Difference Between Silicon Carbide and Aluminum Oxide Abrasive

 

Among various types of abrasives, silicon carbide and aluminum oxide are the most often utilized. Sanding products such as sandpaper sheets, sanding belts, and sanding pads are made of silicon carbide and aluminum oxide and differ in key ways that make one preferable for a given application.

They vary in terms of pricing, adaptability, and performance levels. One of these is usually present in most woodworking and metalworking applications where material surface sanding is necessary. In this article, you'll discover the distinctions between silicon carbide and aluminum oxide abrasives so that you may choose wisely for your tasks.

Silicon Carbide Abrasives

Compared to aluminum oxide, silicon carbide has sharper and harder abrasive grains. However, it is not as resilient as abrasives made of aluminum oxide. This is due to its brittleness and narrower shape, which gradually deteriorate with use. The sharp particles of silicon carbide can cut medium-density fiberboard, glass, and plastics easily with light pressure. However, hardwoods and metals are more difficult to cut.

Silicon carbide is a superior choice for tackling uneven surfaces, thanks to its remarkable brittleness compared to aluminum oxide. Moreover, this versatile material excels in wet sanding, making it an essential tool for achieving a flawless finish.

Compared to ordinary (black) silicon carbide, friable silicon carbide is harder and purer but is also more brittle. Traditional (black) silicon carbide is used for grinding hard nonmetals, ceramics, and non-ferrous metals, while the green type is excellent for polishing the surfaces of materials.

Silicon carbide sanding belts are incredibly versatile, excelling on a wide range of materials. They are a top choice for hard surfaces such as wood finishes, stone, metal, and paint, yet are equally effective on softer materials such as glass, rubber, and plastic. These belts feature a closed coat with optimal grain coverage, making them perfect for preparing surfaces for sealants or lacquers or applying fine grain to harder materials. While silicon carbide is also commonly found in grinding wheels and discs for materials such as cast iron, aluminum, and cemented carbide, these belts in particular provide exceptional polishing and finishing capabilities.

If you want to know the difference between various other abrasive grains, follow the link to ceramic vs aluminum oxide vs zirconia abrasive grains.

Aluminum Oxide Abrasives

The most widely used abrasive grain in the metal and woodworking industries is aluminum oxide.

This is because it performs better than silicon carbide on various surfaces, such as metal, painted surfaces, bare wood, and painted surfaces. Brown, white, and pink are the colors of aluminum oxide abrasives, with brown being the most common type.

• White aluminum oxide:  White aluminum oxide is found in coarse to fine grits; because it generates less heat, it works best on wood and lacquers. Aluminum oxide in white and pink deteriorates more quickly but leaves a smoother, finer surface. Compared to brown aluminum oxide, they resemble silicon carbide more closely.
• Pink aluminum oxide: Available in coarse to fine grits. It applies to softer woods.
• Brown aluminum oxide: The third and most lasting variety of aluminum oxide is brown, whose grains degrade far more slowly than pink and white varieties. Metals, drywall, fiberglass, wood, and painted surfaces are among the very tough materials that can be sanded with it. Compared to smoother pink or white aluminum oxides, it works better and is less expensive.

What to Choose Between Silicon Carbide and Aluminum Oxide Abrasives

When choosing the best abrasive for your job, it is important to consider the kind of material you are working with.

Use Silicon Carbide Belts when:

• You're working with non-metallic materials.
• The material has poor tensile strength.

Use Aluminum Oxide Belts when:

• You're grinding metals with high tensile strengths, such as stainless steel, high-tensile bronze, and certain aluminum alloys.
• Your process is a dry grinding application, as aluminum oxide belts are designed exclusively for dry use.

Remember that successfully pairing silicon carbide and aluminum will result in a significantly finer abrasive effect on the same sanding project. This method is typical in applications involving woodworking. Starting with aluminum oxide abrasives for rough sanding, you move on to silicon carbide for the last stages. Doing this may create a flawless surface finish without using up all of your sandpaper.

Important Key Factors to Consider

The following are some factors to consider while deciding between silicon carbide and aluminum oxide abrasive:

• Hardness of the material: Silicon carbide is highly suitable for extremely hard or brittle materials because of its exceptional hardness and sharpness. Aluminum oxide, on the other hand, can be used to deal with softer materials like wood and soft metals.
• Required Finish: Choosing between Silicon carbide and Aluminum Oxide abrasives is also based on the required finish you want. Fine silicon carbide grits will generate exceptional results, especially on harder coatings.
• Wet and Dry Sanding: Silicon carbide is mainly used for wet sanding due to its anti-clogging qualities, whereas aluminum oxide is used for dry sanding. 
• Cost: Aluminum oxide is highly economical when compared to silicon carbide, especially for general applications. 
• Durability: Aluminum oxide is highly durable compared to silicon carbide, even when working on harder materials.

CONCLUSION

Aluminum oxide and silicon carbide are both highly effective ceramic abrasives, each with its distinct advantages. Silicon carbide is known for its excellent sharpness and hardness, making it ideal for working with non-metallic materials or substances with low tensile strength. While it may be less durable than aluminum oxide, its cutting properties are exceptional for these applications. In contrast, aluminum oxide is the best choice for materials with high tensile strength, providing greater durability.

Also, their combination allows you to take advantage of each abrasive's unique properties, achieving a finer cut while extending the life of your abrasives.