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PL
Zbadano przydatność polilaktydu (PLA) jako spoiwa do wielokrotnego stosowania do mas formierskich wykorzystywanych w procesach odlewniczych. PLA otrzymano z dużą wydajnością (71%) przez polikondensację laktydu. Masy formierskie z 2-proc. zawartością spoiwa uzyskano w wyniku odparowania chloroformowego roztworu PLA. Zbadano wytrzymałość na rozciąganie mas formierskich po ich wielokrotnym zawracaniu. Masy formierskie z 2-proc. zawartością PLA jako spoiwem, stapiane w wysokiej temp. 325°C można było zawracać nawet 13-krotnie, otrzymując masy charakteryzujące się dobrą jakością.
EN
Polylactide (PLA) was used as a binder for recycled molding sands in foundry processes. PLA was produced by lactide polycondensation with a high efficiency (71%). The molding sands with 2% binder content were prepd. by evaporating the solvent from CHCl3 soln. of PLA. The PLA-contg. molding sands cured at 325°C were successfully recycled up to 13 times.
PL
Celem niniejszej pracy jest wykazanie możliwości zastosowania proekologicznych mas z uwodnionym krzemianem sodu na formy do odlewania ablacyjnego. Technologia odlewania ablacyjnego przeznaczona jest przede wszystkim do wykonywania odlewów w formach piaskowych o zróżnicowanej grubości ścianki i skomplikowanych kształtach. W ramach niniejszej pracy przedstawiono wpływ zawartości spoiwa oraz czasu utwardzania na wytrzymałość na zginanie Rg mas formierskich ze spoiwami na bazie uwodnionego krzemianu sodu utwardzanych w technologii utwardzania mikrofalowego. Celem badań jest opracowanie optymalnego składu mas, który zapewni wytrzymałość niezbędną do wytworzenie formy do przeprowadzenia procesu odlewania ablacyjnego. Zastosowana mas musi jednocześnie zagwarantować podatność formy na destrukcyjne działanie medium ablacyjnego, którym jest woda. Przeprowadzone badania wykazały, że utwardzanie mikrofalowe zapewnia uzyskanie zadowalających wytrzymałości przy niskiej zawartości spoiwa w masie.
EN
The aim of this work is to demonstrate the possibility of using Environmentally friendIy molding sands with hydrostated sodium silicate for ablation casting molds. The ablation casting technology is intended primarily for making casts in sand molds with diversified wall thickness and complex shapes. This paper presents the effect of binder content and curing time on the bending strength Rg of molding sands with binders based on hydrated sodium silicate hardened in microwave curing technology. The aim of the research is to develop an optimal molding sand composition that will provide the strength necessary to form a mold for carrying out the ablative casting process. the applied sands must simultaneously guarantee the susceptibility of the mold to the destructive action of the ablative medium, which is water. The tests have shown that microwave curing provides satisfactory strengths with low binder content.
EN
Gas atmosphere at the sand mould/cast alloy interface determines the quality of the casting obtained. Therefore the aim of this study was to measure and evaluate the gas forming tendency of selected moulding sands with alkyd resins. During direct and indirect gas measurements, the kinetics of gas evolution was recorded as a function of the temperature of the sand mixture undergoing the process of thermal destruction. The content of hydrogen and oxygen was continuously monitored to establish the type of the atmosphere created by the evolved gases (oxidizing/reducing). The existing research methodology [1, 7, 8] has been extended to include pressure-assisted technique of indirect measurement of the gas evolution rate. For this part of the studies, a new concept of the measurement was designed and tested. This article presents the results of measurements and compares gas emissions from two sand mixtures containing alkyd resins known under the trade name SL and SL2002, in which the polymerization process is initiated with isocyanate. Studies of the gas forming tendency were carried out by three methods on three test stands to record the gas evolution kinetics and evaluate the risk of gas formation in a moulding or core sand. Proprietary methods for indirect evaluation of the gas forming tendency have demonstrated a number of beneficial aspects, mainly due to the ability to record the quantity and composition of the evolved gases in real time and under stable and reproducible measurement conditions. Direct measurement of gas evolution rate from the tested sands during cast iron pouring process enables a comparison of the results with the results obtained by indirect methods.
