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AHEAD OF PRINT

Volume 67 (2020): Issue 4 (December 2020)

Volume 67 (2020): Issue 3 (September 2020)

Volume 67 (2020): Issue 2 (June 2020)

Volume 67 (2020): Issue 1 (March 2020)

Volume 66 (2019): Issue 4 (December 2019)

Volume 66 (2019): Issue 3 (December 2019)

Volume 66 (2019): Issue 2 (June 2019)

Volume 66 (2019): Issue 1 (March 2019)

Volume 65 (2018): Issue 4 (December 2018)

Volume 65 (2018): Issue 3 (September 2018)

Volume 65 (2018): Issue 2 (September 2018)

Volume 65 (2018): Issue 1 (March 2018)

Volume 64 (2017): Issue 4 (December 2017)

Volume 64 (2017): Issue 3 (September 2017)

Volume 64 (2017): Issue 2 (July 2017)

Volume 64 (2017): Issue 1 (March 2017)

Volume 63 (2016): Issue 4 (December 2016)

Volume 63 (2016): Issue 3 (September 2016)

Volume 63 (2016): Issue 2 (July 2016)

Volume 63 (2016): Issue 1 (May 2016)

Journal Details
Format
Journal
eISSN
1854-7400
First Published
30 Mar 2016
Publication timeframe
4 times per year
Languages
English

Search

Volume 67 (2020): Issue 2 (June 2020)

Journal Details
Format
Journal
eISSN
1854-7400
First Published
30 Mar 2016
Publication timeframe
4 times per year
Languages
English

Search

5 Articles
Open Access

In memoriam – zaslužni profesor dr. Uroš Bajželj

Published Online: 22 Sep 2020
Page range: 39 - 43

Abstract

Open Access

Investigation of Metal-based Composites Vibration Properties Using Modal Analysis in Combination with Wavelet Transforms Under Imitation of Operational Loads

Published Online: 22 Sep 2020
Page range: 45 - 63

Abstract

Abstract

The present article is dedicated to the study of the vibration properties of metal-based composite materials and the application of the non-destructive testing method. The main modal parameters of the metal-based composites were investigated. For experimental determination of natural frequencies and modes of oscillations, the method of scanning laser Doppler vibrometry was used. For the numerical modal analysis, the finite element method was used. The material model was a layered composite with isotropic linearly elastic layers and metal layers. The task of identifying the material model was considered as the problem of minimising the discrepancy between the calculated natural frequencies and the experimental ones. The developed method can be recommended for the determination of parameters of material models for calculating the modal characteristics of polymer–metal sandwich sheets and metallic mono-materials composite products. Methodology for identifying models of elastic behaviour of polymer–metal composite materials, based on the results of the experimental modal analysis, is presented. Wavelet-based damage detection is also presented as an appropriate approach for the identification of integral conditions of the metal–polymer–metal composite materials. Results of wavelet transform convolutions are presented.

Keywords

  • vibration properties
  • laminated metal-reinforced composites
  • experimental modal analysis
  • wavelet transforms
  • laser vibrometry

Ključne besede

  • vibracijske lastnosti
  • kompoziti ojačeni s plastjo kovine
  • eksperimentalna modalna analiza
  • valovna transformacija
  • laserska vibrometrija
Open Access

Effect of Temperature and Time on Decomposition of δ-ferrite in Austenitic Stainless Steel

Published Online: 27 Jul 2020
Page range: 65 - 71

Abstract

Abstract

Microstructure of austenitic stainless steel is primarily monophasic, i.e. austenitic. However, precipitation of the δ-ferrite in the austenite matrix is possible depending on the chemical composition of steel. δ-Ferrite is stable on room temperature but it transforms into σ-phase, carbides and austenite during heat treatment. In this work, the results of analysis of influence of temperature and time on decomposition of δ-ferrite are presented. Magnetic induction method, microstructure and hardness analyses were used for testing the degree of decomposition of the δ-ferrite. Analysis of results showed that increase in temperature and time increases the degree of decomposition of δ-ferrite.

