The main difference between cubic and hexagonal boron nitride lies primarily in their hardness, crystal structure, and the resulting applications:
- Cubic boron nitride: This form has a crystal structure similar to that of diamond and, as a result, exhibits similar properties. The most important characteristic of cubic boron nitride is its extreme hardness, which is why it is often used as a substitute for diamond in industrial applications.
- Hexagonal boron nitride: Unlike the cubic form, hexagonal boron nitride is relatively soft. It is readily available commercially and can be processed into large blocks (ingots) in its solid form. Its outstanding strengths lie not in its hardness, but in its ability to withstand extremely high temperatures, its excellent electrical properties, and its resistance to aggressive molten metals.