EN
The paper presents the results of an investigation of the thermal deformation of moulding sands with an inorganic (geopolymer) binder with a relaxation additive, whose main task is to reduce the final (residual) strength and improves knocking-out properties of moulding sand. The moulding sand without a relaxation additive was the reference point. The research was carried out using the hot-distortion method (DMA apparatus from Multiserw-Morek). The results were combined with linear deformation studies with determination of the linear expansion factor (Netzsch DIL 402C dilatometer). The study showed that the introduction of relaxation additive has a positive effect on the thermal stability of moulding sand by limiting the measured deformation value, in relation to the moulding sand without additive. In addition, a relaxation additive slightly changes the course of the dilatometric curve. Change in the linear dimension of the moulding sand sample with the relaxation additive differs by only 0.05%, in comparison to the moulding sand without additive.
5
EN
The constant growth of foundry modernization, mechanization and automation is followed with growing requirements for the quality and parameters of both moulding and core sands. Due to this changes it is necessary to widen the requirements for the parameters used for their quality evaluation by widening the testing of the moulding and core sands with the measurement of their resistance to mechanical deformation (further called elasticity). Following article covers measurements of this parameter in chosen moulding and core sands with different types of binders. It focuses on the differences in elasticity, bending strength and type of bond destruction (adhesive/cohesive) between different mixtures, and its connection to the applied bonding agent. Moulding and cores sands on which the most focus is placed on are primarily the self-hardening moulding sands with organic and inorganic binders, belonging to the group of universal applications (used as both moulding and core sands) and mixtures used in cold-box technology.
EN
The subject of this paper was to compare the influence of selected coatings on bending strength of moulds and cores manufactured in a furan technology. In a range of study, there were used three kinds of coatings - water based coating and two kind of alcohol based coating manufactured by FOSECO. Coating were applicated by brush, overpouring/flow and spraying. For each application method, there were realized different kind of drying- at ambient temperature, in a furnace and by burning. Physicochemical properties of coatings were such selected to accommodate them to the application method and type of coating. Based on the conducted studies it was observed that for water based coating application method doesn’t have an important influence on bending strength and it is necessary to optimize the time and temperature of drying to achieve better results of bending strength. For alcohol based coatings, drying by burning causes significant deterioration of bending strength of the mould and core and drying process at ambient allows to obtain high bending strength of mould/cores in regard to time of drying.
EN
In the knock-out process, as well as in the preliminary phase of moulding sand reclamation, the issue of energy demand for the process of crushing used sand agglutinations, preferably to single grains, is particularly important. At present, numerical values of moulding sand impact resistance, which would allow energy-related aspects of this process to be forecast, are not known, as such research has not been carried out. It seems that impact resistance tested on very small cross-section samples, which allows us to very precisely reveal some unique features of a moulding sand with organic and inorganic binders, is an important parameter, which so far has not been taken into account for evaluation of mechanical properties of moulding sands. Preliminary attempts to determine impact resistance of moulding sands have been carried out as part of own research of the author. The conducted investigations aimed at determining the relationships between the obtained values of tensile strength and impact resistance of moulding sands. In addition, the effect of holding samples at temperatures of 100oC, 200oC, 300oC on the value of impact resistance was determined, both for sands made with fresh and with reclaimed sand grains.
EN
The essence of ablation casting technology consists in pouring castings in single-use moulds made from the mixture of sand and a water-soluble binder. After pouring the mould with liquid metal, while the casting is still solidifying, the mould destruction (washing out, erosion) takes place using a stream of cooling medium, which in this case is water. This paper focuses on the selection of moulding sands with hydrated sodium silicate for moulds used in the ablation casting. The research is based on the use of Cordis binder produced by the Hüttenes-Albertus Company. It is a new-generation inorganic binder based on hydrated sodium silicate. Its hardening takes place under the effect of high temperature. As part of the research, loose moulding mixtures based on the silica sand with different content of Cordis binder and special Anorgit additive were prepared. The reference material was sand mixture without the additive. The review of literature data and the results of own studies have shown that moulding sand with hydrated sodium silicate hardened by dehydration is characterized by sufficient strength properties to be used in the ablation casting process. Additionally, at the Foundry Research Institute in Krakow, preliminary semi-industrial tests were carried out on the use of Cordis sand technology in the manufacture of moulds for ablation casting. The possibility to use these sand mixtures has been confirmed in terms of both casting surface quality and sand reclamation.
EN
Measurements of the hardening process course of the selected self-hardening moulding sands with the reclaimed material additions to the matrix, are presented in the hereby paper. Moulding sands were produced on the „Szczakowa” sand (of the Sibelco Company) as the matrix of the main fraction FG 0,40/0,32/0,20, while the reclaim was added to it in amounts of 20, 50 and 70%. Regeneration was performed with a horizontal mechanical regenerator capacity of 10 t/h. In addition, two moulding sands, one on the fresh sand matrix another on the reclaimed matrix, were prepared for comparison. Highly-fluid urea-furfuryl resin was used as a binder, while paratoluensulphonic acid as a hardener. During investigations the hardening process course was determined, it means the wave velocity change in time: cL = f(t). The hardening process kinetics was also assessed (dClx/dt = f(t)). Investigations were carried out on the research stand for ultrasound tests. In addition strength tests were performed.
