International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This article describes a method for producing composite materials based on polytetrafluoroethylene with high performance properties. One of the obstacles to achieve this result had been the accumulation of moisture in the semi-finished product, which subsequently led to the appearance of defects in products made of fluorine composites. It is proposed to produce semi-finished preforms under reduced specific pressure, in which the moisture content is easier, cheaper and more efficient to control than with the current technological regulations. It is shown that the use of these semi-finished preforms allows getting almost defect-free products with high performance characteristics.

It was analyzed the methods of constructions the matter with maximal of packing coefficient when the objects consist of the particles with forms either spheres or rods or plates. It was calculated the relations the partial size for relating of maximal packing coefficient. As examples of objects with coefficient of packing theirs particles we look on abrasive materials and products of the powder metallurgy and solid fuel etc.

Debye’s temperature θ_D is the temperature border between areas, C_μ^V(Т) has constant value and, when T<θ_D, begins to decrease monotonically. θ_D is the crystal parameter, which allows to calculate the dimensional border between macro- and nanostates. The statement which is found in scientific discussions that θ_D depends on temperature is incorrect because it contradicts modern crystal-physical theories. The numerical value θ_D is defined experimentally and is related to the structure of crystals and to the processes taking place in them.

The structure of the bulk crystals allow to determine the habit of the nanocrystales on their base only as a source point. It is impossible to neglect the size, form and influence of surface. The liquids surface relatively quickly passes to equilibrium form when free energy is minimum. Debye’s temperature is rather arbitrary parameter. Its determination is based on some approach. However this parameter is introduced to the reference books and is broadly used in the crystal physics. Proposed strategy allows defining habit maximum size of nanoparticles on the base well known physics representations. The L–value is determined the bounder between sizes where it can be done value description and where it’s necessary to take into account the particle sizes.

The structure of the diamond is usually represented as two face-centered cubic cell with the same dimensions, which are shifted relative to each other by the value of +/-(1/4.1/4.1/4) That is eight different ways. However, in this case, there is a possibility of only two enantiomorphous centers, which have the same ф (hkl ) j . They do not affect on the reciprocal lattice, but allow to explain, for example, the presence of twins. The introduction of the concept of the scattering center of diamond shows that his point group is Fm3m with the full symmetry formula 3L44L3(4L3i)6L29PC, whereas the generally accepted model of the diamond structure does not correspond to such symmetry. For example, the L4 axis is missing, C is not at the origin of coordinates, there is only one L3 axis along the diagonal along which the sublattices are shifted, etc.

One of the main problems in the plastic deformation of materials is the determination of the coefficient of friction as well as the subsequent application of the simulation for comparative analysis. However forecasting process and matching between simulation and experimental data is still a problem. Causes of this are factors such as roughness, mechanical properties of the material, chemical composition, etc. which strongly influence the behavior of the material in the simulation of the process.

In this study, an approach is proposed to determine the changeable coefficient of friction in the deformation process experimentally, taking into account implicitly the influence of surface roughness on the friction curves. For the comparative analysis between experiment and simulation of the process, the experimental data for objective assessment was introduced. Nevertheless, there are differences between experiment and simulation, which is most evident in high loads, using lubricants differing from more than 12 units for graphite lubricant, with more than 6 units with oil and with dry friction with 8 units.

The paper presents standard statistical procedures for determining expert assessments for the influence of magnesium alloy components on the controlled mechanical properties: tensile strength and relative elongation. There are obtained neural models describing mechanical characteristics from the amount of aluminum, manganese, nickel, iron and silicon directly related to the exploitation properties of the product. The applied approach makes it possible to determine of compositions ensuring relatively optimal values of the explored quality indicators.

Investigations of wear resistance and tensile strength of steel products with diffusional zinc coating obtained in zinc powders with a nanocrystallized surface of powder particles were carried out. The effect of the structural state of the coating on the wear resistance and adhesive grasping with a steel counterbody was established. The prospects of the nanogalvanizing process to improve the strength of steel products are shown.

The development of technologies in modern machine building aims at improving the mechanical and technological properties of the materials. The present study presents an improvement in the mechanical properties of low carbon steels by thermoffusion coatings with nanofibers obtained under different heat treatment regimes. Depending on the type of heat treatment and the size of the zinc particles, different gradient layers can be obtained in depth. This of course reflects positively on the chemical resistance of the material. In addition, it positively affects the mechanical properties of the material by increasing mechanical strength and technological properties by improving the resistance to plastic deformation. With these first studies, there is an impetus for another look to improve the properties of low-carbon steels that are widely applicable in the field of machine building.

The paper contains results for wear in conditions of impact between a standard welded and tested specimen realized in the presence of a layer of abrasive particles trailing in the contact zone. It gives an idea about the specifics of this type of wear depending on the impact force and the particle size of the abrasive at various hardness achieved by hard-facing with alloys with different carbon equivalent and a degree of hardening of the layer after the test. Based on an experimental research it was proved that the impact-abrasive wear has its specific features expressed via respective graphical relations. The research was funded by Fund “Scientific Research” at the Ministry of Education and Science of the Republic of Bulgaria.

The paper presents the characteristics of a modern software system for modeling and optimization of technological processes MOTP_VTU. It outlines the possibilities also to use the system at the design stage. A comparative analysis is performed of three characteristics to apply the new software system MOTP_VTU related to a similar existing one – DSAT-16. via similar systems it is possible to expand the basis of constructions and of functional materials in low technological level during exploration of the set of properties of these materials. This process of realization of scientific and technical ideas is a process to search via multi criteria support of decision making between the project task and the actual possibility, determined by the chemical composition and the processing-mode parameters.

The paper presents the characteristics of a modern software system for modeling and optimization of technological processes MOTP_VTU. It outlines the possibilities also to use the system at the design stage. A comparative analysis is performed of three characteristics to apply the new software system MOTP_VTU related to a similar existing one – DSAT-16. via similar systems it is possible to expand the basis of constructions and of functional materials in low technological level during exploration of the set of properties of these materials. This process of realization of scientific and technical ideas is a process to search via multi criteria support of decision making between the project task and the actual possibility, determined by the chemical composition and the processing-mode parameters.

The article is dedicated to an approach optimizing a task of statistical modeling of the mechanical properties of products in real production metallurgy design. The approach is designed for the benefit of producers-metallurgists aimed at providing panels of Ti – alloys of a specific set of eventual industrial properties. This is accomplished by a procedure of composition optimizing based on existing certificates of brands Ti – alloys. The article presents an approach using mathematical models of optimization problem following the implementation of approach the classical methodology capable of decision-making in the production practice.