Solid State Phenomena Vol. 223

Abstract: Microbial biofilm formation on membrane surface layer (biofouling) impedes filtration processes through increased material-and energy consumption and causes the risk of contamination by microorganisms and their metabolites. Due to the constantly growing resistance of microorganisms to the commonly used methods of prevention, it is necessary to develop functionalised materials and coatings of stable, non-specific, and effective antimicrobial properties. The integral step in the process of the development of such materials and coatings is universal and reliable testing under process conditions. The intensity of biological fouling is proportional to the microbial cell concentration in the system. Potentially present organisms are systematically varied and may include bacteria, fungi, and microscopic plants. The most convenient and universal method for microbial cell concentration assessment features the measurement of optical density of the liquid. Moreover, biofilm formation is dependent on the physiochemical factors, such as temperature, the chemical composition of feed liquid, membrane material, process flows, and pressures, etc. Additionally, process conditions may affect the activity of the functionalised material used for membrane formation. For this purpose, an integrated approach for multiparameteric assessment is needed, taking into account the measurements of the above listed parameters and allowing for comparisons. The proposed modular test stand includes a number of actuators and measurement sensors, which enable the following control functions: the control over the process fluid flow, the control over the emission on the test object of electromagnetic radiation in the required spectrum, and implementation of the optical density measurements of the fluid. The whole installation test is placed in one closed cubature of controlled thermal conditions. The control system allows the recording and archiving of process data, which are collected (on-line) by a PLC and transferred to a PC via Ethernet interface. Dedicated software application on the PC provides a preliminary analysis and allows remote monitoring via a web browser. Remote access to measurement data can also be used for the creation of a network of series of such test stands, in which different aspects of the studied phenomenon are simultaneously analysed and controlled as the modules of a network control system (NCS). The described system will allow the multiparameteric, universal and reliable assessment of antimicrobial properties of functionalised membranes under process conditions. The modular character of the proposed approach will be fully reconfigurable and adaptive for a wide range of membrane types. The results to be obtained will support the process of sustainable membrane development.

Abstract: This paper presents the results of the fatigue tests carried out on laser welded joints of DUPLEX 2205 steel (X2CrNiMoN22-5-3 according to PN-EN 10027-1:2007). The butt-welded joints were made using an Nd-YAG disk laser with no filler for two different welding parameters. The parameters were selected based on previous tests (according to PN-EN ISO 15614-11: 2005) conducted for joints made with more than ten welding parameters.The tests carried out provided a basis for the determination of optimum parameters for laser welding of DUPLEX 2205 steel in terms of fatigue life. Additionally, the fatigue test results were related to the fatigue life of samples taken from the parent material.

Abstract: The properties of a multi-layered composite can be moulded through a selection of type, shape, and the number of layers of reinforcement material as well as powder fillers. Furthermore, the type and share of the matrix as well as the kind of hardeners also exert a significant influence on mechanical properties of composites. We attempted to experimentally establish the influence of the type of hardeners on mechanical properties. The test used Charpy’s hammer, and it was performed in the configuration of impact loading parallel to the edge. We prepared specimens of the materials. The specimens contained 12 layers of different fibre reinforcement: aramid (kevlar) fibre of 230 g/m² basis weight, glass fibre of 150 g /m2, and carbon fibre of 160 g/m² basis weight. The base was epoxy resin – Epidian 52, which was cured at room temperature by means of the following curing agents: PAC, TFF or Z-1, manufactured by Z. Ch. Organika-Sarzyna S.A. in Nowa Sarzyna. The experiments proved the tremendous influence of the type of the hardeners on toughness KC. It can be increased even by 25% for glass fibre reinforcement, about 20% for carbon fibre reinforcement and about 10% for aramid fibre reinforcement due to the use of an appropriate type of hardener.

