Papers by Author: Agata Dudek

Abstract: The paper presents the results of the structure and chemical composition of materials used to manufacture of gear wheel for the automotive industry. Analyzed gear wheel that is a part of one of the mechanical systems of an automotive vehicle was made of sinter Sint-D 32 in the technology of powder metallurgy and alloy structural steel for quenching and tempering 42CrMo4. The cause of the analysis was to research for an alternative material for sinter Sint-D 32 after identified low static strength according to the requirements applicable in the automotive industry. For the analysis were used standard test methods applicable in materials science. Based on microstructure and mechanical properties analysis performed according to requirements applicable in the automotive industry, the research found that steel 42CrMo4 is relevant material to be used in serial production for this particular gear wheel.

Abstract: The demand for new materials in medicine is on the increase today. Long-lasting implants (joint prostheses, dentistry implants), made typically of metals and their alloys, are characterized with high mechanical properties, however their corrosion resistance and biocompatibility are relatively low. One of the methods to ensure particular functional properties is to employ composite implants, combining improved mechanical properties of metallic material with biocompatibility of ceramic materials. The study aimed to develop and analyse properties of metallic/ceramic composites made of the mixture of powders: austenitic steel (316LHD) and ceramics (Al₂O₃).

Abstract: This study presents opportunities of application of sintered materials for interconnectors in low-temperature fuel cells. The task of these cell components is to provide even distribution of both fuel and oxidant. Materials for interconnectors must possess good thermal conductivity, conduct electricity and have high strength. It is also required that the material is corrosion-resistant under cell operating conditions. Due to multifunctional nature of these elements, selection of materials for interconnectors is extremely difficult. This paper presents analysis of structural properties and effect of pH level in sulphate solutions (pH = 2, 4, 6) on corrosion resistance in austenitic and ferritic sintered materials.

Abstract: Ceramic materials included in the group of advanced materials are increasingly used in different fields of science and technology as well as in everyday life. Hydroxyapatite ceramics (HAp, HA), based on calcium phosphates, i.e. chemical compounds being a constituent of natural bone, is found to be one of the best implantation materials for bone surgeries and dentistry. Due to poor mechanical properties of hydroxyapatite ceramics, the attempts are made to modify HA materials in order to extend the scope of current applications. It is also necessary to maintain high biocompatibility and bioactivity. Reported investigations encompassed comparison of functional properties of HA and HA+ZrO2 coatings (modified with 8%wt. Y2O3) as well as coatings remelted with laser beam. Microstructural and phase analyses of the coatings before and after remelting were carried out. In order to determine biocompatibility of the coatings after plasma spraying and remelting, corrosion resistance testing was also performed in Ringer’s solution.

Abstract: In the aspect of growing popularity of hydroxyapatites and HA-based composites (with addition of ZrO2 phase) used in medicine, it seems to be crucial to determine accurate percentage content of ZrO2 phase addition in the mixture ensuring invariable or predictable changes in dimensions of implants or coatings after the process of sintering. In consideration of the aforementioned statement, combined mathematical and statistical analysis enabling prediction of such changes was carried out.

Abstract: A range of benefits of implants containing hydroxyapatites results, among other things, from their phase composition and degree of porosity. Poor mechanical properties of hydroxyapatite (HA) ceramics considerably limit its wider use. One of the methods for improvement of poor HA properties is addition of solid solution of Y2O3 in ZrO2. [1-8]. The investigations focused on compositions of ceramic powders based on hydroxyapatite with addition of zirconium dioxide (ZrO2 + 8%wt. Y2O3 and ZrO2 + 20%wt. Y2O3). The powders were axially compacted and then sintered at the temperature of 13000C for two hours. After the process of sintering the samples were subjected to analysis of microstructure, phase composition and geometrical measurements in order to determine volume density in each sample.

Abstract: Bipolar plates (BPs) are key components of fuel cells. Functions of materials used for fuel cells include equal distribution of gas fuel and air, conduction of electricity between adjacent cells, heat transfer from the cell as well as prevention of gas leakage and cooldown. Moreover, the material must show particular corrosion resistance in cell’s working conditions. Meeting particular requirements or prevention of the abovementioned situations will enable efficient operation of cells. Due to multifunctional nature of fuel cell plates, choice of materials used for plates is immensely difficult. This paper presents opportunities of application of a new technology of powder sintering for creation of parts for electricity and heat generators. This work also presents analysis of structural and phase-related properties, porosity and strength tests.