Ilona Nejman - Academia.edu (original) (raw)

Papers by Ilona Nejman

Materials

Ensuring adequate reliability of the production process of packaging closures has made it necessa... more Ensuring adequate reliability of the production process of packaging closures has made it necessary to study the effect of annealing and varnishing variants on the strength and structural properties of the stock material. As a test material, EN AW-5052-H28 aluminium alloy sheets with a thickness of 0.21 mm were used. The surface treatment of the test material involved varnishing the sheet metal surface using various varnishes and soaking the sheet metal. The coefficient of friction and the abrasion resistance of the coatings were determined using the T-21 ball-and-disc tribotester. The tested sheets were subjected to tribological analysis by the T-05 roller-block tribotester using countersamples made of Caldie and Sverker 21 tool steels. The results of the tests showed differences in mechanical and structural properties depending on the method of sample preparation. Based on the test results, significant differences in the adhesion of anti-wear coatings were found. The results revea...

Materials

The article presents the results of research on the influence of plastic deformation on the micro... more The article presents the results of research on the influence of plastic deformation on the microstructure and tensile strength of Haynes 282 nickel superalloy produced by direct metal laser sintering (DMLS) and a conventional technique (casting). Samples were tested for dimensional accuracy using a 3D scanner. Then, the samples were subjected to plastic deformation by rolling. The microstructures of the DMLS and the as-cast samples were analysed using a scanning electron microscope. The strength properties of the samples were determined in a static tensile test. Microhardness measurements of the samples were also performed. Based on the analysis of the dimensional accuracy, it was found that the surface quality of the components produced by DMLS is dependent on the input parameters of the 3D printing process. Using the DMLS method, it is possible to produce Haynes 282 with a fine-crystalline microstructure containing dendrites. The fine-crystalline dendritic microstructure and low ...

Archives of Metallurgy and Materials

The present study attempts to apply HE to 99.99% pure copper. The microstructure of the samples w... more The present study attempts to apply HE to 99.99% pure copper. The microstructure of the samples was investigated by both light microscopy and scanning transmission electron microscopy (STEM). Additionally, the microhardness was measured, the tensile test was made, and statistical analysis of the grains and subgrains was performed. Based on Kikuchi diffraction patterns, misorientation was determined. The obtained results show that microstructure of copper deformed by hydrostatic extrusion (HE) is rather inhomogeneous. The regions strongly deformed with high dislocation density exist near cells and grains/subgrains free of dislocations. The measurements of the grain size have revealed that the sample with an initial in annealed-state grain size of about 250 μm had this grain size reduced to below 0.35μm when it was deformed by HE to the strain ε=2.91. The microhardness and UTS are stable within the whole investigated range of deformation.

Journal of achievements in materials and manufacturing engineering, 2010

Purpose: The objective of this work was to present the changes between the plasma sprayed and hig... more Purpose: The objective of this work was to present the changes between the plasma sprayed and high velocity oxy-fuel (HVOF) wear Cr3C2 resistant coats. The differences in microstructure and microhardness of coatings were investigated. The characterization of fully melted, unmelted and partly melted areas was performed. Design/methodology/approach: The investigated coats contained very differentiate areas, especially plasma sprayed layers. Systematic investigations of microstructure by using optical, electron scanning microscopy and transmission electron microscopy selected fully melted, unmelted or partly melted areas and their characteristic features were performed. Microhardness of coats was measured and compared with the similar literature results. Findings: Microstructure of plasma sprayed coats was finding as consisting from elongating splats, additionally contained un-melted previous particle of powder and some voids and oxides. Contrary to this the HFOV coatingss were more un...

