Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 12

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  foundry materials
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
The paper presents results of initial research on the possibility of applying microwave radiation in an innovative process of making casting moulds from silica sand, where gypsum CaSO4∙2H2O was acting as a binding material. In the research were compared strengths and technological properties of moulding mixture subjected to: natural bonding process at ambient temperature or natural curing with additional microwave drying or heating with the use of microwaves immediately after samples were formed. Used in the research moulding sands, in which dry constituents i.e. sand matrix and gypsum were mixed in the ratio: 89/11. On the basis of the results of strength tests which were obtained by various curing methods, beneficial effect of using microwaves at 2.45 GHz for drying up was observed after 1, 2 and 5 hours since moisture sandmix was formed. Applying the microwaves for hardening just after forming the samples guarantees satisfactory results in the obtained mechanical parameters. In addition, it has been noted that, from a technological and economic point of view, drying the silica sand with gypsum binder in microwave field can be an alternative to traditional molding sand technologies.
EN
The article presents the results of studies which form a part of broader research programme executed under the project POIG.01.01.02-00-015/09 "Advanced materials and technologies". In a concise manner, the results of studies on the effect of chemical modification of inorganic binders on the technological properties of moulding sands containing these binders were presented. Special attention was paid to the effect of modification of inorganic binders on their thermal destruction behaviour in the range of pouring temperatures of the non-ferrous metals and their alloys. Also the results of comparative studies of the thermal emission of toxic gases and odours from moulding sands with new inorganic and organic binders were discussed.
3
Content available remote New generation of pattern materials for investment casting
EN
Pattern mixtures (so-called soft mixtures) currently used in investment casting are composed of paraffin, stearin, and - to a lesser extent - of ceresin, polyethylene wax and other natural and synthetic waxes. During studies, several types of soft pattern mixtures were developed by modifying the already existing compositions with appropriate additives. Based on the studies of physico-chemical and performance properties, the composition of pattern material was optimised.
EN
The article discusses the process of advanced oxidation (AO) with application of ultrasounds and surface modification of the dust waste collected during dry dedusting of processed moulding sands with bentonite binder. A beneficial effect of both AO and adsorption modification of dust waste, when performed with the selected type of polyelectrolyte, on the technological and mechanical properties of moulding sands prepared with an addition of this dust has been stated. In spite of the bentonite content in moulding sand reduced by 43% and replaced with modified dust waste, the mechanical properties, i.e. the compression and tensile strengths, examined on sand specimens have been improved by 10% and 13%, respectively, with no harm to other basic technological sand properties. At the same time, it was also possible to reduce by about 30% the emission rate of the main gaseous component from the BTEX group, i.e. benzene.
EN
Technological problems related to mastering the production of castings made of ferritic-austenitic cast steel (duplex type), i.e problems related to low carbon content (Cmax 0.03%) and high hot cracking susceptibility due to phenomena taking place during solidification and cooling of castings, cause that this material, although attractive due to its price and improving company prestige, is rarely produced in Poland. The undertaken attempts have mainly dealt with GX2CrNiMoCu25-6-3-3 grade containing copper due to the requirements of power industry which is the main possible customer with respect to the elements made of duplex cast steel. The authors of this paper have thought it reasonable to present selected aspects of microstructural and mechanical properties for the two cast steel grades described in the PN-EN 10283:2002 Standard, which differ only by Cu addition. The examinations concerned mainly the as-cast condition, because it is decisive for the defective production. It has been shown that the weak austenite-forming copper exerts a strong influence on the primary structure of cast steel, resulting in precipitating the [...] austenite within ferrite, where the austenite is crystallographically dependent on the matrix. The GX2CrNiMoCu25-6-3-3 cast steel in supersaturated state is characterised by Charpy V-notch impact energy lower by about 30% than for the cast steel grade without Cu addition.
