Iron Powder Material

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Iron powder is a versatile ferrous material with diverse industrial and commercial applications owing to its magnetic properties, high strength, ductility and range of available powder sizes. This guide details different types, specifications, manufacturing methods, applications, pricing, comparisons and frequently asked questions about iron powder.

Overview of Iron Powder

Iron powder refers to fine granules of iron metal, usually below 500 microns in size. It exhibits high permeability and often contains small amounts of alloying elements like silicon, nickel, molybdenum or copper to modify magnetic or structural properties.

Key attributes making iron powders useful across industries:

  • High purity iron content (>98%)
  • Controlled powder morphology and grain size
  • Range of electrical resistivity values
  • Adjustable magnetic properties
  • Good machinability and compressibility
  • Capability to tailor mechanical strength
  • Availability in large commercial quantities
  • Lower fabrication costs than solid iron
  • Recyclability of scrap/waste powder

With global demand projected to reach 800 kilo tons annually, iron powder production and variety continues rising driven by automotive, electrical and brazing industry applications.

Types of Iron Powder Compositions

Iron powder is commonly categorized by composition, manufacturing process, particle shape, powder size and powder density:

Table 1: Main types of iron powder compositions

Type Description
Carbonyl iron Ultrafine high purity powder produced via iron pentacarbonyl decomposition
Water atomized Made by atomization of molten iron pumped through nozzle; irregular shapes
Electrolytic Deposited from aqueous iron salt solutions onto cathodes
Reduced iron Produced from mill scale via H2/CO reduction at 400-700°C
Annealed Soft powder generated by annealing electrolytic/water atomized powder
Alloyed Small additions of Si, Al, Cu, Mo to modify powder properties
Insulated iron Each particle coated with inorganic insulating layer
Sand iron Irregular chunks made via crushing/milling cast iron

Shape: Predominantly spherical, dendritic, granular and irregular chunky particles seen.

Size: Between 10 microns to 1 millimeter; smaller is costlier.

Apparent density: 2 gr/cc lightly packed, up to 4 gr/cc for press-compacted powder.

Besides composition, properties are determined by powder production methods and post-processing like annealing, coatings or lubricant addition.

Key Characteristics and Properties of Iron Powder

Commercially available iron powder exhibits a wide spectrum of physical, chemical, electrical and magnetic characteristics:

Table 2: Iron powder properties and test measurement methods

Property Typical Values Test Methods
Chemical composition >98% Fe, <0.8% O2, <0.1% N2, <0.1% C Combustion analysis, XRF
Apparent density 2-4 gr/cc Hall flowmeter
Tap density Up to 6.5 gr/cc binding fraction
Flow rates Cohesion affects powder flow under gravity Hall flowmeter
Compressibility Green compression of 35-65% typical Press tool tests
Hydrogen loss Below 150 ppm from annealing Inert gas fusion method
Permeability 70-150 for annealed iron Hysteresisgraph testing
Resistivity 10-18 μOhm-cm; alloying reduces Four probe method
Loss factor Below 15 kW/m3 at 10 kHz Hysteresisgraph
Hardness Up to 90 HRB post sintering Rockwell hardness

Key factors that determine suitability for industrial usage:

  • Flow characteristics
  • Density consistency
  • Magnetic potential
  • Fabrication amenability
  • Purity level
  • Particle size distribution
iron powder

Production Processes for Iron Powder

The principal manufacturing routes for generating different grades of iron powder are:

Table 3: Overview of key iron powder production processes

Method Description Typical Output
Gas atomization Molten iron stream disintegrated by nitrogen/argon jets Fine spherical powder
Water atomization High pressure water breaks up iron melt into granules Irregular dendritic powder
Electrolysis Iron ions from aqueous solution plated onto cathode Light spongy deposits
Carbonyl decomposition Thermal cracking of iron pentacarbonyl Ultrafine high purity powder
Mechanical comminution Cast/pig iron crushing and grinding Large grain sized powder
Hydrogen reduction Iron oxide powder reduced in hydrogen atmospheres Porous less dense powder
Electro-deposition Electroplating iron onto cathodes from soluble anodes Dense adherent powder

Post-production secondary processes like annealing, crushing, classifying, coating and lubrication can further modify powder properties like grain size, shape, density and flow characteristics.

Table 4: Industry providers of iron powder manufacturing equipment and systems

Company Offerings
BASF Gas atomization equipment
Sandvik Osprey Water atomization turnkey systems
Italprocess Hydrogen reduction units
ECKA Granules Annealing, crushing, classifying
Höganäs Complete powder production solutions
Kastwel Powder processing equipment

200-2000 kg/hour production capacities are typical for gas, water and hydrogen based reduction plants.