Keywords

  • austenitic stainless steel
  • δ-ferrite
  • σ-phase
  • carbides
  • hardness

Ključne besede

  • avstenitno nerjavno jeklo
  • delta ferit
  • sigma faza
  • karbidi
  • trdota
Open Access

Key Metallurgical Parameters of Fe-Ni Production During 1984–1997 and 2007–2017 at the Ferronickel Smelter in Drenas

Published Online: 10 Aug 2020
Page range: 73 - 77

Abstract

Abstract

During 1984–1997, the ferronickel plant in Drenas used iron-nickel ore from the mines of the Republic of Kosovo: Glavica and Çikatove (Dushkaje and Suke) mines. However, during the years 2007–2017, when the plant started operating from the cessation of production, which was from 1998 to 2007, some types of iron-nickel ores from different countries began to be used, starting from iron-nickel ores from Kosovo, iron-nickel ores from Albania, ores from Indonesia, ores from the Philippines, ores from Guatemala, ores from Turkey and ores from Macedonia. The ore composition, however, is mainly oxide-laterite ore. Iron-nickel ores in the plant are characterised by high moisture content, a very important factor influencing the process of scraping the charge in rotary kilns and presenting in general. Among the iron-nickel ore used in the ferronickel plant, the ores from Albania are characterised due to their low moisture content when compared with the other ores as well as the high content of iron oxides, which affect the temperature rise inside the furnaces, as the iron ores play an important role in the pre-casting process in rotary kilns.

Keywords

  • calcine
  • alloys
  • ore
  • foundry
  • Fe-Ni alloy

Ključne besede

  • žganje
  • zlitine
  • rude
  • talilnica
  • Fe-Ni zlitina
Open Access

Petrography of Allanite-bearing Tonalite from Iwo Region, Osun State, Nigeria

Published Online: 27 Jul 2020
Page range: 79 - 89

Abstract

Abstract

Primary, secondary and accessory minerals in tonalitic rocks from Iwo region of the Precambrian Basement Complex of Southwestern Nigeria were identified and analysed with the aim of determining the various processes involved during the crystallisation of magma. Thin sections of tonalite were prepared and studied with the aid of a petrographic microscope. The mineral assemblages observed are biotite, plagioclase, alkali-feldspar, amphiboles, pyroxene, quartz, muscovite and chlorite. Allanite, titanite, apatite and zircon occur as accessory minerals. Muscovite and chlorite are found to be secondary minerals. The mineral allanite has a characteristic form of zoning and shows evidence of metamictisation, and is surrounded by dark-coloured biotite having radioactive haloes. Titanite is anhedral to subhedral crystals and forms reaction rim round opaque minerals. Plagioclase shows evidence of compositional zoning as well as plastic deformation of the twin lamellae. The allanite observed is primary in nature and has undergone radioactive disintegration; chlorite and muscovite are formed by secondary processes of chloritization and sericitisation, respectively. The tonalite is formed as a result of rapid cooling of magma close to the Earth's surface.

Keywords

  • zoning
  • titanite
  • radioactive haloes
  • chloritization
  • sericitisation

Ključne besede

  • conarnost
  • titanit
  • radioaktivni halo
  • kloritizacija
  • sericitizacija
5 Articles
Open Access

In memoriam – zaslužni profesor dr. Uroš Bajželj

Published Online: 22 Sep 2020
Page range: 39 - 43

Abstract

Open Access

Investigation of Metal-based Composites Vibration Properties Using Modal Analysis in Combination with Wavelet Transforms Under Imitation of Operational Loads

Published Online: 22 Sep 2020
Page range: 45 - 63

Abstract

Abstract

The present article is dedicated to the study of the vibration properties of metal-based composite materials and the application of the non-destructive testing method. The main modal parameters of the metal-based composites were investigated. For experimental determination of natural frequencies and modes of oscillations, the method of scanning laser Doppler vibrometry was used. For the numerical modal analysis, the finite element method was used. The material model was a layered composite with isotropic linearly elastic layers and metal layers. The task of identifying the material model was considered as the problem of minimising the discrepancy between the calculated natural frequencies and the experimental ones. The developed method can be recommended for the determination of parameters of material models for calculating the modal characteristics of polymer–metal sandwich sheets and metallic mono-materials composite products. Methodology for identifying models of elastic behaviour of polymer–metal composite materials, based on the results of the experimental modal analysis, is presented. Wavelet-based damage detection is also presented as an appropriate approach for the identification of integral conditions of the metal–polymer–metal composite materials. Results of wavelet transform convolutions are presented.

