Płukanie jest operacją technologiczną pozwalającą na usunięcie z kruszyw minerałów ilastych. Z roku na rok ilość szlamów powstających podczas płukania kruszyw wzrasta. Poza rekultywacją obszarów kopalni, nie ma powszechnej metody utylizacji tych odpadów. Możliwość użycia szlamów z płukania kruszyw wapiennych w ceramice budowlanej może być przyjazną środowisku metodą ich wykorzystania. W artykule przedstawiono wybrane badania laboratoryjne dwóch szlamów z płukania kruszywa: dolomitowego i wapiennego. Odpady scharakteryzowano pod względem zawartości wody, składu granulometrycznego (analiza sitowa i areometryczna), chemicznego (XRF) i mineralnego (XRD), właściwości termicznych (STA/EGA, dylatometria, mikroskopia wysokotemperaturowa) oraz trwałości spieków w obecności pary wodnej. Stwierdzono, że odpad z płukania kruszywa dolomitowego zawiera więcej minerałów ilastych i mniej węglanów oraz jest bardziej drobnoziarnisty niż odpad z płukania wapienia. Odpad z płukania kruszywa wapiennego charakteryzują duże wahania zawartości wody i duża zawartość potencjalnie niebezpiecznych ziaren kalcytu. Podczas ogrzewania wysuszonych próbek szlamów do 1300°C zachodzi dekarbonatyzacja i spiekanie. Odpad z płukania kruszywa dolomitowego mięknie, topi się i płynie przed osiągnięciem temperatury 1300°C. Po wypaleniu szlamów w 1000°C spiek ze szlamu wapiennego nie jest odporny na działanie pary wodnej. Odpad z płukania kruszywa dolomitowego może być wykorzystany w ceramice budowlanej bez jego przetwarzania jako podstawowy składnik mas ceramicznych. Odpad z płukania kruszywa wapiennego nie nadaje się do zastosowania w ceramice budowlanej bez jego poprzedniego zmielenia. Jego właściwości sugerują możliwość zastosowania go jedynie jako dodatek do mas ceramicznych, nie jako ich główny składnik.
This work presents an influence of cooling rate on crystallization process, structure and mechanical properties of MCMgAl12Zn1 cast magnesium alloy. The experiments were performed using the novel Universal Metallurgical Simulator and Analyzer Platform. The apparatus enabled recording the temperature during refrigerate magnesium alloy with three different cooling rates, i.e. 0.6, 1.2 and 2.4°C/s and calculate a first derivative. Based on first derivative results, nucleation temperature, beginning of nucleation of eutectic and solidus temperature were described. It was fund that the formation temperatures of various thermal parameters, mechanical properties (hardness and ultimate compressive strength) and grain size are shifting with an increasing cooling rate.
During the slag refining process, in the real systems, the complex processes of mass exchange appear. Some relations between the stimulators in the environment - slag - metal system allow to initiate mass exchange reactions in the process of slag refining. Due to this kind of influences there is a possibility of direction and control of melting copper and it’s alloys.
The thermal reclamation process as a utilisation method of spent moulding and core sands is more costly than other reclamation methods, but in the majority of cases it simultaneously provides the best cleaning of mineral matrices from organic binders. Thus, the application of the thermal analysis methods (TG-DSC), by determining the temperature range within which a degradation followed by a destruction of bounded organic binders in moulding sands, can contribute to the optimisation of the thermal reclamation process and to the limiting its realisation costs. The thermal analysis results of furan resin, one of the most often applied binder in foundry practice, are presented in the hereby paper. The influence of the heating rate of the sample - placed in the thermal analyser - on its degradation and destruction process under oxygen-free (argon) and oxygen (air) conditions, were compared. The recorded TG and DSC curves were used for analysing these processes as the temperature as well as the time function. The obtained results were analysed with regard to determining the required temperature of the thermal reclamation of the investigated organic binder. The usefulness of the developed methodology was found out, however under conditions of meeting several essential requirements concerning the repeatability of performed analyses.
