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Thermostability of montmorillonitic clays

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China foundry 2014年第3期11卷 201-207页

作者： Petr Jelínek Stanislaw M.Dobosz Jaroslav beňo Katarzyna Major-Gabrys vSb–Technical university of ostrava Faculty of Metallurgy and Material Engineering Department of Metallurgy and Foundry Engineering Czech Republic AGH university of Science and technology Faculty of Foundry Engineering Department of Moulding Materials Mould Technology and Foundry of Non-ferrous Metals Al. Mickiewicza 30 30-059 Krakow Poland

bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites is a natural property of clay minerals and it depends on the genesis, source and chemical composition of the clay. This property is also closely connected to bentonite structure. According to DTA analysis if only one peak of dehydroxylation is observed(about 600 oC), the cis- isomerism of bentonite is expected, while two peaks of de-hydroxylation(about 550 and 850 oC) are expected in the trans- one. In this overview, the bentonite structure, the water – bentonite interaction and the swelling behavior of bentonite in connection with the general technological properties of bentonite molding mixture are summarized. Further, various types of methods for determination of bentonite thermostability are discussed, including instrumental analytical methods as well as methods that employ evaluation of various technological properties of bentonite binders and/or bentonite molding mixtures.

关键词： bentonite thermostability binder clay

Experimental determination of grain density function of AZ91/SiC composite with different mass fractions of SiC and undercoolings using heterogeneous nucleation model

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China foundry 2011年第1期8卷 101-106页

作者： J.Lelito P.Zak J.S.Suchy W.Krajewski A.L.Greer P.Darlak department of foundry Engineering Processes AGH University of Science and Technology department of Materials Science & Metallurgy University of Cambridge foundry Institute

The grain density,Nv,in the solid state after solidification of AZ91/SiC composite is a function of maximum undercooling,ΔT,of a liquid *** type of function depends on the characteristics of heterogeneous nucleation sites and number of SiC present in the *** aim of this paper was selection of parameters for the model describing the relationship between the grain density of primary phase and *** model in connection with model of crystallisation,which is based on chemical elements diffusion and grain interface kinetics,can be used to predict casting quality and its *** models have parameters,which exact values are usually not known and sometimes even their physical meaning is under *** parameters can be obtained after mathematical analysis of the experimental *** composites with 0,1,2,3 and 4wt.% of SiC particles were *** AZ91 alloy was a matrix of the composite reinforcement SiC *** composite was cast to prepare four different thickness *** were taken from the region near to the thermocouple,to analyze the undercooling for different composites and thickness plates and its influence on the grain *** microstructure and thermal analysis gave set of values that connect mass fraction of SiC particles,and undercooling with grain *** values were used to approximate nucleation model adjustment *** model can be very useful in modelling composites microstructure.

关键词： heterogeneous nucleation mass fraction of SiC particles AZ91/SiC composite grain density mathematical modelling

Simulation of cooling channel rheocasting process of A356 aluminum alloy using three-phase volume averaging model

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中国有色金属学会会刊:英文版 2005年第2期15卷 389-394页

作者： T.Wang b.Pustal M.Abondano T.Grimmig A.bührig-Polaczek M.Wu A.Ludwig foundry Institute Aachen University of TechnologyAachenD-52072Germany department of Metallurgy University of LeobenLeobenA-8700Austria Research Center of foundry Engineering Dalian University of TechnologyDalian 116024China

The cooling channel process is a rehocasting method by which the prematerial with globular microstructure can be produced to fit the thixocasting process.A three-phase model based on volume averaging approach is proposed to simulate the cooling channel process of A356 Aluminum *** three phases are liquid,solid and air respectively and treated as separated and interacting continua,sharing a single pressure *** mass,momentum,enthalpy transport equations for each phase are *** developed model can predict the evolution of liquid,solid and air fraction as well as the distribution of grain density and grain *** effect of pouring temperature on the grain density,grain size and solid fraction is analyzed in detail.

关键词： A356 alloy modeling cooling channel three-phase semi-solid

Influence of wet activation of used inorganic binder on cyclically refreshed water glass moulding sands hardened by microwaves

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China foundry 2016年第6期13卷 427-432页

作者： Mateusz Stachowicz Kazimierz Granat department of foundry Plastics and Automation Wroc?aw University of Technology

The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with "dry" or "wet" activation of inorganic binder in waste moulding sand mixtures physically hardened by microwave radiation. The sand mixtures consisting of high-silica sand and water-glass with average molar module 2.5, were subjected to the following cyclical process: mixing the components, compacting, microwave heating, cooling-down, thermally loading the mould to 800 °C, cooling-down to ambient temperature, and knocking-out. After being knocked-out, the waste moulding sands were subjected to either dry or wet activation of the binder. To activate thermally treated inorganic binder, each of the examined processes employed the surface phenomenon usually associated to mechanical reclamation. The study also covered possible use of some elements of wet reclamation to rehydrate waste binder. To evaluate the effectiveness of the two proposed methods of waste binder activation, selected strength and technological parameters were measured. After each subsequent processing cycle, the permeability, tensile strength and bending strength were determined. In addition, the surface of activated sand grains was examined with a scanning electron microscope. Analysis of the results indicates that it is possible to re-activate the used binder such as sodium silicate, and to stabilize the strength parameters in both activation processes. Permeability of the refreshed moulding sands strongly depends on the surface condition of high-silica grains. The wet activation process by wetting and buffering knocked-out moulding sands in closed humid environment makes it possible to reduce the content of refreshing additive in water-glass. The moulding sands cyclically prepared in both processes do not require the addition of fresh high-silica sand. The relatively high quality achieved in the refreshed moulding sands allo

