In this paper the results of studies of polymeric binders on the example of the new BioCo2 binder, including the problem of its renewability, are presented. The results of structural studies (FT-IR) for the BioCo2 binder before and after crosslinking, and bending strength tests Rg u fresh and renewed cured molding sands with BioCo2 binder are discussed. The cross-linking binder and curring of moulding sand was carried out by physical agents (microwave radiation, temperature). On the basis of obtained results was shown that it is possible to restore the initial properties of the adhesive of BioCo2 binder. The initial properties of moulding sand can be achieved, after the cross-linking binders and after curing in the moulding sands with bioCo2 binder , by supplementing the moulding sand composition by the appropriate amount of water.
No-bake process refers to the use of chemical binders to bond the moulding sand. Sand is moved to the mould fill station in preparation for
filling of the mould. A mixer is used to blend the sand with the chemical binder and activator. As the sand exits the mixer, the binder
begins the chemical process of hardening. This paper presents the results of decomposition of the moulding sands with modified ureafurfuryl
resin (with the low content of furfuryl alcohol below 25 % and different activators: organic and inorganic) on a quartz matrix,
under semi-industrial conditions. Investigations of the gases emission in the test foundry plant were executed according to the method
extended in the Faculty of Foundry Engineering (AGH University of Science and Technology). Article presents the results of the emitted
chosen aromatic hydrocarbons and loss on ignition compared with the different activators used to harden this resin. On the bases of the
data, it is possible to determine the content of the emitted dangerous substances from the moulding sand according to the content of loss on
ignition.
Emission of gases under high temperature after pouring molten metal into moulds, which contain the organic binder or other additives
(solvents or curing agent), may be an important factor influencing both on the quality of the produced castings, and on the state of
environment. Therefore, a comprehensive study of the emitted gases would allow to determine restrictions on the use of the moulding
sands in foundry technologies, eg. the probability of occurrence of casting defects, and identify the gaseous pollutants emitted to the
environment. The aim of the research presented in this paper was to determine the amount of gases that are released at high temperatures
from moulding sands bonded by biopolymer binder and the quantitative assessment of the emitted pollutants with particular emphasis on
chemical compounds: benzene, toluene, ethylbenzene and xylenes (BTEX). The water-soluble modified potato starch as a sodium
carboxymethyl starch with low (CMS-NaL) or high (CMS-NaH) degree of substitution was a binder in the tested moulding sands.
A tests of gases emission level were conducted per the procedure developed at the Faculty of Foundry Engineering (AGH University of
Science and Technology) involving gas chromatography method (GC). The obtained results of the determination of amount of BTEX
compounds generated during the decomposition process of starch binders showed lower emission of aromatic hydrocarbons in comparison
with binder based on resin Kaltharz U404 with the acidic curing agent commonly used in the foundries.
The article presents research results of physico-chemical and environmental issues for the dust generated during dedusting of the
installation for the processing and preparation of moulding sand with bentonite. Particular attention was paid to the content of heavy
metals and emission of gases from the BTEX group, which is one of the determinants of the moulding sands harmfulness for the
environment. The analysis of heavy metals in the test samples indicate that there is an increase of the content of all metals in the dust
compared to the initial mixture of bentonite. The most significant (almost double) increase observed for zinc is probably related to the
adsorption of this element on the dust surface by contact with the liquid metal. The study showed, that dust contained more than 20% of
the amount of montmorillonite and had a loss on ignition at a similar level. The addition of 1% of dust to the used moulding sand results in
almost 30% increase in the total volume of gases generated in casting processes and nearly 30% increase of the benzene emission.
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.
