Formation of closed-pore foam ceramic from granite scraps

Closed porosity ceramics and glasses

“…In another study, granite scraps and clay tailings were used to form closed porosity (ϕ T ∼ 83%) mixed oxides having reasonably low‐effective thermal conductivity (0.051 W/m.K. ), intended for building insulations . Porous anorthite/gehlenite ceramics (ϕ T < 60%) were fabricated from clays and paper processing residues.…”

“…While the process does not yield with highly porous samples (ϕ T was generally below 40%), yttria‐stabilized zirconia (3YSZ and 8YSZ), alumina (with superplasticity‐facilitating dispersoids; 3YSZ, 0YZ or spinel) and titania‐based closed porosity ceramics were produced . Similarly, recycled materials (eg, granite scrap and fired clay tailings) were used with SiC to cause gas generation and form closed porosity ceramic foams . In a different technique, closed porosity aluminum oxynitride (AlON) (ϕ C = 80%) foams were made by combustion synthesis in between 2165°C and 2650°C for a very short time (10 seconds).…”

“…[72][73][74][75][76][77][78][79][80] Similarly, recycled materials (eg, granite scrap and fired clay tailings) were used with SiC to cause gas generation and form closed porosity ceramic foams. 81 In a different technique, closed porosity aluminum oxynitride (AlON) (ϕ C = 80%) foams were made by combustion synthesis in between 2165°C and 2650°C for a very short time (10 seconds). Al and Al 2 O 3 were reacted under high (100 MPa) N 2 pressure together with Al(NO 3 ) 3 .9H 2 O which was used as high-temperature decomposing pore-forming agent yielding AlON foams.…”

“…116 The type of forming agent can also influence the viscosity of the blend, for example alkali carbonates or phosphates can further reduce the viscosity because of alkali introduction into the glass network. 108 Besides waste glass, different recycled or natural materials (granite scrap and fired clay residue), 81 ashes (fly, volcanic or sewage sludge), various types of slags and mine/mill tailings [91][92][93][98][99][100] were used with few amounts of additional silicon carbide (<10 wt%) releasing gas species at high temperature, see Equations 1-3. 119 In this way, it was possible to obtain closed porosity foam glass with ϕ T = 82% (calculated via bulk density measured by geometric evaluation) and 1 MPa compressive strength, 91 or glass ceramic foam with wollastonite-diopside crystals having ϕ T = 90% and 2.6 MPa compressive strength, 93 see Figure 11 for representative samples.…”

Recycling Fly Ash and Red Mud to Manufacture Self-Foaming Ceramic Foams

“…where k B is Boltzmann's constant, and r g is the radius of the gas molecules. With the further growth, the bubbles approach each other and start to touch until equilibrium is reached during the insulation stage [19], the diameters of the pores become uniform and the pore walls become thin [20]. The insulation process can bring the surface tension of the liquid phase (γ l ) and the gas pressure (P g ) into balance, as illustrated in Figure 9.…”