Aluminum Oxide vs Silicon Carbide – A Comprehensive Guide


If you want to take your sandpaper skills to the next level, it’s essential to understand the types of abrasive grains. Luckily, the differences are pretty simple to understand. This article will cover what aluminum oxide vs. silicon carbide are and some key differences between them.

Aluminum Oxide vs. Silicon Carbide: Definition

Aluminum oxide is the most popular abrasive grain due to its wide range of uses. The aluminum oxide compound is a white, indissolvable crystallized powder with the chemical formula of Al2O3. It’s an inorganic chemical reagent and is sometimes also called alumina.

Aluminum oxide powder.

Aluminum oxide powder.

Silicon Carbide is another inorganic compound and is slightly less common than alumina. Also known as carborundum, this abrasive grain comes from yellowish-green crystals. Its chemical formula is CSS, and you’ll rarely find it naturally on earth.

Silicon carbide crystals.

Silicon carbide crystals.

Aluminum Oxide vs. Silicon Carbide: Type

Aluminum Oxide

Pink and White

Pink and white abrasives are perfect for producing a smoother finish, but they wear down much faster. Usually, you’ll find them in the more OK grit ranges due to the smoother finish they create. You’ll probably replace pink and white types more frequently than alternative options.

Pink and white sandpaper type.

Pink and white sandpaper type.


Brown alumina are more coarse and durable, so the grain breaks down slowly. While you won’t have to replace sandpaper made of this type very often, the tougher grain creates a rougher finish. You’ll typically see these in the coarser grit ranges.

Silicon Carbide

Friable (Green)

Friable silicon carbide is a purer type of abrasive, but it’s also much more brittle than other options. It will wear down fairly quickly, and you’ll have to replace them more often. You can use crispy types for sanding jobs where you need a lot of material to be worn away quickly.

Regular (Black)

Black abrasive types are the most complex and sharpest option available in sandpaper. While it does wear out quickly, you can use it for sanding back non-ferrous metals, ceramics, and non-hard metals rapidly and easily.

Black sandpaper made of regular carborundum.

Black sandpaper made of regular carborundum.

Difference Between Aluminum Oxide and Silicon Carbide

Molar Mass

Molar mass is the total mass of the atoms in a molecule. Its unit of measurement is grams per mole (g/mol). The molar mass of aluminum oxide is 101.96 g/mol, while carborundum is 40.10 g/mol.

Electrical Conductivity

Alumina is an electrical insulator, meaning it doesn’t allow electricity to flow through it freely. On the other hand, Carborundum is a semiconductor, so it conducts electricity, but only under specific circumstances. 


‘Alumina is white and comes in the form of crystalline powder. Sileasily icon carbide is usually a solid crystal with a yellow or green color. You must understand what the various abrasive grains look like to identify which one you’re using at any time easily.

A range of different abrasive grains on sandpaper.

A range of different abrasive grains on sandpaper.

Melting and Boiling Point

These abrasive grains have extremely high melting and boiling points, with aluminum oxide melting at 2072°C and boiling at 2977°C. Silicon Carbide melts at 2830°C and does not boil since it sublimes.


In this article, you’ve learned about some of the main differences between aluminum oxide and silicon carbide. Please get in touch with us if you want to expand your knowledge of abrasive grains and sandpaper.

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