Wyniki wyszukiwania - BazTech

1

Structure studies on nanocrystalline powder of MgO xerogel prepared by the sol-gel method

Dercz G., Prusik K., Pajak L., Pielaszek R., Jmalinowski J. J., Pudlo W.

Materials Science Poland

|

2009

|

Vol. 27, No. 1

201--207

EN

Structure studies were performed on nanocrystalline powder of MgO xerogel prepared by the sol-gel technique, producing high purity, chemically homogeneous materials of relatively high specific surface area. Magnesium methoxide was used as an MgO precursor. The wet gel was dried under conventional conditions, yielding xerogel with periclase phase; the only crystalline form of magnesium oxide. The X-ray diffraction, scanning and transmission electron microcopies were used as the tools of structure analysis. The Toraya PRO-FIT procedure and the Rietveld refinement method were applied for X-ray data analysis. Both techniques apply the Pearson VII function for the description of line profiles. The gamma crystallite size distribution was determined using the FW(1/5)/(4/5)M method proposed by Pielaszek. The obtained values of and ? (measure of polydispersity) of particle size parameters are equal to 7.1 nm and 2.1 nm, respectively, whereas the average crystallite size, estimated by the Williamson- Hall procedure, was equal to 7.5 nm. The Rwp, and S fitting parameters obtained from the Rietveld refinement were equal to 6.4% and 1.8, respectively. This would seem the most satisfactory result, when considering the nanosize of MgO crystallites and a very probable presence of amorphous phase.

2

X-ray and SEM studies on zirconia powders

Dercz G., Prusik K., Pająk L.

Journal of Achievements in Materials and Manufacturing Engineering

|

2008

|

Vol. 31, nr 2

408-414

EN

Purpose: The microstructure characterization of commercially available zirconia powders was the purpose of this paper. Different methods of structure analysis were applied owing to the complex, multiphase structure of studied materials. Design/methodology/approach: The X-ray diffraction (XRD) and scanning electron microscopy (SEM) investigations were performed on three commercial zirconia ceramic materials: Amdry 204 NS (ZrO2~ 8 wt.% of Y2O3), Metco C8 YZ (ZrO2~ 8 wt.% of Y2O3) and Metco 202 (ZrO2~ 20 wt.% of Y2O3). The Rietveld method appeared to be very useful in the verification of the qualitative phase composition and in the determination of phase abundance. Hill and Howard procedure was applied for quantitative phase analysis. The parameters of the individual diffraction line profiles were determined by PRO-FIT Toraya procedure. The powder morphology was analyzed by SEM method. Findings: In the Amdry sample comparable contents of two phases: monoclinic (44.1 wt.%) and cubic (55.9 wt.%) was stated by XRD analysis. The presence of Y2O3 phase besides of monoclinic, tetragonal and cubic ZrO2 ones were stated for both Metco samples. The tetragonal phase (55.2 wt.%) was found to be the main component of the Metco C8-YZ sample whereas the content of Y2O3 is the lowest (2.7 wt.%). On the other hand cubic phase (68.2 wt.%) was the main component of the Metco 202 sample and the content of Y2O3 is again the lowest (4.5 wt.%). The SEM images of all the samples reveal the spherical shape of powder particles. The morphology of both Metco samples is quite similar. For Metco 202 sample the hierarchical type structure of powder particle is observed; the greater particles contain smaller ones. The shell of particles is composed of distinct patches. On the other hand the structure of spherical particles of Amdry sample is of branched, rather dense skeleton type. From X-ray diffraction data it can be concluded that the crystallite size of all involved phases lies above nanoscale. Practical implications: Performed studies enable the determination of the relation between the microstructure of commercial powders and their utilisable properties. Originality/value: The applied, different methods of structure analysis appeared to be very useful in the microstructure analysis of complex, multiphase material.

3

Microstructure of polymer composite with barium ferrite powder

Nowosielski R., Babilas R., Dercz G., Pająk L.

