Ceramics-Silikáty 53, (4) 287 - 296 (2009)

Compressive strength of bauxite refractories with phenol-formaldehyde resin as binder, used as lining in high temperature furnaces, was investigated in this study. Mechanical properties are used to determine the material’s mechanical resistance and thus they represent the life time of the refractory. Different bauxite grain size, resin content and molding pressure were selected for the preparation of the specimens. The stress - strain data of compression test were modeled using parameters with physical meaning such as maximum stress (σ_max), maximum strain (e_max), elasticity parameter (E), and viscoelastic parameter (p). In addition, simple mathematical models were developed to correlate the maximum stress and corresponding strain to producing conditions and raw materials’ characteristics. After data processing it was noticed that when increasing molding pressure maximum stress and maximum strain increased, while the viscoelastic parameter decreased. As far as elasticity parameter is concerned, at first it decreases with grain size and beyond a critical value of molding pressure, between 100 and 200MPa, it increases. Higher resin content led to higher compressive strength, due to higher cohesion and bonding strength. On the other hand, increased bauxite grain size leads to samples with degraded mechanical properties as larger granules hinder sintering between the granule boundaries.