Papers by Keyword: Materials

Abstract: The paper presents the experimental data on the cement effect typeon the effects of heat generation during the 3D-printable cement materials’setting and hardening. Materials made on the basis of cements CEMI 42.5 RandCEMI 52.5 R, differing in phase contentC₃Ain combination with viscosity modifiers of various compositions,have been studied. To control setting kinetics, a penetrometer test was used, hardening kinetics was evaluated by testing the samples for compressive strength after 1, 3, 7, 14, 28 days of hardening. It was found that the useof CEMI 52.5 Rhigh in compositionC₃Acauses a significant heating of the mixture already after its setting, which is not observed when using ordinary CEMI 42.5R. The combination of a highly active aluminosilicate modifier with high-strength cement causes a technologically unacceptable reduction in the setting time and open time of mixtures.

Abstract: The strength of materials is determined by their atomic molecular structure and the process of decay of atomic molecular bonds, which must be taken into account when optimizing materials strength control technologies. The fracture photomicrograph of metal microdamage of welded joint at various moments of time, a multilevel model of flow of acoustic emission signals of materials are presented. The physical meaning, the scale level of parameters included in the model are revealed. The structure of the mathematical model of the flow of AE signals with components of its informative elements of different scale level by strength characteristics of structural materials and resource of technical objects is shown. The multilevel model of the AE signal flow is hierarchically structured, obtained by generalizing deterministic-statistical variability. It describes the process of randomly recording deterministic accumulated damages in the material both before and after the formation of a crack at the stage of waiting for its next leap. It is shown that the proposed nanotechnology of strength control of materials is reduced to non-destructive determination of parameters of prognostic homogeneous destruction, identification of which is based on multilevel modeling of time dependence of micro-crack formation, formulation of criterion of strength homogeneity, registration of AE parameters related to the model of a specific product, which can be automated processing of registration results and determination of universal strength nanoconstants from already published reference data of fatigue tests of standard material samples.

Abstract: In this work, data on the development of such an important section of Electrical Engineering as “Electrical conductors and methods for their manufacture” are gathered together. The information collected will allow you to compare different materials suitable for the manufacture of electrically conductive structures. The paper also has a history of the development of this section, as well as a patent study of relevant and unusual methods for the manufacture of electrical conductors.

Abstract: The article is devoted to the analysis of the internal structure and properties of a copper-graphite coating applied to a copper electrode. The article provides a calculation of the transient contact resistance of electrodes with a coating obtained using plasma spraying technology. Copper-graphite powder with high arc resistance was used as a spraying substance. Coated electrodes were tested for erosion resistance by an arc at currents of several kiloamperes. The aim of the work is to determine the effect of the composition and internal structure of the coating on the transient processes in the contact gap.

Abstract: This paper deals with mechanical design and material selection process for experimental milling device used in mechanochemistry. Part of this process is right optimizing shapes and dimensions with used material and manufacturing process. Our selection and design process were considering stress on individual parts, purpose of parts, future upgradability, material cost and manufacturing cost. All these factors were resulting into high usage of materials like PLA (polylactic acid) and alloys based on aluminium. These materials are generally very good for prototyping thanks to their mechanical properties and cost. For parts with high stress expectation we therefore used more durable materials. In the end we describe disadvantages of PLA materials against metals in production.

Abstract: The article deals with the process of the development of components, selection and use of materials required to assemble an universal rotation module. The use of the right materials and production processes is an important factor in the development of any new machines. The paper first describes the function of the universal rotation module. Furthermore, it focuses on the development process of selected parts of the prototype, especially the outer cover of the module as well as other important parts. The main problem is to correctly design and manufacture the module so that the engine and other mechanical parts can be placed inside. The technologies that were used in the development of the rotary module are metal machining and plastic printing by additive technology. It also deals with materials that were used in the production of the first generation of the functional prototype and in the development and testing in the pre-production phase.

Abstract: Construction project costs are often related to the availability of construction materials and proximity to the work site. So this paper studied the effect of transportation of materials on the cost of construction projects in the desert and identified the increment percentages of materials cost in comparison with main cities and re-accounted the BOQ items prices in the desert cities. The results showed that the cost of some works may be doubled in the desert areas due to lack of construction materials and high transport costs.

Abstract: Biodegradable vascular stent is mainly made of materials that can be naturally decomposed. After implantation into human blood vessels, the vascular stent can be continuously degraded over time and eventually disappear completely after the treated blood vessels are healed and support from the vascular stent is not needed. The vascular stent materials used in clinic should have good biocompatibility, which mainly involves blood compatibility and cell compatibility. In terms of cell compatibility, the influence of materials on cell growth should be observed. The various biological materials should have good anticoagulant character, so as to reduce the tendency of thrombosis and avoid the occurrence of various risk events in clinical treatment.

Abstract: Biodegradable vascular stent is mainly made of materials that can be naturally decomposed. Magnesium and its alloys have excellent mechanical properties and biocompatibility. The vascular stent made of magnesium and its alloys has the unique advantages of strength of metal scaffolds and bioabsorbability of degradable polymer scaffolds. Due to the special microenvironment inside the blood vessels, the stent should have good resistance against corrosion. After implantation of metal materials for human tissue repair, the surface oxidation film spontaneously formed in the air will react with the human physiological environment. The nature of the interface between materials and tissues will have a certain impact on the corrosion resistance of metals and the degree of metal ion release, thus determining the biocompatibility of materials.

Abstract: Since ancient times, lime, lime pozzolanic, lime-cement, lime-clay binders, the compositions of which our ancestors found empirically, widely and everywhere used in construction. Even in the first half of the XX century, these binders occupied a significant place in the construction practice. The development of production and the relative availability of cement led to a significant reduction in demand for many clinker-free, including lime (Portland) binders. Today, the priorities of scientific and applied technological developments of both traditional building materials and materials of new generations are determined by the actualization of the concept and criteria of resource saving and energy efficiency.