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The influence of adding different amounts of silicon carbide on the properties (density, transverse rupture strength, microhardness and corrosion resistance) and microstructure of low alloy steel was investigated. Samples were prepared by mechanical alloying (MA) process and sintered by spark plasma sintering (SPS) technique. After the SPS process, half of each of obtained samples was heat-treated in a vacuum furnace. The results show that the high-density materials have been achieved. Homogeneous and fine microstructure was obtained. The heat treatment that followed the SPS process resulted in an increase in the mechanical and plastic properties of samples with the addition 1wt. % of silicon carbide. The investigated compositions containing 1 wt.% of SiC had better corrosion resistance than samples with 3 wt.% of silicon carbide addition. Moreover, corrosion resistance of the samples with 1 wt.% of SiC can further be improved by applying heat treatment.

Currently, due to the economic and ecological aspects, light alloys are increasingly important construction material, in particular in the transport industry. one of the popular foundry magnesium alloys is the alloy az91, which among others due to mechanical properties and technological features, is used, for example, for light structural parts. The paper presents the results of research on modification of the az91 alloy surface layer in the plasma electrolytic oxidation process. The change of usable properties of the produced coatings was obtained by introducing additions of silicon carbide or boron nitride. The thickness and hardness of the protective layers produced, resistance to scratches and corrosion resistance were determined. Moreover, the friction coefficient of the coating-steel pair was investigated. The quality of the connections made between the coating and the substrate, i.e. the magnesium alloy, was also evaluated. The results obtained for coatings with silicon carbide or boron nitride additives were always compared to the results obtained for unmodified samples. on the basis of the obtained results, it was shown that the introduction of boron nitride additive to the az91 alloy coating produced in the plasma electrolytic oxidation process significantly improves the resistance to: (i) corrosion and (ii) abrasive wear of the coating. [ABSTRACT FROM AUTHOR]

This paper discusses issues related to optimising the technological parameters of the process of brazing gold in a vacuum furnace. An investigation of the brazing process was carried out for materials used in constructing components for aircraft engine fuel systems. The vacuum brazed material was AMS 5510 stainless steel (in the form of plates and pipes). AMS 4787 (BAu-4) was used as the brazing filler. In particular, the influence of the method of preparing the surface on solder spreading and the thickness of the diffusion zone were analysed. The best spreading of solder was obtained for nickel plated surfaces. When the sample surface was more rough or scratched, the effect of the spreading of solder was limited and the diffusion process of the solder into the base material became dominant. Moreover, the influence of the brazing temperature on microstructure changes and on interdiffusion of the AMS 5510 stainless steel/BAu-4 solder system was determined. It was observed that an increase in the brazing temperature modifies the morphology of the formed joint by forming a massive and rounded phase. Furthermore, an increase in the brazing temperature enhances the exchange of components. [ABSTRACT FROM AUTHOR]

This study showed that several mechanisms of the basal resistance of winter triticale to Microdochium nivale are cultivar-dependent and can be induced specifically during plant hardening. Experiments and microscopic observations were conducted on triticale cvs Hewo (able to develop resistance after cold treatment) and Magnat (susceptible to infection despite hardening). In cv. Hewo, cold hardening altered the physical and chemical properties of the leaf surface and prevented both adhesion of M. nivale hyphae to the leaves and direct penetration of the epidermis. Cold-induced submicron- and micron-scale roughness on the leaf epidermis resulted in superhydrophobicity, restricting fungal adhesion and growth, while the lower permeability and altered chemical composition of the host cell wall protected against tissue digestion by the fungus. The fungal strategy to access the nutrient resources of resistant hosts is the penetration of leaf tissues through stomata, followed by biotrophic intercellular growth of individual hyphae and the formation of haustoria-like structures within mesophyll cells. In contrast, a destructive necrotrophic fungal lifestyle occurs in susceptible seedlings, despite cold hardening of the plants, with the host epidermis, mesophyll and vascular tissues being digested and becoming disorganized as a result of the low chemical and mechanical stability of the cell wall matrix. This work indicates that specific genetically encoded physical and mechanical properties of the cell wall and leaf tissues that depend on cold hardening are factors that can determine plant resistance against fungal diseases. [ABSTRACT FROM AUTHOR]