The spectroscopic FT-IR and FT-Raman methods allowed to identify the cross-linking process of the aqueous composition of poly(acrylic
acid)/sodium salt of carboxymethyl starch (PAA/CMS-Na) applied as a binder for moulding sands (as a novel group binders BioCo). The
cross-linking was performed by physical agent, applying the UV-radiation. The results of structural studies (IR, Raman) confirm the
overlapping of the process of cross-linking polymer composition PAA/CMS-Na in UV radiation. Taking into account the ingredients and
structure of the polymeric composition can also refer to a curing process in a binder - mineral matrix mixture. In the system of bindermineral
matrix under the influence of ultraviolet radiation is also observed effect of binding. However, the bonding process does not occur
in the entire volume of the investigated system, but only on the surface, which gives some possibilities for application in the use of UV
curing surface of cores, and also to cure sand moulds in 3D printing technology
The problem of harmful casting resins has been present in foundries for many years. Manufacturers are introducing new products that contain in their composition environmentally and eco-friendly ingredients. Unfortunately, not all types of technology can be used, sometimes environmental benefits are disproportionate to the quality of castings and their price. In the foundry industry, the most popular binders are based on organic compounds (often carcinogenic) and other harmful substances. Due to strict legal regulations regarding environmental protection, as well as care for the foundry's workers' comfort - their occurrence should be reduce to a minimum. These compounds often behave also depending on the conditions of use (temperature, atmosphere). The application of various methods of thermal analysis and spectroscopic methods allows to verify the mechanism of resin decomposition process in relation to conditions in the form in both inert and oxidizing atmosphere. For analysis the resins from cold-box technology, were used TG–DTG–DSC, Py-GC/MS methods and specified the course of changes occurring in combination of different atmosphere.
In many foundries, the requirements placed on castings production have risen mainly over the few years. Further trends in recent years have been the ever increasing level of automation and introduction of new alloys, especially composites. On the other hand, the foundry environment has become increasingly difficult because is used many organic binders. Environmental regulations will be further tightened up. These processes are pursued at national, European and global level. Conformity with emission limits is becoming increasingly difficult. The problem is emission of aromatic hydrocarbons, phenol, odours and other harmful compounds to environment. The main purpose of many companies is reduction of this toxins. The new cold-box systems (based on phenolic resins) try to reduce the emission by introducing into the resin structure silicate modifiers. Research presented of this article evaluate the effectiveness of these methods. The results show comparison of two resins ("without" and "with" silicate modifier) for assessment of emission of harmful aromatic hydrocarbons and phenol.
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).
It was found that the addition of carbon fibers (CFs) does not affect the crosslinking process in the microwave radiation (800 W, 2.45
GHz) of the BioCo2 binder, which is a water solution of poly(acrylic acid) and dextrin (PAA/D). It has influence on BioCo2 thermal
properties. The CFs addition improves the thermostability of a binder and leads to the reduction of gas products quantity generated in the
temperature range of 300-1100°C (TG-DTG, Py-GC/MS). Moreover, it causes the emission of harmful decomposition products such as
benzene, toluene, xylene and styrene to be registered in a higher temperatures (above 700°C). BioCo2 binder without CFs addition is
characterized by the emission of these substances in the lower temperature range. This indicates the positive effect of carbon fibers
presence on the amount of released harmful products.
The selected technological tests (permeability, friability, bending strength, tensile strength) have shown that the moulding sand with the
0.3 parts by weight carbon fibers addition displays the worst properties. The addition of 0.1 parts by weight of CFs is sufficient to obtain a
beneficial effect on the analyzed moulding sands properties. The reduction of harmful substances at the higher temperatures can also be
observed.
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).
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.
In order to increase wear resistance cast steel casting the TiC-Fe-Cr type composite zones were fabricated. These zones were obtained by
means of in situ synthesis of substrates of the reaction TiC with a moderator of a chemical composition of white cast iron with nickel of
the Ni-Hard type 4. The synthesis was carried out directly in the mould cavity. The moderator was applied to control the reactive
infiltration occurring during the TiC synthesis. The microstructure of composite zones was investigated by electron scanning microscopy,
using the backscattered electron mode. The structure of composite zones was verified by the X-ray diffraction method. The hardness of
composite zones, cast steel base alloy and the reference samples such as white chromium cast iron with 14 % Cr and 20 % Cr, manganese
cast steel 18 % Mn was measured by Vickers test. The wear resistance of the composite zone and the reference samples examined by ballon-disc
wear test. Dimensionally stable composite zones were obtained containing submicron sizes TiC particles uniformly distributed in
the matrix. The macro and microstructure of the composite zone ensured three times hardness increase in comparison to the cast steel base
alloy and one and a half times increase in comparison to the white chromium cast iron 20 % Cr. Finally ball-on-disc wear rate of the
composite zone was five times lower than chromium white cast iron containing 20 % Cr.
Refinement is one of the most energy consuming technological process, aimed at obtaining mineral raw materials of the proper grain size.
