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The Influence of Inorganic Binder Type on Properties of Self-Hardening Moulding Sands Intended for the Ablation Casting Process

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Puzio S. , Kamińska J. , Angrecki M. , Major-Gabryś K.

Journal of Applied Materials Engineering

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2020

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tom Vol. 60, iss. 4

99--108

EN

The aim of the present work is to compare the properties of self-hardening moulding sands based on inorganic binders based on sodium silicate of different modules, geopolymer binders and phosphate binders and to prove they can be used in the ablation casting process. Ablation casting is a process in which, directly after pouring the liquid alloy, the mould is sprayed with water until it is completely eroded and a finished, cooled casting is obtained. The use of proecological water-dilutable binder makes it possible to recover the sand matrix after drying the suspension that remains after the process. Moulding sands were prepared on the basis of four inorganic binders available on the market. For each of the moulding sands the bending strength was tested after 1, 2, 4 and 24 h of hardening. Then, the masses with optimum bending strength were selected and subjected to gas emissivity tests. A thermal analysis of moulding sands selected for testing was also carried out in order to determine the loss of mass during annealing. The susceptibility of moulds to erosion under the influence of ablative medium was also assessed by measuring the time of mould erosion. Tests showed the possibility of using self-hardening moulding sands based on inorganic binders for the ablation casting process of aluminium-silicon alloys.

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The Effect of Zirconium as an Alloying Additive on the Microstructure and Properties of AlSi9Mg Alloy Cast in Sand Moulds

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Kamińska J. , Angrecki M. , Dudek P.

Archives of Foundry Engineering

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2022

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tom Vol. 22, iss. 4

5--13

EN

The aim of the study was to select the optimal content of zirconium introduced as an alloying additive to obtain the best strength properties of Al-Si alloy. A technically important disadvantage is the tendency of silumins to form a coarse-grained structure that adversely affects the mechanical properties of castings. To improve the structure, modification processes and alloying additives are used, both of which can effectively refine the structure and thus increase the mechanical properties. According to the Hall-Petch relationship, the finer is the structure, the higher are the mechanical properties of the alloy. The proposed addition of zirconium as an alloying element has a beneficial effect on the structure and properties of silumins, inhibiting the grain growth. The starting material was an aluminium-silicon casting alloy designated as EN AC-AlSi9Mg (AK9). Zirconium (Zr) was added to the alloy in an amount of 0.1%, 0.2%, 0.3%, 0.4% and 0.5% by weight. From the modified alloy, after verification of the chemical composition, samples were cast into sand moulds based on a phenolic resin. The first step in the research was testing the casting properties of alloys with the addition of Zr (castability, density, porosity). In the next step, the effect of zirconium addition on the structure and mechanical properties of castings was determined.

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Studies of mechanical and technological parameters and evaluation of the role of lustrous carbon carriers in green moulding sands with hybrid bentonite

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Kamińska J. , Stachowicz M. , Puzio S. , Angrecki M.

Archives of Civil and Mechanical Engineering

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2023

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tom Vol. 23, no. 1

art. no. e11, 2023

EN

Green moulding sands containing special carbonaceous additives, which are the source of lustrous carbon (LC), are discussed in this paper. Five potential lustrous carbon carriers, i.e., two types of hard coal dust (No.1 and No.2), amorphous graphite (No.3) and two hydrocarbon resins (No.4 and No.5), were selected for tests as carbonaceous additives to conventional moulding sands. To better emphasize the differences in the additives used, reference green moulding sand (GMS1) was prepared and subjected to a wide range of basic tests focussed on technological parameters, such as permeability (Pw), friability (Fw), Dietert mouldability test (PD) and compactability (Z) and mechanical parameters, such as compressive strength (Rcw), tensile strength (Rmw), strength in the transformation zone (Rkw). The proposed comprehensive spectrum of tests was repeated on sands with five carbonaceous additives. The most important for the use of additives as carbon carriers was to interrelate the content of lustrous carbon (LC), loss on ignition (LOI) and the obtained results of mechanical and technological tests carried out on conventional moulding sands with the surface quality of iron castings. For this purpose, a series of iron castings was made in the prepared moulding sands and used for the assessment of surface quality based on a number of roughness parameters (Ra, Rz, Rp, Rq, Rv, Rlr, RSm). As a result of the studies it was found that the carbonaceous additives proposed for use help to obtain high-quality surfaces in iron castings.

