Journal of Casting & Materials Engineering
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ISSN 2543-9901
Issue Date
2018
Volume
Vol. 2
Number
No. 3
Description
Journal Volume
Journal of Casting & Materials Engineering
Vol. 2 (2018)
Projects
Pages
Articles
Identification of gas products from pyrolysis process of waxes used in lost-wax casting technology
(AGH University of Science and Technology Press, 2018) Żymankowska-Kumon, Sylwia; Kolczyk-Tylka, Joanna
Foundry waxes currently used in lost-wax casting technology are composed of paraffin, stearin, and - to a lesser extent - ceresin, polyethylene wax, and other natural and synthetic waxes. Most of these compounds are non-toxic, however, they may release aromatic hydrocarbons as a result of exposure to high temperatures. Based on a chromatographic analysis (pyrolysis gas chromatography-mass spectrometry, Py-GC/MS), the compounds that are separated from the popular wax mixtures used in foundries were evaluated (as well as the impact they may have on foundry workers). For this purpose, the three main stages of the process (wax, burnout, and pouring) were analyzed, and the appropriate test temperature was chosen (similar to the actual conditions during the process).
Influence of fluoride ions in artificial saliva solution to corrosion behavior of Ti-6Al-4V and Ti-10Mo-4Zr titanium alloys
(AGH University of Science and Technology Press, 2018) Loch, Joanna; Krawiec, Halina
Titanium alloys used in medical applications (especially dentistry) are exposed to the actions of various compounds that appear periodically in the mouth. Fluorine compounds are dangerous for the surface of titanium alloys, because they generate a dissolution of the passive layer. In this way, they destroy the surface of dental implants and cause the absorption of metal ions into the human body. The presented work was aimed to describe the effect of fluoride ions on the corrosive behavior of the commercial Ti-6Al-4V and new Ti-10Mo-4Zr alloys that can be used in stomatology. Electrochemical measurements such as open circuit potential (OCP), linear sweet voltamperometry (LSV) and impedance spectroscopy (EIS) were performed to get information on the corrosive behavior of titanium in artificial saliva solutions (MAS) with different concentrations of NaF. It has been revealed that a high concentration of fluoride ions enhance the current density in the anodic domain, especially for the Ti-10Mo-4Zr alloy. EIS measurements performed at a potential of 0.5 V vs. AgCl (3 M KCl) show that the Ti-10Mo-4Zr alloy has a typical two-layer structure of its passive film. This passive film consists of the outer and inner layers, respectively. The resistance of the outer layer is significantly lower than the resistance of the inner layer.
Novel measurement method to study thermal aspects of molding mixture decomposition
(AGH University of Science and Technology Press, 2018) Svidró, József Tamás; Diószegi, Attila
A wide variety of molding mixtures are extensively used in the process of the sand casting of metal components today. The sector is continuously developing in production volume, moreover, the expectations of customers are increasing on a monthly basis (also from a quality point of view). Even though mold and core manufacturing are well-organized routines in most foundries, technological problems still appear that can lead to technological problems and casting defects. These trends are forcing metal casters to come up with fitting strategies to solve their daily production challenges, while their suppliers are expected to keep up the continuous development of their existing foundry products and to find innovative solutions as well as new material combinations. Research on molding materials and their properties must, therefore, take a step forward accordingly to generate the necessary new knowledge to understand the behavior of mold and core mixtures during casting. This paper summarizes the latest results of a novel measurement method suitable for studying the degradation characteristics of different molding materials from a new perspective. The fundamentals of the method are based on a thermal analysis, focusing on the heat-absorption behavior of greensand and two types of chemically bonded sands regardless of the binder type and amount or the manufacturing process.