Applications and Uses of Iron Powder

The major industrial applications and commercial uses of iron powder include:

Table 5: Major application areas for iron powder

Industry Applications
Automotive Powder metal gears, engine bearings, oil pump components, brake pads, friction parts
Electrical Ferrites, inductors, electromagnetic shielding, contacts
Construction Powder coating feedstock for finishes over metal substrates
Manufacturing Powder injection molding of complex net shape parts
Filtration Water treatment using iron media for removal of arsenic, chromium contaminants
Printing Toner powders for photocopiers, laser printers
Welding Binder in exothermic welding flux mixtures generating heat
Metallurgy Iron powder additions enhance mechanical properties of sintered steels
Chemical Used as catalyst and pigment source
Lubricants Friction control additive to brake fluids, transmission oils
Microwave Iron lossy material for electromagnetic wave absorption

Of these, powder metallurgy and friction component fabrication account for over 50% of iron powder consumption presently.

Iron Powder Specifications

Iron powder is commercially marketed in various standard grades defined by particle size, shape, density and composition:

Table 6: Typical specifications of iron powder grades available

Attribute Range
Size range (microns) 10 to 500
Shape Spherical, granular, dendritic
Alloying elements Cu: 1-4%, Mo: 0.2-5%, Si: 0.1-6%
Apparent density (g/cc) 2-4.5
Tap density (g/cc) up to 6.5
Minimum iron assay 98%
Maximum oxygen 0.8%
Maximum nitrogen 0.1%
Moisture content <0.1 wt %
Flow rates Cohesion affects powder flow under gravity

Besides these, carburization and insulated iron powder have special subsets of grade specifications tailored to unique applications.

International Standards for Iron Powder

Globally traded iron powder conforms to established quality parameters as per industrial standards:

Table 7: Major international iron powder grade standards

Standard Key Aspects Defined
ISO 4491 Method to empirically determine powder flow rates using Hall flowmeter
ISO 4490 Bulk density and tap density measurement procedures
ISO 4497 Sieving techniques to determine particle size distribution
ASTM B831M Standard test methods for particle size distribution of metal powders via sieving
JIS Z 2508 Japanese standard specifying methods for determining compression and green density characteristics
DIN 51733 German standard test procedures for assessing powder flow properties

Reputable manufacturers have quality certifications like ISO 9001 along with fully equipped laboratories to validate chemical, functional and physical properties during production and for user acceptance.

Suppliers and Pricing

As a mass commodity product produced by major metal powder manufacturers, current pricing for iron powder varies from $1.5 to $5 per kilogram based on:

Table 8: Key determinants of iron powder pricing

Parameter Impact on Price
Production process Electrolytic and carbonyl most expensive
Purity level Higher purity commands premium
Powder density Increase with more compressibility
Particle size Finer powder costs more
Purchase quantity Bulk ordering gives discounts
Product consistency Tight distribution tolerances add cost
Alloying elements Most alloy grades cost extra
Location Regional freight and duties affect

Table 9: Major global suppliers and typical price ranges for their iron powders

Company Product Forms Price Range
Höganäs Water atomized, prealloyed $1.8–$3.5/kg
BASF Carbonyl, electrolytic, water atomized $2–$4.8/kg
Rio Tinto Water atomized, annealed, hydrogen reduced $1.7–$3/kg
CNPC Electrolytic, alloyed grades $1.5–$2.5/kg
JFE Steel Carbonyl, alloyed atomized $2–$5/kg
Sandvik Osprey Gas atomized $3.5–$5/kg
AMETEK Fine stainless steel clad $5–$7/kg

Prices depend on annual contracted volumes and width of specification guaranteed. Make quality consistency and certification a priority over merely chasing lowest quoted pricing levels while sourcing iron powder.

Pros and Cons of Iron Powder

Table 10: Comparison between advantages and limitations of iron powders

Advantages Disadvantages
Economical material and processing May not match cast/wrought properties
Easily molded into net shapes Lower strength than steel alloys
Range of magnetic permeabilities Prone to rusting without protective finishes
Higher ductility than most ferrites Limited formability for sheet metal fabrications
Process scrap recyclable Powder handling precautions needed
Uniformity tailorable via processing Property variability between batches possible

For small complex parts like sprockets and gears, powder metallurgy route offerssignificant cost benefits even accounting for lower mechanical strength. But for large structural fabrications, traditional casting or deformation processing of steel is better.

iron powder


Q. How is iron powder classified based on particle sizes?

Iron powder is commercially classified by mesh sizes into:

  • Coarse grades – below 100 mesh size (149 microns)
  • Fine grade – 100 to 400 mesh (37 to 149 microns)
  • Ultra fine grade – over 400 mesh, Below 37 microns

Q. Which grades provide the highest purity iron powder?

Purity levels over 99.5% is possible with carbonyl and electrolytic iron powder. Atomization methods generate >98% purity.

Q. What is the difference between apparent density and tap density?

Apparent density refers to loose packing measured after gentle agitation while tap density is the increased compaction achieved after mechanically tapping loaded measurement cylinder.

Q. Why is flow rate an important iron powder parameter?

Good powder flow ensures ease, consistency and automation suitability for part molding and metallurgy processes like metal injection molding where the material has to flow freely under gravity into dies.

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