shape, size, and size distribution of the obtained powders were investigated. Properties of the synthesized powders were characterized by scanning electron microscopy (SEM) and X-ray powder diffractometry (XRD). It has been shown that it is possible to obtain copper powders with a size of 1 µm by an electrochemical method using the rotary cathode, in sulphate bath with addition of ethylene glycol as a surfactant. Increasing current density causes a decrease in the average size of the obtained powder particles. The addition of 2.5% of ethylene glycol prevents the formation of dendritic powders. The change in the concentration of copper ions in the range from 0.01 to 0.15 mol/dm3 in the electrolyte did not show any significant effect on the size of obtained particles. However, higher concentrations of copper limiting the presence of dendritic-shape particles. Changing the speed of rotation of the electrode affects both the size and the shape of synthesized copper powder. For the rotational speed of the electrode of 115 rpm, the obtained powders have a size distribution in the range of 0-3 µm and an average particle size of 1 µm. The particles had a polygonal shape with an agglomeration tendency.

It consisted mainly of zinc oxide contaminated with metallic zinc, zinc hydroxide chloride and silica. Dissolution of the metals from the material was determined as a function of solid to liquid ratio (50-150 kg/m3), temperature (20°C and 35°C) and agitation rate (300 and 900 rpm). The best results (50 g/dm3 Zn(II) at 78% zinc recovery) were obtained for 100 kg/m3 and the temperature of 20°C. Increase in the agitation rate had weak effect on the zinc yield. The final solutions were contaminated mainly by Fe(II, III) ions. Leaching of the material was an exothermic process with the reaction heat of about 800 kJ/kg.

wykazały, że oba dodatki zwilżające, wpływają na kinetykę redukcji jonów miedzi, lecz obecność CNT ogranicza ich działanie na powierzchni katody, wskutek większej tendencji CTAB i SDS do adsorpcji na hydrofobowej powierzchni cząstek materiału węglowego w głębi elek¬trolitu. CTAB sprzyja wbudowywaniu się CNT w osnowę miedzi, ułatwiając ich adsorpcję na powierzchni katody i dodatkowe zarodkowanie miedzi na nanorurkach. Skutkuje to zabudowywaniem CNT między ziarnami metalicznymi, tworzeniem osadów o wysokiej porowatości i uzyskiwaniem wysokich wydajności prądowych 95 ± 2%. SDS hamuje adsorpcję CNT na elektrodzie, prowadzi do wbudowania nanorurek wewnątrz kryształów metalu i tworzenia osadów katodowych o mniej rozwiniętej powierzchni, przy wydajności prądowej procesu 61 ± 7%.

CNT hinder the action of surfactants on the cathode surface due to higher affinity of CTAB and SDS to adsorption on hydrophobic nanotubes in the bulk of the electrolyte. CTAB favors incorporation of CNT into the copper matrix, improves their adsorption on the cathode surface and enhances additional copper nucleation on nanotubes. It results in the incorporation of CNT between metal crystals, formation of high porous deposits at high current efficiencies of 95 ±21. SDS inhibits adsorption of CNT on the electrode, leads to the incorporation of nanotubes inside metal crystals and forms cathodic deposits with less rough surface with the current efficiency of 61 ±71.

trawiącego. Stwierdzono, że w roztworach HCI następuje roztwarzanie podłoża Al-Mg uszkodzonych mechanicznie talerzy. Powłoka magnetyczna jest odporna na działanie stężonych kwasów i zasad.

solution are presented. It has been found that HCI solution can dissolve selectively the Al-Mg substrate of mechanically damaged platters. The magnetic coating is resistant to the action of concentrated acids and bases.

starzeniu sztucznym. W pierwszym etapie badań wlewek w stanie po odlaniu i po homogenizacji poddano badaniom mikrostruktury oraz testom kalorymetrycznym. Stwierdzono, że nierównowagowe składniki struktury zostały całkowicie rozpuszczone podczas wyżarzania ujednorodniającego. W czasie chłodzenia z temperatury homogenizacji główne składniki umacniające Mg i Si zostały wydzielone głównie w postaci bardzo drobnych cząstek o wielkości do 0,5 μm. W drugim etapie, materiał poddano ściskaniu w temperaturze 500 i 540oC i przesycano bezpośrednio z temperatury kształtowania w wodzie i w powietrzu. Po ściskaniu w temperaturze 540oC, przesyceniu w wodzie i starzeniu uzyskano wysoką twardość stopu, wynoszącą 119 HV2. Po odkształceniu w temperaturze 500oC, uzyskano twardość 108 HV2, typową dla wyrobów wyciskanych w stanie T6. W przypadku chłodzenia stopu z temperatury kształtowania w powietrzu po starzeniu zanotowano wartości twardości niższe o ok. 15% w stosunku do materiału chłodzonego w wodzie.

