Coiling simulations of medium-Mn sheet steels using dilatometry

PING 2019 is organized with the support of funds for specific university research project SVK1-2019-002.The work presents the results of coiling simulations of two medium manganese steels containing 3 and 5% Mn. The steels were subjected to the heat treatment including an austenitization at 1000°C for 300s and next isothermal holding at temperatures of 750, 700, 650 and 500°C for duration of 5 hours. The results of dilatometric analysis showed that in case of the 3Mn steel the ferritic transformation occured during the isothermal holding at 750 and 700°C. The amount of ferrite created during this step at 750°C was smaller compared to 700°C. Lowering the temperature to 650°C led to a transformation lack during the holding time. At 500°C a bainitic transformation occurred. Increasing the manganese content resulted in prolonging the incubation time before any transformations. For the 5Mn steel for all isothermal holding temperatures no transformation occurred within 5 hours. The conclusion was that manganese shifted significantly the ferritic and bainitic regions to longer times

Thermal Stability of Nanocrystalline Ni

Ultrafine-grained structure with grain size of about 100 nm was obtained in nickel by deformation under a pressure of 7 GPa in Bridgman anvils. The structure evolution in ultrafine-grained nickel was studied by residual resistance, transmission electron microscopy, X-ray diffraction, and microhardness measurements. It was established that the evolution of the structure upon heating of ultrafine-grained nickel may be divided into three stages. Stage A corresponds to temperatures below 453 K and is characterised by an insignificant decrease in the resistivity and microhardness. At this stage, a decrease in the internal stresses is not accompanied by grain growth. Stage B, corresponding to the temperatures range of 453-513 K, is characterised by an abrupt decrease in the resistivity and hardness, disappearance of the internal stresses, and by an intense grain growth. Stage C (above 523 K) corresponds to an insignificant increase in the resistivity and further decrease in the hardness

Influence of silver-containing filler on antibacterial properties of experimental resin composites against Enterococcus faecalis

Purpose: The aim of the presented work was to investigate the impact of the S-P introduction into resin-based composites on their effectiveness against Enterococcus faecalis (E. faecalis). Design/methodology/approach: Seven experimental composites based on typical matrix were developed. Six of them contained a filler with antimicrobial properties (silver sodium hydrogen zirconium phosphate, S-P), while the control material contained only common reinforcement fillers. The materials were characterized in terms of the dispersion of the extender in the matrix and then subjected to microbiological tests. The efficiency in the reduction of E. faecalis in the microenvironment was tested. Findings: The composites show a satisfactory distribution of fillers and a high initial reduction of bacteria colonies for the tested strain of E. faecalis. The reduction in bacteria colonies achieved for S-P concentrations from 7% to 13% was similar (median value from 99.8 to 99.9%, when for control material and compound with 1% S-P the number of colonies increased compared to positive control. Research limitations/implications: Laboratory test results may differ from in vivo test performance. In addition, there are many models for conducting laboratory antimicrobial efficacy studies, the results of which are also varied. The cytotoxic tests, long-term investigations and in vivo experiments need to be performed in future experiments. Practical implications: E. faecalis is a Gram-positive bacterium that is commonly detected in persistent endodontic infections and may enter the root canal through the coronal part. Development of composites with antimicrobial properties against this bacterium is as important as obtaining efficacy against cariogenic bacteria. Originality/value: The antimicrobial effectiveness against E. faecalis of experimental composites with submicrometer-sized particles of S-P was not investigated until now

Mechanical Properties and Deformation Behaviour of Ultra-Fine Grained Nickel

score: 0collation: 79-8

Analysis of selected properties of soluble coffees obtained by different methods

Celem pracy była analiza wybranych właściwości fizyko-chemicznych kaw rozpuszczalnych produkowanych różnymi metodami technologicznymi, dostępnych na polskim rynku. Przeprowadzono pomiar takich właściwości fizycznych jak: zawartość suchej masy, aktywność wody, barwa oraz zwilżalność. Badania właściwości chemicznych obejmowały oznaczenie zdolności przeciwutleniających ekstraktów kawowych poprzez oznaczenie zawartości polifenoli ogółem oraz zdolności do inaktywacji rodników DPPH+. Badane kawy rozpuszczalne posiadały bardzo dobre właściwości przeciwutleniające. Stwierdzono wpływ procesu otrzymywania kaw na ich właściwości fizyczne.The aim of this study was to analyze selected physico-chemical properties of soluble coffee produced by various methods which are available on the Polish market. In the research part, physical properties, such as dry matter content, water activity, color and wettability, were measured. The chemical properties of the antioxidant capacity of coffee extracts were indicated by determining the total polyphenol content and the ability to inactivate the DPPH+ radicals. Analysis of the test results led to the conclusion that soluble coffee have a very good antioxidant properties. It was also found that production technology have a very strong influence on the physical properties of the products

Analysis of technical condition of steam turbine rotors based on miniature samples obtained semi-destructively

Precyzyjna ocena stopnia degradacji materiału wirnika turbiny parowej wymaga przeprowadzenia specjalistycznych badań materiałowych, uwzględniających mikroskopię świetlną i skaningową oraz badania wytrzymałościowe. Ponieważ pozyskiwanie próbek o standardowych rozmiarach osłabiłoby pod względem wytrzymałościowym konstrukcję wirnika, w artykule zaprezentowano metodykę pobierania próbek materiału w sposób mało inwazyjny w stosunku do badanego obiektu, pozostawiający powierzchnię wirnika bez karbów i znacznych pocienień. Zastosowanie odpowiednich parametrów cięcia, chłodzenia i mocowania urządzenia umożliwiło pobranie niewielkich próbek o niezmienionej, nieodkształconej i nieprzegrzanej mikrostrukturze. W pracy omówiono metodykę badań wytrzymałościowych pobranego w ten sposób materiału przy wykorzystaniu małych próbek tj. statycznej próby rozciągania oraz metody zginania miniaturowych dysków (Small Punch Test).Accurate evaluation of the turbine rotor material degradation requires specialized material testing, including light microscopy, SE M and tensile test. Since obtaining standard size samples would significantly weaken the rotor construction, the paper presents a methodology for semi-destructive sampling the material, leaving the surface of the rotor without notches and with a relatively small wall loss. The application of suitable cutting parameters, cooling and equipment fixing enabled the sampling of small samples without interfering in their microstructure. The paper discusses the methodology of mechanical testing of the obtained material with the use of miniaturized specimens such as Miniature Specimen Tensile Test (MSTT ) and Small Punch Test (SPT) method

The effect of laser surface treatment on structure and mechanical properties aluminium Alloy enac-AlMg9

The effect of laser surface treatment on structure and mechanical properties aluminium Alloy enac-AlMg9 In this work, the influence of a high power diode laser surface treatment on the structure and properties of aluminium alloy has been determined. The aim of this study was to improve the mechanical and tribological properties of the surface layer of the aluminium alloy by simultaneously melting and feeding tungsten carbide particles into the molten pool. During the process was used high-power diode laser HPDL. In order to remelt the aluminium alloy surface the HPDL laser of 1.8, 2.0 and 2.2 kW laser beam power has been used. The linear laser scan rate of the beam was set 0.5 em's. In order to protect the liquid metal during laser treatment was used argon. As a base material was used aluminium alloy ENAC -AlMg9. To improve the surface mechanical and wear properties of the applied aluminium alloy was used biphasic tungsten carbide WC/W2C. The size of alloying powder was in the range 110-210 μm. The ceramic powder was introduced in the remelting zone by a gravity feeder at a constant rate of 8 g/m