Abstract: Elements of aircraft that are in direct interaction with the environment are exposed to the destructive effects of weather phenomena and the factors influencing them, as well as local environmental phenomena. One such factor is ultraviolet radiation emitted by the sun. This article presents the results of the influence of solar radiation (UV) on the strength properties of laminates with different types of reinforcement. The composites are susceptible to impact damage; therefore, to investigate the effect of UV radiation on such damaged composite, part of the samples were subjected to impact loads. The composites were made of the epoxy resin Epidian 52 with hardener Z1, and reinforced with glass fabric and carbon fabric. In order to carry out the research, we designed two devices – one for the production of low-energy impact and a second device to expose composite on UV radiation. As a result of studies, it was found that the UV radiation has a negative impact on the aesthetic qualities of the composite as well as the flexural strength of the materials. The decrease in strength of the samples subjected to shock loads and the influence of UV radiation is at a level slightly above 50%.

Abstract: The formation of precise products out of difficult to machine materials requires the usage of unconventional techniques and manufacturing technologies; and, above all, it requires adequate knowledge. The worldwide-accepted guidelines in this area are the national and international standards, and corporate experience known as expertise. The aim of this paper is to present the solution to the problem of collecting and sharing data on a variety of materials, within the extended application DBSMP (Database Special Materials Processing). While undertaking the works on the application to support the descriptions of the machining of special materials, it soon became apparent that the fundamental urgency, next to the machining process, is to provide function to the most detailed descriptions of the materials. A draft of the application was prepared with a number of assumptions for the database of standard descriptions and material descriptions, which is presented in this article with an example of high-speed steel.

Abstract: Non-metallic inclusions may be introduced to liquid steel from the outside, usually with charge material, or they may be produced in the metallurgical process. According to literature, if evenly distributed, non-metallic inclusions may affect the functional properties of steel, mainly its fatigue strength. The aim of this study was to determine the quantity and dimensional structure of non-metallic inclusions in high-grade medium carbon steel melted in an electric furnace and subjected to desulfurization. The experimental material consisted of semi-finished products of high-grade, medium-carbon constructional steel containing manganese, chromium, nickel, molybdenum, and boron. The levels of phosphorus and sulphur impurities did not exceed 0.02%. Billet samples were collected to determine the chemical composition, microstructure, the relative volume of non-metallic inclusions, and the size of impurities. The results were processed and presented in graphic form.

Abstract: Results of investigations related to synthesis and thermal properties analysis of the Dy₂Zr₂O₇ phase was presented in this article. This material was obtained during high temperature synthesis in an actual pressure of 15 MPa, in vacuum of 3×10^-6 MPa, and at 1350°C with 2 hours of exposure. Feedstock materials were submicrocrystalline powders of dysprosia Dy₂O₃ and zirconia ZrO₂. Both powders were mechanically blended in alcohol before the sintering process. The final product was analysed from the phase’s composition point of view. It was revealed that main constituent elements were dysprosium zirconate with an overall formula of Dy₂Zr₂O₇ and others were Dy zirconates with a non-stoichiometric character. The presence of zirconia was found with tetragonal types of unite cell. This fact evidences that partial dissolution of Dy₂O₃ in ZrO₂ took place. The obtained material was characterized by calorimetric investigations in the thermal range from 25 to 1450°C.

Abstract: The article discusses some of the issues associated with the use of topology optimization in shaping of the strength of castings. This kind of optimization is performed in the preliminary design phase, when the shape of the constructed part is not yet defined. The limitations that apply to the designing process concern the dimensions, boundary conditions, loads, forces, and cooperation with other structural elements. Topology optimization determines the arrangement of the material in space, so that under the conditions of loads, exploitation, and the design assumptions, the construction will have smallest possible weight. The article presents a few methods of optimization and provides simple examples. The computer calculations were carried out based on, the Finite Element Method (the Abaqus software), and the authors’ subroutines optimization algorithm that uses the results obtained in FEM. The example of the method to optimize the shape of mine shaft tubing is presented. The verification of the casting technology was conducted in MAGMASoft, taking into account the influence of the topology optimization on the production possibilities.

Abstract: The article presents preliminary results of the research on the ablation casting technology. The guidelines for the designing of an equipment to carry out the process were described. Based on the above-mentioned instructions a test stand was developed and built. Many tests were performed concerning the influence of the water jet directed at a sand mould on its removal tendency. The effect of the cooling rate of a tested cast parts on its microstructure was studied based on metallographic and radiographic examinations.