Σκόνη μολυβδαινίου

Επισκόπηση της σκόνης μολυβδαινίου

Molybdenum is a silvery-white refractory transition metal with very high melting point, excellent corrosion resistance, and good thermal/electrical conductivity. In powder form, it exhibits high strength at elevated temperatures along with stability in harsh environments.

Key properties of molybdenum powder include:

• High temperature strength and creep resistance
• Εξαιρετική αντοχή στη διάβρωση
• Καλή θερμική και ηλεκτρική αγωγιμότητα
• Χαμηλός συντελεστής θερμικής διαστολής
• Υψηλή σκληρότητα και αντοχή στη φθορά
• Good lubricity in sulfide atmospheres
• Διατίθεται σε διάφορες διανομές μεγέθους σωματιδίων

Molybdenum powder is used where its heat resistance, corrosion resistance, conductivity, and lubricity can be utilized. Major applications include alloying, electronics, coatings, welding, and specialty metals fabrication.

Composition of Molybdenum Powder

Molybdenum powder has the following typical composition:

Στοιχείο	Αγνότητα
Μολυβδαίνιο (Mo)	ελάχιστο 99%
Οξυγόνο (O)	0.01-0.5%
Άνθρακας (C)	0.01-0.1%
Σίδηρος (Fe)	0.2-2%
Χαλκός (Cu)	0.1-0.5%
Πυρίτιο (Si)	0.05-1%
Βολφράμιο (W)	0.1-1%
Θείο (S)	0.01-0.1%

High purity grades contain over 99% molybdenum with low impurity levels. Commercial powders have higher permissible impurities.

Properties of Molybdenum Powder

Molybdenum powder exhibits the following properties:

Ακίνητη περιουσία	Αξία
Πυκνότητα	10.22 g/cm3
Σημείο Τήξης	2623¡«C
Θερμική αγωγιμότητα	138 W/m?K
Ηλεκτρική ειδική αντίσταση	5.5 Ã×´Î?cm
Μονάδα Young	324 GPa
Συντελεστής Poisson	0.31
Αντοχή σε εφελκυσμό	350 MPa
Αντοχή σε επιμήκυνση	220 MPa
Επέκταση	20%
Vickers Hardness	200 HV

Molybdenum offers very high melting point, strength at elevated temperatures, good thermal/electrical conductivity, and low thermal expansion.

Production Methods for Molybdenum Powder

Molybdenum powder can be produced by methods like:

• Hydrogen Reduction?- Molybdenum trioxide reduced with hydrogen gas to produce molybdenum powder.
• Thermal Decomposition?- Heating molybdenum compounds like ammonium molybdate to form molybdenum oxide followed by hydrogen reduction.
• Electrolytic Production?- Aqueous electrowinning from acidic molybdate solutions produces molybdenum powder deposit.
• Calciothermic Reduction?- Reduction of molybdenum trioxide using calcium.

Hydrogen reduction is a common industrial method. The powder morphology, size and purity can be controlled.

Εφαρμογές της σκόνης μολυβδαινίου

Molybdenum powder has the following major applications:

• Alloying Addition?- Added to stainless steels, nickel alloys, tool steels to enhance properties.
• Metal Coatings & Spraying?- Thermal spray coatings, plating processes use molybdenum for wear/corrosion resistance.
• Electronics & Contacts?- Used in circuitry, vacuum tubes, cathode ray tubes and electrical contacts.
• Συγκόλληση?- As filler material for stainless, high-nickel and refractory metal welding.
• Λιπαντικά?- Added to greases and oils to provide lubrication in high temperature sulfide environments.
• Πυροτεχνήματα?- Combined with other powders for pyrotechnic delay compositions requiring controlled burn rates.

Specifications of Molybdenum Powder

Molybdenum powder is available under various specifications:

• Purity Grades?- From commercial purity to 99.999% ultra high purity grades.
• Μεγέθη σωματιδίων?- Ranging from 1 micron to 150 microns for different applications.
• Μορφολογία?- Irregular, spherical and nodular powder shapes are available.
• Εμβαδόν επιφάνειας?- Low to high surface area powder grades.
• Περιεκτικότητα οξυγόνου?- High purity, low oxygen powders for specialty applications.

