The paper presents the properties of surface oxide layers with an increased content of carbon for tribological applications. The composite surface oxide layers were produced using a two-step technology through hard anodising of the surface of an aluminium alloy, followed by thermochemical treatment of anodic oxide coatings. The surface oxide layers were subjected to tribological tests in an oil-less sliding couple with T5W plastic. The presented test results confirm the usefulness of the proposed modifications of surface oxide layers for the purpose of enhancing the operational durability of oil-less sliding couples in a reciprocating motion.
The presented in the paper investigations were aimed at the determination of the reclaimed material (obtained in the dry mechanical reclamation process) addition influence on properties of moulding sands with hydrated sodium silicate modified by colloidal suspension of zinc oxide nanoparticles in propanol. Nanoparticles originated from the thermal decomposition of alkaline zinc carbonate, were used. The results of the reclamation of the spent moulding sand with hydrated sodium silicate performed in the AT-2 testing reclaimer are presented in the paper. Both, spent sands from the Floster S technology and from the technology with the modified water-glass were subjected to the reclamation processes. The following determinations of the reclaimed material were performed: pH reaction, acid demand, ignition loss and Na2O content. The obtained reclaim was used as a matrix component of moulding sands with water-glass in the Floster S technology, in which it constituted 60% and 50% of the sand matrix. The strength properties of the prepared moulding sands were determined (bending strength Rg u , tensile strength Rm u ) after samples storing times: 1h, 2h, 4h and 24 hours.
The ceaseless progress of nanotechnology, observed in the last years, causes that nanomaterials are more and more often applied in several fields of industry, technique and medicine. E.g. silver nanoparticles are used in biomedicine for disinfection and polymer nanoparticles allow insulin transportation in pharmacology. New generation materials containing nanoparticles are also used in the chemical industry (their participation in the commercial market equals app. 53 %). Nanomaterials are used in electronics, among others for semiconductors production (e.g. for producing nanoink Ag, which conducts electric current). Nanomaterials, due to their special properties, are also used in the foundry industry in metallurgy (e.g. metal alloys with nanocrystalline precipitates), as well as in investment casting and in moulding and core sand technologies. Nanoparticles and containing them composites are applied in several technologies including foundry practice, automotive industry, medicine, dentistry etc. it is expected that their role and market share will be successively growing.
The nanocomposites based on water glass matrix were attempted in the study. Nanoparticles of ZnO, Al2O3 or MgO in organic solutions were applied into water glass matrix in the amounts of: 1.5; 3; 4 or 5 mas. %. Wettability of the quartz sad by the nanocomposites based on water glass matrix was determined by testing changes of the wetting angle θ in time τ for the system: quartz – binder in non-stationary state, by means of the device for measuring wetting angles. Wettability measurements were carried out under isothermal conditions at an ambient temperature (20 – 25 oC). The modification improves wettability of quartz matrix by water glass, which is effective in improving strength properties of hardened moulding sands. Out of the considered modifiers in colloidal solution of propyl alcohol water glass modified by MgO nanoparticles indicated the smallest values of the equilibrium wetting angle θr. This value was equal app. 11 degrees and was smaller no less than 40 degrees than θr value determined for not modified water glass. Viscosity η of nanocomposites based on water glass matrix was determined from the flow curve, it means from the empirically determined dependence of the shearing stress τ on shear rate γ: τ = f (γ) (1), by means of the rotational rheometer. Measurements were carried out at a constant temperature of 20 oC. The modification influences the binder viscosity. This influence is conditioned by: amount of the introduced modifier as well as dimensions and kinds of nanoparticles and organic solvents. The viscosity increase of the modified binder does not negatively influence its functional properties.
The aim of the present study was to develop a modifier for water glass. The method of thermal generation of metal oxide nanoparticles was adapted and used in the research. Nanoparticles of ZnO from the thermal decomposition of basic zinc carbonate were used. A method for the modifier introduction was developed, and the effect of modifier content and organic solvent type on the physico-chemical properties of binder (viscosity) and quartz wettability was determined. Binder viscosity was examined from the flow curves plotted with the help of a RHEOTEST 2 rotational rheometer equipped with proper software. Quartz wettability was determined examining timerelated changes in the value of the contact angle in a quartz-binder system, until full stabilisation of the angle value has been achieved. Binder modification was carried out on sodium water glass designated as R"145". The water glass modifiers were suspensions of ZnO nanoparticles in propanol and methanol at a fixed concentration of c = 0.3 M and with the size of nanoparticles comprised in a range of <61 - 981 nm>. Water glass modification with the suspensions of ZnO nanoparticles in methanol and propanol showed the effect of modifier on the water glass viscosity and quartz wettability. This effect depends on the type of alcohol used. The ZnO suspension in propanol (alcohol with a longer hydrocarbon chain) affects more strongly the viscosity of binder and quartz wettability than the methanol suspension.
