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1

The effect of energies on the impact breakage characteristic of magnetite ores

Si Liang, Cao Yijun, Li Guosheng

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 1

art. no. 159098

EN

The energy applied during breakage is the key to enhancing the magnetite liberation degree and improving quality. The relationship between energy and liberation properties remains unclear due to various complicated factors affecting mineral liberation. Therefore, this work aims to study the effect of energy on the breakage characteristics of magnetite ores; the impact breakage test was conducted on magnetite particle groups at different energies using a drop weight impact tester; the statistical analysis was performed based on the fractal theory to research the particle size distribution; the fracture morphology and liberation properties of these ores were analyzed using scanning electron microscope and mineral liberation analyzer. Results show that the particle size distribution of magnetite after breakage conforms to the fractal law. The larger the energy, the greater the fractal dimension for this distribution, showing a linear relation between them, which implies that the fractal dimension can evaluate the breakage degree. The fracture morphology of magnetite ores indicates that as the energy increases, the intergranular fracture evolves into transgranular fracture, proving the influence of energy on fracture modes. It is found that the magnetite liberation degree first increases and then decreases with the rising of energy, indicating that the magnetite liberation can be improved at an appropriate amount of energy. The above conclusions provide a theoretical reference for optimizing energy and improving broken product quality.

2

Thermal Fatigue Damage and Residual Mechanical Properties of WCu45/FeCr18Ni9 Steel Brazed Joint with NiCrSiBFe Filler Metal

Xia Chunzhi, Fu Linling, Du Wenchao, Xu Xiangping, Wang Xiling, Zou Jiasheng

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 1

197--203

EN

Thermal fatigue properties of WCu45/ FeCr18Ni9 steel brazed joint with Ni-Cr-Si-B filler metal were investigated. Results indicated that the fatigue damage of Ni-based joint was aggravated with the increased of thermal fatigue cycles times. Moreover, the fatigue cracks appeared in the brazing seam and FeCr18Ni9 steel side near the brazing seam, and the bending strength of the brazed joint decreased from 333 MPa of original joint to 160 MPa of having experienced 200 thermal fatigue cycles. The fracture characteristic of Ni-based joint underwent 200 cycles was identified as mixed ductile-brittle fracture under the combined effect of external bending load and internal fatigue damage.

3

Influence of high-energy milling parameters on the synthesis of single-phase yttrium aluminium perovskite (YAP)

Smoleń Jakub, Michalik Daniel, Plewa Julian, Pawlik Tomasz

Materiały Ceramiczne

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2020

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T. 72, nr 4

235--246

EN

Yttrium aluminium perovskite with the formula YAlO3 (YAP) is one of the three oxides that occur in the Al2O3-Y2O3 system; YAM and YAG are stable coexisting phases of this system. YAP single crystals are known to be used as optical materials due to their favourable properties, especially when they are doped with rare earth or transition metal ions. The preparation of a monophase yttrium aluminium perovskite is a difficult task as the solid phase synthe- sis method leads to the formation of coexisting phases. High-energy milling is the most effective way to obtain a homogeneous mixture of yttrium and aluminium oxide powders (YAP precursors). In this work, different types of homogenization were compared and then the optimal parameters (rotational speed, milling ball size, milling time) influencing the phase composition and morphology of the product after synthesis were established. The X-ray diffraction (XRD) technique was used to study the phase composition and the morphology was characterized using a scanning electron microscope. The obtained results proved that the method of energy supply to the milled system has a significant impact on the course of synthesis and the morphology of the sintered product.