6
Content available remote The analysis of solidification process of ferritic-austenitic cast steel
EN
One of the most common defects leading to the rejection of faulty castings made of duplex cast steel is hot cracking. Hot cracking - differently from cold cracking which occur on cooling, when the material exhibits already distinct elastic properties - proceeds in the semi-solid state, particularly when the temperature of solidifying casting is close to the equilibrium solidus point. There exist a range of temperatures in the vicinity of the solidus point within which the solidifying metal shows very small deformation ability and small strength. Therefore even little stresses occurring at the solidification stage and caused by density difference between ferrite and austenite, or restricted shrinkage, or various temperature gradients, can be the reason of hot cracking. Copper addition, as it is used in cast steel grades implemented in Polish power industry applications, decreases the temperature of the end of solidification, thus affecting beneficially the surface reproduction quality, but on the other hand it can promote, along with several other elements contained in duplex cast steel, the peritectic transformation during the last stage of solidification. The presence of peritectic solidification, i.e. strictly speaking the structural stresses accompanying that process, is the well-known and significant reason of the increased steel defectiveness in the continuous steel casting (CSC) technology if the steel with carbon content promoting the peritectic transformation is processed. The authors have presented the examination results of the solidification phenomenon for two duplex cast steel grades - one without copper addition, and the other with addition of about 3.0% Cu.
EN
The article presents the results of investigations, which make a fragment of the broad-scale studies carried out as a part of the statutory activity on optimising the foundry sand technology using new, modified, inorganic binders. The results of investigations regarding the effect of lustrous carbon carriers on the technological properties of foundry sands with inorganic binders were presented in a concise manner. The selected additives were introduced to moulding sands prepared with the new, modified, inorganic binders bonded by the chemical reaction or by blowing with gaseous CO2. Attention was focussed on the effect of selected additives promoting the formation of lustrous carbon on the knocking out properties of moulds and cores prepared from sands with the new types of inorganic binders. The quality of the test castings was also evaluated along with the tendency to the formation of lustrous carbon at the metal - mould interface, basing on the results of microscopic examinations and analysis of the chemical composition using an X-ray microanalyser.
EN
This article presents results of the experimental trial of combination of the chemical method of water glass molding sands' curing, used in foundry industry, with an innovative microwave heating. The research objective was to indicate at new areas of microwave energy application. The sands prepared, according to recommendations for curing technology, with the use of ethylene glycol diacetate, have been subject to microwave influence. The attempt at determination of microwave influence on qualitative changes of the binding bridges created during the curing process concerned such parameters as: bending and tensile strength, permeability as well as wear resistance. Moreover, we also determined the influence of microwave curing on the phenomena accompanying the process as well as bond stability (storage time of the prepared molding and core sands). It has been found, basing on the result analysis, that the innovative microwave heating might constitute a very good supplementation of the ester curing method. The advantages of the combined chemical and microwave gelation process include, among others, improvement of the described resistance and technological parameters as well as significant decrease of preparation time of foundry moulds and cores. The subject discussed in this article will be continued in its second part.
EN
This article, constituting continuation of the subject discussed in the first part, presents results of the experimental trial of water glass molding sands' curing method modification with application of fluid esters and innovative microwave heating. The research objective was to determine possibilities of microwave application for curing of water glass molding sands prepared with addition of hardening agents sold under the trade name of Mach. After initial chemical curing molding sands, prepared with addition of the above mentioned hardeners, have been heated with microwaves in order to determine their influence on changes of basic technological and strength parameters of the sands, and indirectly on the quality of quartz grains binding. Studies aimed at determination of water content changes in the sands have also been undertaken. As our studies demonstrated, microwave heating allows for quick reduction of water content, thus resulting in improvement of strength parameters such as bending and tensile strength. Application of the combined methods of ester curing and innovative microwave heating facilitates production of high quality foundry moulds and cores, while simultaneously improving mould and core preparation procedures at the foundries and as a result reduces their time to an indispensable minimum.