Materials

Recent work indicates that the high-velocity oxy-fuel (HVOF) thermal spraying WC–Co coatings have... more Recent work indicates that the high-velocity oxy-fuel (HVOF) thermal spraying WC–Co coatings have been used to enhance the wear resistance of various engineering components in a variety of industrial environments. In the present work, WC–Co powder, containing Cr particles in an amount of 10%, was deposited on ductile cast iron with the HVOF thermal spray coating technique. An investigation was conducted to determine the role of Cr particles in the WC–Co coating produced with the HVOF technique on microstructure, mechanical, and wear properties in a system of type: WC-Co coating/ductile cast iron. The microstructure of the HVOF-sprayed WC–Co + Cr coating was characterised by light microscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDS). The analysis of the microstructure showed the formation of a coating with low porosity, compact structure, and good adhesion to the substrate with ...

Journal of Surface Engineered Materials and Advanced Technology

The paper describes the research of coatings on the AK9 aluminum alloy substrate and hybrid coati... more The paper describes the research of coatings on the AK9 aluminum alloy substrate and hybrid coatings deposited on graphite substrate. Coatings on the AK9 alloy were deposited by thermal spraying and PVD method (physical vapour deposition). Hybrid coatings consisting of a tungsten interlayer and an external layer of Zr + DLC (diamond-like carbon) and CVD were deposited on the graphite surface. Plasma methods-PVD and CVD-were used. The structure and composition of coatings were analyzed.

Metals

Hydrometallurgical recovery of zinc from electric arc furnace dust was investigated on a laborato... more Hydrometallurgical recovery of zinc from electric arc furnace dust was investigated on a laboratory scale, using aqueous sodium hydroxide solution as a leaching agent. Special attention was paid to the effect of NaOH concentration, temperature and liquid/solid phase ratio on the zinc leachability. It was found that all tested factors increased the leachability, with the maximum efficiency of 88% obtained in a 6 M NaOH solution at a temperature of 80 °C and the liquid/solid phase ratio of 40. The test results confirmed the high selectivity of the zinc leaching agent. In spite of this, complete recovery of zinc from steelmaking dust has proved to be very difficult due to the occurrence of this element in the form of stable and sparingly soluble ZnFe2O4 ferrite. Purification of the solution by cementation and electrolysis gave zinc of purity 99.88% in powder form.

Epitoanyag - Journal of Silicate Based and Composite Materials

The paper presents the results of friction stir processing (FSP) process of cast aluminium alloy ... more The paper presents the results of friction stir processing (FSP) process of cast aluminium alloy AlSi9Mg. The studies included a modification of the microstructure in the grain refinement, elimination of voids and the production of composite material AlSi9Mg + Re. Rhenium is famous for its refractory character, high density as well as high hardness. It is well known as alloying element for improvement of strength, plasticity, weldability, reduction of the degree of recrystallization embrittlement mainly in W, Mo and Ni based alloys. Re is used in superalloys as a solid-solution strengthening alloying element and increasing corrosion resistance at high temperatures. Rhenium containing alloys have high electrical resistivity and refractory character. The modification was carried out single-and multiple runs. The results show significant fragmentation in the mixing microstructure, and a metallic continuity. Fragmentation in the mixing microstructure was confirmed by SEM research. The study revealed that mechanical alloying technology FSP allows to increase the hardness of the material. The ability to produce graded materials AlSi9Mg alloy matrix by frictional treatment is also indicated.

Metallurgy and Foundry Engineering

The results of our research on the application of coatings for protecting industrial casting mold... more The results of our research on the application of coatings for protecting industrial casting molds are presented. Tests were carried out on graphite molds with deposited Al 2 O 3 coatings containing the addition of glassy carbon and with W/Zr/DLC coatings, both examined after the process of pouring molds with molten aluminum bronze. The coatings were applied by two different methods; i.e., plasma spraying in the case of Al 2 O 3 + glassy carbon coating and PVD in the case of W/Zr/DLC coating. Reference tests were also conducted on graphite molds without coating. The use of protective coatings on graphite molds seems to be an effective solution. Studies have shown that coatings have good resistance during the casting process. The liquid metal sticking to the surface did not penetrate deep inside the graphite mold. The use of coating technology reduces the amount of downtime necessary to replace worn molds and increases the efficiency of the casting process.