PL

Perowskit itrowo-glinowy o wzorze YAlO3 (YAP) jest jednym z trzech tlenków występujących w układzie Al2O3-Y2O3; YAM i YAG to współistniejące stabilne fazy tego układu. Wiadomo, że monokryształy YAP są stosowane jako materiały optyczne ze względu na ich korzystne właściwości, zwłaszcza gdy są domieszkowane jonami pierwiastków ziem rzadkich lub metali przejściowych. Przygotowanie jednofazowego perowskitu itrowo-glinowego jest trudnym zadaniem, ponieważ metoda syntezy w fazie stałej prowadzi do powstania faz współistniejących. Najbardziej efektywnym sposobem otrzymywania homogenicznej mieszaniny proszków tlenków itru i glinu (prekursorów YAP) jest mielenie wysokoenergetyczne. W pracy porównano różne rodzaje homogenizacji, a następnie ustalono optymalne parametry (prędkość obrotowa, wielkość mielników, czas mielenia) wpływające na skład fazowy i morfologię produktu po syntezie. Do badania składu fazowego wykorzystano technikę dyfrakcji rentgenowskiej (XRD), a morfologię scharakteryzowano za pomocą skaningowego mikroskopu elektronowego. Uzyskane wyniki dowiodły, że sposób dostarczania energii do mielonego układu ma istotny wpływ na przebieg syntezy i morfologię spiekanego produktu.

4

The analysis of strength and fracture morphology of Al-Si compound made from moulding sand formulation with bentonite binding material and Portland cement

Andoko F., Puspitasari P., Gapsari F.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 89, nr 1

5--12

EN

Purpose: This research aimed to analyse the casting result of Al-Si compound used formulation of moulding sand with bentonite binding material and Portland cement. Design/methodology/approach: Bentonite binding material’s type consisted of swelling (Na-bentonite) and non-swelling (Ca-bentonite). Optimum formulation of the moulding sand was 4% of swelling bentonite and 6% of Portland cement, 6% of non-swelling bentonite and 4% of Portland cement. The optimum formulation result of molding sand with bentonite binding material and Portland cement was used in Al-Si compound casting. The result of Al-Si compound casting strength was examined which in terms of its tensile strength, toughness, and hardness. Besides the three tests, the result was also supported by the fracture shape morphology of tensile test and impact toughness test result. Based on the Al-Si compound tensile test result, it was found that the best value was obtained when using 105.52 MPa of swelling bentonite. Findings: The impact toughness test result presented that the use of non-swelling bentonite produced better toughness value which was 0.00592 J/hour while the mickroVickers hardness test result showed that Al-Si compound result using non-swelling bentonite produced 111.04 HV hardness. Based on the fracture morphology test result using SEM of Al-Si compound casting result using swelling and non-swelling bentonite after being tested its tensile strength and impact toughness showed that the same fracture which was brittle fracture tended to appear. Research limitations/implications: In this casting process, combination which is being used is bentonite (swelling and non-swelling) and Portland cement as mould sand binding material. Practical implications: The combination can be used to find the bentonite type that can produce binding material formula with high binding level which can minimize defects on the resulted casting products. Originality/value: In this study swelling and non-swelling bentonite mixed with certain level of Portland cement combination are used.

5

Structure and properties changes of Fe78Si9B13 metallic glass by low-temperature thermal activation process

Griner S., Babilas R., Nowosielski R.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 50, nr 1

18--25

EN

Purpose: The paper presents a structural relaxation process of Fe78Si9B13 metallic glasses and structure and properties changes in a temperature range up to 300°C after annealing from 2 to 16 hours. Design/methodology/approach: The relaxation and crystallization of Fe78Si9B13 metallic glasses were examined by mechanical test, relaxation test, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. Findings: The influence of thermal activation on the structural relaxation process of Fe78Si9B13 metallic glasses was determined after annealing from temperature of 100 to 300°C. The beginning of the structural relaxation was revealed after annealing at 100 and 150°C, especially after long annealing times of 8 and 16 hours. The structural relaxation process was confirmed by examination of dimensional changes of samples associated with partial reduction of free volume and the ordering of topological and chemical structure of metallic glass. Significant changes in the structure and properties of the alloy was observed after annealing at 300°C. The reduction of tensile strength and high fragility of samples was also determined. This decrease is associated with extending of the structural relaxation and beginning of crystallization process by formation of small crystallites of α-Fe phase in amorphous matrix. Research limitations/implications: The structural relaxation process and beginning of crystallization on changes of strength, ductility, fracture morphology, structure, process of stress relaxation and geometry of studied alloy were also achieved in function of temperature and time of annealing. Practical implications: The course of relaxation processes can be used for analysis of thermal stability of metallic glasses. Originality/value: The paper presents a significant influence of low-temperature thermal activation, which was conducted up to 16 hours, on the structural relaxation and changes of selected mechanical properties.

