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EN
As part of the presented work, tests were carried out to check the possibility of replacing of conventional reducers used in the lead pyrometallurgical processes by cheaper, but equally effective substitutes. For research of lead oxide reduction, the following fine-grained carbonaceous materials were used, ie anthracite dust and coal flotation concentrate, as well as traditional used coke breeze for comparison. The obtained test results indicate a similar ability to reduce the lead oxide of all studied carbonaceous materials.
EN
In the paper results of the microstructure and mechanical properties (HB, Rm and R0,2) of AlSi17Cu5 alloy, subjected by solution heat treatment (500ºC/6h/woda) and aging (200ºC/16h/piec) are presented. In next step the alloy was modified and heated significantly above the Tliq temperature (separately and together). It was found that the increase in the strength properties of the tested alloy after heat treatment compared to alloys without solution heat treatment and aging was due to precipitation hardening. The applied aging treatment of ingots (preceded by solution heat treatment), causes not only increase in concentration in α(Al) solid solution, but also a favorable change of the primary Si crystals morphology. During stereological measurements significant size reduction and change in the morphology of hypereutectic silicon crystals ware found. This effects can be further enhanced by overheating the alloy to a temperature of 920ºC and rapid cooling before casting of the alloy.
PL
W pracy przedstawiono wyniki badań mikrostruktury i właściwości mechanicznych (HB, R,m i R0,2) odlewów ze stopu AlSi17Cu5 poddanych przesycaniu (500ºC/6h/wrząca woda) i starzeniu (200ºC/16h/piec) po procesie modyfikowania i znacznego przegrzania powyżej temperatury Tliq. (oddzielnie oraz łącznie). Stwierdzono, że podwyższenie właściwości wytrzymałościowych badanego stopu po obróbce cieplnej w stosunku do odlewów bez przesycania i starzenia nastąpiło na skutek utwardzania wydzieleniowego. Zastosowany zabieg starzenia poprzedzony przesycaniem, wywołuje nie tylko wzrost stężenia w roztworze stałym α(Al), ale też korzystną zmianę morfologii pierwotnych kryształów krzemu. Na podstawie pomiarów parametrów stereologicznych stwierdzono istotne zmniejszenie i zmianę morfologii nadeutektycznych kryształów krzemu, co dodatkowo można zintensyfikować przegrzaniem stopu do temperatury 920ºC i szybkim chłodzeniem przed odlaniem.
EN
In the paper, results of the study on manganese evaporation from the OT4 alloy are presented. In the experiments, the effects of pressure on the manganese evaporation kinetics and the stages that limit the evaporation rate were investigated. It was demonstrated that the rate of manganese evaporation from the alloy increased with pressure reduction in the system. When the pressure decreases from 1000 Pa to 10 Pa, the value of overall mass transfer kMn increases from 3.9*10-6 ms-1 to 208.4*10-6 ms-1. At the same time, the manganese fraction in the alloy decreased from 1.49% mass to 0.045% mass. Within the whole pressure range, the analysed evaporation process is diffusion-controlled. For pressures above 50 Pa, the determining stage is transfer in the gaseous phase, while for pressures below 50 Pa, it is transfer in the liquid phase.
PL
W prezentowanym opracowaniu przedstawiono wyniki badań odparowania manganu ze stopu OT4. W ramach prowadzonych eksperymentów badano wpływ ciśnienia na kinetykę procesu odparowania manganu i jednocześnie określono etapy limitujące jego szybkość. Wykazano, że szybkość procesu odparowania manganu ze stopu rośnie wraz z obniżaniem ciśnienia w układzie. Przy obniżeniu ciśnienia od 1000 Pa do 10 Pa wartość ogólnego współczynnika transportu masy kMn rośnie od 3.9x10-6 ms-1 do 208.4x10-6 ms-1. Jednocześnie następowało obniżenie zawartości manganu w stopie od 1.49% mas. Do 0.045% mas.. W całym zakresie ciśnień analizowany proces parowania ma kontrolę dyfuzyjną. Dla ciśnień powyżej 50 Pa etapem determinujacym jest transport w fazie gazowej, a dla ciśnien poniżej 50 Pa transport masy w fazie ciekłej.
EN
Purpose: The main purpose of the study was to determine methodology for estimation of the operational reliability based on the statistical results of abrasive wear testing. Design/methodology/approach: For research, a traditional tribological system, i.e. a friction pair of the AlSi17CuNiMg silumin in contact with the spheroidal graphite cast iron of EN-GJN-200 grade, was chosen. Conditions of dry friction were assumed. This system was chosen based on mechanical cooperation between the cylinder (silumin) and piston rings (spheroidal graphite cast iron) in conventional internal combustion piston engines with spark ignition. Findings: Using material parameters of the cylinder and piston rings, nominal losses qualifying the cylinder for repair and the maximum weight losses that can be smothered were determined. Based on the theoretical number of engine revolutions to repair and stress acting on the cylinder bearing surface, the maximum distance that the motor vehicle can travel before the seizure of the cylinder occurs was calculated. These results were the basis for statistical analysis carried out with the Weibull modulus, the end result of which was the estimation of material reliability (the survival probability of tribological system) and the determination of a pre-operation warranty period of the tribological system. Research limitations/implications: The analysis of Weibull distribution modulus will estimate the reliability of a tribological cylinder-ring system enabled the determination of an approximate theoretical time of the combustion engine failure-free running. Originality/value: The results are valuable statistical data and methodology proposed in this paper can be used to determine a theoretical life time of the combustion engine.
EN
Purpose: Major problems with smelting of light titanium-based alloys are related to their strong reactivity in the liquid phase with virtually all melting pot materials. Another problem regarding titanium alloy smelting is an unfavourable process of alloy component evaporation due to high melting temperatures of the alloys and significant differences in vapour pressures of their individual components. In the present paper, results of a study on manganese evaporation from the OT4 alloy are presented. Design/methodology/approach: The OT4 alloy contained 94.29, 3.50 and 1.49 %mass of Ti, Al and Mn, respectively. The experiments were performed at 5 to 1000 Pa for 1973 K and 2023 K. During each smelting experiment, metal samples were collected and analysed for titanium, aluminium and manganese contents. Findings: During inductive OT4 alloy smelting from the Ti-Al-Mn system at reduced pressure, significant manganese losses from the alloy are observed as a result manganese evaporation. For manganese and titanium, the evaporation coefficient Ω Mn/Ti values were within 12421–42899, while for manganese and aluminium (Ω Mn/Al), they were within 34 to 52, suggesting that, thermodynamically, there is a potential for intense manganese evaporation from the investigated alloy .Research limitations/implications: The study findings may be a basis for a full kinetic analysis of Mn evaporation from the OT4 alloy which enables determination of process-controlling stages.Practical implications: The study results regarding changes in manganese content in the OT4 alloy during its smelting with the use of VIM technology suggest that one of conditions that may limit the unfavourable process of manganese evaporation is shortening the smelting time or performing the process at about 1000 Pa. Originality/value:In literature, there are no data regarding results of studies on manganese elimination from Ti-Al-Mn alloys during their smelting.
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