# Aggregates

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Solidly bound or molten particles, whose resulting surface may be much smaller than the sum of the calculated surfaces of the individual components. Aggregates are held together by strong forces such as covalent bonds or forces caused by sintering or complex physical hooking. Aggregates, just as agglomerates, are referred to as secondary particles. See also ISO/TS 27687:2008 (E) International Organization for Standardization.