The paper presents a research results concerning impact of volume modification (ceramic filter containning cobalt aluminate and hafniumpowder) and simultaneous surface and volume modification on solidification and stereological parameters of macrostructure of castingsmade from post-production scrap of nickel superalloy IN-713C. Research included investigation of the influence of chemical compositionon the temperature Tliq i Tsol and evaluation of following macrostructure parameters: the number of grains per mm2, average grain area andshape coefficient. Results indicate high influence of carbon content on Tliq. Macrostructure of sample castings indicate positive effect of surface and volume modification, however impact of surface modification is more pronounced.
Superalloys show a good combination of mechanical strength and resistance to surface degradation under the influence of chemically active environments at high temperature. They are characterized by very high heat and creep resistance. Their main application is in gas turbines, chemical industry, and in all those cases where resistance to creep and the aggressive corrosion environment is required. Modern jet engines could never come into use if not for progress in the development of superalloys. Superalloys are based on iron, nickel and cobalt. The most common and the most interesting group includes superalloys based on nickel. They carry loads at temperatures well in excess of the eighty percent of the melting point. This group includes the H282 alloy, whose nominal chemical composition is as follows (wt%): Ni - base, Fe - max. 1.5%, Al - 1.5% Ti - 2.1%, C - 0.06% Co - 10% Cr - 20% Mo - 8.5%. This study shows the results of thermal analysis of the H282 alloy performed on a cast step block with different wall thickness. Using the results of measurements, changes in the temperature of H282 alloy during its solidification were determined, and the relationship dT / dt = f (t) was derived. The results of the measurements taken at different points in the cast step block allowed identifying a number of thermal characteristics of the investigated alloy and linking the size of the dendrites formed in a metal matrix (DAS) with the thermal effect of solidification. It was found that the time of solidification prolonged from less than ome minute at 10 mm wall thickness to over seven minutes at the wall thickness of 44 mm doubled the value of DAS.
In the dissertation it has been shown, that so called “time-thermal treatment” (TTT) of the alloy in liquid state as overheating the metal with around 250o C above Tliq. and detailing it in temperature for 30 to 40 minutes has the influence on changing the crystallization parameters (Tliq., TEmin. , TEmax., TE(Me), TSol.). It was ascertained, that overheating the AlSi17Cu5Mg alloy substantially above Tliq. results with microcrystalline structure. Evenly distributed in the eutectic warp primeval silicon crystals and supersaturated with alloying additives of base content (Cu, Mg, Fe) of α(Al) solution, ensures not only increase durability in ambient temperature, but also at elevated temperature (250o C), what due to it’s use in car industry is an advantage.
The results of investigations of spent moulding sands taken from the mould in which the metal core cooling system - to increase the cooling rate of the ladle casting - was applied, are presented in the hereby paper. The changes of the spent moulding sand at the casting external side being the result of degradation and destruction processes of organic binder, were analysed in this publication. Since the reclaimed material, obtained as a result of the mechanical reclamation of spent sands of the same type, is used as a grain matrix of the moulding sand, the amount of a binder left from the previous technological cycle is essential for the sound castings production. On the bases of investigations of the thermal analysis, ignition losses, dusts contents and pH values of the samples taken from the spent sand the conditions under which the process of gases displacing in the casting mould was realised as well as factors limiting the efficient mould degassing - were considered in this study. The possible reason of a periodical occurrence of an increased number of casting defects due to changing gas volume emission, being the reason of the realised technological process, was indicated.
Suitability of the given binding agent for the moulding sands preparation depends on the one hand on the estimation of technological properties of the sand and the mould made of it and the obtained casting quality and on the other hand on the assessment of this sand influence on the natural and working environment. Out of moulding sands used in the foundry industry, sands with organic binders deserve a special attention. These binders are based on synthetic resins, which ensure obtaining the proper technological properties and sound castings, however, they negatively influence the environment. If in the initial state these resins are not very dangerous for people and for the environment, thus under an influence of high temperatures they generate very harmful products, being the result of their thermal decomposition. Depending on the kind of the applied resin (phenol-formaldehyde, urea, furfuryl, urea–furfuryl, alkyd) under an influence of a temperature such compounds as: furfuryl alcohol, formaldehyde, phenol, BTEX group (benzene, toluene, ethylbenzene, xylene), and also polycyclic aromatic hydrocarbons (PAH) can be formed and released. The aim of the study was the development of the method, selection of analytical methods and the determination of optimal conditions of formation compounds from the BTEX group. An emission of these components constitutes one of the basic criteria of the harmfulness assessment of binders applied for moulding and core sands. Investigations were carried out in the specially designed set up for the thermal decomposition of organic substances in a temperature range: 5000 C – 13000 C at the laboratory scale. The object for testing was alkyd resin applied as a binding material for moulding sands. Within investigations the minimal amount of adsorbent necessary for the adsorption of compounds released during the decomposition of the resin sample of a mass app. 15 mg was selected. Also the minimal amount of solvent needed for the desorption of compounds adsorbed in the column with adsorbent was found. The temperature range, in which the maximal amounts of benzene, toluene, ethylobenzene and xylenes are released from the resin, was defined. The qualitative and quantitative analyses of compounds from the BTEX group were performed by means of the gas chromatography combined with the mass spectrometry (GC/MS).