PL
Autorzy opracowali oryginalną metodę i sposób prowadzenia badania kinetyki wydzielania się gazów z materiałów stosowanych w technologii form poddawanych intensywnemu nagrzewaniu. Do tych materiałów pracy zalicza się masy formierskie oraz powłoki ochronne stosowane na formy i rdzenia piaskowe lub formy metalowe zalewane grawitacyjnie. Badania prowadzone są dwutorowo: z wykorzystanie zmodyfikowanej metody oznaczania gazotwórczości w piecu rurowym oraz badania gazotwórczości cienkich, przypowierzchniowych warstw form zalewanych ciekłym metalem. Kinetyka wydzielania gazów prezentowana jest w funkcji czasu nagrzewania oraz w funkcji temperatur próbki nagrzewanej masy lub powłoki. Badania obejmują również monitorowanie tych samych zjawisk przy nagrzewania cienkich warstw formy. Stwierdzono, iż zarówno w przypadku mas ze spoiwami jak i w przypadku powłok występują dwa maksima szybkości wydzielania gazów: przy temperaturze około 200 i około/ponad 500 ºC. Powłoki ochronne są znaczącym źródłem gazów po zalaniu formy metalem, co rzadko jest uwzględniane w ogólnym bilansie gazów powstających w formie. Warstwy wierzchnie form i rdzeni pokryte powłokami wydzielają dużo więcej gazów niż warstwy bez tych powłok. Z tego powodu odlewy wytwarzane w formach/rdzeniach z powłokami są w większym stopniu narażone na powstawania wad pochodzenia gazowego.
EN
The authors developed the original method and the way of performing investigations of the kinetics of gases emission from materials applied in the mould technology and subjected to intensive heating. Moulding sands and protective coatings applied for sand moulds and cores or for metal moulds poured gravitationally belong to these materials. Investigations are performed in two ways: with utilising the modified method of determining the gas evolution rate in the tubular furnace and testing the gas evolution rate from thin near surface layers poured with liquid metal. The gas emission kinetics is presented as the heating time function and as the temperature function of the heated sample of the moulding sand or coating. Investigations encompass also monitoring of these effects at heating thin layers of moulds. It was found that in case of moulding sands with binders as well as in case of coatings two maxima of gases emission rates occur: at a temperature of approximately 200 ºC and of approximately/above 500 ºC. Protective coatings are significant sources of gases after the mould is poured with metal, which is seldom taken into account in the general balance of gases formed in the mould. Surface layers of moulds and cores covered with coatings emit much more gases than layers without these coatings. Due to this, castings produced in moulds/cores with coatings are, in a higher degree, exposed to defects of gaseous origin.
PL
W niniejszym opracowaniu przedstawiono zakres i efekty badań prowadzonych z zakresu odświeżania masy przy użyciu mieszanek dynamicznych. Celem tych badań było określenie przebiegu procesu oraz wyznaczenie zakresu wartości parametrów konstrukcyjno - eksploatacyjnych, optymalnych ze względu na uzyskiwanie właściwości masy odświeżanej i nakłady energetyczne procesu.
PL
Opisano wykorzystane w badaniach metody modyfikacji uwodnionego krzemianu sodu jako spoiwa krzemianowego masy formierskiej. Określono zmianę wytrzymałości końcowej masy formierskiej z zastosowanymi spoiwami krzemianowymi oraz efektywność zmian wytrzymałości końcowej w funkcji temperatury wygrzewania badanych próbek masy formierskiej. Stwierdzono, że najkorzystniejszym spoiwem w aspekcie zmiany wytrzymałości końcowej masy formierskiej jest spoiwo krzemianowe modyfikowane chemicznie dodatkiem organofunkcyjnym oraz spoiwo geopolimerowe, natomiast najkorzystniejszą efektywność zmian wytrzymałości końcowej masy formierskiej zapewnia spoiwo krzemianowe modyfikowane chemicznie dodatkiem organofunkcyjnym.
