Category: Guides

Iron oxide powder is one of the most widely used industrial minerals. It colours concrete and paint, goes into magnets and welding fluxes, and is used for polishing and as a catalyst. Most buyers need one of two forms: red iron oxide or black iron oxide. They come from the same element, but they are different compounds and they are not interchangeable.

Red iron oxide (Fe₂O₃, hematite)

Red iron oxide is ferric oxide, the same compound as the mineral hematite. It is stable, non-magnetic in ordinary use, and gives a strong red-brown colour.

Where it is used:

• Pigments: colouring paints, coatings, concrete, paving blocks, tiles, plastics and rubber.
• Ferrites: as a raw material for soft and hard ferrite magnets.
• Polishing: fine red oxide, sometimes called jeweller’s rouge, polishes glass and metals.
• Catalysts and chemicals: as a catalyst or catalyst support, and as an iron source in chemical processes.
• Welding and ceramics: in electrode coatings and in ceramic bodies and glazes.

Black iron oxide (Fe₃O₄, magnetite)

Black iron oxide is magnetite, which contains iron in two oxidation states. Its two most useful properties are its deep black colour and its strong magnetism.

Where it is used:

• Pigments: black colour for concrete, coatings and plastics.
• Magnetic applications: toners, magnetic inks, and some ferrite and magnetic-separation uses.
• Welding: in electrode coatings and fluxes.
• Heavy media and other uses: where its density and magnetism are an advantage.

How to tell them apart

Property	Red iron oxide	Black iron oxide
Chemical formula	Fe₂O₃	Fe₃O₄
Mineral name	Hematite	Magnetite
Colour	Red to red-brown	Black
Magnetism	Weak / non-magnetic	Strongly magnetic
Main uses	Pigments, ferrites, polishing, catalysts	Black pigment, magnetic uses, welding

A quick check is a magnet: black iron oxide is drawn to it, and red iron oxide is not.

What to specify when buying iron oxide powder

• Form: red (Fe₂O₃) or black (Fe₃O₄).
• Purity: the Fe₂O₃ or Fe₃O₄ content, and limits on moisture and water-soluble salts.
• Particle size: mesh or micron range. Pigment and polishing uses need fine powder.
• Colour and tint strength: important for pigment buyers. Ask for a sample to match against your standard.
• End use: tell the supplier what the powder is for, so they can recommend the right grade.

Iron oxide powder from Powdrox

Powdrox supplies red, black and yellow iron oxide powder to your specification, for buyers across India and for export. Each supply comes with a Certificate of Analysis and MSDS on request, and trial quantities are available. Send us your requirement and we will quote a matching grade.

Alumina (aluminium oxide, Al₂O₃) is one of the most useful industrial materials. It is very hard, resists high temperatures and does not react easily with most chemicals. White fused alumina is one of its most widely used forms, especially where hardness and purity both matter.

What is white fused alumina?

White fused alumina, often shortened to WFA, is made by melting high-purity alumina in an electric arc furnace at more than 2,000 °C. The melt is then cooled, crushed and graded into grains and powders of different sizes.

Melting and re-solidifying the alumina gives large, dense crystals of alpha-alumina, the hardest and most stable form. The result is a white material with high purity and very high hardness, about 9 on the Mohs scale. Only diamond and a few other materials are harder.

White vs brown fused alumina

You will often see white fused alumina compared with brown fused alumina. Brown fused alumina is made from bauxite and keeps some titanium oxide and other impurities. That makes it tougher and cheaper, but less pure.

Property	White fused alumina	Brown fused alumina
Raw material	High-purity alumina	Bauxite
Purity	High Al₂O₃, low impurities	Lower; contains TiO₂ and others
Colour	White	Brown
Behaviour	Very hard, sharper and more friable	Tougher, more impact-resistant
Typical choice when	Purity, cool cutting or no colour contamination matter	Heavy-duty grinding at lower cost

“Friable” means the grain breaks down gradually during use and exposes fresh sharp edges. This helps white fused alumina cut cleanly and cool, which is why it is popular for precision grinding and polishing.