Journal of Achievements in Materials and Manufacturing Engineering

|

2008

|

Vol. 31, nr 2

269-274

EN

Purpose: The aim of the paper is the microstructure characterization of commercial BaFe12O19 powder and its composite material in polymer matrix; XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscopy) methods were applied. Design/methodology/approach: The Rietveld method appeared to be very useful in the verification of the qualitative phase composition and in the determination of phase abundance. Hill and Howard procedure was applied for quantitative phase analysis. The parameters of the individual diffraction line profiles were determined by PRO-FIT Toraya procedure. The morphology of barium ferrite powders and a fracture surface of the examined composite material was analyzed using the scanning electron microscope. Findings: The X-ray diffraction analysis enabled the identification of BaFe12O19 and Fe2O3 phases in examined material. Basing on Rietveld and Toraya methods the determination of lattice parameters, crystallite size and the lattice distortion was performed. Distribution of powders of barium ferrite in polymer matrix is irregular and powder particles are of irregular shapes and different sizes. Research limitations/implications: Maked researches are limited only to characterization the microstructure of commercial material, because obtained results will be helpful to prepare barium ferrite powders by mechanical alloying and subsequent annealing in the future. As prepared BaFe12O19 powders will be used as the starting material for magnets bonded with polymer material. Originality/value: The obtained results of investigations by different methods of structure analysis confirm their useful in the microstructure analysis of powder materials.

4

Microstructure investigations of Co-Si-B alloy after milling and annealing

Nowosielski R., Babilas R., Dercz G., Pająk L.

Journal of Achievements in Materials and Manufacturing Engineering

|

2007

|

Vol. 23, nr 1

59-62

EN

Purpose: The work presents the microstructure characterization of Co77Si11,5B11,5 metallic glass after high-energy ball milling and heat treatment processes. Design/methodology/approach: The studies were performed on ribbon prepared by melt spinning and this ground in high-energy vibratory ball mill. The tested ribbon and obtained powders were also annealed in specified heat treatment conditions. The morphology of the powder particles of milled ribbon was analyzed by using the confocal laser scanning microscope. The methods of X-ray diffraction were used for the qualitative phase analysis. The parameters of the individual diffraction line profiles were determined by PRO-FIT Toraya procedure. The average crystallite sizes and lattice distortions for Co phase were estimated using Williamson-Hall method. Findings: The studied Co77Si11,5B11,5 metallic glass in annealed state contains hexagonal Co crystalline phases emerged in amorphous matrix. The crystallite size of Co phase in as-cast sample lies in nanoscale. After annealing process the crystallite size increases to 72 nm and diminishes to 46 nm in the powder sample after 30 hours of milling. The milling causes decrease of the crystallite size and increase of lattice distortions of crystalline phase. The powder particles after 30 hours of milling are of spherical shape. Practical implications: The powder particles obtained after milling process of Co-based metallic glass could be suitable components in production of ferromagnetic nanocomposites. Originality/value: The obtained results confirm the utility of applied investigation methods in the microstructure analysis of powder materials with nanocrystalline phases.

5

Structure investigations of commercial zirconia ceramic powder

Dercz G., Prusik K., Pająk L.

Journal of Achievements in Materials and Manufacturing Engineering

|

2006

|

Vol. 18, nr 1-2

259--262

EN

Purpose: The microstructure characterization of commercially available zirconia powder was the purpose of this paper. Different methods of structure analysis were applied owing to the complex, multiphase structure of studied material. Design/methodology/approach: The X-ray diffraction (XRD) and scanning electron microscopy (SEM) investigations were performed on commercial zirconia ceramic material (Metco 202 (ZrO 2 - 20 wt.%Y 2O 3)). The Rietveld method appeared to be very useful in the verification of the qualitative phase composition and in the determination of phase abundance. Hill and Howard procedure was applied for quantitative phase analysis. The parameters of the individual diffraction line profiles were determined by PRO-FIT Toraya procedure. The powder morphology was analyzed by SEM method practical. Findings: The presence of Y2O3 phase besides of monoclinic, tetragonal and cubic forms of ZrO2 phase was stated. The cubic zirconia phase appeared to be the main component of the sample (68.2 wt.%) whereas the content of Y2O3 is the lowest (4.5 wt. %). The crystallite size of all involved phases lies above nanoscale. The images obtained by SEM reveal the spherical shape of powder particles; their hierarchical type of structure is clearly seen. The greater particles contain smaller ones. The shell of spherical particles is composed of distinct patches. Practical implications: Performed studies enable the detrmination of the relation between the microstructure of commercial powders and their utilizable properties. Originality/value: The applied, different methods of structure analysis appeared to be very useful in the microstructure analysis of complex, multiphase material.

