Carbon-bonded alumina refractories offer excellent thermal shock performance but are lacking in terms of mechanical strength. In the present contribution, the influence of the particle packing and the addition of graphene oxide (GO) to carbon-bonded alumina refractories on the physical and mechanical properties before and after thermal shock was investigated. Coarse tabular alumina grains were coated by a GO suspension and used to prepare dry-pressed compacts. The included graphite fraction (15 wt%) was either regarded as a lubricating matrix component or as a quasi-spherical component of a calculated density-optimized aggregate size distribution. During coking, the GO was reduced to thermally reduced graphene. The porosity, true density and thermal shock behavior in terms of the cold modulus of rupture (CMOR) and Young's modulus were compared. Samples with a higher density were obtained when the irregularly shaped graphite was considered as the matrix component (lubricant). The results showed that the use of GO had a positive impact on the mechanical properties of the graphene-reinforced Al2O3-C refractories, especially in the case of a less optimized packing, due to the bridging of delamination gaps. In addition, the thermal shock only had a minor impact on the Young's modulus and CMOR values of the samples. SEM investigation revealed very similar microstructures in coked as well as thermally shocked samples.

• Keywords
• composites, graphene oxide, packing density, refractories, thermal shock resistance,
• Publication type
• Journal Article MeSH

The aim of this paper is to prepare nano-functionalized ceramic foam filters from carbon-bonded alumina. The carbon-bonded filters were produced via the Schwartzwalder process using a two-step approach. The prepared ceramic foam filters were further coated using graphene oxide. Graphene oxide was prepared by the modified Tour method. The C/O of the graphene oxide ratio was evaluated by XPS, EDS and elemental analysis (EA). The amount and type of individual oxygen functionalities were characterized by XPS and Raman spectroscopy. The microstructure was studied by TEM, and XRD was used to evaluate the interlayer distance. In the next step, filters were coated by graphene oxide using dip-coating. After drying, the prepared composite filters were used for the purification of the water containing lead, zinc and cadmium ions. The efficiency of the sorption was very high, suggesting the potential use of these materials for the treatment of wastewater from heavy metals.

• Keywords
• carbon-bonded alumina, ceramic foam filters, graphene oxide, water treatment,
• Publication type
• Journal Article MeSH

The aim of this paper is to prepare and characterize partially-oxidized graphite oxide and consider if it is possible to affect the level of oxidation of particles by an adjustment of the oxidizing agent. Several samples were prepared, using different amounts of oxidizing agent. The samples were subsequently analyzed. The C/O ratio was evaluated from XPS, EDS, and EA. The amount and type of individual oxygen functionalities were characterized by XPS, Raman spectroscopy, and cyclic voltammetry. The structure was studied by SEM and XRD. Thermal stability was investigated by STA-MS in argon atmosphere. The results can be useful in order to design simple technology for graphite oxide synthesis with required oxygen content.

• Keywords
• graphene derivatives, graphite oxide, modified Tour method, partial oxidation,
• Publication type
• Journal Article MeSH