Structure–Property Functions of Inorganic Chemical Binders for Refractories

Abstract

For refractory application, amongst others, inorganic chemical binders are used to shape and process loose, unpacked materials. The binder influences the chemical composition within the ceramic body during setting, aging and firing and thus the finally reached properties of the refractory material. For an effective design of tailored materials with required properties, the mode of action of the binder systems should carefully be investigated. A combination of both structure analysis techniques and macroscopic property investigations proved to be a powerful tool for a detailed description of structure–property correlations. This is shown on the basis of X-ray powder diffraction and nuclear magnetic resonance spectroscopy analyses combined with observation of (thermo)mechanical and chemical investigations.

Infrared irradiation to drive phosphate condensation as a route to direct additive manufacturing of oxide ceramics

“…27 These condensation reactions can occur at low temperatures (<500 • C) and result in an inorganic polymer with good mechanical toughness. 28 This inorganic polymer is an interesting low process temperature binder for higher sintering temperature oxide ceramic par-ticles. Prior work has shown an ability to thermally convert Al(H 2 PO 4 ) 3 into crystalline AIPO 4 to bind oxide ceramics such as silica and alumina 29,30 and form a monolithic ceramic.…”

“…28 This inorganic polymer is an interesting low process temperature binder for higher sintering temperature oxide ceramic par-ticles. Prior work has shown an ability to thermally convert Al(H 2 PO 4 ) 3 into crystalline AIPO 4 to bind oxide ceramics such as silica and alumina 29,30 and form a monolithic ceramic. 31 The adhesive ceramic binding mechanism of ADP occurs via condensation reactions between the hydroxyl groups of dihydrogen phosphate and the hydroxyl groups on the ceramic powder surface (Figure 1B).…”

“…Cation exchange reactions can also be driven between the phosphate and oxide ceramic phases to further densify the material and create an oxide-phosphate interlayer with higher temperature and mechanical binding performance. 27,30,32 Several examples of using ADP to bind ceramics can be found in the literature. Li et al 32 used ADP to coat and bind SiC particles to form porous ceramics for catalysis, heat exchangers, diesel particle filters, and hightemperature electronic and photonic devices.…”

Alumina dissolution process to fabricate bimodal pore architecture alumina with superior green and sintered properties

“…Each type of binder has its own set of advantages and disadvantages. Among all the various binder types, phosphate binders are a well‐recognized class that is widely used in refractory applications 35 . Some research studies have also demonstrated that the use of sulfate, in combination with phosphate, has a relatively superior binding effect 36 .…”

“…Among all the various binder types, phosphate binders are a well-recognized class that is widely used in refractory applications. 35 Some research studies have also demonstrated that the use of sulfate, in combination with phosphate, has a relatively superior binding effect. 36 However, the application of aluminum sulfate exclusively as a binding agent to form green, porous structures is yet to be reported.…”