Aluminum Oxide Vs Silicon Carbide

Aluminum oxide and silicon carbide are among the most frequently utilized abrasives used for sandpaper sheets and belts, offering varied properties to tackle many tasks effectively. Both offer advantages for certain tasks when used properly.

Regular (black) and friable silicon carbide can both be used for polishing, deburring, and refinishing of rough surfaces. Silicon carbide grits tend to be harder and sharper than aluminum oxide but deteriorate more quickly over time.


Understanding abrasives’ properties, applications and advantages/disadvantages can help workers make informed decisions and achieve the best results for their project or process.

Hardness is an essential feature to consider when choosing an abrasive type for use with fragile materials such as metals, ceramics and glasses. Aluminum oxide has superior hardness and wear resistance – ideal features to look for when selecting an abrasive to cut or grind through these tougher substances like metals, ceramics and glasses.

Silicon carbide abrasives, on the other hand, are not as tough as aluminum oxide ones. Although its razor-sharp grains can easily cut through glass, plastic and medium-density fiberboard with minimal pressure applied, they struggle with harder woods and metals due to its brittle grain structure that wears down faster compared to its aluminum oxide counterparts – you may need to use higher grit counts when working with silicon carbide for tougher jobs.

Thermal Conductivity

Silicon carbide boasts higher thermal conductivity than aluminum oxide, helping power electronics dissipate heat quickly to prevent overheating and ensure optimal performance.

Power electronic substrates must dissipate heat efficiently to avoid short circuiting and maintain signal integrity, making this property an essential one. Furthermore, its high thermal conductivity makes it suitable for insulating and supporting electronic components on an electric vehicle.

Silicon carbide is extremely scarce in nature and must be synthetically produced using diamond-tipped blades to synthesize it. Modern methods for producing silicon carbide for use in abrasives, metallurgical, and refractories industries rely on a chemical reaction between pure silica sand mixed with carbon in ground coke form in an electrical resistance-type furnace using electric current running through carbon conductors to bring about this reaction.

Sintered silicon carbide SiSiC can be reaction bonded or cast, and then formed using cold isostatic pressing or extrusion. Large single crystals can also be grown using Lely’s method and later cut to form gemstones known as moissanite gemstones.

Chemical Stability

Silicon Carbide, commonly referred to as SiC, is an extremely hard ceramic substance often used in bulletproof vests. Due to its durable surface characteristics and hardness, silicon carbide also serves as an important abrasive in modern lapidary and is utilized for industrial machining processes like grinding, cutting and waterjet cutting.

Moissanite is a layered crystal material with multiple polytypes. Large single crystals can be grown using the Lely method and cut into gemstones known as synthetic moissanite gemstones.

Silicon carbide has the unique property of being both an insulator and semiconductor when undoped with elements such as boron or aluminum dopants; when doped, however, its wide bandgap requires excessive energy for electrons to move from its valence band into its conduction band and vice versa.

American Elements manufactures silicon carbide in multiple grades and sizes to meet the demands of various industries, including Mil Spec; ACS Reagent Grade; Food, Agricultural, Pharmaceutical Grade (FAPG); USP/BP Grade. If you would like more information or have purity questions please don’t hesitate to get in touch.

Wear Resistance

Aluminum oxide comes in brown, white and pink varieties and is an extremely tough durable abrasive grain with a blocky structure, ideal for holding up against most materials. Available from coarse to fine grit sizes for power sanding and hand sanding applications on belts, disks and sponges – aluminum oxide works well on metal, glass and painted surfaces but less effectively when applied directly to wood surfaces.

Silicon carbide, being more friable than aluminum oxide, can be used to polish automotive components and remove rust from metal and glass surfaces. Furthermore, silicon carbide can also be useful for refinishing wood flooring (smoothing out between coats) as well as deburring metal surfaces.

Spark plasma sintering produced graphene-reinforced Al2O3-SiCw/Alumina nanocomposites display superior tribological properties compared to pure ceramic under similar loads, with lower friction coefficient and wear rates than pure ceramic due to tribolayer formation from adhered graphene platelets on worn surfaces that provide adequate lubrication while suppressing wear. This was due to an adhered protective tribolayer of graphene platelets on worn alumina ball surfaces which provided sufficient lubrication while suppressing wear.

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