Tungsten Powder

Tungsten powder is a fine gray powder made from tungsten metal. It has unique properties that make it useful across many industrial and commercial applications. This article provides a comprehensive overview of tungsten powder covering its composition, properties, production methods, applications, specifications, pricing, pros and cons, and leading global suppliers.

Overview of tungsten powder

Tungsten powder is composed almost entirely of elemental tungsten metal in powder form. The powder particles are very fine, ranging from 0.5 to 10 microns in size. The powder has a grayish coloration and high density due to the intrinsic properties of metallic tungsten.

Tungsten powder offers exceptional hardness, heat resistance, and density compared to most other metals and alloys. Key properties that make tungsten powder suitable for various functions include:

  • High density similar to gold and almost twice that of lead
  • Melting point of 3410°C – highest of all metals
  • Low electrical resistivity comparable to common metals
  • Excellent radiation shielding density
  • Strength retention at high temperatures
  • Corrosion resistance in many environments

These attributes allow tungsten powder uses in applications like radiation shielding, electrodes, heating elements, ballast weights, dyes, catalysts, and more. The powder can be pressed into shapes or sintered into end-use components with special characteristics.

tungsten powder

Types of Tungsten Powder

Tungsten powder is manufactured in several forms with differences in particle size distribution, shape, purity levels, and powder surface chemistry. The major types of tungsten powder include:

TypeDescription
Fine powderParticle size of 0.5 to 10 microns suitable for pressing into shapes
Coarse powderLarger spherical particles over 10 microns for improved flow and packing
Crushed powderIrregular jagged particles sized 1 to 44 microns from crushing ingots
Alloy powdersComposite powders blended with carbon, cobalt, nickel, copper, silver etc.
Chemical powdersUltrafine nanostructure tungsten and oxide powders

The particle shape, size distribution, flow characteristics, compaction density, and microstructure requirements determine the type of tungsten powder selected for an application.

Composition of Tungsten Powder

Tungsten powders for industrial uses typically contain over 99.95% pure tungsten metal to ensure consistent performance. Trace impurities from raw materials and manufacturing can be present up to these levels:

ElementMaximum ContentRole
Carbon (C)100 ppmGrain growth inhibitor
Oxygen (O)100 ppmSurface oxide films
Phosphorus (P)10 ppmResidual impurity
Sulfur (S)10 ppmResidual impurity
Potassium (K)10 ppmResidual impurity
Silica (Si)10 ppmResidual impurity

Higher purity grades minimize contamination issues during sintering and improve ductility. Special high-purity tungsten suitable for lighting filaments, electronics, and laboratory uses have only 10-100 ppb impurities.

Alloy tungsten powders are commonly blended with 1-5% cobalt, nickel, iron, silver, or copper to enhance sintering, machinability, or high-temperature behavior. Small amounts of inorganic additives can provide unique functional properties.

Properties of Tungsten Powder

Tungsten metal powder has intrinsic properties that stem from its elemental composition and crystalline structure. Being pure tungsten, the powder exhibits related thermal, electrical, mechanical, and chemical characteristics.

Physical Properties

Key physical properties of tungsten powder:

PropertyValue
Density19.3 g/cm<sup>3</sup>
Melting Point3410°C
Thermal Conductivity170 W/m·K
Vapor PressureLow, ~10<sup>-6</sup> bar at ~1700°C
Specific Heat Capacity130 J/kg·K
Coefficient of Thermal Expansion4.5 μm/m·K
ColorGray to black

The ultrahigh melting point, high density, good conductivity, and excellent dimensional stability under heat make tungsten useful for extreme temperature applications.

Mechanical Properties

Tungsten powder can be compacted and sintered to obtain very high hardness and strength with moderate ductility levels:

PropertySintered Condition
HardnessUp to 550 VPN
0.2% Yield Strength~800 MPa
Ultimate Tensile Strength~900 MPa
Fracture Toughness30-35 MPa√m
Young’s Modulus~400 GPa

Tungsten retains strength exceptionally well even at temperatures approaching 2000°C in inert atmospheres or vacuum thanks to its refractory nature.

Electrical Properties

Tungsten powder and sintered parts offer good electrical and thermal conductivity ideal for heating elements:

PropertyValue
Electrical Resistivity5.5 μΩ·cm
Temperature Coefficient of Resistance~4 x10<sup>-3</sup> Ω/Ω/K

The stability, low resistivity, and positive tempco ensure excellent performance in electrical discharge machining electrodes too.