Keywords

  • vibration properties
  • laminated metal-reinforced composites
  • experimental modal analysis
  • wavelet transforms
  • laser vibrometry

Ključne besede

  • vibracijske lastnosti
  • kompoziti ojačeni s plastjo kovine
  • eksperimentalna modalna analiza
  • valovna transformacija
  • laserska vibrometrija
Open Access

Effect of Temperature and Time on Decomposition of δ-ferrite in Austenitic Stainless Steel

Published Online: 27 Jul 2020
Page range: 65 - 71

Abstract

Abstract

Microstructure of austenitic stainless steel is primarily monophasic, i.e. austenitic. However, precipitation of the δ-ferrite in the austenite matrix is possible depending on the chemical composition of steel. δ-Ferrite is stable on room temperature but it transforms into σ-phase, carbides and austenite during heat treatment. In this work, the results of analysis of influence of temperature and time on decomposition of δ-ferrite are presented. Magnetic induction method, microstructure and hardness analyses were used for testing the degree of decomposition of the δ-ferrite. Analysis of results showed that increase in temperature and time increases the degree of decomposition of δ-ferrite.

Keywords

  • austenitic stainless steel
  • δ-ferrite
  • σ-phase
  • carbides
  • hardness

Ključne besede

  • avstenitno nerjavno jeklo
  • delta ferit
  • sigma faza
  • karbidi
  • trdota
Open Access

Key Metallurgical Parameters of Fe-Ni Production During 1984–1997 and 2007–2017 at the Ferronickel Smelter in Drenas

Published Online: 10 Aug 2020
Page range: 73 - 77

Abstract

Abstract

During 1984–1997, the ferronickel plant in Drenas used iron-nickel ore from the mines of the Republic of Kosovo: Glavica and Çikatove (Dushkaje and Suke) mines. However, during the years 2007–2017, when the plant started operating from the cessation of production, which was from 1998 to 2007, some types of iron-nickel ores from different countries began to be used, starting from iron-nickel ores from Kosovo, iron-nickel ores from Albania, ores from Indonesia, ores from the Philippines, ores from Guatemala, ores from Turkey and ores from Macedonia. The ore composition, however, is mainly oxide-laterite ore. Iron-nickel ores in the plant are characterised by high moisture content, a very important factor influencing the process of scraping the charge in rotary kilns and presenting in general. Among the iron-nickel ore used in the ferronickel plant, the ores from Albania are characterised due to their low moisture content when compared with the other ores as well as the high content of iron oxides, which affect the temperature rise inside the furnaces, as the iron ores play an important role in the pre-casting process in rotary kilns.

Keywords

  • calcine
  • alloys
  • ore
  • foundry
  • Fe-Ni alloy

Ključne besede

  • žganje
  • zlitine
  • rude
  • talilnica
  • Fe-Ni zlitina
Open Access

Petrography of Allanite-bearing Tonalite from Iwo Region, Osun State, Nigeria

Published Online: 27 Jul 2020
Page range: 79 - 89

Abstract

Abstract

Primary, secondary and accessory minerals in tonalitic rocks from Iwo region of the Precambrian Basement Complex of Southwestern Nigeria were identified and analysed with the aim of determining the various processes involved during the crystallisation of magma. Thin sections of tonalite were prepared and studied with the aid of a petrographic microscope. The mineral assemblages observed are biotite, plagioclase, alkali-feldspar, amphiboles, pyroxene, quartz, muscovite and chlorite. Allanite, titanite, apatite and zircon occur as accessory minerals. Muscovite and chlorite are found to be secondary minerals. The mineral allanite has a characteristic form of zoning and shows evidence of metamictisation, and is surrounded by dark-coloured biotite having radioactive haloes. Titanite is anhedral to subhedral crystals and forms reaction rim round opaque minerals. Plagioclase shows evidence of compositional zoning as well as plastic deformation of the twin lamellae. The allanite observed is primary in nature and has undergone radioactive disintegration; chlorite and muscovite are formed by secondary processes of chloritization and sericitisation, respectively. The tonalite is formed as a result of rapid cooling of magma close to the Earth's surface.

Keywords

  • zoning
  • titanite
  • radioactive haloes
  • chloritization
  • sericitisation

Ključne besede

  • conarnost
  • titanit
  • radioaktivni halo
  • kloritizacija
  • sericitizacija

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