The key difference between silicon carbide and boron carbide is that silicon carbide has one silicon atom bonded to one carbon atom, whereas boron carbide has four boron atoms bonded to one carbon atom.

Both silicon carbide and boron carbide are carbon-containing compounds. Both these are very hard material. They have different chemical and physical properties.

CONTENTS

1. Overview and Key Difference
2. What is Silicon Carbide
3. What is Boron Carbide
4. Side by Side Comparison – Silicon Carbide vs Boron Carbide in Tabular Form
5. Summary

What is Silicon Carbide?

Silicon carbide is a semiconductor material composed of silicon and carbon atoms. The chemical formula of this compound is SiC. Therefore, it has one silicon atom bonded to one carbon atom via covalent chemical bonding. This material is also called carborundum and it occurs in nature in the form of moissanite, an extremely rare mineral. Therefore, silicon carbide is mostly made as a synthetic material.

Figure 01: Silicon Carbide

The molar mass of silicon carbide is 40 g/mol. This material appears as a bluish-black, iridescent crystal structure, but the pure form is colourless. The black colour is due to the presence of iron as an impurity. Moreover, it is insoluble in water but soluble in molten iron and molten alkalis. However, we can find silicon carbide in about 250 crystal forms. This compound shows polymorphism. Here, alpha silicon carbide is the most common and stable form. It forms at very high temperatures and it has a hexagonal crystal structure.

There are many uses of silicon carbide. Mainly, it is useful as an abrasive and in the production of cutting tools. It is also an important structural material. E.g. in composite armour, in ceramic plated bulletproof vests, high-temperature kilns, etc. In addition, silicon carbide is useful in the manufacture of automobile parts and as semiconductor materials.

What is Boron Carbide?

Boron carbide is an extremely hard material composed of boron and carbon atoms. The chemical formula of this compound is B4C. Therefore, it has four boron atoms bonded to a single carbon atom. It is only third to diamond and cubic boron nitride in its hardness. Therefore, it is also called “black diamond”.

Figure 02: Boron Carbide

The molar mass of boron carbide is 55.25 g/mol. It appears as a dark grey or black powder or crystal. It is insoluble in water. This material is well-known for its high hardness, the high cross-section for neutron absorption, high stability towards ionizing radiation, etc. Moreover, it has semiconductor properties. For this, the electronic properties of boron carbide are dominated by hopping-type transport. Typically, it is of a p-type semiconductor.

Boron carbide is a synthetic material. It can be prepared by the reduction of boron trioxide into boron carbide in the presence of carbon. This reaction requires carbon or magnesium as the reducing agent.

What is the Difference Between Silicon Carbide and Boron Carbide?

The key difference between silicon carbide and boron carbide is that silicon carbide has one silicon atom bonded to one carbon atom whereas boron carbide has four boron atoms bonded to one carbon atom. Silicon carbides are bluish-black crystals while boron carbides are dark grey or black crystals.

The following infographic summarizes the difference between silicon carbide and boron carbide.

Summary – Silicon Carbide vs Boron Carbide

Both silicon carbide and boron carbide are carbon-containing compounds. They have different chemical and physical properties. The key difference between silicon carbide and boron carbide is that silicon carbide has one silicon atom bonded to one carbon atom, whereas boron carbide has four boron atoms bonded to one carbon atom.

Reference:

1. Bell, Terence. “The Properties and Uses of Silicon Metal.” ThoughtCo, Jan. 31, 2020, Available here.
2. “Silicon Carbide.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 28 Aug. 2008, Available here.
3. “Boron Carbide.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 14 Apr. 2010, Available here.
4. “Silicon Carbide.” Wikipedia, Wikimedia Foundation, 8 Mar. 2020, Available here.

Image Courtesy:

1. “SiC p1390066” By David Monniaux – (CC BY-SA 3.0) via Commons Wikimedia
2.”Boron carbide” By Preslav – Own work, (Public Domain) via Commons Wikimedia

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