Stabilizing the pore structures of foam glasses for improving the mechanical and physical properties at a low sintering temperature

We investigate the foaming stabilizing effects of K3PO4 and Li2CO3 to the physical and mechanical properties of foam glasses and find an optimal amount of 0.75 wt% K3PO4 and 1.5 wt% Li2CO3 that enables a balanced combination of superior low bulk density (0.33 g/cm3) and high compressive strength (3.28 MPa). The chemical stability of foam glasses with Li2CO3 exhibits a low weight loss of 0.50 wt% and ion dissolution in aqueous solutions with pH of 3 and 7, showing that Li2CO3 can effectively enhance the chemical stability of the foam glasses subject to acid solution and water. Next, the combinational effects of MnO2, polycrystal mullite fiber, K3PO4, and Li2CO3 are investigated, where the physical and mechanical properties are overall improved especially in compressive strength, but other properties show minor improvement. The foam glasses stabilized by K3PO4 and Li2CO3 are weaker than those stabilized by commonly-used stabilizer Na2HPO4, but are lighter with a homogeneous foaming structure of more uniformly-distributed pores. This work finds more alternative ways in effectively stabilizing the foaming, and should inspire more systematic approaches to controlling the foaming for diversified engineering needs by establishing fundamental structure-property-process relationships, thereby customizing the design of foam glasses with desirable properties.