Microstructure and mechanical properties of Titanium grade 23 produced by selective laser melting

Selective laser melted Titanium grade 23 was characterized by low porosity, relatively large surface roughness and pronounced surface texture (i.e. surface grooves orientation). The band/layer microstructure was built of mixed α and β phases. The as printed structure exhibited very high compressive residual stresses with strong anisotropy (i.e., − 512 ± 17 MPa and − 282 ± 14 MPa along the laser scanning direction and along the transverse direction, respectively) and strong fiber crystallographic texture. The latter one is responsible for the anisotropy of hardness in the material. Annealing at 600 °C during four hours significantly removed residual stresses (i.e. to − 14 ± 2.8 MPa) and slightly weakened the texture. Yield strength, 1120 ± 50 MPa, and ultimate tensile strength, 1210 ± 50 MPa, of the annealed material are significantly higher and tensile elongation, 3.9%, lower than for commercial Titanium grade 23. Final mechanical polishing to obtain flat and relatively smooth surface induced desired compression residual stress in the subsurface (i.e., equal to about − 90 MPa). Low absorbed gas contents (oxygen, nitrogen, hydrogen) and low porosity of the printed material indicates the correctness of the technology and allows the printed material to be classified as meeting the requirements of ASTM standards for Titanium grade 23. Besides traditional testing techniques, the optical profilometry, X-ray analysis (texture and residual stresses measurement) and infrared absorption method were applied for the product characterization and some potential of these testing methods and usefulness in technological practice was discussed, what can be particularly interesting both to practitioners from industry and researches from scientific laboratories.

Rheology of Highly Concentrated Suspensions with a Bimodal Size Distribution of Solid Particles for Powder Injection Molding

Powder injection molding (PIM) is one of the modern and prospective technologies in processing different materials. We proposed to use bimodal compositions of particles for increasing their content in the final products. A set of model suspension of Al with low-molecular-weight poly (ethylene glycol) as a binder based on theoretical arguments concerning the filling capacity of bimodal suspensions was prepared. Studying the rheological properties of these compositions showed that they demonstrate elasto-viscous behavior with significant plasticity that is favorable for the technological process. Using compositions with bimodal distributions allows for increasing the content of the solid phase up to 75 vol. % for PIM technology, which is significantly higher than the standard practical limit. This rheological approach developed for model formulations was applied to processing compositions containing aluminum oxide as typical ceramics and polyolefines as a binder widely used in technological practice. The obtained sintered ceramic samples have quite acceptable mechanical properties of the usual corundum articles.

Maize and Sorghum as Raw Materials for Brewing, a Review

Brewing is among the oldest biotechnological processes, in which barley malt and—to a lesser extent—wheat malt are used as conventional raw materials. Worldwide, 85–90% of beer production is now produced with adjuvants, with wide variations on different continents. This review proposes the use of two other cereals as raw materials in the manufacture of beer, corn and sorghum, highlighting the advantages it recommends in this regard and the disadvantages, so that they are removed in technological practice. The use of these cereals as adjuvants in brewing has been known for a long time. Recently, research has intensified regarding the use of these cereals (including in the malted form) to obtain new assortments of beer from 100% corn malt or 100% sorghum malt. There is also great interest in obtaining gluten-free beer assortments, new nonalcoholic or low-alcohol beer assortments, and beers with an increased shelf life, by complying with current food safety regulations, under which maize and sorghum can be used in manufacturing recipes.

INNOVATIVE TECHNOLOGY OF FISH-VEGETABLE PATE FORMULATION WITH ANTIOXIDANT AND ANTIVIRAL PROPERTIES

The article is focused on the increased interest of the Russian people to the natural food products for preventive purposes, which has led to the development of new generation com-bined products with an extended spectrum of action. The method of processing combined fish and vegetable products with antiviral properties has been analyzed for the first time in technological practice. In-depth study has been carried out and proved the innovative nature of the developed food products with antioxidant and antiviral properties. Formulations have been made up and the chemical composition of multicomponent fish-vegetable pates has been determined. The pates have a high nutritional value and comply with the latest safety standards.