The paper presents the results of thermoanalytical studies by TG/DTG/DTA, FTIR and GC/MS for the oil sand used in art and precision foundry. On the basis of course of DTG and DTA curves the characteristic temperature points for thermal effects accompanying the thermal decomposition reactions were determined. This results were linked with structural changes occurred in sample. It has been shown that the highest weight loss of the sample at temperatures of about 320°C is associated with destruction of C-H bonds (FTIR). In addition, a large volume of gases and high amounts of compounds from the BTEX group are generated when liquid metal interacts with oil sand. The results show, that compared to other molding sands used in foundry, this material is characterized by the highest gaseous emissions and the highest harmfulness, because benzene emissions per kilogram of oil sand are more than 7 times higher than molding sand with furan and phenolic binders and green sand with bentonite and lustrous carbon carrier.
Tests concerning EN AC 48000 (AlSi12CuNiMg) alloy phase transition covered (ATD) thermal analysis and (DSC) differential scanning calorimetry specifying characteristic temperatures and enthalpy of transformations. ATD thermal analysis shows that during cooling there exist: pre-eutectic crystallization effect of Al9Fe2Si phase, double eutectic and crystallization α(Al)+β(Si) and multi-component eutectic crystallization. During heating, DSC curve showed endothermic effect connected with melting of the eutectic α(Al)+β(Si) and phases: Al2Cu, Al3Ni, Mg2Si and Al9Fe2Si being its components. The enthalpy of this transformation constitutes approx. +392 J g-1 . During freezing of the alloy, DSC curve showed two exothermal reactions. One is most likely connected with crystallization of Al9Fe2Si phase and the second one comes from freezing of the eutectic α(Al)+β(Si). The enthalpy of this transformation constitutes approx. –340 J g-1 . Calorimetric test was accompanied by structural test (SEM) conducted with the use of optical microscope Reichert and scanning microscope Hitachi S-4200. There occurred solution's dendrites α(Al), eutectic silicon crystal (β) and two types of eutectic solution: double eutectic α(Al)+β(Si) and multi-component eutectic α+AlSiCuNiMg+β.
In this article, there were presented results of research on influence of reclamation process on the ecological quality of reclaim sand with furan resin used in nonferrous foundry. The quality of reclaimed sand is mainly define by two group of chemical substances from elution of reclaimed sand: Dissolves Organic Carbon (DOC) and Total Dissolves Solids (TDS). Reclaimed sand used in test was prepared in experimental thermal reclaimer and mechanical vibration reclaimer REGMAS installed in Faculty of Foundry Engineering at University of Science and Technology in Krakow. The reference point is molding sand shaking out and crumble in jaw crusher. Test of elution was made in acreditation laboratory in Center For Research and Environmental Control in Katowice up to the standard with Dissolves Organic Carbon (DOC) - PN-EN 1484:1999; Total Dissolves Solids (TDS) - PN-EN 15216:2010. The standard for elution test is PN-EN 12457- 4:2006. Except that we were made loss of ignition test, to check how many resin was rest on sand grains.