Cast structural elements such as jaws or hammers in crushing machines operate under conditions of an intensive wear. The data indicate
that 80 % of failures of machines and devices is caused by wearing of rubbing surfaces. This problem became the subject of several
scientific and industrial investigations carried out in the whole world in order to produce materials ultra- wear resistant. Methods allowing
to obtain wear resistant composite castings are discussed in the hereby paper. Within the performed research microstructures of the
produced composite zones were presented and the comparative analysis with regard to mechanical and functional properties of local
composite reinforcements in relation to the commercial alloys of increased wear resistance was performed. The results show almost twenty
five times increase in wear resistance compared to manganese cast steel containing 18 % Mn.
This paper focuses on the thermal behavior of the starch-based binder (Albertine F/1 by Hüttenes-Albertus) used in foundry technology of molding sand. The analysis of the course of decomposition of the starch material under controlled heating in the temperature range of 25-1100°C was conducted. Thermal analysis methods (TG-DTG-DSC), pyrolysis gas chromatography coupled with mass spectrometry (Py-GC/MS) and diffuse reflectance spectroscopy (DRIFT) were used. The application of various methods of thermal analysis and spectroscopic methods allows to verify the binder decomposition process in relation to conditions in the form in both inert and oxidizing atmosphere. It was confirmed that the binder decomposition is a complex multistage process. The identification of CO2 formation at set temperature range indicated the progressive process of decomposition. A qualitative evaluation of pyrolysis products was carried out and the course of structural changes occurring in the presence of oxygen was determined based on thermo-analytical investigations the temperature of the beginning of binder degradation in set condition was determined. It was noticed that, significant intensification of Albertine F/1 sample decomposition with formation of more degradation products took place at temperatures above 550ºC. Aromatic hydrocarbons were identified at 1100ºC.
The paper presents the results of an investigation of the gases emission 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 in accordance with the procedure developed at the Faculty of Foundry Engineering of AGH - University of Science and Technology, on the patented stand for determining gas emissions. Quantification of BTEX compounds was performed involving gas chromatography method (GC).The study showed that the introduction of relaxation additive has no negative impact on gas emissions - both in terms of the total amount of gases generated, as well as emissions of BTEX compounds. Among the BTEX compounds, only benzene is emitted from the tested moulding sands. Its emission is associated with the introduction a small amount of an organic hardener from the group of esters.
The study investigates the effect of the organic compound representing the cellulose derivative - sodium salt of carboxymethyl cellulose (CMC/Na) on the structure of the main component of bentonite (B) - montmorillonite (MMT). Structural analysis revealed that the CMC/Na of different viscosity interacts with the mineral only via surface adsorption, causing at the same time partial or full delamination of its layered structure. This was confirmed by the XRD diffraction tests. Such polymer destructive influence on the structure of the modified main component of the bentonite limits the use of its composites as an independent binder in moulding sand technology, but does not exclude it from acting as an additive being a lustrous carbon carrier. According to the IR spectra of the B/CMC/Na materials, it can be stated that the interaction between the organic and inorganic parts is based on the formation of hydrogen bonds. That kind of the interpretation applies especially to the MMT modified in the bentonite with a lower viscosity polymer. The characteristics of the main IR absorption bands for composites with a higher viscosity polymer indicates the formation of less stable structures suggesting the random nature of the hydrogen bonds formation.
The intercalation into interlayer spaces of montmorillonite (MMT), obtained from natural calcium bentonite, was investigated. Modification of MMT was performed by the poly(acrylic acid-co-maleic acid) sodium salt (co-MA/AA). Efficiency of modification of MMT by sodium salt co-MA/AA was assessed by the infrared spectroscopic methods (FTIR), X-ray diffraction method (XRD) and spectrophotometry UV-Vis. It was found, that MMT can be relatively simply modified with omitting the preliminary organofilisation – by introducing hydrogel chains of maleic acid-acrylic acid copolymer in a form of sodium salt into interlayer galleries. A successful intercalation by sodium salt of the above mentioned copolymer was confirmed by the powder X-ray diffraction (shifting the reflex(001) originated from the montmorillonite phase indicating an increase of interlayer distances) as well as by the infrared spectroscopy (occurring of vibrations characteristic for the introduced organic macromolecules). The performed modification causes an increase of the ion exchange ability which allows to assume that the developed hybrid composite: MMT-/maleic acid-acrylic acid copolymer (MMT-co- MA/AA) can find the application as a binding material in the moulding sands technology. In addition, modified montmorillonites indicate an increased ability for ion exchanges at higher temperatures (TG-DTG, UV-Vis). MMT modified by sodium salt of maleic acid-acrylic acid copolymer indicates a significant shifting of the loss of the ion exchange ability in the direction of the higher temperature range (500–700°C).
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