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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

Carbonyl ironUltrafine high purity powder produced via iron pentacarbonyl decomposition
Water atomizedMade by atomization of molten iron pumped through nozzle; irregular shapes
ElectrolyticDeposited from aqueous iron salt solutions onto cathodes
Reduced ironProduced from mill scale via H2/CO reduction at 400-700°C
AnnealedSoft powder generated by annealing electrolytic/water atomized powder
AlloyedSmall additions of Si, Al, Cu, Mo to modify powder properties
Insulated ironEach particle coated with inorganic insulating layer
Sand ironIrregular 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

PropertyTypical ValuesTest Methods
Chemical composition>98% Fe, <0.8% O2, <0.1% N2, <0.1% CCombustion analysis, XRF
Apparent density2-4 gr/ccHall flowmeter
Tap densityUp to 6.5 gr/ccbinding fraction
Flow ratesCohesion affects powder flow under gravityHall flowmeter
CompressibilityGreen compression of 35-65% typicalPress tool tests
Hydrogen lossBelow 150 ppm from annealingInert gas fusion method
Permeability70-150 for annealed ironHysteresisgraph testing
Resistivity10-18 μOhm-cm; alloying reducesFour probe method
Loss factorBelow 15 kW/m3 at 10 kHzHysteresisgraph
HardnessUp to 90 HRB post sinteringRockwell hardness

Key factors that determine suitability for industrial usage:

  • Flow characteristics
  • Density consistency
  • Magnetic potential
  • Fabrication amenability
  • Purity level
  • Particle size distribution
iron powder
Iron Powder Material 3

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

MethodDescriptionTypical Output
Gas atomizationMolten iron stream disintegrated by nitrogen/argon jetsFine spherical powder
Water atomizationHigh pressure water breaks up iron melt into granulesIrregular dendritic powder
ElectrolysisIron ions from aqueous solution plated onto cathodeLight spongy deposits
Carbonyl decompositionThermal cracking of iron pentacarbonylUltrafine high purity powder
Mechanical comminutionCast/pig iron crushing and grindingLarge grain sized powder
Hydrogen reductionIron oxide powder reduced in hydrogen atmospheresPorous less dense powder
Electro-depositionElectroplating iron onto cathodes from soluble anodesDense 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

BASFGas atomization equipment
Sandvik OspreyWater atomization turnkey systems
ItalprocessHydrogen reduction units
ECKA GranulesAnnealing, crushing, classifying
HöganäsComplete powder production solutions
KastwelPowder 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

AutomotivePowder metal gears, engine bearings, oil pump components, brake pads, friction parts
ElectricalFerrites, inductors, electromagnetic shielding, contacts
ConstructionPowder coating feedstock for finishes over metal substrates
ManufacturingPowder injection molding of complex net shape parts
FiltrationWater treatment using iron media for removal of arsenic, chromium contaminants
PrintingToner powders for photocopiers, laser printers
WeldingBinder in exothermic welding flux mixtures generating heat
MetallurgyIron powder additions enhance mechanical properties of sintered steels
ChemicalUsed as catalyst and pigment source
LubricantsFriction control additive to brake fluids, transmission oils
MicrowaveIron 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

Size range (microns)10 to 500
ShapeSpherical, granular, dendritic
Alloying elementsCu: 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 assay98%
Maximum oxygen0.8%
Maximum nitrogen0.1%
Moisture content<0.1 wt %
Flow ratesCohesion 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

StandardKey Aspects Defined
ISO 4491Method to empirically determine powder flow rates using Hall flowmeter
ISO 4490Bulk density and tap density measurement procedures
ISO 4497Sieving techniques to determine particle size distribution
ASTM B831MStandard test methods for particle size distribution of metal powders via sieving
JIS Z 2508Japanese standard specifying methods for determining compression and green density characteristics
DIN 51733German 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

ParameterImpact on Price
Production processElectrolytic and carbonyl most expensive
Purity levelHigher purity commands premium
Powder densityIncrease with more compressibility
Particle sizeFiner powder costs more
Purchase quantityBulk ordering gives discounts
Product consistencyTight distribution tolerances add cost
Alloying elementsMost alloy grades cost extra
LocationRegional freight and duties affect

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

CompanyProduct FormsPrice Range
HöganäsWater atomized, prealloyed$1.8–$3.5/kg
BASFCarbonyl, electrolytic, water atomized$2–$4.8/kg
Rio TintoWater atomized, annealed, hydrogen reduced$1.7–$3/kg
CNPCElectrolytic, alloyed grades$1.5–$2.5/kg
JFE SteelCarbonyl, alloyed atomized$2–$5/kg
Sandvik OspreyGas atomized$3.5–$5/kg
AMETEKFine 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

Economical material and processingMay not match cast/wrought properties
Easily molded into net shapesLower strength than steel alloys
Range of magnetic permeabilitiesProne to rusting without protective finishes
Higher ductility than most ferritesLimited formability for sheet metal fabrications
Process scrap recyclablePowder handling precautions needed
Uniformity tailorable via processingProperty 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.

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Iron Powder Material 4


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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