How to Change Chromium Corundum Suppliers Without Changing Your Production Formula

Low, medium or high chromium?

For chromium corundum, the answer is not simply “more Cr₂O₃ is better.”

Chromium oxide changes the toughness of fused alumina. As the chromium level increases, the grain generally becomes tougher and less prone to fracture. But that does not mean every grinding wheel, coated abrasive or refractory formulation needs the highest-chromium grade.

HONREL supplies three Chromium Corundum PA grades from 0.20% to 2.20% Cr₂O₃, with standard abrasive sizes from F16 to F320.

Why Is Your Chromium Corundum Breaking Down Too Fast?

Chromium corundum is produced by adding chromium oxide during the fusion of alumina.

This creates the familiar pink to deep-red colour, but colour is only the visible change.

The more important change is grain toughness.

White fused alumina is hard and relatively friable. It fractures more readily and exposes new cutting edges. Adding chromium shifts that balance toward a tougher grain while retaining high hardness.

That matters when the abrasive is breaking down faster than the grinding operation needs.

In practical terms:

More friable → grain fractures sooner

More tough → grain holds together longer

Neither is automatically better. The correct balance depends on the workpiece, bond, grinding pressure and required finish.

HONREL Chromium Corundum Grades

HONREL divides its standard PA grains by Cr₂O₃ content:

Calificación	Cr₂O₃	Al₂O₃	Na₂O	Fe₂O₃	Tamaño
Low-Chromium PA	0.20–0.45%	≥98%	≤0.35%	≤0.3%	F16–F320
Medium-Chromium PA	0.45–1.00%	≥98%	≤0.35%	≤0.3%	F16–F320
High-Chromium PA	1.00–2.20%	≥98%	≤0.35%	≤0.3%	F16–F320

All three standard grades have a listed refractoriness above 1850°C and apparent density of at least 3.8 g/cm³.

The chemistry changes. The grit range does not.

This lets an abrasive producer adjust chromium content without automatically changing the nominal F-grit used in an existing product.

Low Chromium: When You Do Not Want Too Much Toughness

Low-Chromium PA contains 0.20–0.45% Cr₂O₃.

This is the closest of the three grades to the behaviour of alúmina fundida blanca.

It makes sense when you want to move away from a highly friable white alumina grain but do not want a large change in abrasive behaviour.

That can matter during raw-material substitution.

A wheel formulation that currently runs on white fused alumina should not automatically jump to the highest Cr₂O₃ grade. A large change in grain toughness can also change how the wheel cuts, wears and exposes fresh abrasive.

For a first trial away from WFA, low-chromium material may therefore be the more logical comparison point.

Medium Chromium: The Middle Ground

Medium-Chromium PA contains 0.45–1.00% Cr₂O₃.

It sits between the lower-chromium pink grade and the tougher high-chromium material.

This range is useful when the buyer needs more grain retention but does not have a reason to move directly to the highest chromium level.

This is especially relevant for established abrasive formulations.

If your current PA works well, matching its Cr₂O₃ range is normally more sensible than changing grade because another material has a higher chromium number on the COA.

High Chromium: More Cr₂O₃ Is a Process Choice

HONREL High-Chromium PA contains 1.00–2.20% Cr₂O₃.

This is the toughest end of the standard HONREL PA range.

It can be considered where grain durability is more important and premature abrasive breakdown is a known problem.

But high chromium should solve a process requirement.

If the actual issue is the wrong grit, wheel bond, grinding pressure or abrasive concentration, increasing Cr₂O₃ alone will not fix the operation.

That distinction matters when troubleshooting short wheel life.

Before changing the chromium grade, check whether the grain itself is failing too quickly. If it is not, the problem may sit elsewhere in the abrasive system.

Do Not Use Colour as a Grade Specification

Pink. Rose. Ruby. Deep red.

These names are common in the fused alumina market, but they are poor purchasing specifications.

Different suppliers use Pink Fused Alumina, Pink Corundum, Chromium Corundum and Ruby Fused Alumina differently.

A darker colour normally indicates more chromium, but a colour name does not tell purchasing exactly how much Cr₂O₃ is in the material.

Cr₂O₃ Is Not the Only Number on the COA

This is where many chromium corundum comparisons stop too early.

Two products can both fall into the same chromium range and still not be equivalent.

Check the complete chemistry.

For HONREL standard PA:

Al₂O₃ ≥98%

Na₂O ≤0.35%

Fe₂O₃ ≤0.3%

Sodium matters because Na₂O is an impurity in fused alumina. Iron content may also matter where contamination limits or product consistency are important.

The grit specification matters just as much.

An F46 abrasive cannot be qualified from Cr₂O₃ content alone. Its particle-size distribution still determines how that grain behaves in the abrasive product.

Bulk Density Must Be Read with Grit Size

HONREL lists bulk density at 1.4–1.9 g/cm³ for its F16–F320 chromium corundum range.

That is a range, not a single target for every grit.

Coarse and fine abrasive grains pack differently. When comparing bulk-density data between two suppliers, first check whether both values refer to the same grit and test basis.

Otherwise, the numbers may look different even when the raw materials are not directly comparable.

This is particularly important when bulk density affects abrasive-tool formulation, filling behaviour or batch calculations.

Match Your Current PA with HONREL

HONREL supplies Chromium Corundum in low-, medium- and high-chromium PA grades for abrasive and refractory requirements.

If you already use pink fused alumina, chromium corundum or another PA grade, send the existing COA or TDS + grit size + quantity.

HONREL can compare the current chemistry against the available grade instead of selecting material from colour or product name alone.

You can also review HONREL’s broader Materiales abrasivos y refractarios range or Contactar con HONREL with an existing material specification.

The simplest starting point is the material you already know works.

Preguntas frecuentes

What is the difference between low-, medium- and high-chromium corundum?

The main difference is Cr₂O₃ content. HONREL specifies 0.20–0.45% for low chromium, 0.45–1.00% for medium chromium and 1.00–2.20% for high chromium.

Does higher Cr₂O₃ mean better chromium corundum?

No. Higher chromium generally shifts the grain toward greater toughness, but the correct grade depends on the abrasive or refractory requirement.

Can I replace white fused alumina with chromium corundum?

Possibly, especially when more grain toughness is required. But treat it as a material change and run a production trial rather than assuming the same grit will behave identically.

Is pink fused alumina the same as chromium corundum?

They are commonly used as names for chromium-modified fused alumina. Commercial naming varies, so Cr₂O₃ content and the actual specification are more reliable than colour names.

What should I send HONREL for a replacement grade?

Send the current COA or TDS, F-grit and required quantity. If there is a specific problem such as premature grain breakdown or short abrasive life, include that as well.