6

Apparatus for Measuring the Bending Fatigue Properties of High Performance Polyethylene Fibre

Cai G., Shi X., Yu W.

Fibres & Textiles in Eastern Europe

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2012

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Vol. 20, no. 4 (93)

37--40

EN

A test method for bending fatigue has been developed to determine the bending fatigue strength of fibres. This new equipment is capable of performing the bending fatigue testing of fibres under different pre-tensions, bending angles and temperatures. This article presents results from tests on single high performance polyethylene fibre (HPPE) to characterise its bending fatigue behaviour under cyclic loading and temperatures. The curve of the cyclic tension shows that the cyclic tension changes in periods during the cyclic bending process. The S-N and č-N curves indicated that the pre-tension and bending angle had great influences on the bending fatigue life of HPPE fibre. A CCD camera was utilised to allow observation of the bending fatigue fracture morphology of the fibre. It showed the fracture mechanism of the HPPE fibres. The bending fatigue life of HPPE fibre was tested at different temperatures to show that its bending fatigue strength is strongly influenced by the temperature.

PL

Opracowano metodę oceny wytrzymałości zmęczeniowej włókien polietylenowych przy zginaniu. Przewidziano możliwość badania włókien przy rożnym obciążeniu wstępnym, kącie zginania i temperaturze. Przeprowadzono próby badania włókien polietylenowych w różnych temperaturach i przy rożnym kącie zginania. Stwierdzono, że naprężenie zginające zmienia się okresowo podczas cyklicznego procesu zginania. Stwierdzono również, że wstępne naprężenie oraz kąt zginania mają istotny wpływ na wytrzymałość zmęczeniową badanych włókien. Kamerę CCD zastosowano dla obserwacji morfologii przełomu zmęczeniowego włókien, pozwalającego na identyfikację mechanizmu przełomu. Stwierdzono wyraźny wpływ temperatury, w której przeprowadzano próby.

7

Influence of thermal activation on the changes of physical properties and structure of cobalt-based metallic glass

Spilka M., Griner S., Kania A.

Archives of Materials Science and Engineering

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2012

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Vol. 56, nr 2

61--68

EN

Purpose: In this paper the analysis of influence of heat treatment on the structure and properties of AMM type (Co70.5Fe2.5Mn2Mo1Si9B15) metallic glass was shown. Moreover the discussion of the changes of tensile strength, plasticity, cracking energy, remanence, coercive force, resistivity, crystallization effect and fracture morphology of alloy in “as quenched” state and hold at the temperature range of 100-400°C for 2 hours are presented. Design/methodology/approach: Tensile test and investigation of elementary cracking energy of amorphous ribbon carried out using the testing machine were performed. Plastic properties of examined material was studied by using of transverse bend test. Investigation of magnetic properties with annular method with 50 Hz field frequency was carried out. The alloy electrical resistivity was determined with resistance bridge. Fractography investigation after tensile test was made using scanning microscope. Findings: The investigations showed that for the analysed heat treatment temperature range of 100-400°C significant changes of physical properties, fracture morphology and alloy structure are observed. Research limitations/implications: Usage of metallic glasses is possible only in a narrow range of temperatures which does not lead to significant changes of properties or after proper heat treatment carried out in the aim of specified physical properties obtaining. Practical implications: Usage of metallic glasses depending on control and regulations of alloy properties changes with proper heat treatment. It is important the prediction of alloy properties changes during temperature changes and material using. Originality/value: In the article influence of thermal activation processes on structure changes and significant changes of mechanical and magnetic properties of cobalt-based metallic glass were presented.

