The paper deals with possibility to improve operating performance of cast-iron heat exchangers by providing them with a copper alloy (CuTi2Cr) with the use of the flame spraying method. A test exchanger was cast of a gray cast iron with vermicular graphite in ferriticpearlitic matrix obtained in production conditions at KAW-MET Iron Foundry with the wire method used to vermicularize the material. The test samples were two plates cast in sand molds, of which one was given a flame-sprayed CuTi2Cr coat on one side. The operating performance of such model cast-iron heat exchangers, with and without CuTi2Cr coating, was tested on a set-up for determining the heat flow rate (thermal power) transferred by the heat exchanger to environment. The obtained results indicate that the value of the heat flow rate characterizing the CuTi2Cr-coated cast-iron heat exchanger was by 10% higher compared to the flow rate of heat conveyed to environment by the heat exchanger without coating.
The paper presents results of an analysis of material density distribution in stampings press-moulded in metal dies from raw refractory materials based on alumina-magnesia-carbon aggregate. The stampings, fabricated on LAEIS HPF 1250 pressing machine, are blanks from which refractory precast shapes are manufactured by means of drying and firing. Samples for material density evaluation were cut out from test stampings with the use of diamond-reinforced disc. Density of the material was determined in thirteen layers of stampings denoted with letters A through M.
Purpose: The purpose of this research is to defi ne the total number of septa and the total number of antra in the sphenoid sinuses (created as a result of the presence of additional septa), as well as the relation between the number of the septa and their location in the adult population. Materials and Methods: The study was conducted as a retrospective analysis of the computed tomography (CT) scans of the paranasal sinuses of 296 patients (147 females and 149 males), who did not present any pathology in the sphenoid sinuses. The CT scans of the paranasal sinuses were done with the spiral CT scanner (Siemens Somatom Sensation 16) by using a standard procedure, in the option Siemens CARE Dose 4D, without using any contrast medium. After obtaining the transverse planes, the frontal and sagittal planes were created using secondary reconstruction tool (multiplans reconstruction — MPR). Results: The analysis of the obtained images in the transverse plane and secondary CT reconstructions has shown the presence of only one sphenoid septum (main septum — MS) in 21.96% of the patients, which divided the sphenoid sinus into two sphenoid antra. In 78.04% of the patients, there were more than one sphenoid septa present in the posterior part of the sphenoid sinuses, hence there were additional septa (AS) present. One AS was present in 22.97% of the patients. The most common variant — two AS — was found in 32.09% of the cases. The presence of more than two AS was found in the following number of patients: three AS in 9.8%, four AS in 7.09%, five AS in 1.69%, six AS in 3.04% and seven AS in 1.01%. Th e rarest variant was the presence of more than seven AS: eight AS in 0.34% and nine AS also in 0.34%. Th ere were no sphenoid sinuses that would have more than nine AS in the researched material. Conclusions: Due to the high incidence of the anatomical variants of the paranasal sinuses, a CT scan is recommended in all patients before a planned surgery in order to avoid the potential complications that might arise as a result of the complicated structure of the paranasal sinuses.
The paper summarises results of measurements of remelting area geometry, thermal efficiency and melting efficiency characterising the surface remelting process applied to castings of MAR-M-509 cobalt alloy. The remelting process was carried out with the use of GTAW (Gas Tungsten Arc Welding) method in protective atmosphere of helium, at the electric current intensity in the range from 100 A to 300 A, and the electric arc scanning velocity vs in the range from 200 mm/min to 800 mm/min. The effect of current intensity and electric arc scanning velocity on geometrical parameters of remeltings, thermal efficiency, and melting efficiency characterising the remelting process has been determined.
The gas-tungsten arc (GTA) welding behaviors of a magnesium matrix composite reinforced with SiC particles were examined in terms of microstructure characteristics and process efficiencies. This study focused on the effects of the GTAW process parameters (like welding current in the range of 100/200 A) on the size of the fusion zone (FZ). The analyses revealed the strong influence of the GTA welding process on the width and depth of the fusion zone and also on the refinement of the microstructure in the fusion zone. Additionally, the results of dendrite arm size (DAS) measurements were presented.
The aim of the study is to present cycling as an active form of tourism in the context of the motivation of people cultivating it – in particular residents of the Municipality of Radom. The work indicates the essence and importance of cycling tourism, taking into account its types and infrastructure. Factors and trends influencing the development of cycling tourism – promoting a healthy lifestyle were discussed. Also presented are the results of research on the motivation of moving residents of the Municipality of Radom using the bike in individual age groups.
This study presents results of stress rupture test of MAR-M-509 cobalt alloy samples, as-cast and after surface refining with a concentrated stream of heat. Tests were conducted on samples of MAR-M-509 alloy castings, obtained using the lost-wax method. Casting structure refining was performed with the GTAW method in argon atmosphere, using the current I = 200 A and electrical arc scanning velocity vs = 100, 150, 200 and 250 mm/min. The effect of rapid resolidification of the MAR-M-509 alloy on the microstructure was examined and significant improvement in stress rupture test was observed.
The paper proposes a methodology useful in verification of results of dilatometric tests aimed at determination of temperatures defining the start and the end of eutectoid transformation in the course of ductile cast iron cooling, based on quenching techniques and metallographic examination. For an industrial melt of ductile cast iron, the effect of the rate of cooling after austenitization at temperature 900°C carried out for 30 minutes on temperatures TAr1 start and TAr1 end was determined. The heating rates applied in the study were the same as the cooling rates and equaled 30, 60, 90, 150, and 300°C/h. It has been found that with increasing cooling rate, values of temperatures TAr1 start and TAr1 end decrease by several dozen degrees.
The paper presents an analysis of factors affecting the wear of cylinder liners. The effect of the graphite precipitation morphology on the cylinder liner wear mechanism is presented. Materials used to cast cylinder liners mounted in a number of engines have been examined for their conformity with requirements set out in applicable Polish industrial standard. A casting for a prototype cylinder liner has been made with a microstructure guaranteeing good service properties of the part.
Elaborated shapes of many car components are the reason for which the use of casting techniques to fabricate them is a solution wellfounded from the economical point of view. Currently applicable regulatory requirements concerning emissions of exhaust fumes force the carmakers to reduce the overall weight of their products, as this is a basic precondition for reducing fuel consumption. As a result, newly launched car models contain a continuously increasing share of thin-walled castings made of materials which ensure a satisfactory level of service properties. At the same time, developing new technological processes allowing to extend the service life of individual components by means of surface improving becomes more and more important.