This volume on silicon nitride, which is characterized as a reactant, covers electrochemical behaviour, colloid chemistry and part of the chemical reactions. The most important types of reactions are reactions with metals and reactions with metal oxides under nonoxidative conditions.Other types of reactions include thermal decomposition, effects of radiaion, tribochemical reactions and reactions with other metal nitrides. Not only are results reported for pure silicon nitride but also for ceramic silicon nitride materials, which may contain up to 20% additives.