The paper presents the results of studies on the development of correlation of solidification parameters and chemical composition of nickel superalloy IN-713C, which is used i.a. on aircraft engine turbine blades. Previous test results indicate significant differences in solidification parameters of the alloy, especially the temperatures Tliq and Tsol for each batch of ingots supplied by the manufacturer. Knowledge of such a relationship has important practical significance, because of the ability to asses and correct the temperatures of casting and heat treatment of casts on the basis of chemical composition. Using the statistical analysis it was found that the temperature of the solidification beginning Tliq is mostly influenced by the addition of carbon (similar to iron alloys). The additions of Al and Nb have smaller but still significant impact. Other alloying components do not have significant effect on Tliq. The temperature Teut is mostly affected by Ni, Ti and Nb. The temperature Tsol is not in any direct correlation with the chemical composition, which is consistent with previous research. The temperature Tsol depends primarily on the presence of non-metallic inclusions present in feed materials and introduced during the melting and casting processes.
The paper presents the results of evaluation of the metallurgical quality of master heat ingots and of the identification of non-metallic inclusions (oxides of Al., Zr, Hf, Cr, etc.), which have been found in the shrinkage cavities formed in these ingots. The inclusions penetrate into the liquid alloy, and on pouring of mould are transferred to the casting, especially when the filtering system is not sufficiently effective. The specific nature of the melting process of nickel and cobalt alloys, carried out in vacuum induction furnaces, excludes the possibility of alloy refining and slag removal from the melt surface. Therefore, to improve the quality of castings (parts of aircraft engines), it is so important to evaluate the quality of ingots before charging them into the crucible of an induction furnace. It has been proved that one of the methods for rapid quality evaluation is an ATD analysis of the sample solidification process, where samples are taken from different areas of the master heat ingot. The evaluation is based on a set of parameters plotted on the graph of the dT/dt derivative curve during the last stage of the solidification process in a range from TEut to Tsol.
With the use of differential scanning calorimetry (DSC), the characteristic temperatures and enthalpy of phase transformations were defined for commercial AlSi9Cu3 cast alloy (EN AC-46000) that is being used for example for pressurized castings for automotive industry. During the heating with the speed of 10oCmin-1 two endothermic effects has been observed. The first appears at the temperature between 495 oC and 534 oC, and the other between 555 oC and 631 oC. With these reactions the phase transformation enthalpy comes up as +6 J g-1 and +327 J g-1 . During the cooling with the same speed, three endothermic reactions were observed at the temperatures between 584 oC and 471 oC. The total enthalpy of the transitions is – 348 J g-1 . Complimentary to the calorimetric research, the structural tests (SEM and EDX) were conducted on light microscope Reichert and on scanning microscope Hitachi S-4200. As it comes out of that, there are dendrites in the structure of α(Al) solution, as well as the eutectic (β) silicon crystals, and two types of eutectic mixture: double eutectic α(Al)+β(Si) and compound eutectic α+Al2Cu+β.
The article presents results of studies of silicon – molybdenum cast iron (4.42% Si, 2.59% Mo and 2.48% C wt.-%) crystallization process. Metallographic analysis was carried out using SEM-scanning electron microscopy with the EDS system. In order to determine the phase composition, X-ray diffraction studies were performed. Thermo-Calc, a computer simulation program, was used to simulate the crystallization process. . The obtained data allowed to describe the effect of some elements on the crystallization process. The silicon phase of MnSi could not be identified during metallographic studies. Also, computer simulation of the crystallization process did not answer the question at which point the silicon phase of MnSi crystallizes in the tested alloy. Therefore, not all results obtained were linked to the registered crystallization process (TDA process). The EDS analysis revealed an unusual distribution of molybdenum in the microstructure of the sample, where it is clearly visible that the area enriched with this element is also the separation of spheroidal graphite. The possibility of occurrence of Mo-rich micro-areas found in graphite is considered. The case is debatable and difficult to resolve at this stage. Perhaps, at such a high concentration of molybdenum (2.59% Mo) in the alloy, conditions are created for simultaneously crystallization of graphite and molybdenum phases.
In the article we were studing the impact of the remelting on transformations in Co-Cr-Mo prosthetics alloy. The TDA curves were analyzed, the microstructure was examined, the analysis of the chemical composition and hardness using the Brinell method was made. It was found that the obtained microstructure of the alloys that we studied do not differ significantly. In all four samples, microscopic images were similar to each other. The volume, size and distribution of the phases remain similar. Analysis of the chemical composition showed that all the samples fall within the compositions provided for the test alloy. Further to this the hardness of the samples, regardless of the number of remeltings did not show any significant fluctuations and remained within the error limit.After analyzing all the results, it can be concluded that the remeltings of the alloys should not have a significant impact on their properties. Secondarily melted alloys can be used for prosthetics works.
