|Karina Jagielska-Wiaderek, Henryk Bala, Dorota Denis-Brewczyńska
The study characterizes the acid corrosion resistance of six iron alloys containing additions from 0.007 to 1.03 wt. % of tin. The alloys were obtained by way of remelting in a Tamman furnace made of pure iron (99.98% Fe) with additions of spectrally pure tin. The obtained melts underwent studies of acid corrosion resistance by means of an atmospheric corrosion test, electrochemical tests and corrosion rate measurements (determination from the analysis of the corrosion solutions in respect of the Fe2+ content). The performed electrochemical measurements show that both in the environment of sulfuric acid and acidified sodium sulfate, the presence of 0.007-1.03% Sn in the iron does not exhibit a significant effect on the corrosion rate of the examined alloys. The obtained values of icor (determined by way of extrapolation to Ecor and based on Rp), within their measurement error, can be treated as independent of the tin content in the alloy. However, one can observe the effect of the presence of tin on the course of atmospheric corrosion in the acid salt spray - this rate is reduced with an increase of the Sn content in the analyzed samples.
Keywords: tin, Fe-Sn casting alloys, corrosion rate, atmospheric corrosion,
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Kamil Kuglin, Dorota Kalisz
In the research, computer calculations were performed, consisting in solving the equation of population balance and the equation of the collision frequency of non-metallic inclusion particles, depending on the type of collision. In the simulations, the PSG method (Particle Grouping Method) was applied. The studies were conducted for a specific number of aluminium oxide particles. The particle radius and the power of mixing ε were assumed as variables. The simulation results were presented in the form of diagrams showing the change of the number of precipitates in respect of their initial number (n1/N0) for the first group of sizes (n1) in real-time, for each analyzed initial size of the particle radius: 1, 5 and 10 μm. The analysis of the elaborated results made it possible to conclude that, in the case of particles characterized by a larger radius, the increased energy mix intensifies the process of inclusions joining in agglomerates, which, in consequence, favours the processes of their removal from the volume of the liquid metal.
Keywords: steel, non-metallic inclusions, agglomeration, computer simulation, PSG method,
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Agnieszka Roczniak, Mariusz Holtzer, Angelika Kmita
The article presents the results of the pyrolysis of resin, the fast hardener as well as cured resin used in the ALPHASET technology. It is an alkaline phenolic resin of the resol type cured with an ester mixture. The pyrolysis was performed at 900°C in an atmosphere of helium. For the identification of the pyrolysis products, the technique of gas chromatography combined with mass spectrometry (Py-GC/MS) was applied. The products of the uncured resin pyrolysis were mainly methyl derivatives of phenol and benzene, whereas the products of the cured resin pyrolysis, beside these compounds, also included substances derived from the hardener (esters). Acetone was identified as the product of the pyrolysis hardener, which originated from the decomposition of propylene carbonate.
Keywords: pyrolysis, Py-GC/MS, phenolic resol resin, esters, moulding sands,
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Natalia Kaźnica, Jerzy Zych, Joanna Kolczyk
An analysis of the drying process of surface layers of sand moulds and cores (made of loose self-hardening moulding sand with hydrated sodium silicate hardened with a liquid ester hardener) which was previously subjected to the process of moisture sorption is presented in the hereby paper. After a 12-hour process of moisture sorption from the environment under conditions of high relative air humidity (over 85%) as well as temperature (28-33°C), an analysis was performed using the drying (desorption) process on the surface layers of sand moulds and cores under conditions of lower values of temperature and humidity on the example of water glass moulding sand. The investigations involved the use of the gravimetric method. Based on the obtained results, it was demonstrated that the moistened surface layers dry up with different intensities depending on the environmental conditions as well as the size of the sand grains (intergranular pores).
The knowledge of the course of both the sorption and desorption of moisture by surface layers of sand mould components is necessary to prevent the formation of casting surface defects, which periodically appear in foundries.
Keywords: sand moulds, surface layers, drying, water glass,
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Joanna Kolczyk, Natalia Kaźnica, Sylwia Żymankowska-Kumon, Łukasz Jamrozowicz
The die casting method is based on casting into permanent metal moulds, which makes it possible to obtain a large amount of casts with practically identical shapes. Compared to the technology of sand mould casting, this method has many advantages. However, it thus faces completely different requirements concerning the conditions of both filling the mould and metal solidification. That is why it seems important to select the appropriate protective coatings applied on the moulds, which provide control over the particular processes as well as facilitate the removal of the cast and prolong the durability of the metal moulds.
The study included investigations of the dynamic and relative viscosity of protective coatings (ground, insulating and thermal conductive) used for metal moulds. The examinations were performed at 25°C. Also, an attempt was made at evaluating the environmental performance of the used coatings at the temperature of their application onto the metal moulds (200°C) as well as the temperature of the moulds’ operation (400°C) based on chromatographic tests.
Keywords: protective coatings, metal moulds, dynamic viscosity, chromatographic tests,
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Emilia Wildhirt, Jarosław Jakubski, Małgorzata Sapińska, Sylwia Sitko
Protective coatings are applied in order to obtain casts with an even surface, without faults. Protective coatings can contain a solvent based on water or alcohol; however, due to their harmfulness, it is recommended to limit the use of alcohol coatings. The manner of applying the coatings onto the surface of a core or a mould depends on the requirements and needs of the executor. This article presents test results demonstrating the effect of the thickness of a protective coating, with different solvent contents, on selected properties of masses. The studies were performed on II generation masses bound with organic and inorganic binders. The effect of the coating’s thickness on the bending strength as a function of deformation degree was determined. The profiles were also tested in respect of the hot distortion parameter. Additionally, microscopic photos were taken showing the depth of the coating’s penetration towards the inside of the mass. The hot distortion parameter tests showed that, depending on the type of binder used in the mass, the addition of a diluent produces different results.
Keywords: core materials, protective coatings, hot distortion parameter,
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