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A novel approach to investigate the oxidation behaviour of bilayer TiN/TiC coatings deposited on WC-Co substrate by CVD method was employed. Two coatings with different structures and mechanical properties were manufactured using different processing parameters. Energy dispersive X-ray analysis was utilized to monitor the elemental composition during oxidation tests at 800 °C for up to 40min, which simulated the high temperature conditions experienced by the coated cutting tools. The obtained results demonstrated that the oxygen content increased significantly, reached ~68.8 at.%, while carbon and nitrogen contents decreased due to the formation of gaseous by-products. X-ray diffraction confirmed complete transformation of the TiN layer into rutile-TiO2 after 20min of oxidation. The microhardness of the coated samples significantly decreased due to the oxide formation and development of pores and cracks during the oxidation process. Tribological tests revealed a significant increase in the volume loss during dry sliding against zirconia counterpart after 20min of oxidation time. Moreover, surface colour of the oxidized coated samples changed from silver-white to grey-black with oxidation progression, enabling visual evaluation of oxidation damage.

Due to their favorable production conditions and promising properties (e.g., low shrinkage after foaming, mechanical and chemical stability, high-temperature resistance), geopolymer foams are suitable for heat- and sound insulating refractory building materials. Another promising field of application may be their use as catalyst supports in water treatment. Metakaolin-based foams were prepared by a direct foaming process with high total porosity (> 75 vol%), low bulk density (< 500 kg/m3), approximately 1 MPa compressive strength, and low thermal conductivity (0.095 W/mK). By varying the concentration of foaming agent (H2O2 solution) and stabilizing agent (sodium oleate), it is possible to produce foams with designed porosity and pore size distribution. Foams with mainly closed pores are suitable for thermal insulation, while those with significantly open pores can use as catalyst supports. The computed tomography images showed that the concentration of stabilizing agent is a key parameter in forming a homogeneous pore structure and open pores; up to 24 vol% open porosity can be achieved without significantly affecting other properties. The physical properties of the foams are equally influenced by the thickness of cell walls and the size of the cells themselves.

Untreated and pH-reduced red mud is used as a potential raw material in ceramic technology. During the alkalinity reduction process, CO2 is bubbled through the untreated red mud, which is particularly important as it can reduce the CO2 content of the atmosphere, and the pH of the red mud. Therefore, this method serves as a CO2 capture technique that utilizes waste as a raw material with low costs. Besides, reducing CO2 emission, it allows the production of material suitable for brick manufacturing from waste. In this study, treated and reduced alkalinity red mud was mixed with clay in the range of 5–30 wt%, and the physical, chemical, mechanical, and technologically important properties of the dried and sintered bricks were examined. The application of reduced alkalinity red mud as an additive offers advantages, as the resulting bricks require less water for processing, are less sensitive to drying, and their strength values exceed those of the commercially available bricks. Therefore, the technique presented in the study enables the production of bricks and roof tiles with advantageous properties using waste materials. [ABSTRACT FROM AUTHOR]

Background: Although numerous studies have been conducted to investigate the acute effects of shoe drops on running kinematics and kinetic variables, their effects on muscle forces remain unknown. Thus, the primary aim of this study was to compare the muscle force, kinematics, and kinetic variables of habitually rearfoot runners with heel-to-toe drops of negative 8 mm shoes (minimalist shoes) and positive 9 mm shoes (normal shoes) during the running stance phase by using musculoskeletal modeling and simulation techniques. Methods: Experimental data of lower limb kinematics, ground reaction force, and muscle activation from 16 healthy runners with rearfoot strike patterns were collected and analyzed in OpenSim. Using Matlab, the statistical parameter mapping paired t-test was used to compare the joint angle, moment, and muscle force waveform. Results: The results revealed differences in the sagittal ankle and hip angles and sagittal knee moments between the different heel-to-toe drops of running shoes. Specifically, it showed that the negative 8 mm running shoes led to significantly smaller values than the positive 9 mm running shoes in terms of the angle of ankle dorsiflexion, ankle eversion, knee flexion, hip flexion, and hip internal and hip external rotation. The peak ankle dorsiflexion moment, ankle plantarflexion moment, ankle eversion moment, knee flexion moment, knee abduction moment, and knee internal rotation also decreased obviously with the minimalist running shoes, while the lateral gastrocnemius, Achilleas tendon, and extensor hallucis longus muscles were obviously greater in the minimalist shoes compared to normal shoes. The vastus medialis, vastus lateralis and extensor digitorum longus muscles force were smaller in the minimalist shoes. Conclusions: Runners may shift to a midfoot strike pattern when wearing negative running shoes. High muscle forces in the gastrocnemius lateral, Achilleas tendon, and flexor hallucis longus muscles may also indicate an increased risk of Achilleas tendonitis and ankle flexor injuries. [ABSTRACT FROM AUTHOR]