Engineered low-density heterogeneous microparticles and methods and formulations for producing the microparticles
A low density material and a method for preparing a low-density material and precursor for forming a low-density material are provided. An aqueous mixture of inorganic primary component and a blowing agent is formed, the mixture is dried and optionally ground to form an expandable precursor. Such a precursor is then fired with activation of the blowing agent being controlled such that it is activated within a predetermined optimal temperature range. The firing conditions are also controlled to provide a low density sphere containing a heterogeneous sphere wall structure comprising a combination of amorphous glass and a crystalline phase or gas phase or both.
1. An engineered, low-density, heterogeneous microparticle, comprising:
a wall defining a primary void in the microparticle, wherein the wall comprises an amorphous phase and a crystalline phase, wherein the amorphous comprises an amorphous aluminum silicate based material and a pre-determined amount of solid micro-inclusions embedded in said amorphous aluminum silicate based material, wherein the solid micro-inclusions are comprised of materials that are not in an amorphous phase.
2. The microparticle of claim 1 , wherein the micro-inclusions comprise crystalline solids.
3. The microparticle of claim 1 , wherein the micro-inclusions comprise at least 5% of the volume of the microparticle.
4. The microparticle of claim 1 , wherein the micro-inclusions comprise no more than 50% of the volume of the microparticle.
5. The microparticle of claim 1 , wherein each micro-inclusion has a length of no greater than 0.1 mm.
6. The microparticle of claim 1 , wherein the amount of micro-inclusions is pre-determined by the desired density of the microparticle.
7. A cementitious article incorporating the microparticle of claim 1 .
8. A composite article incorporating the microparticle of claim 1 .