6

Microstructure of composite material with powders of barium ferrite

Nowosielski R., Babilas R., Dercz G., Pająk L.

Journal of Achievements in Materials and Manufacturing Engineering

|

2006

|

Vol. 17, nr 1-2

117--120

EN

Purpose: The aim of the present work is the microstructure characterization of commercial powder BaFe12O19(as-prepared) and composite material with BaFe12O19 powders and polymer matrix, using XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscopy) methods. Design/methodology/approach: The morphology of barium ferrite powders and a fracture surface of the examined composite material was realized by using the scanning electron microscope. The methods of X-ray diffraction were used for the qualitative phase analysis. The parameters of diffraction line profiles were determined by PRO-FIT Toraya procedure. Findings: The X-ray diffraction analysis permitted on identification the BaFe12O19 and Fe2O3 phases in an examined material. Basing on Toraya method is determination of: lattice parameters, crystallite size (D) and the lattice distortion (<∆a/a>). Distribution of powders of barium ferrite in polymer matrix is irregular and powder particles have irregular shapes and dimensions. Research limitations/implications: For future research the X-ray analysis should be performed by the Rietveld method, which allows to characterization the microstructure of tested material and verification of its qualitative phase composition. Originality/value: The applied Toraya method of structure analysis appeared to be very useful in the microstructure analysis.

7

Analiza profilu linii dyfrakcyjnych litych próbek stopu Fe-13,7Cr-24,3Ni-1,9Ti-1,3Mo

Pająk L., Ducki K.

Archiwum Nauki o Materiałach

|

2002

|

T. 23, nr 1

51-66

PL

W pracy dokonano analizy profilu linii dyfrakcyjnych, wykorzystując procedurę Toranyi dla litych próbek polikrystalicznego austenitycznego stopu Fe-13,7Cr-24,3Ni-1,9Ti-1,3Mo po obróbce cieplnej. Procedura Toranyi umożliwia doapsowanie profili zarówno pojedynczych linii dyfrakcyjnych, jak i całego rentgenogramu polikrystalicznego. W odróżnieniu od rezultatów uzyskanych przez Torayę dla modelowego materiału proszkowego alfa-SiO2, w niniejszej pracy stwierdzono złożoną zależność wartości poszczególnych parametrów opisujących profile linii dyfrakcyjnych od kąta dyfrakcji 2 teta dla badanych próbek. Jest to związane ze specyfiką badanego materiału, jakim jest stop austenityczny. Porównano wartości stałych sieciowych wyznaczonych za pomocą funkcji ekstrapolacyjnej cos kwadrat teta na podstawie położeń linii dyfrakcyjnych uzyskanych w wyniku dopasowania profili pojedynczych linii dyfrakcyjnych z wartościami otrzymanymi w wyniku dopasowania profili linii dyfrakcyjnych całego rentgenogramu Rietvelda. Stwierdzono dobrą zgodność wartości stałych sieciowych z użyciem funkcji ekstrapolacyjnej i metodą Rietvelda.

EN

Profiles of diffraction lines using Toraya procedure for heat-treated, solid samples of polycrystalline, austhenitic Fe-13.7Cr-24.3Ni-1.9Ti-1.3Mo alloy were analysed. Toraya procedure enables the fitting of both individual diffraction lines and the whole powder pattern. Contrary to the results obtained by Toraya for alpha-SiO2 powder material a complex dependence of the values of particular profile parameters of diffraction lines on the diffraction angle 2 theta was found. This is connected with the specific nature of the solid, austhenitic alloy. The values of lattice constants estimated with the use of the 2 theta extrapolation function basing on the diffraction line on the positions determined by individual diffraction line fitting were compared with the ones determined by the whole powder pattern fitting procedure and by the Rietveld method. Good agreement between the values of lattice constants determined using the extrapolation function and the Rietveld method was found.