Search Results

You are looking at 1 - 6 of 6 items for

  • Author: M. Gwoździk x
Clear All Modify Search
Open access

M. Gwoździk

Abstract

The paper contains results of studies into the formation of oxide layers on 13CrMo4-5 (15HM) steel long-term operated at an elevated temperature. The oxide layer was studied on a surface and a cross-section at the inner and outer surface of the tube wall. The 13CrMo4-5 steel operated at the temperature of 470°C during 190,000 hours was investigated. X-ray structural examinations (XRD) were carried out, microscope observation s using an optical, scanning microscope were performed. The native material chemical composition was analysed by means of emission spark spectroscopy, while that of oxide layers on a scanning microscope (EDS). The studies on the topography of the oxide layers comprised studies on the roughness plane, which were carried out using a AFM microscope designed for 2D and 3D studies on the surface. Mechanical properties of the oxide layer – steel (substrate) were characterised on the basis of scratch test. The adhesion of oxide layers, friction force, friction coefficient, scratching depth were determined as well as the force at which the layer was delaminated.

Open access

M. Gwoździk

Abstract

The paper contains results of studies into the formation of oxide layers on 10CrMo9-10 (10H2M) steel long-term operated at an elevated temperature (T = 545°C, t = 200,000h). The oxide layer was studied on a surface and a cross-section at the inner and outer surface of the tube wall on the outlet both on the fire and counter-fire side of the tube wall surface.

The obtained results of research have shown a higher degree of degradation, both of the steel itself and oxide layers, on the fire side. In addition, it has been shown that on the outside tube wall, apart from iron oxides, there are also deposits composed mainly of Al2SiO5.

Open access

M. Gwozdzik and Z. Nitkiewicz

The paper contains results of studies on X-ray diffraction analysis XRD (studying the phase composition, crystallite sizes and lattice deformations) of oxide layers on P91 steel, operated for a long time at an elevated temperature (T = 535°C, t = 70,000 h). X-ray studies were carried out on the inner surface of a tube, and then the layer surface was polished down to 3.5 μm and the diffraction measurements were performed again to determine individual oxide layers. It has been found that a three-zone oxide layer is formed as a result of long-term operation of P91 steel at the temperature of 535°C. Hematite occurs on the inner surface of the tube. Then magnetite appears below hematite. Going deeper into the layer there is a spinel, i.e. a mixture of magnetite and chromite. A visible decay of total intensity for Fe2O3 is observed already at the polishing depth of 3.5 μm. In the case of Fe3O4 and FeCr2O4 an increase in total intensity is observed already from 7 μm, what manifests in narrowing the diffraction line and hence in increasing the crystallites size and in the relaxation of stresses in this oxide layer. The broadening of a diffraction line caused by a small size of crystallites is expressed by the Scherrer relationship. Instead, the β2 broadening resulting from lattice distortions (relaxation of stresses) was determined from the Taylor relationship.

Open access

P. Zygoń, J. Peszke, M. Gwozdźik, Z. Nitkiewicz and M. Malik

Abstract

The paper presents results of studies on carbon nanotubes - as received, after cleaning and also after modification. Functional groups as well as metal nanoparticles have been attached, originating from cobalt sulphate, copper acetate and a mixture of hydrogen bromide and bromide. The surface studies on an atomic forces microscope (AFM), X-ray studies (phase composition analysis, crystallite sizes determination) as well as Raman spectroscopy studies were carried out on such nanotubes.

The surface topography studies have shown that after the modification the diameter and length of nanotubes change. Also the surface development changes, which has been determined through roughness parameter measurements.

The change of intensity, of crystallite size and of half-value width of main reflections originating from carbon for nanotubes modified in various ways have been determined using the X-ray analysis.

Open access

P. Zygoń, M. Gwoździk, J. Peszke and Z. Nitkiewicz

Abstract

Carbon nanotubes because of their high mechanical, optical or electrical properties, have found use as semiconducting materials constituting the reinforcing phase in composite materials. The paper presents the results of the studies on the mechanical properties of polymer composites reinforced with carbon nanotubes (CNT). Three-point bending tests were carried out on the composites. The density of each obtained composite was determined as well as the surface roughness and the resistivity at room temperature.

Moreover the surface studies on an atomic forces microscope (AFM) and X-ray studies (phase composition analysis, crystallite sizes determination) were carried out on such composites. Measurements of the surface topography using the Tapping Mode method were performed, acquiring the data on the height and on the phase imaging. The change of intensity, of crystallite size and of half-value width of main reflections originating from carbon for composites have been determined using the X-ray analysis.

Carbon nanotubes constituting the reinforcement for a polymer composite improve the mechanical properties and con-ductivity of the composite.

Open access

P. Zygoń, M. Gwoździk, J. Peszke and Z. Nitkiewicz

The paper presents properties of polymer composites reinforced with carbon nanotubes (CNT) containing various mixtures of dispersion. Acrylates of different particle size and viscosity were used to produce composites. The mechanical strength of composites was determined by three-point bending tests. The roughness parameter of composites was determined with a profilometer and compared with the roughness parameter determined via atomic force microscopy (AFM). Also X-ray studies (phase composition analysis, crystallite sizes determination) were carried out on these composites. Measurements of the surface topography using the Tapping Mode method were performed, acquiring the data on the height and on the phase imaging. The change of intensity, crystallite size and half-value width of main reflections originating from carbon within the composites have been determined using the X-ray analysis. The density of each obtained composite was determined as well as the resistivity at room temperature. The density of composites is quite satisfactory and ranges from 0.27 to 0.35 g/cm3. Different composites vary not only in strength but also in density. Different properties were achieved by the use of various dispersions. Carbon nanotubes constituting the reinforcement for a polymer composite improve the mechanical properties and conductivity composite.