EN
The article discusses the ways of modification of hydrated sodium silicate as a silicate binder of moulding sands which were applied in the studies. It determines the change in the residual strength of the moulding sand with used silicate binders as well as the effectiveness of the changes in the residual strength as a function of the annealing temperature of the examined moulding sand samples. It was established that the most advantageous binder with regards to changes in the residual strength of the moulding sand is a silicate binder chemically modified with an organofunctional addition as well as a geopolymer binder, whereas the most beneficial effect of the changes in the residual strength of the moulding sand is ensured by a silicate binder chemically modified with an organofunctional addition.
PL
W pracy podjęto próbę uzupełnienia informacji na temat wpływu zagęszczenia masy formierskiej ze spoiwami nieorganicznymi na podstawowe parametry wytrzymałościowe, tj.: wytrzymałość na rozciąganie i zginanie mas formierskich z uwodnionym krzemianem sodu po procesie szybkiego nagrzewania mikrofalowego. W badaniach zastosowano świeży piasek kwarcowy średni oraz trzy gatunki handlowego niemodyfikowanego uwodnionego krzemianu sodu o module molowym (SiO2/Na2O) w przedziale od 1,9 do 3,4. Masy sporządzone z 0,5% cz. mas. wody i 1,5% cz. mas. spoiwa zagęszczano wibracyjnie tak, aby osiągnąć różną gęstość pozorną (ϱ0) masy formierskiej. Badane parametry wytrzymałościowe po utwardzeniu i ostudzeniu próbek mas odnoszono do gęstości pozornej. Wyniki badań nad wpływem zróżnicowanego zagęszczenia odnoszono do dostępnych danych literaturowych. Występowanie zależności między gęstością pozorną a wytrzymałością na rozciąganie i zginanie utwardzonych mas potwierdzono za pomocą modeli liniowych dla korzystnego nagrzewania mikrofalowego, podobnie jak to ma miejsce w dotychczas opisanych przypadkach stosowania chemicznych metod sieciowania spoiw nieorganicznych. Ponadto na podstawie wykonanych badań stwierdzono występowanie podobnych przyrostów wytrzymałości na skutek zmian gęstości pozornej mas nagrzewanych mikrofalowo do tych, które zaobserwowano w masach utwardzanych chemicznie. Wyniki badań posłużyły do oceny jakości spoiw chemicznych stosowanych w odlewnictwie według kryteriów wytrzymałości przypadających na 1% wag. spoiwa w masie. W przypadku wszystkich badanych spoiw nieorganicznych stwierdzono korzystny stosunek wytrzymałości przeliczonej na udział 1% wag. spoiwa powyżej wartości 1,20 g/cm3 gęstości pozornej mas na osnowie piasku kwarcowego średniego.
EN
The study attempts to complement the information on the effect of the density of moulding sands with inorganic binders on basic strength parameters, i.e. the tensile and bending strength of moulding sands with hydrated sodium silicate, after the process of fast microwave heating. The tests applied fresh medium quartz sand and three types of commercial non-modified hydrated sodium silicate with a molar module (SiO2/Na2O) ranging from 1.9 to 3.4. The masses made of 0.5 wt. % of water and 1.5 wt. % of binder underwent vibrational densification so as, to obtain different apparent densities (ϱ0) of the moulding sand. The examined strength parameters, after hardening and cooling of the mass samples, were compared to apparent density. The results of the studies of the effect of a diversified density were referred to in the literature data. The occurrence of relations between the apparent density and the tensile and bending strength of the hardened masses was confirmed by means of linear models for advantageous microwave heating, similarly to the previously discussed cases of the use of chemical methods of curing inorganic binders. Also, based on the performed tests, similar strength increases were established, as a result of the changes in the apparent density of the microwave heated masses to those which were observed in the chemically hardened masses. The tests results were used to evaluate the quality of the chemical binders applied in casting according to the strength criteria per 1 wt. % of binder in the mass. In the case of Poall the tested inorganic binders, an advantageous ratio of strength recalculated to 1 wt. % of binder above the value of 1.20 g/cm3 of the apparent density of the masses based on medium quartz sand, was established.
EN
Core sands for blowing processes, belong to these sands in which small amount of the applied binding material has the ability of covering the sand matrix surface in a way which - at relatively small coating thickness - allows to achieve the high strength. Although the deciding factor constitute, in this aspect, strength properties of a binder, its viscosity and ability to moisten the matrix surface, the essential meaning for the strength properties of the prepared moulding sand and the mould has the packing method of differing in sizes sand grains with the coating of the binding material deposited on their surfaces. The knowledge of the influence of the compaction degree of grains forming the core on the total contact surface area can be the essential information concerning the core strength. Forecasting the strength properties of core sands, at known properties of the applied chemically hardened binder and the quartz matrix, requires certain modifications of the existing theoretical models. They should be made more realistic with regard to assumptions concerning grain sizes composition of quartz sands and the packing structure deciding on the active surface area of the contacts between grains of various sizes and - in consequence - on the final strength of cores.