billet in as-cast state and after homogenization in industrial conditions was subjected to microstructure investigations and DSC tests. It was found that during homogenization, unequilibrium microstructure components were fully dissolved. During cooling from homogenization temperature, main alloying additions, Mg and Si were precipitated mainly in the form of very fine particles, with up to 0,5 um in size. In the second stage, the material was subjected to compression at the temperature of 500 as well as 540°C and was quenched directly from hot working temperature in water and in air. After compression at the temperature of 540°C, water quenching and ageing, the high hardness of the alloy, 7 79 HI/2, was obtained. After deformation at the temperature of 500°C, the hardness of 108 HI/2, was obtained, which is typical value for extruded products in the T6 temper. In the case of air quenching from hot compression temperature, hardness values lower by about 15% were obtained after ageing, compared to water quenched material.

effect of the cooling rate after homogenization on the course of melting during a rapid heating. Moreover, the samples after solution heat treatment (with short time annealing) and ageing, were subjected to the microstructure investigations and the microhardness of grains interiors measurements. It was found that cooling after homogenization at 160 °C/h is sufficient for precipitation of fine θ phase particles, which dissolve during the subsequent rapid heating. The cooling at 40 °C/h, causes the precipitation of θ phase in the form of large particles, incapable of further fast dissolution.

tests and TEM/STEM/EDX structural observations. Structural observations complemented by literature data lead to the conclusion that in the case of highly refined structure of commercial 2024 alloys prepared by severe plastic deformation, typical multi-step G-P-B →θ” →θ’ →θ precipitation mechanism accompanied with G-P-B →S” →S’ →S precipitation sequences result in skipping the formation of metastable phases and direct growth of the stable phases. Exothermic effects on DSC characteristics, which are reported for precipitation sequences in commercial materials, were found to be reduced with increased milling time. Moreover, prolonged milling of 2024 chips was found to shift the exothermic peak to lower temperature with respect to the material produced by means of common metallurgy methods. This effect was concluded to result from preferred heterogeneous nucleation of particles at subboundaries and grain boundaries, enhanced by the boundary diffusion in highly refined structures. Transmission electron microscopy and diffraction pattern analysis revealed the development of very fine Al4C3 particles that grow due to the chemical reaction between the Al matrix and graphite flakes introduced as a process control agent during the preliminary milling of chips. Al4C3 nano-particles are formed at high temperatures, i.e. during hot extrusion and the subsequent solution treatment of the samples. Highly refined insoluble particles such as aluminum carbide particles and aluminum oxides were found to retard recrystallization and reduce recovery processes during solution treatment of preliminarily milled materials. Therefore, the as-extruded material composed of a milled part and chip residuals retained its initial bimodal structure in spite of solution heat treatment procedures. This points to a high structural stability of the investigated materials, which is commonly required for new technologies of high-strength Al-based materials production.

applied to evaluate the dissolution of the Mg2Si particles and concentration of the main alloying additions in the grains interiors, depending on soaking conditions. In the case of alloy with lower Mg and Si content, homogenization the temperature of 535ºC for 8h is sufficient for significant Mg2Si particles dissolution. For the alloy with higher Mg and Si content, after homogenization the temperature of 550ºC for 8h, the amount of undissolved Mg2Si particles decreases visibly, compared to homogenization at 535ºC for 8h. However, an unfavourable tendency of dispersoids growth is observed and these soaking conditions are not found to be recommended. At the second research stage, the influence of homogenization cooling rate on the size and distribution of the Mg2Si particles observed in the alloys microstructure was analysed. The ability of the Mg2Si particles, precipitated during various homogenization coolings, to rapid dissolution was estimated. For this purpose, the hardness after solution heat treatment with short annealing and ageing was determined and the DSC tests were performed. It was found, that cooling after homogenization at 315ºC/h is sufficient for precipitation of fine Mg2Si particles, which dissolve during subsequent rapid heating. Cooling at 40ºC/h, causes precipitation of Mg2Si phase in the form of large particles, unable for further fast dissolution.

