2.2.1 Chemistry, Types and Characteristics of Silicon
Silicon carbide, also known as carborundum and SiC, is used as abrasive material in its hexagonal form, a-SiC (Fig. 2.10) [MALK08, p. 24]. It is composed of 70.05 wt % Si and 29.95 wt% C [LIET08]. Each C atom is surrounded by four Si atoms and vice versa. The proportion of covalent atom bonds to ionic atom bonds is 90-10 % [MULL01, p. 25]. Silicon carbide occurs in two modifications: cubic P-SiC and aSiC (mostly hexagonal and rhombohedral).
Fig. 2.10 Basic properties of а-silicon carbide, picture source [PRES08]
• Green silicon carbide has higher purity and is mainly used for precision grinding [TYRO03b].
• Black silicon carbide has higher toughness and is used for rough grinding operations [TYRO03b].
The chemical composition is shown in Table 2.2.