8

Influence of geometry of rapidly solidified rods on properties of Fe-Co-based alloy

Lesz S., Griner S., Nowosielski R.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 41, nr 1-2

16-25

EN

Purpose: The main aim of the paper was investigation of influence of geometry of rapid solidified rods on properties (structure, fracture morphology, microhardness) of Fe36Co36B19Si5Nb4 alloy. Design/methodology/approach: The following experimental techniques were used: differential thermal analysis (DTA), scanning electron microscopy (SEM), light microscopy (LM), X-ray diffraction (XRD) method, Vickers microhardness. Findings: Changes of mechanical properties (microhardness) and different fracture morphology of rapidly solidified rods were presented. Research limitations/implications: Obtained structures are depended on cooling rate and glass forming ability of the alloy. Practical implications: The rapidly solidified bulk alloys have been commercialized in magnetic application and high strength materials. Originality/value: Diverse fracture morphology as well as changes of microhardness in amorphous regions of differently relaxated rate are observed.

9

Formation and physical properties of Fe-based bulk metallic glasses with Ni addition

Lesz S., Kwapuliński P., Nowosielski R.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 31, nr 1

35-40

EN

Purpose: The main aim of the paper was investigations of formation and changes of physical properties (magnetic properties and microhardness) of Fe based bulk metallic glasses (BMGs) with Ni addition. Design/methodology/approach: The following experimental techniques were used: transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) phase analysis method to test the structure, electrical resistivity in situ measurements (four-point probe), measurements of magnetic properties, microhardness of investigated ribbons was determined by Vickers method. Findings: The structural studies revealed an amorphous structure for the ribbons with thicknesses up to 0.27 mm, regardless of their thickness. Research limitations/implications: More investigations for example Mössbauer spectrometry have to be conducted on different thickness of ribbons in order to confirm conclusions contained in the work. Practical implications: According to the results presented in the present paper the examined Fe-based bulk glassy alloys with Ni addition as a soft ferromagnetic material may be utilized in construction of magnetic cores such as choke coils, common mode and noise filter and is of great technological interest. Originality/value: The originality of the paper are examinations of changes of structure and physical properties on cross section and on surface of ribbons.

10

Correlation between fracture morphology and mechanical properties of NANOPERM alloys

Lesz S., Szewieczek D., Tyrlik-Held J.

Archives of Materials Science and Engineering

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2008

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Vol. 29, nr 2

73-80

EN

Purpose: The purpose of this paper is to present of influence of heat treatment on the changes of structure, ductility, mechanical properties and particularly fracture morphology of the amorphous NANOPERM ribbons. The alloy was obtained in ribbons form by melt spinning method. Design/methodology/approach: The following experimental techniques were used: scanning electron microscopy (SEM) and X-ray diffraction (XRD) phase analysis method to test the structure. The measurement of mechanical properties, like: tensile strength Rm, ductility ε were made. Tensile tests were performed on testing machine INSTRON 1195. Plastic properties of investigated ribbons were determined in bending test. Findings: Morphology of fractures obtained after decohesion process in tensile test shows the history of amorphous alloys crystallization. Practical implications: The relationship between heat treatments parameters, structure and mechanical properties can be useful for practical application of these alloys. Originality/value: The temperature ranges of structure and mechanical properties changes after heat treatment of NANOPERM alloys it has been determined.

11

The structure and tribological properties of Fe-Al based intermetalics alloys

Komorek Z., Bojar Z., Czujko T.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, Spec. is

365-368

EN

The main purpose of presented work was to describe basic tribological properties of Fe-Al intermetalics depending on their structure and selected mechanical properties. Two different kind of intermetallic alloys with predominant contents of Fe3Al or FeAl intermetallic phases, in as-cast, homogenized or softened conditions were investigated by microstructure and chemical analysis, microhardness measurement, compression and impact testing. Alloys with significantly different condition of structure were tribologically tested using pin-on disc method and the relationship between properties and abrasive wear resistance of Fe-Al intermetallics in bulk form was discussed.