10
Content available remote Dilatometric studies of plaster sandmix in raw and heat treated state
EN
Results of dilatometric studies of bounded plaster sandmix applied in precision pressure below atmospheric casting, are presented in this paper. Sandmix composed of half-hydrate alpha-CaSO4ź2H2O with different parts of silica SiO2 was a subject of investigations. Silica is a factor weakening the influence of phase transformations on total distortion of the mould during heating and thus influences the accuracy of prepared cast. Experimental moulders of dimensions 735 made of plaster sandmix with silica fraction equal 30; 40; 50; 60 and 70% were used during studies. Sandmix was tested in raw state and after heat treatment changing the alpha-half hydrate into anhydrite II (CaSO4). It was demonstrated that addition of the silica at level about 50% influences most advantageously on dimension changes of heated sandmix by lowering dilatations 3 times in comparison with sandmix composed of pure alpha-half hydrate. The transformation of plaster structure into anhydrite II is also important - the shrinkability phase disappears and expansion similar to linear-like appears. It was determined that it is possible to obtain sandmix of small, stabile distortion on the way of appropriate selection of components and heat treatment parameters what improves dimensional and shape accuracy limits of the cast and significantly limits internal stresses in the mould eliminating risk of its cracking.
PL
Artykuł prezentuje jeden z najbardziej korzystnych kierunków rozwoju światowej energetyki -wykorzystanie siłowni wiatrowych. Jedną trzecią masy instalacji siłowni wiatrowej stanowią odlewy. Do 2006 roku przewidywany jest wzrost zapotrzebowania na tego rodzaju odlewy, a co za tym idzie szans dla europejskiego i polskiego odlewnictwa. Krakowskie Przedsiębiorstwo METALODLEW SA, za główny element swojej strategii rozwoju, przyjęło zwiększenie produkcji wielkogabarytowych, zaawansowanych technicznie odlewów z wysokojakościowych tworzyw odlewniczych, przeznaczonych głównie na eksport. Elementy dla siłowni zaliczają się właśnie do tej grupy odlewów. Wyzwaniem dla METALODLEWU i krakowskiego środowiska naukowego, z którym Przedsiębiorstwo to współpracuje, było zlecenie wykonania odlewu platformy siłowni wiatrowej typu N-60 według ściśle wyznaczonych warunków odbioru, kontroli jakości oraz sposobów zabezpieczenia antykorozyjnego. Autorzy artykułu przedstawili charakterystykę odlewu platformy siłowni wiatrowej typu N-60 oraz prace przygotowawcze do realizacji zlecenia. W zakończeniu podano uzyskane własności mechaniczne odlewu, pozwalające na jego zastosowanie w ekstremalnych warunkach obciążenia statyczno-dynamicznego i w niskiej temperaturze.
EN
The article presents one of the most advantageous trends of the development in the world power industry, it means the wind power stations. One third of the weight of the installations in the wind power stations consists of castings. Till the year 2006 the increase in the demand for such castings and what is connected with it, the increase in the chances of the European and Polish foundries is foreseen. The Enterprise METALODLEW S.A. (Joint Stock Company) in Krakow as the main element of its development strategy assumed an increase in the production of large-sized, technologically advanced castings made in high quality foundry materials and designed chiefly for export. Among this group of castings are castings of parts for the wind power stations. A challenge for METALODLEW and the scientific circles in Krakow, with whom this enterprise cooperates, was an order for a casting of a platform for the wind power station of the type N-60 according to the strictly determined acceptance requirements, quality inspection and anticorrosion protection. The authors of the article presented the characteristics of the above-mentioned casting of the platform and the preparatory work connected with the realisation of this order for the wind power station of the type N-60. Finally, the obtained mechanical properties of this casting which allow its application under extreme static and dynamic loads and low temperature were given.
