主权项 |
1. A method for preparing an aggregate comprising a plurality of particles, the method comprising forming a mixture comprising glass powder and an additive, forming green pellets from the mixture, coating the surface of the pellets with a refractory material and heating the pellets at a required temperature to produce a plurality of particles, the additive being such that it at least partially breaks down at the required temperature to generate gas, which gas is at least partially retained in the microstructure of the mixture to cause the formation of pores within the microstructure, the additive also being such that upon heating the additive and glass combine to produce a glass ceramic system. |