AN INTEGRATIVE APPROACH TO ASSESSING THE RESULTS OF PRACTICAL TRAINING OF UNIVERSITY STUDENTS (ON THE EXAMPLE OF THE DIRECTION 44.04.01 "PEDAGOGICAL EDUCATION")

The practical training of a university student takes a significant place from the standpoint of the formation and assessment of competencies (indicators). The article substantiates the need to use an integrative approach to assessing the results of practical training of students (on the example of the direction 44.04.01 "Pedagogical education"). Approaches and methods used: integrative approach; theoretical analysis of literature; modeling; questioning of teachers of practice bases, universities and students. Integration at the stage of giving the final mark for the practice is explained by the need to take into account several aspects: the mark given to the student on the basis of practice for the work done (lessons, extracurricular activities, performance of other types of work); assessment for the prepared documentation; protection grade; assessment of competence, as well as the opinion of the student. Using the example of educational technological (design and technological) practice, indicators for evaluating the results of practice are highlighted, points are determined using the rating, a scale for converting the scores into a standard mark is presented. The described approach is positively assessed by the heads of practice bases, heads of practices from the university and students. The described approach can be carried over to other areas of training; will allow to implement uniform requirements for students, increase the objectivity of the final grade for practice.

The Influence of Cooling Rate on Microstructure and Mechanical Properties of AlSi9Cu3

The aim of this study was to determine the correlation between the size and the distribution of microstructural constituents and their cooling rate, as well as the correlation between the mechanical properties and the cooling rate of AlSi9Cu3 aluminum alloy when cast in high-pressure die casting (HPDC) conditions. In other words, the ultimate goal of the research was to determine the mechanical properties for a casting at different cooling rates. Castings with different wall thicknesses were chosen, and different cooling rates were assumed for each one. Castings from industrial technological practice were systematically chosen, and probes were extracted from those castings for the characterization of their mechanical properties. Special non-standard cylinders were created on which compressive tests were carried out. The uniqueness of this research lies in the fact that the diameters of the designed cylinders were in direct correlation to the actual wall thickness of the castings. This is important because the solidification of metal in the die cavity is complex, in that the cooling rates are higher on the surface of the casting than in the center. Local in-casting cooling rates were determined using numerical simulations. It was discovered that with increasing cooling rates from 60 K/s to 125 K/s the values for strength at 5% deformation increased on average from 261 MPa to 335 MPa.

Iron Production at Meroe

The archaeometallurgical remains evident at the Royal City of Meroe represent some of the most extensive evidence for ancient iron production in Africa. Recently, renewed investigations of these remains have generated a number of new insights into Kushite ferrous technology. The duration of iron production at Meroe is now known to span over one thousand years. Currently available data indicates a particularly intensive level of production during the early periods of Kush, while post-Meroitic iron production has been identified at Meroe and at the nearby site of Hamadab. Throughout the long history of iron production in the area, certain aspects of the technological process appear to have remained relatively constant, notably those associated with the acquisition and use of raw materials (iron ore and charcoal fuel). Other facets of the technological practice appear to have changed over time, for example the manufacture of technical ceramics and the design of the furnaces. Such levels of diachronic consistency and variability within technological practice potentially reflect the evolving social, political, and economic circumstances of Kush. Due to the socio-politically embedded nature of technology, interesting insights into broader Kushite history are becoming accessible through greater understandings of Meroe’s iron production remains.

Exploring the hospitality-tourism nexus: Directions and questions for past and future research

Hospitality has often been conceived primarily as a supporting component of the tourism product. This commentary synthesises inter and multidisciplinary literature to examine alternative and more complex intersections of hospitality and tourism. It discusses four thematic areas of hospitality research: labour; the transformation of place (experiences); socio-material and socio-technological practice; and human encounters. It argues that applying hospitality as a sensitising concept in these domains of enquiry, and studying hospitality’s abstract and concrete dimensions, enhances our understanding of tourism as socio-economic phenomena and a global system, and helps to appreciate tourism’s implications for multiple stakeholders. Moreover, it proposes a range of questions for future research.