Where white fused alumina powder is used

• Abrasives and polishing: grinding wheels, coated abrasives, lapping and polishing compounds, and blasting media for surface preparation.
• Refractories: grains and fines in castables, bricks and ramming mixes that must handle high temperatures.
• Technical and structural ceramics: where hardness, wear resistance and electrical insulation are needed.
• Thermal spray and coatings: as a feedstock for hard, wear-resistant ceramic coatings.
• Catalyst supports and fillers: where an inert, hard, heat-resistant filler is needed.

How to specify white fused alumina

To get the right material, share these details when you enquire:

• Al₂O₃ content and your limits on impurities such as Na₂O, Fe₂O₃ and SiO₂.
• Grit or particle size: the FEPA or mesh grit size for abrasive grains, or a micron range for fine powders.
• Particle size distribution: especially important for polishing and thermal spray.
• Bulk density: useful for refractory and abrasive formulations.
• End use: tell the supplier what the material is for, so they can recommend a suitable grade.

White fused alumina from Powdrox

Powdrox supplies white fused alumina powder, including custom-milled grades and fine and ultra-fine fractions on enquiry. We supply across India and for export, with a Certificate of Analysis and MSDS on request, and small trial quantities are available. Request a quote with your grade, quantity and destination.

Iron powder looks like a simple material, but the way it is made changes how it behaves in your process. Two powders with the same iron content can press, sinter, flow and react very differently. If you buy iron powder for sintered parts, welding consumables, friction linings or chemical work, knowing the three main production routes will help you ask for the right grade.

The three main types of iron powder

Reduced (sponge) iron powder

Reduced iron powder is made by reducing iron ore or mill scale with carbon or hydrogen at high temperature. The result is a porous, “spongy” particle with an irregular shape and a large surface area.

That irregular shape is useful. The particles lock together well when pressed, which gives good green strength (the strength of a pressed part before sintering). The high surface area also makes sponge iron reactive, which suits chemical and reduction processes.

Typical uses: sintered structural parts with moderate density, friction and brake materials, welding electrode coatings, and chemical applications.

Water-atomized iron powder

Atomized iron powder is made by pouring a stream of molten iron and breaking it up with high-pressure water jets. The droplets freeze into dense, fairly irregular particles with low internal porosity.

Because the particles are dense and the powder compresses well, water-atomized iron is the usual choice when you need higher density in pressed and sintered parts. It is the workhorse of modern powder metallurgy for gears, bushes and structural components.

Typical uses: higher-density sintered parts, soft magnetic components, and alloyed powder blends.

Electrolytic iron powder

Electrolytic iron powder is deposited from an iron salt solution by electrolysis, then milled and annealed. This route gives very high purity with low levels of carbon, oxygen and other impurities.

High purity matters in applications where trace elements affect the result, such as some magnetic, chemical, food-fortification and laboratory uses. Electrolytic powder usually costs more, so it is chosen when purity is the deciding factor.

Typical uses: high-purity chemical and laboratory work, special magnetic parts, and applications with tight impurity limits.

Properties to specify when you enquire

Whichever type you choose, these are the properties that decide whether a powder will work in your process. It helps to share them when you ask for a quote:

• Iron content (Fe %) and the limits you need on carbon, oxygen, sulphur and other impurities.
• Particle size distribution: the mesh or micron range, and whether you need a fine or coarse fraction.
• Apparent density: how much powder fills a fixed volume, which affects die filling.
• Flow rate: how freely the powder flows, which matters for automatic presses.
• Compressibility and green strength: how dense and strong the part is after pressing.
• Loss on hydrogen reduction: a measure of the oxygen content in the powder.

A quick way to decide

• Need good green strength and a cost-effective powder for friction, welding or chemical use? Start with reduced (sponge) iron.
• Need higher density in sintered or magnetic parts? Look at water-atomized iron.
• Need the highest purity? Choose electrolytic iron.

If you are not sure, share your process, the part or product you make, and the properties you need. A supplier can then match a grade to your requirement instead of selling you a standard one.

Getting the right grade from Powdrox

Powdrox supplies iron powder to your required specification across India and for export. We share a datasheet and Certificate of Analysis with each grade, and small trial quantities are available so you can test before you commit. Request a quote with your grade, quantity and destination, and we will come back with a specification-matched offer.