Production of Tungsten Powder

Tungsten metal powder is primarily produced by the reduction of tungsten oxide followed by crushing and grinding stages. The manufacturing steps are:

1. Concentration of ore: Natural tungsten ores containing the mineral scheelite or wolframite are physically upgraded to higher tungsten levels by crushing and grinding, gravity, magnetic, or flotation processes.

2. Conversion to oxide: The concentrated mineral is reacted at high temperature with hydrogen, carbon, or carbon monoxide gas to yield crude tungsten oxide WO<sub>3</sub>. Lime or soda ash fluxing agents help produce a porous, easily reducible oxide.

3. Hydrogen Reduction: The oxide is reduced with dry hydrogen gas passed over it heated to about 800°C in pusher or rotary furnaces. This produces blue tungsten oxide W<sub>3</sub>O which is further reduced to yield tungsten metal powder.

4. Milling and Blending: The reduced tungsten powder goes through pulverization and size classification to obtain specific particle size distributions. Powders can be blended with dopants like potassium or grain growth inhibitors. Heat treatment and annealing provide proper powder tap density and morphology.

5. Packaging: Tungsten powder is packed into drums or bags under controlled humidity conditions for shipment to pressing and sintering facilities.

Secondary scrap recovery, recycling of tungsten hardmetals, electronic waste, and used cemented carbide tools also provide a growing source of tungsten powder feedstock.

Applications of Tungsten Powder

Key applications using tungsten powder as feed material include:

Cemented carbides

Over 60% of tungsten powder is used to manufacture hardmetal composites with cobalt or nickel binders. Grades like WC-Co are very widely used.

Mill products

Tungsten metal shapes like rods, wires, and sheets made by powder metallurgy contain pressed and sintered tungsten powder.

Lighting filaments

Tungsten wires for household incandescent bulbs are fabricated from very pure pressed and sintered tungsten.

Heating elements

The high temperature strength and electrical resistivity allow all-tungsten or doped heating elements for furnaces, heaters etc.

Electrodes

Tungsten electrodes for welding, electrical discharge machining, and plasma cutting applications derive from pressed powder preforms.

Electronics

Sintered tungsten contacts, heat sinks bases, and packages take advantage of its thermal-electrical attributes.

Radiation shielding

Tungsten alloys or composite mixtures provide shielding from gamma rays and X-rays in nuclear, medical, and space fields.

Ballast weights

Tungsten metal provides very high density in a compact form factor ideal for weighting of rotors, vibration dampening etc.

Catalysts

Tungsten oxide species dispersed on substrates give specialized catalysts for chemical processes.

Tungsten Powder Specifications

Tungsten metal powders are standardized based on metrics like particle size distribution, shape, purity levels, surface area, apparent density, and flow rates.

Grades

Common tungsten powder varieties are:

GradeDescriptionParticle SizeApparent Density
Extra fineHigh purity, thin flake morphology1-5 μm2.2-3.5 g/cc
FineGeneral use, rounded particles1-10 μm3-8 g/cc
MediumFree-flowing, pressed into mill shapes5-25 μm7-9 g/cc
CoarseBest flowability, high green strength15-45 μm8-10 g/cc

Specialized tungsten powder alloys have cobalt, copper, silver, nickel, or other alloying additions like W-Ni-Fe, W-Ni-Cu etc.

Standards

Tungsten powder manufacture and testing adheres to these main international specifications:

  • ASTM B776 – Standard for Tungsten Powders and Tungsten Powder Products
  • ISO 4492 – Metallic powders – Determination of tap density
  • ISO 4497 – Metallic powders – Determination of flow rate by means of a calibrated funnel (Hall flowmeter)
  • IEC 60804 – Tungsten powders and tungsten metal powders for lamps
  • GB/T 33137-2016 – Tungsten powder and tungsten powder products

Based on application and regional needs, JIS, DIN, BS, and other standards may cover tungsten powder also.

Pricing

Pricing depends on tungsten powder grade, purity, particle size, quantity, and geographical market. Some indicative costs of tungsten powder (USD per metric tonne, 2023):

RegionFine GradeMedium Grade
China$35,000$32,000
Europe$52,000$47,000
USA$57,000$50,000
Japan$62,000$55,000

Higher density, more uniform particle distribution, special dopants, finer sizes, and smallest packing sizes command premium pricing of over $250/kg for ultrafine and nanopowders.