The article presents a description and analysis of the causes of damage to a road viaduct, made of prefabricated compressed beams of the WBS type in the 1970s. Both the design and damage are typical for objects made in those years. Damage results from the deck slab being too thin, low quality waterproof membrane, easily deformable deck surface, leaking bridge deck expansion joints, linear-contact bearings at excessively long spans, undurable drainage system elements. On the basis of the static and strength analysis, proposals for a way of repairing the viaduct were given, which, taking into account the occurrence of similar structural solutions in existing facilities, can be used as a guide when designing renovation and modernization.

This article presents a procedure for selecting optimal ceramic paste formulations dedicated to the 3D printing process using robocasting technology. This study investigated pastes with varying ceramic powder particle sizes and different proportions of additives, such as ceramic microspheres and nutshells. This selection process allowed for the classification of ceramic mixtures into those suitable and unsuitable for this additive manufacturing technique. Subsequently, the viscosity of the pastes was measured, and extrudability tests were performed to determine the force required for extrusion and evaluate the quality of the extruded material. In the final stage, the setting time of the ceramic pastes was assessed to establish the drying time of the printed elements. It was found that the length of the extruded band of ceramic paste was inversely proportional to the Al₂O₃ content. Moreover, the extrusion force for samples with varying ceramic powder particle sizes (MG1-MG5) ranged from 133 to 166 N, compared to 77 N for the base sample (BM1). The obtained results enable further development in robocasting additive technology, including the development of a rapid and effective method for validating ceramic pastes used in this process.

The continued global urbanization of the world is driving the development of the construction industry. In order to protect the environment, intensive research has been carried out in recent years on the development of sustainable materials and ecological construction methods. Scientific research often focuses on developing building materials that are renewable, energy-efficient, and have minimal impact on the environment throughout their life cycle. Therefore, this article presents research results aimed at developing a concrete mixture using cement with reduced CO 2 emissions. In the context of increasing ecological awareness and in line with European Union policy, the development of a mixture based on environmentally friendly cement is of key importance for the future development of the construction industry. The article compares the physical properties of two mixtures, their foaming possibilities, and the influence of the added polypropylene (PP) fibers on the strength properties of the produced composites. It was found that bending strength and compressive strength were highest in the material with silica fume and aluminum powder at 5.36 MPa and 28.76 MPa, respectively. Microscopic analysis revealed significant pore structure differences, with aluminum foamed samples having regular pores and hydrogen peroxide foamed samples having irregular pores. Optimizing aluminum powder and water content improved the materials' strength, crucial for maintaining usability and achieving effective 3D printing. The obtained results are important in the development of research focused on the optimization of 3D printing technology using concrete.

The concept of ecology, historically rooted in the economy of nature, currently needs to evolve to encompass the intricate web of interactions among humans and various organisms in the environment, which are influenced by anthropogenic forces. In this review, the definition of ecology has been adapted to address the dynamic interplay of energy, resources, and information shaping both natural and artificial ecosystems. Previously, 3D (and 4D) printing technologies have been presented as potential tools within this ecological framework, promising a new economy for nature. However, despite the considerable scientific discourse surrounding both ecology and 3D printing, there remains a significant gap in research exploring the interplay between these directions. Therefore, a holistic review of incorporating ecological principles into 3D printing practices is presented, emphasizing environmental sustainability, resource efficiency, and innovation. Furthermore, the 'unecological' aspects of 3D printing, disadvantages related to legal aspects, intellectual property, and legislation, as well as societal impacts, are underlined. These presented ideas collectively suggest a roadmap for future research and practice. This review calls for a more comprehensive understanding of the multifaceted impacts of 3D printing and the development of responsible practices aligned with ecological goals.