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The Effect of the Addition of Bentonite Clay to Traditional Sand Mixtures on the Surface Quality of Iron Castings

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Kamińska J. , Puzio S. , Angrecki M. , Stachowicz M.

Journal of Ecological Engineering

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2020

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tom Vol. 21, nr 1

160--167

EN

Successful casting demands that during pouring of the foundry mould with molten metal the mould cavity suffers no deformation. This, in turn, demands the use of binding materials that can give the base sand adequate strength. The main bonding materials are clay binders. The foundry industry uses minerals rich in clay, such as kaolinite, halloysite, hydromica, montmorillonite, polygorskite, vermiculite and allophane. Due to their binding capacity, montmorillonites are the most interesting minerals of all the plastic clay rocks. The basic clay rock containing montmorillonite, used as a common binding material for traditional foundry sand mixtures, is bentonite. The domestic demand for raw bentonite materials is almost entirely satisfied by imports from Slovakia, Turkey, Italy, Germany and the Czech Republic, in order of import size. In Poland, the bentonite deposits occur in very small quantities. The exploitation of bentonites is carried out only in the Krzeniów deposit, where they constitute a mineral accompanying basalt. Much more common are bentonite clays containing in addition to smectites also a large amount of other clay minerals. The article presents the results of studies of the physico-chemical and mechanical properties of moulding sand mixtures containing pure bentonite, pure clay or hybrid bentonites which are a bentonite-clay mixture. Melting was also carried out to determine the effect of the type of binder on the surface quality of iron castings.

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Utwardzane mikrofalowo masy formierskie ze spoiwami nieorganicznymi przeznaczone do odlewania ablacyjnego

88%

Puzio S. , Kamińska J. , Angrecki M. , Hosadyna-Kondracka M. , Major-Gabryś K.

Przegląd Odlewnictwa

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2019

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tom Vol. 69, nr 5-6

114--120

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.

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Preliminary Tests of Innovative Eco-Friendly Furfuryl Resins and Foundry Sand Mixtures Based on These Resins

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Kamińska J. , Puzio S. , Angrecki M. , Stachowicz M. , Łoś A.

Journal of Ecological Engineering

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2019

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tom Vol. 20, nr 9

285--292

EN

The foundry industry in Poland and EU member states is growing steadily. The alloys based on ferrous metals (cast steel and cast iron) largely contribute to this upward trend. Currently, foundries are facing the problem of increasing requirements, which enforce the production of castings characterized by high dimensional accuracy and surface smoothness with parallel elimination of casting defects. Castings are mostly made in moulding sand mixtures, which are also subject to more and more stringent requirements to meet the above-mentioned casting acceptance conditions. Additionally, moulding sands should ensure adequate mould stiffness to avoid the risk of dimensional deformations during the pouring of liquid metal to this mould and casting solidification. For these reasons, the production of this type of castings has been dominated by loose self-hardening sands with furfuryl resin, commonly called furan sands. In the group of self-hardening sands with synthetic resins, loose self-hardening sands with furfuryl resin enjoy the greatest popularity. What accounts for this fact is the high level of the reclamability of these sands, the possibility of obtaining castings with high dimensional accuracy, the ability to make intricate moulds and cores, the binding process taking place at ambient temperature, and low content of binder. Unfortunately, this technology also has some disadvantages, which include short lifetime of the sand mixture, harmful gases emitted from the sand, and currently also high cost of the sand mixture. The anticipated tightening of the environmental protection regulations in the EU countries, including limiting the content of free furfuryl alcohol in resins (<25% by mass) and reducing the emission of furfuryl alcohol, formaldehyde and BTEX compounds at workplaces, necessitated the development of a new generation of furfuryl resins friendly to the environment. The article compares the results of testing the strength properties of foundry moulding sands using two types of resins, i.e. the resin of a new generation synthesized by Grupa Azoty JRCh and a commercial resin used in the foundry industry. Additionally, derivatographic studies of the above mentioned sand mixtures were conducted, and the loss on ignition and the amount of gases emitted by the sand mixture were determined. Melting was also carried out to study the impact of the resin used on the surface quality of iron castings.