podczas wygrzewania oraz zawartość głównych składników stopowych we wnętrzach ziarn. Oceny parametrów wygrzewania dokonano w oparciu o badania SEM/EDS oraz testy DSC. W przypadku stopu z niższą zawartością Mg i Si, homogenizacja w temperaturze 535ºC przez 8 h jest wystarczająca dla znaczącego rozpuszczenia cząstek fazy Mg2Si. W przypadku stopu z wyższą zawartością Mg i Si, po homogenizacji w temperaturze 550ºC przez 8h, udział nierozpuszczonych cząstek Mg2Si spada wyraźnie, w porównaniu z homogenizacją w temperaturze 535ºC przez 8h. Jednakże, stwierdzono niekorzystną tendencję do rozrostu dyspersoidów, zatem tych warunków wyżarzania nie uznano za rekomendowane. W drugim etapie analizowano wpływ szybkości chłodzenia z temperatury homogenizacji na wielkość i dystrybucję cząstek Mg2Si obserwowanych w strukturze stopów. Wykonano badania SEM oraz dokonano oceny możliwości szybkiego rozpuszczania cząstek Mg2Si wydzielonych podczas chłodzenia z temperatury homogenizacji z różnymi szybkościami. W tym celu wykonano badania twardości stopów po przesycaniu z krótkim wygrzewaniem oraz starzeniu, jak również badania DSC. Stwierdzono, że studzenie z temperatury homogenizacji z szybkością 315ºC/h jest wystarczające dla wydzielenia drobnych cząstek Mg2Si, które ulegają rozpuszczeniu podczas późniejszego gwałtownego nagrzewania. Chłodzenie z temperatury homogenizacji z szybkością 40ºC/h powoduje wydzielanie fazy Mg2Si w postaci dużych cząstek, które nie ulegają pełnemu rozpuszczeniu podczas późniejszego szybkiego nagrzewania.

conditions (-1.0 - -1.2 V vs. Ag/AgCl) porous deposits (~7-10 wt% Ni) were obtained, while dense coatings (~15-34 wt% Ni) were produced in the galvanostatic conditions (0.5-1.5 A/dm2). In both cases, deposits consisted of β - Sn and Ni3Sn4 phases. Speciation of the bath was also calculated.

Ag/AgCl) otrzymano warstwy porowate (7-10%mas Ni), natomiast w warunkach galwanostatycznych (0.5-1.5 A/dm2) tworzyły się warstewki zwarte (15-34%mas Ni). We wszystkich przypadkach uzyskano dwufazowe osady katodowe zawierające (β-Sn i Ni3Sn4. Obliczono także rozkład form jonowych w stosowanej kąpieli.

próbie rozciągania. Uzyskane wyniki przedstawiono jako wykresy zależności wielkości badanych (Rm, R0,2, A) od temperatury i czasu starzenia. Zależności te opisano równaniami matematycznymi. Takie opracowanie wyników badań pozwala w prosty sposób dobrać warunki starzenia prowadzące do osiągnięcia oczekiwanych własności mechanicznych.

time varying from 0,5 to 128 h. In order to determine the effect of heat treatment on the mechanical properties, tensile tests were performed. The received results (Rm, R0,2, A) were shown depending on ageing temperature and time in three dimensional diagrams. The obtained surfaces were approximated by polynomial equations. Presentation of the received results in the form of simple graphs allows, by selecting proper ageing conditions, to obtain the required mechanical properties.

