This article presents different solutions to reduce natural gas consumptions of the aluminum melting furnaces, through recovery of the heat from flue gases. In order to be able to analyze the recovery solutions, a mathematical model for energy balance of these furnaces was adapted. This mathematical model allows drawing up energy balances together with the main working technique and economical parameters of these types of furnaces, in actual conditions, and the same, under optimizing conditions, by applying recovery solutions. The mathematical model which can elaborate energy balances for aluminum melting furnaces, was transposed in M. Excel based software, where the quantification of different solutions for natural gas consumption saving is possible. One of the applications of this computer software for an aluminum melting furnace, either for actual working conditions or per upgraded furnace by use an air pre-heater, materials pre-heater, or a regenerative burner system, is presented in this article.

The paper analyzes the states of stresses that are born in a circular plate with radial ribs placed on one side, under the action of different pressures. The study is done using the finite element method and the experimental method. For this purpose, the value of the stresses for the plate is determined, in case of different solicitations. From the analyzed study we can see the close results that have been obtained.

This article is a study of the mechanism interaction between sparks electric discharges and a AISI 316L biocompatible metallic samples. The AISI 316L steel samples were analyzed compositionally by OES spectrometry and the sparked areas in the samples were subjected to optical microscopy and SEM electron microscopy investigations. The experimental results highlighted new aspects regarding the attack mode of sparks with the metal sample and explain why the edges of the sparked areas are blackened / smoked.

In this presentation are evidenced instrumental characterization by Electronic Scanning Microscopy (SEM) equipped with EDS / WDS of aluminum alloys such 2024 alloy with multiple synergistic purposes as: acquisition of new knowledge, increase the amount of information obtainable about the material, increasing the efficiency and the quality of the tests, characterization of special destination alloys and assessing their conformity with the specified requirements. In this direction, it requires both the knowledge the test methods (theoretical basis, test method, procedure relating to the method, quality assurance testing) as well material characteristics investigated. These aspects are necessary for test system design, and preliminary interpretation of experimental results.

The structural transformations occurring at tempering for some high-speed steels are a subject of research for which have been dedicated numerous studies. More complex compositions of the high-speed steels were direct consequence of the complexity of structural transformations which occur during heat treatment. On the other hand, current tendency in energy requires maximum efficiency and rational use of heating sources used in industry. Thus, only a precise knowledge of the kinetics of transformations occurring at tempering can be a basis for optimizing this treatment. Although cobalt is used for a long time as an alloying element, though relatively recently it was considered important to the properties of rapid steel. These circumstances, combined with the lack of quantitative information on the kinetics transformation at tempering operation treatment for some steel has led to this paper. The thickness of the studied samples is 5 mm and was taken from the annealed steel bars. These samples were subjected to hardening and tempering treatment in salts bath. Heating for hardening was performed in two steps, at 5500C and 8300C. Austenitizing was done at 12000C, during 120 seconds. The cooling was done up to 5300C in salts bath, with a keeping of 15 seconds, and then air cooling was done. On these samples were carried out, HRC Rockwell hardness measurements, and X-ray diffraction analysis.

The paper presents an overview of (i) the different polluting materials, classified according to their (bio)degradability, (ii) the sources of pollution (iii) the general effects of pollution on natural resources and on the economy and people’s health. The paper also summarizes directions/solutions to eliminate these effects, including “eco” technologies, and their effectiveness on environmental conservation and regional and global ecosystem protection, in the context of a clean and sustainable environment, in accordance with the 2030 Agenda for Sustainable Development.