The objective of the present study was to evaluate a method for the measurement of oxygen activity in liquid cast iron to predict the cast iron properties after solidification. A series of experimental melts were made, testing the activity of oxygen after melting down of the charge, treatment with varying amounts of magnesium alloys, and during prolonged holding of the melt in a crucible furnace. The basic chemical composition of cast iron, the graphite form, and in some cases, the total gas content (O, N, H) as well as the strength and elongation were determined. The influence of oxygen activity on the morphology of graphite was stated and, provided certain technical and organisational conditions are met, the usefulness
of this method in control of the ductile iron manufacturing process was confirmed.
Keywords: cast iron, graphite, oxygen, activity, Celox®-Foundry,
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Artur Kudyba, Aleksandra Siewiorek, Natalia Sobczak
The aim of this study was to determine the effect of temperature and Zn content on the solderability of Cu substrates with liquid Sn-xZn alloys (4.5; 90; 95 wt.% Zn). Solderability tests were carried out by the wetting balance test which allows the measurement of wetting force and wetting time and determination of the size of contact angle. The study was performed at two different temperatures applied to each of the examined alloys, i.e. for Sn-4.5Zn at 230 and 250°C, for Sn-90Zn at 400 and 450°C, and for Sn-95Zn at 410 and 450°C. After the solderability tests, structural analysis was performed on sample cross-sections using optical microscopy and scanning electron microscopy coupled with energy dispersive spectroscopy for chemical analysis. It was found that the temperature increase improves the solderability of each of the systems investigated. With process temperature increased to 450°C for alloys with 90 and 95 wt%. Zn, a complete wetting of the tested Cu substrates was obtained (the value of contact angle θ = 0°).
Keywords: lead free solder, Sn-Zn, wetting balance test, solderability, wetting balance curve, contact angle,
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Aleksander Palma, Irena Izdebska-Szanda
The paper presents the results of laboratory and industrial tests undertaken in order to develop and implement in foundry production the high-quality bentonite made from the raw dried material and selected fractions formed in the production of hygiene sorbents. Hygiene sorbents are solid materials with high-developed surface area and increased absorption rate of undesirable substances, intended for animals (so-called hygiene bentonite litter). Formed as a by-product in the manufacture of sorbents, the selected fine fractions of less than 1 mm were initially returned to the sorbent production cycle, but it soon became apparent that the small particles adversely affect the quality of produced sorbents. The conducted preliminary studies have shown that, due to a large content of montmorillonite and high degree of refinement, the selected dust fractions and the raw dried bentonite, both being by-products from the production line of sorbents, can be used as valuable components in the production of foundry bentonite. The article presents the results of tests and studies on the processing and refining of the starting materials under laboratory conditions and the newly developed, experimental production technology to obtain bentonite from raw dried material and selected fine fractions generated in the production of hygiene sorbents. The results of trials on the application of newly developed high-quality bentonite in the manufacture of moulding sands, moulds and pilot castings were also presented.
Keywords: foundry binders, synthetic moulding sands, bentonite,
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Aleksandra Siewiorek, Artur Kudyba, Marta Homa, Natalia Sobczak
This paper presents the results of tests on the effect of the surface coating and flux type on the solderability of PCB by lead-free tin-based SAC305 (SnAg3.0Cu0.5) alloy determining the size of the contact angle by a wetting balance method. The study was performed at a temperature of 260°C on PCB with three types of coatings (HASL LF - lead-free, ENIG - gold, OSP - organic coating), using two types of flux (EF2202 and RF800). The shortest wetting time t0 = 0.6 s for the EF2202 flux and t0 = 0.98 s for the RF800 flux was obtained for plates with the OSP coating. For ENIG-coated PCB, the wetting time t0 = 1.36 s (EF2202 flux) and t0 = 1.55 s (RF800 flux) was the longest. The calculated angle θ was as follows: for PCB with HASL LF - θ = 45°, with ENIG - θ = 58°, and for the OSP coating - θ = 63°.
Keywords: wetting balance method, solderability, contact angle, PCB, flux, Pb-free solder, SAC305 alloy,
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Janusz Faber, Katarzyna Perszewska, Maria Żmudzińska
The emission of odours associated with the activities of various industrial plants and facilities is treated as a nuisance, and not as a factor harmful to humans and the environment. The smell, even when subjectively perceived as pleasant, with a significant concentration and longer persistence in the air becomes a nuisance and can cause discomfort and negative emotions in people living near the source of the emissions. Depending on the technology used and the type of production, odours emitted from a foundry can be felt both as pleasant or unpleasant. This paper presents the results of investigations regarding various composition of odours emitted from investment foundry where castings are produced from the lost wax patterns.
Keywords: environmental protection, aromatic compounds, investment foundry, lost wax casting technology,
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The article presents how to perform a chemical modification of the soluble sodium silicate with morphoactive, organic compounds. An attempt was made to determine the effect of chemical modifiers of the soluble sodium silicate on its physicochemical and structural properties. The kinetics of changes in the Zeta potential of a "chemically modified soluble sodium silicate - ester hardener" gelling system was described.
Keywords: soluble sodium silicate, chemical modification, Zeta potential,
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