In terms of its chemical composition, biomass is a very complex type of fuel. Its combustion leads to the formation of materials such as alkaline ash and gases, and there is evidence of the corrosive effect this process has on refractory linings, thus shortening the service life of the combustion unit. This frequently encountered process is known as “alkaline oxidative bursting”. Corrosion is very complex, and it has not been completely described yet. Alkaline corrosion is the most common cause of furnace-lining degradation in aggregates that burn biomass. This article deals with an experiment investigating the corrosion resistance of 2 types of refractory materials in the Al₂O₃-SiO₂ binary system, for the following compositions: I. (53 wt.% SiO₂/42 wt.% Al₂O₃) and II. (28 wt.% SiO₂/46 wt.% Al₂O₃/12 wt.% SiC). These were exposed to seven types of ash obtained from one biomass combustion company in the Czech Republic. The chemical composition of the ash is a good indicator of the problematic nature of a type of biomass. The ashes were analyzed by X-ray diffraction and X-ray fluorescence. Analysis confirmed that ash composition varies. The experiment also included the calculation of the so-called “slagging/fouling index” (I/C, TA, Sr, B/A, Fu, etc.), which can be used to estimate the probability of slag formation in combustion units. The corrosive effect on refractory materials was evaluated according to the norm ČSN P CEN/TS 15418, and a static corrosion test was used to investigate sample corrosion.

The continuous steel casting process must simultaneously meet the requirements for production performance, quality and safety against breakouts. Knowing the thickness of the solidified shell, particularly at the exit of the mould, is useful for the casting process control and breakout prevention. Shell thickness is difficult to measure during casting; in practice, it is predicted by indirect methods and models. But after undesired rupture of the shell and leakage of the liquid steel, it is possible to measure the shell thickness directly. This article is focused on the problem of the growth and measurement of the solid shell obtained after the breakout of a round block with a diameter of 410 mm. An original methodology was developed in which a surface mesh of points was created from the individual scanned parts of the block using a 3D laser scanner. Research has shown differences of up to 6 mm between the maximum and minimum shell thickness at the mould exit. A regression function of the average shell thickness on time was found. The results of the real shell growth were further used for the verification of the original numerical model of cooling and solidification of the round block.

An alternative binder to calcium aluminate cement (CAC) was prepared by the sol-gel method. Chemically pure systems such as tetraethylorthosilicate (SiC₈H₂₀O₄) and nonahydrate of alumina nitrate (Al(NO₃)₃·9H₂O) were used as major raw materials. The manufacturing process of binder via solution is mentioned, and transitions in binder structure as a function of thermal treatment in the range between 85 and 1400 °C are described. Finally, binder efficiency was verified by its application in high-temperature concrete instead of calcium aluminate cement (CAC). Newly developed sol-gel binder was characterized by XRFS quantitative analyses, XRD diffraction, STA-DTA and TG analyses and the BET method. Samples of concrete which were based on natural bauxite raw material showed cold compressive strength of 42 MPa compared to the same material where a conventional CAC was applied, and samples reached cold compressive strength of 44 MPa.

The rapid expansion of renewable energy technologies, particularly photovoltaic systems, has led to sustained annual growth rates on the order of several tens of percent. This dynamic development is expected to fundamentally transform the structure and operation of the energy sector. One promising approach to mitigating the challenges associated with increasing shares of intermittent energy sources is the implementation of high-temperature thermal energy storage systems. The objective of this study was to develop a rapid and experimentally efficient method for determining the thermal conductivity of insulating materials suitable for high-temperature thermal energy storage systems. The investigation focused on two primary material categories: thermal insulation materials designed for elevated temperature operation and materials intended for thermal energy storage. A key contribution of this work is the development of a rapid and experimentally efficient method for determining the thermal conductivity coefficient of solid materials. The proposed technique is based on controlled heating to a steady thermal regime, enabling evaluation of thermal conductivity within a non-negligible reduction of measurement time compared to conventional steady-state approaches (e.g., guarded hot plate). The method requires minimal sample preparation and is well-suited for comparative screening of candidate materials under identical experimental conditions. This measurement approach was applied to a series of insulation material samples, allowing for consistent and reproducible assessment of their thermophysical properties. The results demonstrate that, from the perspective of maximizing retained thermal energy in the form of sensible heat and enthalpy, the most advantageous solution involves the use of insulation materials characterized by a minimal thermal conductivity coefficient in combination with a low thermal diffusivity. Such a combination effectively slows heat transfer and temperature equalization between the storage medium and the surrounding insulation, thereby preserving the usable thermal potential of the storage system for extended periods. In addition, the study indicates that targeted material modifications offer viable pathways for simultaneously enhancing thermal insulation performance and mechanical properties, highlighting the potential for further optimization of materials for high-temperature energy storage applications.