Das wichtigste Mineral für die Herstellung von Molybdän ist Molybdänit (MoS2). Die größten Molybdänvorkommen sind in Nord- und Südamerika sowie in China zu finden. In den Kupferminen Chiles fällt Molybdän als Nebenprodukt der Kupfergewinnung an. Diese Erze enthalten etwa 0,5 Gewichtsprozent Molybdänglanz. Mithilfe der sogenannten Flotation werden die Begleitmineralien vom Molybdän getrennt. Nach diesem Verfahren enthält das Konzentrat durchschnittlich etwa 85 % Molybdänglanz (MoS2). Dieses Konzentrat wird bei 600 °C geröstet. Das Molybdänit (MoS2) wird zu Molybdäntrioxid (MoO3) oxidiert.!!

Molymet

With our holding in the Chilean company Molibdenos y Metales (Molymet) we have made an important step towards safeguarding our long-term supply of molybdenum. Molymet is the world's largest processor of molybdenum ore concentrates.

Did you know that molybdenum concentrate contains approximately 0.1 % rhenium? During the roasting process, this rhenium is sublimated as rhenium heptoxide (Re2O7) and is retrieved in the dust separator as a by-product of the molybdenum preparation process.

!!Das geröstete Molybdänkonzentrat oder auch technisches Molybdänoxid wird bei ca. 1 000 °C sublimiert oder durch chemische Verfahren weiter gereinigt. Die so erhaltenen Produkte für die Herstellung metallischen Molybdäns sind:!!

  • ADM (ammonium dimolybdate) / (NH4)2O 2MoO3 (white)
  • Molybdenum trioxide / MoO3 (green)

!!Aus den oben genannten Vorprodukten fertigen wir durch eine Zwei-Stufen-Reduktion mit Wasserstoff metallisches Molybdänpulver. Wir reduzieren Molybdäntrioxid unter Wasserstoffatmosphäre und erhalten ein leicht reduziertes Molybdänoxid (MoO2) mit der typischen Farbe rotbraun. Daher wird Molybdändioxid auch "Molybdänrot" genannt:!!

Two-stage reduction process in the presence of hydrogen in order to obtain metallic molybdenum powder

The second reduction is also performed in a hydrogen atmosphere and results in the end product – a metallic grey molybdenum powder:

Two-stage reduction process in the presence of hydrogen in order to obtain metallic molybdenum powder

How do we do it? With powder metallurgy!

So what is powder metallurgy? It is well known that nowadays most industrial metals and alloys, such as steels, aluminum and copper, are produced by melting and casting in a mold. In contrast, powder metallurgy does away with the melting operation and the products are manufactured by compacting metal powders which are then subjected to a heat treatment (sintering) below the melting temperature of the material. The three most important factors in the field of powder metallurgy are the metal powder itself as well as the compacting and sintering operations. We are able to control and optimize all these factors in-house.

Why do we use powder metallurgy? Powder metallurgy allows us to produce materials with melting points of well over 2 000 °C. The procedure is particularly economical even when only small quantities are produced. In addition, by using tailor-made powder mixes, we can produce a range of extremely homogeneous materials endowed with specific properties.

!!Das Molybdänpulver wird mit möglichen Legierungselementen gemischt und anschließend in Formen gefüllt. Es folgt der Pressvorgang bei Drücken bis zu 2 000 bar. Der so entstandene Pressling (auch Grünling genannt) wird danach in speziellen Öfen bei Temperaturen über 2000 °C gesintert. Dabei wird er dicht und bildet seine Mikrostruktur aus. Die ganz besonderen Eigenschaften unserer Werkstoffe, wie ihre hohe Warmfestigkeit und Härte oder ihr Fließverhalten, entstehen durch die richtige Umformung, zum Beispiel beim Schmieden, Walzen oder Ziehen. Nur wenn all diese Schritte perfekt zusammenspielen, können wir unseren hohen Qualitätsanspruch erfüllen und Produkte mit höchster Reinheit und Güte erzeugen.!!

Oxide
Reduction
Mixing
Alloying
We compress our metal powders and powder mixes at pressures of up to 2 t/cm² (tonnes per square centimetre) to form a so-called green compact. When end products with particularly demanding geometries are required, we make sure as ear
Pressing
Sintering
Forming
Heat
treatment
Mechanical
treatment /
bonding
Quality
assurance
Recycling

Here you can download our safety data sheets:

  • Mo, TZM, MHC, ML, MY
  • MoRe
  • MoW
  • MoCu
  • MoTa