PL
W artykule przedstawiono działania i wyniki badań laboratoryjnych i przemysłowych, mających na celu ulepszenie poliuretanowego procesu cold-box. Proces poliuretanowy, umożliwiający szybkie uzyskiwanie rdzeni o dużej wytrzymałości, ma również mankamenty, które wymagały usunięcia lub, co najmniej, ograniczenia. Do mankamentów tych można zaliczyć, oprócz emisji substancji toksycznych, zapachu (odoru) i dymu, zbyt dużą wartość indeksu fenolowego oraz kondensację produktów pirolizy. Wprowadzane ulepszenia powodowały stopniową eliminację lub ograniczanie tych mankamentów i powstawanie kolejnych odmian poliuretanowego procesu cold-box, nazwanych w artykule generacjami. W 1. generacji zastąpiono rozpuszczalniki aromatyczne, dodawane do żywicy i poliizocyjanianu, olejemrzepakowym, co spowodowało zmniejszenie emisji substancj i toksycznych. Modyfikacjątej generacji było zastosowanie, jako rozpuszczalnika, estru metylowego kwasu tłuszczowego (2. generacja). W 3. generacji zredukowano zawartość wolnego fenolu w żywicy, co spowodowało znaczne zmniejszenie wartości indeksu fenolowego, ważnego wskaźnika przy ocenie możliwości wykorzystania masy zużytej. Ostatnim osiągnięciem było zastosowanie krzemianu etylujako rozpuszczalnika składników spoiwa (4. generacja). Jakość, toksyczność, wydzielanie zapachu oraz indeks fenolowy mas, uzyskiwanych przy stosowaniu poszczególnych odmian poliuretanowego procesu cold-box, zostały potwierdzone wynikami badań laboratoryjnych i/lub przemysłowych, które wykazały wyraźne stopniowe polepszanie procesu w stosunku do metody wyjściowej. Stwierdzono bowiem wyraźne zmniejszenie (o ok. 65-75%) stężenia wydzielanych substancji toksycznych, takich jak: benzen, toluen i ksylen. Wyraźnie została zmniejszona emisja zapa-chu oraz dymu, szczególnie po zastosowaniu krzemianu etylu jako rozpuszczalnika składników spoiwa. Ten nowy rozpuszczalnik spowodował także ograniczenie skłonności do kondensacji produktów pirolizy spoiwa. Zmniejszenie indeksu fenolowego (wg niemieckich przepisów LAGA) ułatwia gospodarkę materiałami formierskimi w odlewni, w zakresie możliwości wykorzystywania masy zużytej. Te korzystne zmiany mają istotne znaczenie praktyczne, gdyż obecnie ok. 50 % rdzeni wykonuje się metodą cold-box i stosowanie zmodyfikowanych odmian poliuretanowego procesu cold-box polepsza wyraźnie warunki pracy pod względem ochrony środowiska, higieny pracy i gospodarki materiałami formierskimi w odlewni.
EN
In the article the activities and results of laboratory and industrial tests, aiming at the improvement of the polyurethane cold-box process have been described. The polyurethane process, which enables quick fabrication of high-strength cores, has also some disadvantages which should be removed or at least limited. To these disadvantages can be included, besides the emission of toxic substances, also their odour and fumes, too high value of phenol index and condensation of the pyrolysis products. The improvements, which were being introduced, caused gradual elimination or reduction of these disadvantages and the development of new variants of polyurethane cold-box process, called in the article "generations", was continued. In the first generation the aromatic solutions added to the resin and polyisocyanate were substituted by rape oil, what caused a reduction of the emission of toxic substances. A modification in this generation was using, as solution, methyl ester of the fatty acid (the second generation). In the third generation the content of free phenol was reduced in the resin, which resulted in the reduction of the value of phenol index, an important index when evaluating the possibility of utilisation of the used moulding sand. The last achievement was the application of the ethyl silicate as a solution of the binder components (the fourth generation). The quality, toxicity, and the emission of odour, produced when using the particular generations of polyurethane cold-box process, were confirmed by the laboratory and/or industrial tests. These tests indicated a distinct gradual improvement of the process in relation to the initial method. A considerable reduction (by about 65-75%) of the condensation of the emitted toxic substances such as: benzene, toluene and xylene was stated. The emission of the odour and fumes was also considerably reduced, especially after the application of ethyl silicate as a solvent of the binder components. This new solvent also reduced the tendency to condensation in the products of the binder pyrolysis. The reduction of the emission factor (according to the German LAGA regulations) makes easier the management of moulding matenals in a foundry shop as regards the possibility to reuse the waste sand. These advantageous changes are of an essential practical importance because now about 50% of cores are made by the cold-box method and the application of the modified variants of the polyurethane cold-box process considerably improves the working conditions, the environmental protection, work safety and economy of foundry materials in foundries.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.