Key Engineering Materials, 2016

Key Engineering Materials, 2015

The effect of plasma gases (argon, helium) on the structure and properties of the WC-CrC-Ni coati... more The effect of plasma gases (argon, helium) on the structure and properties of the WC-CrC-Ni coatings deposited at the graphite substrate has been investigated. The coatings were deposited by plasma spraying method in equipment Cham Pro –Thermal Spray Systems produced by Sulzer company. The microstructure of coatings were investigated by light microscopy (MO) and scanning electron microscopy (SEM). The performed investigations have been shown that with the increasing of amounts of argon and reducing volumes of helium and nitrogen, the microhardnees increased. The plasma gases also influenced on the porosity of coatings. Keywords: WC-CrC-Ni coatings, plasma spraying, microstructure, porosity Acknowledgement: The work was supported by project No INNOTECH – K2/IN2/9/181851/NCBR/13

Materials Science Forum, 2011

In the present work, the microstructure, phase composition and microhardness of Cr3C2-NiCr, WCCo,... more In the present work, the microstructure, phase composition and microhardness of Cr3C2-NiCr, WCCo, and powdered composite NiCrSiBCr10%,Fe2.5%,Si3.1%,Bi2.1%C; NiCrSiBFe5; NiCrSiBCr5; NiCrSiBFe2.5Cr2.5; HVOF coatings applied on the Al-Si substrate have been compared. The coating cross-sections were examined by optical microscopy (OM), scanning electron microscopy (SEM) and electron transmission microscopy (TEM). For hard Cr3C2-NiCr and WC-Co coatings, a total microhardness level of about 860 and 1240 HV, respectively, was obtained. The microhardness of composite coatings was essentially lower and comprised in the range of values between 420 and 540 HV. The lowest level of microhardness showed the NiCrSiBFe2.5Cr2.5 coating. The most refined microstructure was found in Cr3C2 and WC coatings. The mean size of splat granules obtained in Cr3C2-NiCr had the value of about 2.7 m and of 0.5 m in WC-Co. For comparison, the granules obtained in composite coatings had the dimensions of about ...

Surface and Coatings Technology, 2016

Key Engineering Materials, 2016

Materials

Ensuring adequate reliability of the production process of packaging closures has made it necessa... more Ensuring adequate reliability of the production process of packaging closures has made it necessary to study the effect of annealing and varnishing variants on the strength and structural properties of the stock material. As a test material, EN AW-5052-H28 aluminium alloy sheets with a thickness of 0.21 mm were used. The surface treatment of the test material involved varnishing the sheet metal surface using various varnishes and soaking the sheet metal. The coefficient of friction and the abrasion resistance of the coatings were determined using the T-21 ball-and-disc tribotester. The tested sheets were subjected to tribological analysis by the T-05 roller-block tribotester using countersamples made of Caldie and Sverker 21 tool steels. The results of the tests showed differences in mechanical and structural properties depending on the method of sample preparation. Based on the test results, significant differences in the adhesion of anti-wear coatings were found. The results revea...

Materials

The article presents the results of research on the influence of plastic deformation on the micro... more The article presents the results of research on the influence of plastic deformation on the microstructure and tensile strength of Haynes 282 nickel superalloy produced by direct metal laser sintering (DMLS) and a conventional technique (casting). Samples were tested for dimensional accuracy using a 3D scanner. Then, the samples were subjected to plastic deformation by rolling. The microstructures of the DMLS and the as-cast samples were analysed using a scanning electron microscope. The strength properties of the samples were determined in a static tensile test. Microhardness measurements of the samples were also performed. Based on the analysis of the dimensional accuracy, it was found that the surface quality of the components produced by DMLS is dependent on the input parameters of the 3D printing process. Using the DMLS method, it is possible to produce Haynes 282 with a fine-crystalline microstructure containing dendrites. The fine-crystalline dendritic microstructure and low ...

Archives of Metallurgy and Materials

The present study attempts to apply HE to 99.99% pure copper. The microstructure of the samples w... more The present study attempts to apply HE to 99.99% pure copper. The microstructure of the samples was investigated by both light microscopy and scanning transmission electron microscopy (STEM). Additionally, the microhardness was measured, the tensile test was made, and statistical analysis of the grains and subgrains was performed. Based on Kikuchi diffraction patterns, misorientation was determined. The obtained results show that microstructure of copper deformed by hydrostatic extrusion (HE) is rather inhomogeneous. The regions strongly deformed with high dislocation density exist near cells and grains/subgrains free of dislocations. The measurements of the grain size have revealed that the sample with an initial in annealed-state grain size of about 250 μm had this grain size reduced to below 0.35μm when it was deformed by HE to the strain ε=2.91. The microhardness and UTS are stable within the whole investigated range of deformation.

Journal of achievements in materials and manufacturing engineering, 2010

Purpose: The objective of this work was to present the changes between the plasma sprayed and hig... more Purpose: The objective of this work was to present the changes between the plasma sprayed and high velocity oxy-fuel (HVOF) wear Cr3C2 resistant coats. The differences in microstructure and microhardness of coatings were investigated. The characterization of fully melted, unmelted and partly melted areas was performed. Design/methodology/approach: The investigated coats contained very differentiate areas, especially plasma sprayed layers. Systematic investigations of microstructure by using optical, electron scanning microscopy and transmission electron microscopy selected fully melted, unmelted or partly melted areas and their characteristic features were performed. Microhardness of coats was measured and compared with the similar literature results. Findings: Microstructure of plasma sprayed coats was finding as consisting from elongating splats, additionally contained un-melted previous particle of powder and some voids and oxides. Contrary to this the HFOV coatingss were more un...

Materials

Recent work indicates that the high-velocity oxy-fuel (HVOF) thermal spraying WC–Co coatings have... more Recent work indicates that the high-velocity oxy-fuel (HVOF) thermal spraying WC–Co coatings have been used to enhance the wear resistance of various engineering components in a variety of industrial environments. In the present work, WC–Co powder, containing Cr particles in an amount of 10%, was deposited on ductile cast iron with the HVOF thermal spray coating technique. An investigation was conducted to determine the role of Cr particles in the WC–Co coating produced with the HVOF technique on microstructure, mechanical, and wear properties in a system of type: WC-Co coating/ductile cast iron. The microstructure of the HVOF-sprayed WC–Co + Cr coating was characterised by light microscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDS). The analysis of the microstructure showed the formation of a coating with low porosity, compact structure, and good adhesion to the substrate with ...

Journal of Surface Engineered Materials and Advanced Technology

The paper describes the research of coatings on the AK9 aluminum alloy substrate and hybrid coati... more The paper describes the research of coatings on the AK9 aluminum alloy substrate and hybrid coatings deposited on graphite substrate. Coatings on the AK9 alloy were deposited by thermal spraying and PVD method (physical vapour deposition). Hybrid coatings consisting of a tungsten interlayer and an external layer of Zr + DLC (diamond-like carbon) and CVD were deposited on the graphite surface. Plasma methods-PVD and CVD-were used. The structure and composition of coatings were analyzed.

Metals

Hydrometallurgical recovery of zinc from electric arc furnace dust was investigated on a laborato... more Hydrometallurgical recovery of zinc from electric arc furnace dust was investigated on a laboratory scale, using aqueous sodium hydroxide solution as a leaching agent. Special attention was paid to the effect of NaOH concentration, temperature and liquid/solid phase ratio on the zinc leachability. It was found that all tested factors increased the leachability, with the maximum efficiency of 88% obtained in a 6 M NaOH solution at a temperature of 80 °C and the liquid/solid phase ratio of 40. The test results confirmed the high selectivity of the zinc leaching agent. In spite of this, complete recovery of zinc from steelmaking dust has proved to be very difficult due to the occurrence of this element in the form of stable and sparingly soluble ZnFe2O4 ferrite. Purification of the solution by cementation and electrolysis gave zinc of purity 99.88% in powder form.

Epitoanyag - Journal of Silicate Based and Composite Materials

The paper presents the results of friction stir processing (FSP) process of cast aluminium alloy ... more The paper presents the results of friction stir processing (FSP) process of cast aluminium alloy AlSi9Mg. The studies included a modification of the microstructure in the grain refinement, elimination of voids and the production of composite material AlSi9Mg + Re. Rhenium is famous for its refractory character, high density as well as high hardness. It is well known as alloying element for improvement of strength, plasticity, weldability, reduction of the degree of recrystallization embrittlement mainly in W, Mo and Ni based alloys. Re is used in superalloys as a solid-solution strengthening alloying element and increasing corrosion resistance at high temperatures. Rhenium containing alloys have high electrical resistivity and refractory character. The modification was carried out single-and multiple runs. The results show significant fragmentation in the mixing microstructure, and a metallic continuity. Fragmentation in the mixing microstructure was confirmed by SEM research. The study revealed that mechanical alloying technology FSP allows to increase the hardness of the material. The ability to produce graded materials AlSi9Mg alloy matrix by frictional treatment is also indicated.

Metallurgy and Foundry Engineering

The results of our research on the application of coatings for protecting industrial casting mold... more The results of our research on the application of coatings for protecting industrial casting molds are presented. Tests were carried out on graphite molds with deposited Al 2 O 3 coatings containing the addition of glassy carbon and with W/Zr/DLC coatings, both examined after the process of pouring molds with molten aluminum bronze. The coatings were applied by two different methods; i.e., plasma spraying in the case of Al 2 O 3 + glassy carbon coating and PVD in the case of W/Zr/DLC coating. Reference tests were also conducted on graphite molds without coating. The use of protective coatings on graphite molds seems to be an effective solution. Studies have shown that coatings have good resistance during the casting process. The liquid metal sticking to the surface did not penetrate deep inside the graphite mold. The use of coating technology reduces the amount of downtime necessary to replace worn molds and increases the efficiency of the casting process.

Key Engineering Materials, 2016

Key Engineering Materials, 2015

The effect of plasma gases (argon, helium) on the structure and properties of the WC-CrC-Ni coati... more The effect of plasma gases (argon, helium) on the structure and properties of the WC-CrC-Ni coatings deposited at the graphite substrate has been investigated. The coatings were deposited by plasma spraying method in equipment Cham Pro –Thermal Spray Systems produced by Sulzer company. The microstructure of coatings were investigated by light microscopy (MO) and scanning electron microscopy (SEM). The performed investigations have been shown that with the increasing of amounts of argon and reducing volumes of helium and nitrogen, the microhardnees increased. The plasma gases also influenced on the porosity of coatings. Keywords: WC-CrC-Ni coatings, plasma spraying, microstructure, porosity Acknowledgement: The work was supported by project No INNOTECH – K2/IN2/9/181851/NCBR/13

Materials Science Forum, 2011

In the present work, the microstructure, phase composition and microhardness of Cr3C2-NiCr, WCCo,... more In the present work, the microstructure, phase composition and microhardness of Cr3C2-NiCr, WCCo, and powdered composite NiCrSiBCr10%,Fe2.5%,Si3.1%,Bi2.1%C; NiCrSiBFe5; NiCrSiBCr5; NiCrSiBFe2.5Cr2.5; HVOF coatings applied on the Al-Si substrate have been compared. The coating cross-sections were examined by optical microscopy (OM), scanning electron microscopy (SEM) and electron transmission microscopy (TEM). For hard Cr3C2-NiCr and WC-Co coatings, a total microhardness level of about 860 and 1240 HV, respectively, was obtained. The microhardness of composite coatings was essentially lower and comprised in the range of values between 420 and 540 HV. The lowest level of microhardness showed the NiCrSiBFe2.5Cr2.5 coating. The most refined microstructure was found in Cr3C2 and WC coatings. The mean size of splat granules obtained in Cr3C2-NiCr had the value of about 2.7 m and of 0.5 m in WC-Co. For comparison, the granules obtained in composite coatings had the dimensions of about ...

Surface and Coatings Technology, 2016

Key Engineering Materials, 2016