The work presents results of solution combustion method utilization for yttria (Y2O3) nanopowder fabrication. Experiments were carried out with four different reducing agents: urea, glycine, citric acid and malonic acid added in stoichiometric ratio. The reactions were investigated using simultaneous DSC/DTA thermal analysis. After synthesis the reaction products were calcined at temperature range of 800-1100°C and analyzed in terms of particle size, specific surface area and morphology. Best results were obtained for nanoyttria powder produced from glycine. After calcination at temperature of 1100°C the powder exhibits in a form of nanometric, globular particles of diameter <100 nm, according to SEM analysis. The dBET for thus obtained powder is 104 nm, however the powder is agglomerated as the particle size measured by dynamic light scattering analysis is 1190 nm (dV50).
This paper deals with influence on segregation of iron based phases on the secondary alloy AlSi7Mg0.3 microstructure by nickel. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich intermetallic phases. It is impossible to remove iron from melt by standard operations. Some elements eliminates iron by changing iron intermetallic phase morphology, decreasing its extent and by improving alloy properties. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of nickel as iron corrector of iron based phases.
The paper deals with the influence of manganese in AlSi7Mg0.3 alloy with higher iron content. Main aim is to eliminate harmful effect of intermetallic – iron based phases. Manganese in an alloy having an iron content of about 0.7 wt. % was graded at levels from 0.3 to 1.4 wt. %. In the paper, the effect of manganese is evaluated with respect to the resulting mechanical properties, also after the heat treatment (T6). Morphology of the excluded intermetallic phases and the character of the crystallisation of the alloy was also evaluated. From the obtained results it can be concluded that the increasing level of manganese in the alloy leads to an increase in the temperature of the β-Al5FeSi phase formation and therefore its elimination. Reducing the amount of β-Al5FeSi phase in the structure results in an improvement of the mechanical properties (observed at levels of 0.3 to 0.8 wt. % Mn). The highest addition of Mn (1.4 wt.%) leads to a decrease in the temperature corresponding to the formation of eutectic silicon, which has a positive influence on the structure, but at the same time the negative sludge particles were also present
According to the analysis of the current state of the knowledge shows that there is little information on the process of phase transformations that occur during the cooling Cu-Al-Fe-Ni hypo-eutectoid bronzes with additions of Cr, Mo and/or W, made additions individually or together, for the determination of: the type of crystallizing phases, crystallizing phases, order and place of their nucleation. On the basis of recorded using thermal and derivative analysis of thermal effects phases crystallization or their systems, analysis of the microstructure formed during crystallization - observed on the metallographic specimen casting ATD10-PŁ probe, analysis of the existing phase equilibrium diagrams forming elements tested Cu-Al-Fe-Ni bronze, with additions of Cr, Mo, W and/or Si developed an original model of crystallization and phase transformation in the solid state, the casting of high quality Cu-Al-Fe-Ni bronze comprising: crystallizing type phase, crystallizing phase sequence, place of nucleation.
This work is dealing with the impact of molybdenum on the structure properties of commercial cast AlSi10Mg(Cu) alloy. The solidification path of AlSi10Mg(Cu) alloy with various content of molybdenum has been investigated using cooling curve techniques. The samples for testing have been poured into permanent steel mold. The content of molybdenum has been varied from 0 to 0.20 wt. %.The desired chemical composition was achieved by adding of master alloy AlMo10 into commercial AlSi10Mg(Cu) alloy. The micro hardness of as cast alloys with different content of molybdenum has been measured. The microstructure and EDX analysis from the casted samples has been carried out. The results show that molybdenum in commercial AlSi10Cu(Mg) alloy precipitate in the interdendritic region isolated in the form of Al(FeMnMoMg)Si rich intermetallic. The increased content of molybdenum increase slightly liquidus temperature, prolonging precipitation of the last eutectic and surprisingly decrease the micro hardness of commercial alloy for approximately 16 %.
This paper deals with influence of chrome addition and heat treatment on segregation of iron based phases in the secondary alloy AlSi7Mg0.3 microstructure by chrome and heat treatment. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich intermetallic phases. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition some other elements that affect the segregation of intermetallics in less harmful type or by heat treatment. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases.