W. Arabczyk - Academia.edu (original) (raw)

Papers by W. Arabczyk

Catalysts, 2021

Nitriding of nanocrystalline iron and reduction of nanocrystalline iron nitride with gaseous mixt... more Nitriding of nanocrystalline iron and reduction of nanocrystalline iron nitride with gaseous mixtures of hydrogen with ammonia were studied at 375 °C and atmospheric pressure using the chemical potential programmed reaction (CPPR) method coupled with in situ XRD. In this paper, a series of phase transitions occurring during the processes is shown, and a detailed analysis of the phase composition and the structure of the material is given. The influence of a variable nitriding potential on the lattice parameters of α-Fe, γ′-Fe4N, and ε-Fe3-2N phases is shown. The α phase interplanar space changes irrelevantly in the one phase area but decreases linearly with average increases in crystallite size when α→γ′ transformation occurs. The nanocrystallite size distributions (nCSDs) were determined, with nCSD of the α phase for nitriding and nCSD of the ε phase for reduction. The reduction of the ε phase can occur directly to α or indirectly with an intermediate step of γ′ formation as a resu...

Scripta Metallurgica, 1986

Studies in Surface Science and Catalysis, 1988

Publisher Summary The presence of phosphorus plays a fundamental role in corrosion protection of ... more Publisher Summary The presence of phosphorus plays a fundamental role in corrosion protection of iron. Mainly, the Auger electron spectroscopy (AES) has been used for the determination of the chemical surface composition and the bonding states. For the experiments an iron(111) monocrystal was used with two different surface phosphorus concentrations. The high-concentration surface was obtained by reaction between iron and phosphorus hydride (PH3). This preparation resulted in the formation of a phosphorus-iron compound of the Fe x P form on both the surfaces of the specimen as a thin layer. This chapter discusses such segregation of iron as well as sulfur at several temperatures. In the case of low phosphorus concentration, the initial segregation of phosphorus and sulfur occurs simultaneously. The specimen concentrations were determined for C s = 12 ppm and C P = 40 ppm. When examining the curves over time, the complete coverage with sulfur is finally attained. This fact is to be attributed to the higher surface activity of sulfur resulting in a higher segregation enthalpy. Because of the lower surface activity the phosphorus diffusion into the bulk is relatively slow—that is, the signals result from the P(1×1)-S structure and from the phosphorus atoms in deeper but still near-surface atom layers.

Studies in Surface Science and Catalysis, 1995

Publisher Summary This chapter discusses the preparation method of a novel catalyst of K–C–Fe/Al ... more Publisher Summary This chapter discusses the preparation method of a novel catalyst of K–C–Fe/Al 2 O 3 for ammonia synthesis at mild conditions. This method includes (1) the coprecipitation of iron and aluminum hydroxides, (2) calcination, (3) the reduction of iron oxides/Al 2 O 3 to Fe/Al 2 O 3 , (4) carbon coatings of Fe/Al 2 O 3 , and (5) the activation of C–Fe/Al 2 O 3 precursor by metallic potassium. In a study discussed in the chapter, when the well-crystallized metallic iron detected by X-ray diffraction (XRD) was stated in a catalyst, the maximum of activity was reached. The creation of a thin film of carbon with metallic potassium on Fe/Al 2 O 3 was postulated. The high activity of the catalyst was attributed to presence of K–C–Fe sites where 2s electrons of metallic potassium were transported by the carbon electron system toward supported iron metal. Carbons prepared by the decomposition of hydrocarbons have variable physical and chemical properties—for example, the possibilities of electrons transport and electron accumulation. Therefore, they are useful to application in new areas, including catalysis.

Materials Science-Poland, 2013

Promoted nanocrystalline iron was carburized in a differential tubular flow reactor with thermogr... more Promoted nanocrystalline iron was carburized in a differential tubular flow reactor with thermogravimetric measurement of mass changes. The carburization process was carried out in the presence of pure methane under atmospheric pressure at 650 °C to obtain different carburization degrees of the sample. The carburized iron samples were characterized by the X-ray diffraction, high-resolution transmission electron microscope in the energy-dispersive X-ray spectroscopy mode, thermoprogrammable oxidation, and Raman spectroscopy. As a result of the methane decomposition on the nanocrystalline iron the following nanocrystalline products were observed: iron carbide Fe3C, graphite, iron and nanotubes. The crystallinity of the samples increased with the carburization degree.

Vacuum, 1987

The nitrogen content of the near surface region of an Fe(111) sample was increased by N~-implanta... more The nitrogen content of the near surface region of an Fe(111) sample was increased by N~-implantation (energy 5 keV, current density lOOpA/cm2). After recrystallization the surface showed a p(1 x 1)-N superstructure. Careful heating of the iron sample rich in nitrogen to 370 K produces a peak at 404.5 eV in the N(1 s) core level spectrum. Owing to segregation of the bulk nitrogen there are two different atomic nitrogen bonding states. They are characterized by nitrogen atoms localized on and under the first layer of iron atoms. This possibility is reflected by peaks of N(1 s) emission at 397.5 eV and at 397.0 eV, respectively. If both types of adsorption sites are occupied a molecular-like arrangement of nitrogen atoms with nearly perpendicular orientation of the molecule axis to the surface is formed. The N(1 s) binding energy value is placed at 404.5 eV and the nitrogen coverage measures 2. In cases where a nitrided surface was exposed to oxygen the molecularlike arrangement of surface nitrogen is formed, too, since oxygen displaces partially the atomic nitrogen from the nitrogen-iron bonding. After nitriding and oxidation the sputter profile displays immediately nitrogen at the surface followed by an oxidized region depleted in nitrogen and, finally, nitride phases are to be seen.

Physical Chemistry Chemical Physics, 2016

In a nanoFe/NH3/H2 system a hysteresis phenomenon occurs and two phases coexist, according to the... more In a nanoFe/NH3/H2 system a hysteresis phenomenon occurs and two phases coexist, according to the extended phase rule of Gibbs due to a degree of freedom associated with the nanocrystallite size.

Polish Journal of Chemistry, 1998

Materials Science and Engineering: C, 2007

The nanocrystalline cobalt used in experiment was prepared by means of cobalt hydroxide precipita... more The nanocrystalline cobalt used in experiment was prepared by means of cobalt hydroxide precipitation, followed by calcination and reduction. A small amount of structural promoters (CaO and Al2O3) was added to stabilize the nanocrystalline cobalt structure at elevated temperatures. The fcc-Co and hcp-Co phases were determined in the prepared samples. The metal was carburised with methane in a temperature range

Journal of Physics: Conference Series, 2005

Surface Science, 1998

The segregation kinetics studies of sulphur and carbon in iron and the adsorption kinetics of oxy... more The segregation kinetics studies of sulphur and carbon in iron and the adsorption kinetics of oxygen on iron have been discussed, taking into account the real structure of the monocrystalline sample. The deviation of the kinetics results from the t1/2 law has been interpreted as the effect of the presence of the adsorption sites in the defects of the monocrystalline iron sample. The equilibrium between the adsorption states of sulphur, carbon and oxygen atoms in the defects and on the surface has been assumed. For sulphur and carbon atoms, the energetically more favourable adsorption sites are in the defects; however, for oxygen atoms the adsorption sites on the surface are more favourable. The free energy of the segregation of sulphur and carbon atoms from the defects to the surface has been assumed to be a linear function of the degree of filling of the adsorption sites in the defects. The calculations of the energies of iron clusters with a contaminant atom have been also considered.

International Journal of Adhesion and Adhesives, 2013

ABSTRACT Inorganic fillers can improve coating properties, such as scratch resistance and UV stab... more ABSTRACT Inorganic fillers can improve coating properties, such as scratch resistance and UV stability and can significantly enhance the fillers usability in coatings and realize new market opportunities. In the pressure-sensitive adhesive (PSA) technology the inorganic fillers are used to change the very important properties of pressure-sensitive adhesives, such as tack, peel adhesion and shear strength. In the current study, the above mentioned properties of synthesized acrylic PSA using iron carbide filler in carbon matrix were investigated. The acrylic PSA containing iron carbide filler (Fe3C,C) was examined with SEM/EDX technique and the PSA adhesive and cohesive properties were examined by using a special strength machine according to AFERA tests. The conclusion is that the application of this kind of fillers allows the manufacturing of self-adhesive materials with moderate adhesiveness and very good removability.

