Diatomaceous earth was mixed with Brazil nut shell ash (BNS ash) in different amounts between 0 and 30 wt% and sintered at temperatures between 750 and 950 °C. The BNS ash contains 33 wt% K2O and 11 wt% CaO mainly in carbonate form. The addition of BNS ash into the diatomaceous earth caused significant changes of the microstructure after sintering. The BNS ash addition produces lightweight porous bricks with acceptable strength at lower sintering temperature. The best combination of strength and porosity was achieved for a mixture of 10 wt% of BNS ash in the diatomaceous earth sintered at 850 °C. The achieved high porosity was 49%, density 1.06 g/cm3, thermal conductivity 0.20 W/(m K) and the compressive strength was 8.5 MPa.

The thermal behaviour of two types of clays collected from different locations in Bolivia has been studied. The clays contain kaolinite, illite, quartz and small amounts of microcline. The phase evolutions have been characterized from room temperature to 1250 °C. For both clays, kaolinite is completely transformed into metakaolinite when heated up to 650 °C. During further heating to 1050 °C, illite undergoes total dehydroxylation. Mullite is formed in the temperature interval of 1050–1150 °C and its formation rate is dependent on the amount of K and Fe present in the clays. The clay with higher amounts of K (3.2 mass %) and Fe (5.6 mass%) has an onset temperature for sintering at about 900 °C and an onset temperature for liquid formation at 1080 °C. This is about 50 °C lower onset temperature for sintering and 94 °C lower onset temperature for liquid formation when compared with the clay with lower amounts of K (2.3 mass %) and Fe (1.6 mass %).

Changes, over a period of 8 years, in the chemical composition and morphology of deposit and lining materials in a production rotary kiln for iron ore pellet manufacture are described. The following have been studied: two types of refractory brick used as lining material; deposited chunk materials from the lining; the interaction zones between deposits and linings. Morphological changes at the deposit/lining interface, and the active chemical reactions, are established. Larger hematite grains in the deposit material (5–50 μm) primarily remain at the original deposit/lining interface. The remainder penetrates fissures, voids and brick joints, forms a laminar structure with corundum from the bricks, and migrates in grains in the lining material. Potassium penetrates more deeply into the bricks than hematite, resulting in the formation of kalsilite, leucite and potassium β-alumina, which contribute to degradation of the lining.

Cobalt nanoparticles were prepared at room temperature by reducing cobalt sulfate heptahydrate with sodium borohydride using functionalized SBA-15 mesoporous silica as a hard template. It was found that both external and internal fuctionalization of silica walls play a crucial role on the infiltration and reaction of the reagents in the silica framework. Subsequent heat treatment of the impregnated silica at 500 °C in air or nitrogen atmospheres leads to growth of crystals of the deposited cobalt and formation of cobalt oxide and cobalt nanoparticles, respectively. Dissolution of the silica template by NaOH resulted in well dispersed Co and Co3O4 nanoparticles ranging in size between 2 and 4 nm. The functionalization of the silica was studied by FTIR, N2-physisorption, and thermogravimetric techniques and the obtained nanoparticles were characterized by XRD, TEM and EDX analysis.

The aim of this study was to compare the thermal behaviour of clays containing illite and kaolinite in various proportions. The clays contained small amounts of K and Fe, which act as fluxing agents. In order to investigate the phase formations during heating, the samples were examined in a differential scanning calorimeter at temperatures up to 1300°C. The thermal expansion of the samples was determined by dilatometer measurements from room temperature up to 1150°C. Phases were identified using x-ray diffraction and scanning electron microscopy. In all samples, most of the kaolinite was transformed into metakaolinite during heating up to 650°C, while illite remained unchanged up to 950°C. There was no influence of K and Fe on dehydroxylation. Metakaolinite formed at temperatures above 950°C leading to a Si-Al spinel. Furthermore, mullite was formed in the temperature interval 1050-1150°C. In this temperature range, the mechanism of mullite formation depended on the amount of K and Fe in the samples, changing the temperature of formation of mullite. It was observed by x-ray diffraction that most of the illite was transformed into a Si-Al spinel phase at 1050°C, and during further heating transformed into mullite. An increased amount of illite in the clays slightly decreased the melting temperature. The dilatometer measurements showed expansion and shrinkage for the dehydroxylation and spinel-phase formation, respectively.

The lattice strain tensor evolution for single bulk grains of austenite and ferrite in a duplex stainless steel during tensile loading to 0.02 applied strain has been investigated using in situ high-energy X-ray measurements and finite-element modeling. Single-grain X-ray diffraction lattice strain data for the eight austenite and seven ferrite grains measured show a large variation of residual lattice strains, which evolves upon deformation to the point where some grains with comparable crystallographic orientations have lattice strains different by 1.5 × 10-3, corresponding to a stress of ≈300 MPa. The finite-element simulations of the 15 measured grains in three different spatial arrangements confirmed the complex deformation constraint and importance of local grain environment.

Two types of refractory bricks were used in reaction tests with slag from a production kiln for iron ore pellet production. Electron microscopy was used to characterize morphological changes at the slag/brick interface and active chemical reactions. Phases such as kalsilite, nepheline and potassium β-alumina form, in a layered structure, as a consequence of alkali metals migration in the brick. Larger hematite grains (50-100 μm) in the slag remain at the original slag/brick interface, while smaller grains dissolve and move through the partly dissolved brick bulk, and forms micrometer sized needle shaped crystals deeper in the lining material. Thermodynamic simulations predict the formation of a solid solution between hematite and corundum which is also observed in the reaction zone after extended time periods.

Degradation of bricks in an iron ore pellet producing kiln has been investigated. Lab-scale tests of brick/slag interaction performed under different temperatures, atmospheres, and alkali additions show that addition of alkali dissolves the mullite in the brick and leads to formation of the phase nepheline (Na2O·Al2O3·2SiO2). At a high temperature, the grain boundary where nepheline is formed disintegrates due to volume expansion. At increased temperature, the nepheline transforms to an amorphous phase. Thus, a wear mechanism is proposed in the kiln using these bricks that involves these chemical reactions in combination with erosion by the continuously flowing slag.

This method consists of a combination of vacuum sintering at 1600 °C followed by hot isostatic pressing (HIP) at 1500 °C of a highly agglomerated commercial powder. The use of evacuated glass capsules to perform HIP treatment allowed samples that showed open porosity after vacuum sintering to be sintered to transparency. The sintering response of the investigated powder was studied by careful microstructural observations using scanning electron microscopy and optical microscopy both in reflection and transmission. The successful key of this method was to keep porosity intergranular during pre-sintering, so that it can be removed subsequently by HIP treatment. It was found that agglomerates of closely packed particles are helpful to reach that purpose, since they densify fully and leave only intergranular porosity. However, performing HIP treatment at 1625 °C was found to result in opaque samples. This was attributed to the diffusion of argon inside the capsule. Contamination at different steps of processing was also investigated by inductively coupled plasma mass spectrometry (ICP-MS).

Small-angle x-ray scattering was used to study in situ decomposition of an arc evaporated TiAlN coating into cubic-TiN and cubic-AlN particles at elevated temperature. At the early stages of decomposition particles with ellipsoidal shape form, which grow and change shape to spherical particles at higher temperatures. The spherical particles grow at a rate of 0.18 Å/°C while coalescing.