starzenia w warunkach odkształcania w podwyższonej temperaturze, które sprzyjają wydzielaniu dynamicznemu. Pierwszy sposób realizacji procesu starzenia obejmował nagrzewanie z prędkością 5 i 25 [stopni] C/min, analizę kalorymetryczną i pomiar twardości próbek nagrzanych do określonej temperatury i ochłodzonych w wodzie. Maksymalną twardość dla próbek nagrzewanych z prędkością 5 [stopni] C/min - 154 HV - uzyskano po nagrzaniu do temperatury 225 [stopni] C, natomiast dla 25 [stopni] C/min uzyskano 142 HV po nagrzaniu do 250 [stopni] C. W porównaniu do starzenia przy stałej szybkości nagrzewania, maksymalne umocnienie przesyconego stopu w warunkach odkształcania ze stałą prędkością obserwowano w temperaturze 100-200 [stopni]C. Najwyższą twardość - 190 HV - uzyskano po odkształceniu et 0,4 w temperaturze 100 [stopni]C. Stwierdzono, że wyższa twardość materiału odkształconego w warunkach wydzielania dynamicznego wynika z nałożenia się i wzajemnego oddziaływania procesów starzenia i odkształcania, natomiast niższa temperatura uzyskania maksimum twardości wynika ze złożonego oddziaływania wymienionych procesów strukturalnych i końcowego efektu umocnienia odkształceniowo-wydzieleniowego. Czas starzenia w powyższych próbach starzenia jest wielokrotnie krótszy (1-40 min) niż w konwencjonalnych zabiegach izotermicznego starzenia (kilka godzin), jednakże uzyskane wyniki pomiarów twardości są nieco niższe niż podawane dla wyrobów w stanie T6.

of view. To omit time-consuming methods used in an industrial practice, some unconventional ageing procedures were proposed and tested to analyze related structural and mechanical aspects of the hardening processes. Nonconventional methods of the heat treatment described below include: (1) experiments on the ageing of solution treated AA7075 alloy during monotonic temperature increase and at constant heating rate, and (2) during hot deformation of solution treated samples. The first mentioned ageing procedure was performed at constant heating rate of 5 and 25 [degrees] C/min for the samples solution treated at 470 [degrees] C/1h. Solid solution decomposition and following precipitation sequences were traced by means of the dilatometer scanning calorimetry (DSC) method accompanied by the hardness measurements. It was found that the heating parameters i.e. heating rate and final temperature of the sample, have to be very carefully selected to get the hardness maximum. Maximum hardness 154HV at 225 [degrees] C, and 142HV at 250 [degrees]C was reached at the heating rate 5 and 25 [degrees] C/min, respectively. Hot compression tests at constant deformation rate were performed on overaged and solution treated samples to test the effect deformation temperature on the flow stress at 20-500 [degrees]C. Solution treated samples were annealed at 470 [degrees] C/1h and water quenched. Overaged samples were slowly cooled with a furnace after annealing. Hot deformation of overaged samples was found to result in monotonic decrease of the flow stress with increasing deformation temperature. The most effective hardening of the solution treated material was observed at 100-200 [degrees] C. The flow stress value for solution treated samples was twice as that for overaged samples. It was ascribed to the combined dynamic precipitation effect and effective strain hardening being intensified due to suppressed dynamic recovery at dynamic precipitation conditions. Maximum hardness for solution treated and hot deformed samples was observed at deformation temperature 100 [degrees] C. For comparison, the hardness maximum for the samples aged at constant heating rate was reached 225-250 [degrees] C. Such large difference in the hardness maximum development can result from the complex strain-precipitation interaction during dynamic precipitation and some differences in the precipitation mechanisms. Hot deformation gives an additional power to the precipitation process due to intensified nucleation of particles on dislocation tangles. Moreover, it is commonly believed that the deformation process result in an increase of point defects density that intensify the diffusion process. In consequence, both heterogeneous precipitation on dislocations and intensified diffusion process can be responsible for the acceleration of the precipitates growth and related reduction of the maximum hardening temperature for the hot deformed material.

against corrosion and which reduces the SFE of the alloy. The obtained silver alloys without copper, of 925 fineness, are characterized by high resistance to the action of sulfur corrosion and good mechanical properties.

ochronę przed korozją oraz obniżające EBU stopu. Wytworzone bezmiedziowe stopy srebra próby 925 cechują się bardzo dobrą odpornością na działanie korozji oraz dobrymi właściwościami mechanicznymi.

przesyconego stopu, dokonano identyfikacji tworzących się faz oraz ustalono rolę składników stopowych w umocnieniu stopu.

was determined. The phases identification was made and the role of alloying constituents in strengthening of alloy was established.