Pros and Cons

Tungsten demonstrates benefits and certain limitations for applications:

Advantages

  • Highest melting point metal
  • Best high temperature strength
  • High hardness when sintered
  • Excellent radiation shielding
  • Dimensional stability under heat
  • Resists corrosion and oxidation

Disadvantages

  • Brittleity when sintered and forged
  • Challenging forming and machining
  • Heavy weight compared to titanium/aluminum
  • Subject to surface defects if impure
  • Lower electrical/thermal conductivity than silver, copper, aluminum
  • Expensive compared to steel, lead

By understanding strengths and weaknesses of tungsten powder, suitable applications can employ its uniqueness optimally.

Suppliers

Leading global producers supplying tungsten metal powder include:

CompanyHQ Location
Wolfram CompanyAustria
Buffalo TungstenUSA
Midwest TungstenUSA
Tungsten Heavy PowderChina
Xiamen TungstenChina
JX Nippon MiningJapan
H Cross CompanyJapan
GTP Gudelsky Technical PowdersGermany

These corporations offer reliable large volume capacity and product diversity catering to a wide range of commercial and industrial needs.

tungsten powder

FAQs

QuestionAnswer
What is tungsten powder made of?≈99.95% pure elemental tungsten metal in powder form along with minor residual impurities
What is tungsten powder used for?Manufacturing cemented carbides, heating elements, lighting filaments, radiation shielding, electrodes, metal injection molding precursors
What are the different varieties of tungsten powder?Based mainly on particle size distribution – ultrafine, fine, medium and coarse grades from 0.5 to 45 microns
What are the advantages of using fine tungsten powders?Allow pressing of detailed, thin-walled shapes; impart strength through extensive sintering; distribute uniformly in an alloy matrix
What are the characteristics of coarse tungsten powders?Free-flowing spherical particles fill die cavities well; high green strength resists cracking; form skeleton structure to support alloy mix
How is tungsten powder made?Reduction of tungsten oxide combined with particle size diminution via milling/grinding of reduced tungsten metal
Is tungsten powder toxic?Elemental tungsten is relatively inert and non-toxic. However inhalation of fine powders can cause lung irritation requiring protective equipment
Is tungsten powder flammable or explosive?No, tungsten metal itself does not burn or explode under normal situations. But fine powders can form explosive mixtures with air
Is tungsten environmentally friendly?Yes, tungsten mining and metal production follows modern sustainability protocols. Powder provides green strength for creative use of tungsten properties

Conclusions

With extraordinary refractory properties setting it apart from alternatives, tungsten in powder form enables unique high-temperature applications across industries. Pressed and sintered shapes exploit exceptional hardness, electrical/thermal conductivity, radiation shielding density, corrosion resistance, and dimensional stability under demanding environments.

Careful specification coupled with understanding of powder attributes allows reliable functionality. Blending altered alloy varieties expands possibilities while secondary scrap feeds circular economy. Future progress in powder quality through advanced atomization promises exciting material and energy efficiencies harnessing tungsten powder’s full potential.

know more 3D printing processes

Share This Post:

Leave a Reply

Your email address will not be published. Required fields are marked *

Table of Contents

Most Popular

Get In Touch

Get in touch with us

On Key

Related Posts

wear resistance powder

Low-Alloy Steels Powder

Low-alloy steels powder is a vital material in modern manufacturing, offering a blend of versatility and strength that makes it a preferred choice for a wide range of applications. From

Read More »
diffusion alloy powder

Dual-Phase Alloy Powder

Welcome to the fascinating world of dual-phase alloy powder! Whether you’re a materials scientist, an engineer, or just someone curious about advanced materials, this guide is designed to inform, teach,

Read More »

High Purity Iron Powder

High purity iron powder is a crucial material in various industries, known for its exceptional quality and performance. In this extensive guide, we’ll delve into everything you need to know

Read More »
Metal Injection Molding

Advanced Materials

Overview of Advanced Materials Advanced materials are the cutting-edge of material science, comprising high-performance substances designed to meet the rigorous demands of modern technology and industrial applications. These materials exhibit

Read More »
small_c_popup.png

Let's have a chat

Get In Touch With Us