Global Suppliers of Molybdenum Powder

Some of the major global molybdenum powder suppliers include:

• H.C. Starck (Germany)
• Molymet (USA)
• JDC Molybdenum (China)
• Exploiter Molybdenum (China)
• Plansee (Austria)
• Midwest Tungsten (USA)

These companies produce molybdenum powder grades using various methods at commercial to ultra high purity levels.

Pricing of Molybdenum Powder

Molybdenum powder prices depend on factors like:

• Purity Grade?- From $5/kg for commercial purity to over $500/kg for ultra high purity grades.
• Μέγεθος σωματιδίων?- Nanoscale and sub-micron powders are higher priced.
• Μορφολογία?- Spherical powders command premium over irregular grades.
• Ποσότητα?- Prices reduce for bulk quantities due to economy of scale.
• Κατασκευαστής?- Major global suppliers offer competitive pricing.
• Γεωγραφία?- Prices vary in different world regions.

Storage and Handling of Molybdenum Powder

Molybdenum powder requires controlled storage and handling:

• Prevent exposure to air and moisture to minimize oxidation.
• Avoid dust accumulation and ignition hazards from fine powders.
• Use appropriate ventilation and respiratory protection when handling.
• Follow precautions in Safety Data Sheet from supplier.
• Store sealed containers in a cool, dry place away from incompatibles.

Proper grounding, inert gas blanketing, PPE should be used when handling molybdenum powder.

Inspection and Testing of Molybdenum Powder

Typical inspections and tests carried out on molybdenum powder:

• Chemical Analysis?- ICP and XRF techniques used to verify composition meets specifications.
• Μέγεθος σωματιδίων?- Laser diffraction analysis as per ASTM B822 standard.
• Μορφολογία?- SEM imaging used to determine particle shape and surface area.
• Specific Surface Area?- BET gas absorption method used.
• Impurity Testing?- ICP-MS used to quantify levels of oxygen, iron, copper, tungsten and other impurities.
• Powder Flow?- Tested as per ASTM B213 standard using Hall flowmeter.

Comparison of Molybdenum and Tungsten Powders

Molybdenum and tungsten powders are two refractory metal powders compared:

Παράμετρος	Μολυβδαίνιο	Βολφράμιο
Πυκνότητα	10.22 g/cm3	19.3 g/cm3
Σημείο Τήξης	2623¡«C	3422¡«C
Αντοχή σε εφελκυσμό	350 MPa	350 MPa
Θερμική αγωγιμότητα	138 W/mK	163 W/mK
Ηλεκτρική ειδική αντίσταση	5.5 Ã×´Î.cm	5.5 Ã×´Î.cm
Κόστος	Χαμηλότερη	Υψηλότερα
Τοξικότητα	Χαμηλότερη	Υψηλότερα

Molybdenum has lower density, melting point, and cost but offers similarly high strength and conductivity as tungsten.

Molybdenum Powder FAQs

Q: How is molybdenum powder produced?

A: Common industrial production methods for molybdenum powder include hydrogen reduction of molybdenum trioxide and thermal decomposition of molybdates followed by reduction.

Q: What is molybdenum powder used for?

A: Major applications of molybdenum powder include alloying, thermal spray coatings, electronics, welding, lubricants, pyrotechnics, and as a pure metal.

Q: What powder size is used for thermal spray coatings?

A: For most thermal spray processes, molybdenum powder is typically used in size ranges of 45-150 microns. Finer powder can be challenging to fully melt.

Q: Is molybdenum powder flammable or explosive?

A: Yes, like other finely divided metals, molybdenum powder can potentially be flammable or explosive. Proper precautions are needed for safe handling and storage.

Q: Where can I purchase high purity molybdenum powder?

A: Ultra high purity (99.999%) molybdenum powder can be purchased from major suppliers including H.C. Starck, Molymet, Plansee, and JDC Molybdenum.