The purpose of the presented experiment was to develop an effective water glass modifier. In the conducted research, an attempt was made to determine the effect of modifier addition on the wettability of quartz grains, viscosity and cohesion of binder and strength Rm U of the sand mixture. Water glass modification was carried out with, obtained in electrochemical process , colloidal suspension of ZnO nanoparticles in methanol (modifier I) or propanol (modifier II), characterised by a constant molar concentration of c = 0.3 M. It was demonstrated that the addition of a colloidal suspension of ZnO nanoparticles in propanol (modifier II) had a significant effect on wettability of quartz grains improvement without the accompanying increase in binder viscosity. Testing the mechanical properties Rm U of sand mixtures containing modified binder (modifier II) hardened at ambient conditions showed an approximately 28% increase in strength compared with the Rm U of the sand bonded with an unmodified binder.
The results of investigations of three commercial binders applied in the Alphaset technology marked as: Sample E , Sample T and Sample S are presented in the hereby paper. These samples were subjected to the pyrolysis process at a temperature of 900°C (inert atmosphere, He 99.9999). The gas chromatograph coupled with the mass spectrometer and pyrolizer (Py-GC/MS) were used in the study. The identification of gases emitted during the thermal decomposition was performed on the basis of the mass spectral library. The obtained results indicate a certain diversification of emitted gases. Among the pyrolysis products the following harmful substances were identified: furfuryl alcohol, formaldehyde, phenol and also substances from the BTEX (benzene, toluene and ethylobezneze and xylenes) PAHs (Polycyclic Aromatic Hydrocarbons) and VOC groups (Volatile Organic Compounds). Therefore, from the environment protection point of view performing systematic investigations concerning the harmfulness of binders applied in the moulding and core sands technology, is essential.
In this article, there were presented results of research on influence of reclamation process on the ecological quality of reclaim sand with furan resin used in nonferrous foundry. The quality of reclaimed sand is mainly define by two group of chemical substances from elution of reclaimed sand: Dissolves Organic Carbon (DOC) and Total Dissolves Solids (TDS). Reclaimed sand used in test was prepared in experimental thermal reclaimer and mechanical vibration reclaimer REGMAS installed in Faculty of Foundry Engineering at University of Science and Technology in Krakow. The reference point is molding sand shaking out and crumble in jaw crusher. Test of elution was made in acreditation laboratory in Center For Research and Environmental Control in Katowice up to the standard with Dissolves Organic Carbon (DOC) - PN-EN 1484:1999; Total Dissolves Solids (TDS) - PN-EN 15216:2010. The standard for elution test is PN-EN 12457- 4:2006. Except that we were made loss of ignition test, to check how many resin was rest on sand grains.
There are two methods to produce primary copper: hydrometallurgical and pyrometallurgical. Copper concentrates, from which copper matte is melted, constitute the charge at melting primary copper in the pyrometallurgical process. This process consists of a few stages, of which the basic ones are roasting and smelting. Smelting process may be bath and flash. Slag from copper production, on the end of process contain less 0,8%. It is treat as a waste or used other field, but only in a few friction. The slag amount for waste management or storage equaled 11 741 – 16 011 million tons in 2011. This is a serious ecological problem. The following slags were investigated: slag originated from the primary copper production process in the flash furnace of the Outtokumpuja Company in HM Głogów 2 (Sample S2): the same slag after the copper removal performed according the up to now technology (Sample S1): slag originated from the primary copper production process in the flash furnace of the Outtokumpuja Company in HM Głogów 2, after the copper removal performed according the new technology (Sample S3). In practice, all tested slags satisfy the allowance criteria of storing on the dumping grounds of wastes other than hazardous and neutral.
Abstract An attempt has been made to determine the effect of an addition of colloidal suspensions of the nanoparticles of magnesium oxide on the structure of water glass, which is a binder for moulding and core sands. Nanoparticles of magnesium oxide MgO in propanol and ethanol were introduced in the same mass content (5wt.%) and structural changes were determined by measurement of the FT-IR absorption spectra.
The furan resin offers advantages such as high intensity, low viscosity, good humidity resistance and is suitable for cast different casting alloys: steel, cast iron and non-ferrous metal casting. For hardening furan resins are used different hardeners (acid catalysts). The acid catalysts have significant effects on the properties of the cured binder (e,g. binding strength and thermal stability) [1 - 3]. Investigations of the gases emission in the test foundry plant were performed according to the original method developed in the Faculty of Foundry Engineering, AGH UST. The analysis is carried out by the gas chromatography method with the application of the flame-ionising detector (FID) (TRACE GC Ultra THERMO SCIENTIFIC).