The identification of pyrolysis products of the alphaset binder with gas chromatography/mass spectrometry

Pyrolysis-gas chromatography-mass spectrometry (PyGC/MS) was used to identify the major organic products created by pyrolysis of the ALPHASET binder components: hardener/catalyst, resin and cured resin. During the casting process, the cores and moulds are subjected to intense heat from the molten metal. As a result the organic components undergo thermal decomposition and produce a number of complex organic compounds. In this study, the organics were tentatively identified by GC/MS after pyrolysis of the components at 700, 900 and 1100°C

Montmorilonit – usporedba metoda za njegovo određivanje u ljevaoničkim bentonitima

A comparison and estimation of usefulness of a quantitative analysis of montmorillonite in foundry bentonites, was the aim of this research. The investigations were made by means of three different techniques: methylene blue (MB) adsorption method, Cu(II)-triethylenetetramine complex (Cu(II)-TET) adsorption method, and infrared spectroscopy (FTIR) method. Tests were performed for 9 kinds of bentonites originated from various producers. The achieved results indicated that, the results obtained by the FTIR method were, in general, even 10% lower than the ones obtained by other methods. The best correlation with the data given by the producers were obtained for the Cu(II)-TET method. In addition, this method was characterised by the smallest value of standard deviations. A very essential advantage of the Cu(II)-TET method is a much shorter time needed for the analysis and its easier execution, which is important under production conditions.Cilj ovog istraživanja je bila procjena upotrebljivosti kvantitativne analize montmorilonita u ljevaoničkim bentonitima. Istraživanja su provedena pomoću tri različite tehnike: adsorpcija metilenskog modrila (MB), adsorpcija Cu(II)-trietilentetramin kompleksa (CU(II)-TET), i infracrvena spektroskopija (FTIR). Ispitivanja su provedena na 9 vrsta bentonita koji potječu od različitih proizvođača. Rezultati dobiveni FTIR metodom u prosjeku su za čak 10,0% niži od rezultata dobivenih ostalim metodama. Najbolja korelacija s podatcima od proizvođača dobivena je primjenom Cu(II)-TET metode. Osim toga, kod te metode najmanje su vrijednosti standardnih devijacija. Vrlo važna prednost Cu(II)-TET metode je znatno kraće vrijeme potrebno za anaalizu i lakše provođenje, što je značajno u proizvodnim uvjetima

Investigations of Protective Coatings for Castings of High-manganese Cast Steels

When cast steel castings are made in moulding sands on matrices of high-silica sand, which has a low fire resistance the problem of theso-called chemical penetration is distinctly visible. Whereas this effect appears to a small degree only when moulding sand matrices are of chromite, zircon or olivine sands. Therefore in case of making castings of high-manganese cast steel (e.g. Hadfield steel) sands not containing free silica should be applied (e.g. olivine sand) or in case of a high-silica matrix protective coatings for moulds and cores should be used. Two protective coatings, magnesite alcoholic (marked as coating 1 and coating 2) originated from different producers and intended for moulds for castings of the Hadfield steel, were selected for investigations. Examinations of the basic properties were performed for these coatings: viscosity, thermal analysis, sedimentation properties, wear resistance. In order to estimate the effectiveness of protective coatings the experimental castings were prepared. When applying coating 1, the surface quality of the casting was worse and traces of interaction between the casting material (cast steel) and the coating were seen. When protective coating 2 was used none interactions were seen and the surface quality was better

Thermal decomposition of foundry resins: A determination of organic products by thermogravimetry–gas chromatography–mass spectrometry (TG–GC–MS)

AbstractThe article presents the results of research on thermal decomposition of Ester-Cured Alkaline Phenolic No-Bake (ALPHASET) binders used in molding technology. In the ALPHASET system phenol-formaldehyde resin of resole type is cured with a liquid mixture of esters. Under the influence of the molten metal the thermal decomposition of the binder follows, resulting in the evolution of gases, often harmful, e.g. from benzene, toluene, ethylbenzene and xylenes (BTEX) or Polycyclic Aromatic Hydrocarbon (PAH) groups. The identification of gases evolved during the pyrolysis of the binders was carried out and their decomposition temperatures were determined using the Thermogravimetry–Gas Chromatography–Mass Spectrometry (TG–GC–MS) technique. The tests were subjected to two types of binders from different manufacturers. Among the products of pyrolysis there have been identified mainly benzene and its derivatives, and phenol and its derivatives. Compounds identified in pyrolytic gas are largely considered to be harmful to humans and the environment (some of the compounds are carcinogenic and mutagenic). The presented results of the TG–GC–MS measurements show that the applied analytic methods are feasible to perform a qualitative and also quantitative characterization of the binder samples