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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

Kamińska Jadwiga, Stachowicz Mateusz, Puzio Sabina, Angrecki Michał

Archives of Civil and Mechanical Engineering

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2023

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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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Computer modelling of the ablation casting process and prediction of the strength properties of AC-42000 castings

Małysza Marcin, Puzio Sabina, Major-Gabryś Katarzyna, Głowacki Mirosław, Wilk-Kołodziejczyk Dorota, Kamińska Jadwiga

Computer Methods in Materials Science

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2022

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Vol. 22, No. 2

79--88

EN

The demand for castings with superior properties has compelled the development and optimization of manufacturing technologies. By further developing already known techniques, we are able to contribute to the introduction of new research possibilities. The article presents the methodology of conducting simulation tests of the gravity casting process into sand moulds with the use of ablation. The ablation technique consists in spraying water through evenly spaced nozzles onto a mould into which the liquid casting alloy has been poured. The conducted research focuses on an alloy from the group of Al-Si alloys. In order to compare the effects of different techniques, additional tests were carried out for gravity casting into sand and metal die moulds. At the same time, virtual experiments were conducted to develop a simulation methodology for ablation casting technology, taking into account mould degradation. Additionally, the possibility of predicting the final mechanical properties of various manufacturing technologies was tested. Destructive tests were carried out to determine the mechanical properties in the cast samples, as well as microstructure tests and secondary dendrite spacing. The results of the mechanical tests are compared with the predicted simulation properties.

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The Use of Phosphate Binder for Ablation Casting of AlSi7Mg Modified TiB Alloy

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

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 1

62--68

EN

The possibilities of using an inorganic phosphate binder for the ablation casting technology are discussed in this paper. This kind of binder was selected for the process due to its inorganic character and water-solubility. Test castings were made in the sand mixture containing this binder. Each time during the pouring liquid alloy into the molds and solidification process of castings, the temperature in the mold was examined. Then the properties of the obtained castings were compared to the properties of the castings solidifying at ambient temperature in similar sand and metal molds. Post-process materials were also examined - quartz matrix and water. It has been demonstrated that ablation casting technology promotes refining of the microstructure, and thus upgrades the mechanical properties of castings (Rm was raised about approx. 20%). Properties of these castings are comparable to the castings poured in metal moulds. However, the post-process water does not meet the requirements of ecology, which significantly reduces the possibility of its cheap disposal.

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The Influence of Various Matrixes on the Strength Properties of Moulding Sands with Thermally Hardened Hydrated Sodium Silicate for the Ablation Casting Process

Major-Gabryś Katarzyna, Puzio Sabina, Bryłka Agata, Kamińska Jadwiga

Journal of Casting & Materials Engineering

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2021

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Vol. 5, no. 2

31--35

EN

The essence of ablation casting technology consists in pouring castings into single-use moulds made from the mixture of sand and a water-soluble binder. After pouring the mould with liquid metal yet 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 ablation casting. The research is based on the use of water glass 145 and 150 as binders. As part of the research, loose moulding mixtures based on two silica sands from different sand mines with different content of binders were prepared. 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. Our own research also confirmed the possibility of using these sand mixtures in terms of both casting surface quality and sand reclamation. The results presented in this paper prove that both sand grains and types of binder tested may be used as components in moulding sands devoted to ablation casting.

5

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

Kamińska Jadwiga, Puzio Sabina, Angrecki Michał, Stachowicz Mateusz

Journal of Ecological Engineering

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2020

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

Puzio Sabina, Kamińska Jadwiga, Angrecki Michał, Major-Gabryś Katarzyna

Journal of Applied Materials Engineering

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2020

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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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Utwardzane mikrofalowo masy formierskie ze spoiwami nieorganicznymi przeznaczone do odlewania ablacyjnego

Puzio Sabina, Kamińska Jadwiga, Angrecki Michał, Hosadyna-Kondracka Małgorzata, Major-Gabryś Katarzyna

Przegląd Odlewnictwa

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2019

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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

Kamińska Jadwiga, Puzio Sabina, Angrecki Michał, Stachowicz Mateusz, Łoś Anna

Journal of Ecological Engineering

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2019

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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.