EN
This paper presents the impact of microwave penetration depth on the process of heating the moulding sand with sodium silicate. For each material it is affected by: the wavelength in vacuum and the real and imaginary components of the relative complex electrical permittivity εr for a selected measurement frequency. Since the components are not constant values and they change depending on the electrical parameters of materials and the frequency of the electromagnetic wave, it is indispensable to carry out laboratory measurements to determine them. Moreover, the electrical parameters of materials are also affected by: temperature, packing degree, humidity and conductivity. The measurements of the dielectric properties of moulding sand with sodium silicate was carried out using the perturbation method on a stand of waveguide resonance cavity. The real and imaginary components of the relative complex electrical permittivity was determined for moulding sand at various contents of sodium silicate and at various packing degrees of the samples. On the basis of the results the microwave penetration depth of moulding sand with sodium silicate was established. Relative literature contains no such data that would be essential to predicting an effective process of microwave heating of moulding sand with sodium silicate. Both the packing degree and the amount of sodium silicate in moulding sand turned out to affect the penetration depth, which directly translates into microwave power density distribution in the process of microwave heating of moulding sand with sodium silicate.
EN
The aim of the study was to determine the applicability of a new product added to water glass-containing foundry sands hardened with ethylene glycol diacetate. The new additive designated by the symbol "B" is a composition of aqueous solutions of modified polyalcohols, improving the sand knocking out properties. The scope of studies included testing various mechanical and technological properties of foundry sand mixtures, such as permeability, friability, life cycle of cores and knocking out properties. In the technological studies, two types of water glass with different values of the silica modulus and density, designated as R145 and R150, were used. Moulding sands were prepared with the additive "B". For comparison, reference sands with water glass but without the additive "B" were also made. In Part I of the article, the results of studies of the effect of additive "B" on the properties of foundry sands with water glass hardened by CO2 blowing were discussed.
EN
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.
EN
The effects of silica additive (Poraver) on selected properties of BioCo3 binder in form of an aqueous poly(sodium acrylate) and dextrin (PAANa/D) binder were determined. Based on the results of the thermoanalytical studies (TG-DTG, FTIR, Py-GC/MS), it was found that the silica additive results in the increase of the thermostability of the BioCo3 binder and its contribution does not affect the increase in the level of emissions of organic destruction products. Compounds from group of aromatic hydrocarbons are only generated in the third set temperature range (420-838°C). The addition of silicate into the moulding sand with BioCo3 causes also the formation of a hydrogen bonds network with its share in the microwave radiation field and they are mainly responsible for maintaining the cross-linked structures in the mineral matrix system. As a consequence, the microwave curing process in the presence of Poraver leads to improved strength properties of the moulding sand […]. The addition of Poraver's silica to moulding sand did not alter the permeability of the moulding sand samples, and consequently reduced their friability. Microstructure investigations (SEM) of microwave-cured samples have confirmed that heterogeneous sand grains are bonded to one another through a binder film (bridges).
EN
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.
EN
A large number of defects of castings made in sand moulds is caused by gases. There are several sources of gases: gases emitted from moulds, cores or protective coatings during pouring and casting solidification; water in moulding sands; moisture adsorbed from surroundings due to atmospheric conditions changes. In investigations of gas volumetric emissions of moulding sands amounts of gases emitted from moulding sand were determined - up to now - in dependence of the applied binders, sand grains, protective coatings or alloys used for moulds pouring. The results of investigating gas volumetric emissions of thin-walled sand cores poured with liquid metal are presented in the hereby paper. They correspond to the surface layer in the mould work part, which is decisive for the surface quality of the obtained castings. In addition, cores were stored under conditions of a high air humidity, where due to large differences in humidity, the moisture - from surroundings - was adsorbed into the surface layer of the sand mould. Due to that, it was possible to asses the influence of the adsorbed moisture on the gas volumetric emission from moulds and cores surface layers by means of the new method of investigating the gas emission kinetics from thin moulding sand layers heated by liquid metal. The results of investigations of kinetics of the gas emission from moulding sands with furan and alkyd resins as well as with hydrated sodium silicate (water glass) are presented. Kinetics of gases emissions from these kinds of moulding sands poured with Al-Si alloy were compared.
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