Vacuum, 1990

The sulphur segregation and the influence of the adsorbed oxygen on the bonding states were inves... more The sulphur segregation and the influence of the adsorbed oxygen on the bonding states were investigated by means of AES, XPS and LEED methods. The iron surface, initially covered with sulphur, was exposed to an oxygen atmosphere. Adsorbed oxygen displaced sulphur from the iron-sulphur bond, sulphur atoms moved into lower but still near-surface layers, and Fe-O or O-Fe-O and S clusters were formed. At low sulphur coverages, X the metal-sulphur interaction prevailed. The higher the sulphur atom concentration on the iron surface, the shorter was the distance between its atoms, so allowing the formation of a chemical bond between them. By heating up to 720 K, the oxides were decomposed.

Nanotechnology, 2007

This paper presents a method of preparing nanocrystalline iron-carbon materials which can be appl... more This paper presents a method of preparing nanocrystalline iron-carbon materials which can be applied as fillers for polymers. Nanocrystalline iron samples were carburized either under ethylene/hydrogen mixture or under pure ethylene. Three kinds of samples were prepared: cementite/carbon (Fe3C/C), iron/cementite (Fe/Fe3C) and iron/carbon (Fe/C) ones. After carburization the samples were characterized using XRD and SEM methods. The obtained samples of

Carbon, 2004

Three powder samples with different content of iron carbide in a carbon matrix have been synthesi... more Three powder samples with different content of iron carbide in a carbon matrix have been synthesised by carburisation of nanocrystalline iron with methane. The samples have been characterised by XRD and TEM methods. The mean crystallite size of the obtained iron carbide has been found to be in the range from 41 to 67 nm. The magnetic resonance measurements of these samples have been performed at room temperature. Very intense magnetic resonance lines have been recorded for each of the samples. A resonance field, an integral intensity and a linewidth strongly depend on the concentration of iron carbide. The observed magnetic resonance lines have been fitted with two Lorentzian-shape lines, one centred at lower and the other at higher magnetic fields. Strong magnetic anisotropy was observed for all the samples and for the sample with lower concentration of iron carbide it is more intense. The resonance absorption signal arises from the agglomerates of iron carbide nanoparticles interacting strongly among themselves. The observed shift of the resonance field is connected with a strong ferromagnetic interaction between agglomerates of nanoparticles.

Catalysts, 2021

Nitriding of nanocrystalline iron and reduction of nanocrystalline iron nitride with gaseous mixt... more Nitriding of nanocrystalline iron and reduction of nanocrystalline iron nitride with gaseous mixtures of hydrogen with ammonia were studied at 375 °C and atmospheric pressure using the chemical potential programmed reaction (CPPR) method coupled with in situ XRD. In this paper, a series of phase transitions occurring during the processes is shown, and a detailed analysis of the phase composition and the structure of the material is given. The influence of a variable nitriding potential on the lattice parameters of α-Fe, γ′-Fe4N, and ε-Fe3-2N phases is shown. The α phase interplanar space changes irrelevantly in the one phase area but decreases linearly with average increases in crystallite size when α→γ′ transformation occurs. The nanocrystallite size distributions (nCSDs) were determined, with nCSD of the α phase for nitriding and nCSD of the ε phase for reduction. The reduction of the ε phase can occur directly to α or indirectly with an intermediate step of γ′ formation as a resu...

Scripta Metallurgica, 1986

Studies in Surface Science and Catalysis, 1988

Publisher Summary The presence of phosphorus plays a fundamental role in corrosion protection of ... more Publisher Summary The presence of phosphorus plays a fundamental role in corrosion protection of iron. Mainly, the Auger electron spectroscopy (AES) has been used for the determination of the chemical surface composition and the bonding states. For the experiments an iron(111) monocrystal was used with two different surface phosphorus concentrations. The high-concentration surface was obtained by reaction between iron and phosphorus hydride (PH3). This preparation resulted in the formation of a phosphorus-iron compound of the Fe x P form on both the surfaces of the specimen as a thin layer. This chapter discusses such segregation of iron as well as sulfur at several temperatures. In the case of low phosphorus concentration, the initial segregation of phosphorus and sulfur occurs simultaneously. The specimen concentrations were determined for C s = 12 ppm and C P = 40 ppm. When examining the curves over time, the complete coverage with sulfur is finally attained. This fact is to be attributed to the higher surface activity of sulfur resulting in a higher segregation enthalpy. Because of the lower surface activity the phosphorus diffusion into the bulk is relatively slow—that is, the signals result from the P(1×1)-S structure and from the phosphorus atoms in deeper but still near-surface atom layers.

Studies in Surface Science and Catalysis, 1995

Publisher Summary This chapter discusses the preparation method of a novel catalyst of K–C–Fe/Al ... more Publisher Summary This chapter discusses the preparation method of a novel catalyst of K–C–Fe/Al 2 O 3 for ammonia synthesis at mild conditions. This method includes (1) the coprecipitation of iron and aluminum hydroxides, (2) calcination, (3) the reduction of iron oxides/Al 2 O 3 to Fe/Al 2 O 3 , (4) carbon coatings of Fe/Al 2 O 3 , and (5) the activation of C–Fe/Al 2 O 3 precursor by metallic potassium. In a study discussed in the chapter, when the well-crystallized metallic iron detected by X-ray diffraction (XRD) was stated in a catalyst, the maximum of activity was reached. The creation of a thin film of carbon with metallic potassium on Fe/Al 2 O 3 was postulated. The high activity of the catalyst was attributed to presence of K–C–Fe sites where 2s electrons of metallic potassium were transported by the carbon electron system toward supported iron metal. Carbons prepared by the decomposition of hydrocarbons have variable physical and chemical properties—for example, the possibilities of electrons transport and electron accumulation. Therefore, they are useful to application in new areas, including catalysis.

Materials Science-Poland, 2013

Promoted nanocrystalline iron was carburized in a differential tubular flow reactor with thermogr... more Promoted nanocrystalline iron was carburized in a differential tubular flow reactor with thermogravimetric measurement of mass changes. The carburization process was carried out in the presence of pure methane under atmospheric pressure at 650 °C to obtain different carburization degrees of the sample. The carburized iron samples were characterized by the X-ray diffraction, high-resolution transmission electron microscope in the energy-dispersive X-ray spectroscopy mode, thermoprogrammable oxidation, and Raman spectroscopy. As a result of the methane decomposition on the nanocrystalline iron the following nanocrystalline products were observed: iron carbide Fe3C, graphite, iron and nanotubes. The crystallinity of the samples increased with the carburization degree.

Vacuum, 1987

The nitrogen content of the near surface region of an Fe(111) sample was increased by N~-implanta... more The nitrogen content of the near surface region of an Fe(111) sample was increased by N~-implantation (energy 5 keV, current density lOOpA/cm2). After recrystallization the surface showed a p(1 x 1)-N superstructure. Careful heating of the iron sample rich in nitrogen to 370 K produces a peak at 404.5 eV in the N(1 s) core level spectrum. Owing to segregation of the bulk nitrogen there are two different atomic nitrogen bonding states. They are characterized by nitrogen atoms localized on and under the first layer of iron atoms. This possibility is reflected by peaks of N(1 s) emission at 397.5 eV and at 397.0 eV, respectively. If both types of adsorption sites are occupied a molecular-like arrangement of nitrogen atoms with nearly perpendicular orientation of the molecule axis to the surface is formed. The N(1 s) binding energy value is placed at 404.5 eV and the nitrogen coverage measures 2. In cases where a nitrided surface was exposed to oxygen the molecularlike arrangement of surface nitrogen is formed, too, since oxygen displaces partially the atomic nitrogen from the nitrogen-iron bonding. After nitriding and oxidation the sputter profile displays immediately nitrogen at the surface followed by an oxidized region depleted in nitrogen and, finally, nitride phases are to be seen.

Physical Chemistry Chemical Physics, 2016

In a nanoFe/NH3/H2 system a hysteresis phenomenon occurs and two phases coexist, according to the... more In a nanoFe/NH3/H2 system a hysteresis phenomenon occurs and two phases coexist, according to the extended phase rule of Gibbs due to a degree of freedom associated with the nanocrystallite size.

Polish Journal of Chemistry, 1998

Materials Science and Engineering: C, 2007

The nanocrystalline cobalt used in experiment was prepared by means of cobalt hydroxide precipita... more The nanocrystalline cobalt used in experiment was prepared by means of cobalt hydroxide precipitation, followed by calcination and reduction. A small amount of structural promoters (CaO and Al2O3) was added to stabilize the nanocrystalline cobalt structure at elevated temperatures. The fcc-Co and hcp-Co phases were determined in the prepared samples. The metal was carburised with methane in a temperature range

Journal of Physics: Conference Series, 2005

Surface Science, 1998

The segregation kinetics studies of sulphur and carbon in iron and the adsorption kinetics of oxy... more The segregation kinetics studies of sulphur and carbon in iron and the adsorption kinetics of oxygen on iron have been discussed, taking into account the real structure of the monocrystalline sample. The deviation of the kinetics results from the t1/2 law has been interpreted as the effect of the presence of the adsorption sites in the defects of the monocrystalline iron sample. The equilibrium between the adsorption states of sulphur, carbon and oxygen atoms in the defects and on the surface has been assumed. For sulphur and carbon atoms, the energetically more favourable adsorption sites are in the defects; however, for oxygen atoms the adsorption sites on the surface are more favourable. The free energy of the segregation of sulphur and carbon atoms from the defects to the surface has been assumed to be a linear function of the degree of filling of the adsorption sites in the defects. The calculations of the energies of iron clusters with a contaminant atom have been also considered.

International Journal of Adhesion and Adhesives, 2013

ABSTRACT Inorganic fillers can improve coating properties, such as scratch resistance and UV stab... more ABSTRACT Inorganic fillers can improve coating properties, such as scratch resistance and UV stability and can significantly enhance the fillers usability in coatings and realize new market opportunities. In the pressure-sensitive adhesive (PSA) technology the inorganic fillers are used to change the very important properties of pressure-sensitive adhesives, such as tack, peel adhesion and shear strength. In the current study, the above mentioned properties of synthesized acrylic PSA using iron carbide filler in carbon matrix were investigated. The acrylic PSA containing iron carbide filler (Fe3C,C) was examined with SEM/EDX technique and the PSA adhesive and cohesive properties were examined by using a special strength machine according to AFERA tests. The conclusion is that the application of this kind of fillers allows the manufacturing of self-adhesive materials with moderate adhesiveness and very good removability.

Vacuum, 1990

The sulphur segregation and the influence of the adsorbed oxygen on the bonding states were inves... more The sulphur segregation and the influence of the adsorbed oxygen on the bonding states were investigated by means of AES, XPS and LEED methods. The iron surface, initially covered with sulphur, was exposed to an oxygen atmosphere. Adsorbed oxygen displaced sulphur from the iron-sulphur bond, sulphur atoms moved into lower but still near-surface layers, and Fe-O or O-Fe-O and S clusters were formed. At low sulphur coverages, X the metal-sulphur interaction prevailed. The higher the sulphur atom concentration on the iron surface, the shorter was the distance between its atoms, so allowing the formation of a chemical bond between them. By heating up to 720 K, the oxides were decomposed.

Nanotechnology, 2007

This paper presents a method of preparing nanocrystalline iron-carbon materials which can be appl... more This paper presents a method of preparing nanocrystalline iron-carbon materials which can be applied as fillers for polymers. Nanocrystalline iron samples were carburized either under ethylene/hydrogen mixture or under pure ethylene. Three kinds of samples were prepared: cementite/carbon (Fe3C/C), iron/cementite (Fe/Fe3C) and iron/carbon (Fe/C) ones. After carburization the samples were characterized using XRD and SEM methods. The obtained samples of

Carbon, 2004

Three powder samples with different content of iron carbide in a carbon matrix have been synthesi... more Three powder samples with different content of iron carbide in a carbon matrix have been synthesised by carburisation of nanocrystalline iron with methane. The samples have been characterised by XRD and TEM methods. The mean crystallite size of the obtained iron carbide has been found to be in the range from 41 to 67 nm. The magnetic resonance measurements of these samples have been performed at room temperature. Very intense magnetic resonance lines have been recorded for each of the samples. A resonance field, an integral intensity and a linewidth strongly depend on the concentration of iron carbide. The observed magnetic resonance lines have been fitted with two Lorentzian-shape lines, one centred at lower and the other at higher magnetic fields. Strong magnetic anisotropy was observed for all the samples and for the sample with lower concentration of iron carbide it is more intense. The resonance absorption signal arises from the agglomerates of iron carbide nanoparticles interacting strongly among themselves. The observed shift of the resonance field is connected with a strong ferromagnetic interaction between agglomerates of nanoparticles.