Materials Science Forum Vol. 812

Abstract: Metal matrix syntactic foams (MMSFs) were produced by low-pressure inert gas infiltration technique. Matrixes of the produced syntactic foams were Al99.5, AlSi12, AlMgSi1 and AlCu5 respectively, and each was reinforced by pure Fe based hollow. The produced blocks were investigated by optical and scanning electron microscopy. The microstructural investigations revealed proper infiltration with small amount of unwanted voids and an effective and thin interface layer between the matrix materials and the reinforcing spheres. The produced MMSFs were also tested under quasi-static compression loading to get characteristic mechanical properties. The test results showed that the MMSFs with iron spheres have outstanding mechanical properties compared to ‘conventional’ foams.

Abstract: Polyurethane (PU) products produced from the reaction of isocyanates and polyols have one of the most extensive consumption of plastics. After the invention in 1937 PU had to wait until the 50’s to spread worldwide and since then their development have been continuous. In PU systems are used varied additives, including plasticizers, which are use by several large companies.In our work a new class of plasticizers, namely N-alkyl-pyrrolidones were used in polyurethane systems. Their trade names are Flexidone^® 100, Flexidone^® 300 and Flexidone^® 500 containing 8, 12 and 18 C-atom long alkyl chain, respectively. These plasticizers showed excellent results in our previous works and the literature has also confirmed their great properties. We supposed that this chemical structure can form a strong interaction with the urethane group.The effect was monitored by hardness and dynamic mechanical (DMA) measurements. Migration and thermally stimulated discharge (TSD) measurments are in progress.

Abstract: Medical images were generated in computed tomography devices at the medical partner. The medical image format was transformed into engineering data format by the authors and these data were used for printing the macroscopic model of the spine and the spinal disc and subsequently they were assembled. In addition to this macroscopic prototyping process, a novel microstructure based prototyping process was used for generating structure details of the spinal disc. The fiber reinforced and layered structure of the annulus fibrosus was modeled and in a prototype realized using soft and stiff polymeric materials. This method is based on the material microstructure prototyping methodology developed by the research group of the authors.This basic model could be used for medical education, for patient counselling and to support prosthesis development efforts.

Abstract: The aim of our investigation was to study the effect of deformation on the start temperature of the austenite-ferrite transformation. The deformation was carried out during cooling before the beginning of the transformation. The transformation start temperature was determined by dilatometric measurement with a Gleeble 3800 thermomechanical simulator. A novel method was developed to study the deformation induced ferrite transformation (DIFT) effect and successful experiments were carried out on S460MC grade steel specimens to determine the effect of the deformation stored energy on the transformation temperature of the austenite. Evaluating the dilatograms a strong relationship was observed between the temperature of the deformation and the austenite transformation start and finish temperatures. Lower deformation temperature resulted finer microstructure after austenite transformation.

Abstract: The objective of this article is to present the first results of our research work. In order to determination and comparison of the fatigue resistance, high cycle fatigue tests (HCF) were performed on RUUKKI OPTIM S690QL quenched and tempered high strength steel. In parallel these; welded joints were made on the same steel using gas metal arc welding (GMAW, MIG/MAG) to preparation of the cyclic investigations of the welded joints. In the article, the performance of the welding experiments will be presented; along with the results of the HCF tests executed on the base material and its welded joints. Furthermore, our results will be compared with different literary data.

Abstract: In the illuminant industry, for producing arc tube parts for high intensity discharge lamps the applied method is the ceramic injection molding. The ceramic arc tube parts are made of high purity alumina powder. By producing ceramic parts, one of the most critical step is to optimizing the injection molding process, [1] but first of all we need to know the properties of injection molding raw material, because later the molding process will be optimized for this material, to decrease the amount of cracked ceramics.For producing ceramic arc tube parts (plugs), there are used two different major components for producing injection molding raw material (feedstock): high purity alumina powder as the main component, and an organic paraffin wax as a binder material. It is expressly important to know the material, physical and chemical properties of these components, since mainly these have affect on the homogenity of feedstock, and therefore on the quality of end product. [3]In this research, both of the main components and the moldable raw material was investigated by visual, physical, chemical and thermal methods. As most important and main statement, the researchers found that the dynamic viscosity of the injection molding raw material depends on the used mixer equipment and the applied deformation velocity.Applied analitycal methods were laser granulometry, differential thermal analysis, and rheological analysis.

Abstract: ZnO nanostructures were synthesized by two wet-chemical methods (hydrothermal and electrochemical) featuring low temperature (95°C) and atmospheric pressure onto nonwoven substrates. We investigated a hydrothermal method using reagents Zn (NO₃)₂.6H₂O and hexamethylenetetramine (HMTA) as well as an electrochemical method using ZnCl₂, and KCl containing electrolyte with H₂O₂ and/or O₂ bubbling. The surface condition of substrate material and the experimental conditions played a key role in the nanowire formation. The morphologies observed by scanning electron microscopy (SEM) include wurtzit or cabbage-like. These morphologies were found to vary with the method applied.

Abstract: The fatigue life of the structural materials 15H2MFA and 08H18N10T of VVER-440 reactor pressure vessel under completely reserved total strain controlled tests were investigated. The measurements were carried out with isothermal condition at 260°C on GLEEBLE 3800 servo-hydraulic thermal mechanical simulator. The isothermal low cycle fatigue results were evaluated with the plastic strain based Coffin-Manson law, and plastic strain energy based model as well. It was shown that both methods are able to predict the fatigue life of reactor pressure vessel steels accurately.

Abstract: Supersaturated Cu-3at.% Ag alloy was processed by cold rolling and short-time annealing in order to achieve a combination of high strength and good tensile ductility. After annealing of the rolled samples a heterogeneous solute atom distribution was developed due to the dissolution of nanosized Ag particles in some volumes of the matrix. In regions with higher solute content, the high dislocation density formed due to rolling was stabilized, while in other volumes the dislocation density decreased. The heterogeneous microstructure obtained after annealing exhibited a much higher ductility and only a slightly lower strength than in the as-rolled state.