关键词： moulding sand reclamation water-glass microwave heating refreshing

biodegradable materials as binders for Ivth generation moulding sands

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China foundry 2015年第5期12卷 375-381页

作者： K.Major-Gabrys AGH university of Science and technology Faculty of Foundry EngineeringDepartment of Moulding MaterialsMould Technology and Foundry of Non-ferrous Metals

This paper focuses on the possibility of using the biodegradable materials as binders(or parts of binders' compositions) for foundry moulding and core sands. Results showed that there is a great possibility of using available biodegradable materials as foundry moulding sand binders. Using biodegradable materials as partial content of new binders, or additives to moulding sands may not only decrease the toxicity and increase reclamation ability of tested moulding sands, but also accelerate the biodegradation rate of used binders, and the new biodegradable additive(PCL) did not decrease the strength and thermal properties. In addition, using polycaprolactone(PCL) as a biodegradable material may improve the flexibility of moulding sands with polymeric binder and reduce toxicity.

关键词： foundry practice moulding sand binder resin biodegradable material toxicity reclamation

Medical implants by using RP and investment casting technologies

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China foundry 2011年第1期8卷 107-111页

作者： Milan Horáek Ondej Charvát Tomá Pavelka Josef Sedlák Martin Madaj Jindich Nejedl Jan Dvoáek Faculty of Mechanical Engineering Institute of Manufacturing Technology-Department of Foundry EngineeringBrno University of Technology

The paper deals with the production technology of knee joint replacement by using rapid prototyping *** aim of the work is to outline the manufacturing technology intended for prototype production with the use of rapid prototyping and investment casting technology for use in orthopaedics and the surgery of knee joint *** research results should make an effective contribution in the attempts to minimize the invasive surgical procedure,shorten the production of knee joint replacement as well as reduce the *** present,the research is focused on the preparation of STL data from CT (Computed Tomography) and verification of the production technology of prototypes made using available RP technology and its evaluation.

关键词： rapid prototyping investment casting knee joint replacement computed tomography

Strength properties examination of high zinc aluminium alloys inoculated with Ti addition

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China foundry 2017年第3期14卷 211-215页

作者： J.buras M.Szucki G.Piwowarski W.K.Krajewski P.K.Krajewski AGH university of Science and technology-Faculty of foundry Engineering-department of foundry Processes Engineering 23 ReymontaStreet30-059 KrakowPoland

This paper includes studies on the influence of grain refinement treatment with respect to the composition and structure of high zinc aluminium casting alloys on the changes of their tensile properties. The Al-20 wt.%Zn alloy was inoculated with master alloys Al Ti5b1 and Al Ti3C0.15 to determine the impact of a variable titanium addition on the tensile properties of Al Zn20 alloy, and determine on this basis an optimal addition of Ti that would ensure the improvement of elongation of alloys cast in the sand mould, at the same time maintaining high tensile strength. Within the studies, light microscopy(LM) and strength tests were applied. Experimental results showed that the inoculation of high zinc aluminium alloy Al Zn20 with the master alloys Al Ti5b1 and Al Ti3C0.15 causes intensive structure refinement, while the intensity of reaction of both master alloys is comparable. The Al Ti3C0.15 master alloy addition, selected for further studies, introducing about 100 ppm Ti, enhances the tensile properties of the alloy; the elongation increases about 20% and tensile strength increases about 10% against the initial values(uninoculated alloy). Further increase of the Ti addition up to 500–600 ppm leads to the "overinoculation" effect that is accompanied by the decrease of elongation. Therefore,the Ti addition should be reduced to the level of about 100 ppm which ensures obtaining a set of optimal properties.

关键词： high zinc aluminium alloys grain refinement grain fragmentation strength properties elongation

The mystery of molten metal

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China foundry 2010年第4期7卷 425-437页

作者： Natalia Sobczak Jerzy Sobczak Rajiv Asthana Robert Purgert foundry Research Institute department of Engineering & technology University of Wisconsin-Stout Energy Industries of Ohio

Recent advances in scientific understanding of high-temperature materials processing using novel experimental methodologies have shed light on the complex role of surface and interface phenomena. New in-situ studies on molten metal/solid ceramic interactions using a unique experimental complex at the foundry Research Institute, Krakow, have revealed a number of unusual observations in materials processing at high temperatures. We present some such unusual observations and their explanation with reference to liquid metal processing of Al, Ni, and Ti, and their alloys in contact with oxide ceramics. In particular, we focus on the following aspects: primary oxidation of Al from residual water vapor or oxygen, capillary purification to remove surface oxide, substrate protection by CvD carbon, roughening due to spinel whisker formation, inclusions in castings due to mechanical detachment, floatation due to buoyancy forces, and segregation due to directional solidifciation, modification of the solid surface morphology by metal vapor ahead of the liquid, and the complication due to multi-component alloys melted in crucibles made from complex oxide-based ceramics. In the case of Ti, rapid reactions with oxides result in undesirable volumetric changes that create difficulty in casting high-quality Ti parts, particularly by investment casting. Nanoscale (e.g., colloidal) coatings based on Y2O3 protect crucibles and hold ladles against such attack. Practical insights and recommendations for materials processing emerging from the fundamental studies on high-temperature interfacial phenomena have been described.

关键词： molten metal high-temperature phenomena in-situ observation casting defects

Influence of AlTi3C0.15 modification treatment on damping properties of ZnAl10 alloy

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China foundry 2017年第4期14卷 292-296页

作者： Grzegorz Piwowarski Janusz buras Michal Szucki department of foundry Processes Engineering Faculty of Foundry EngineeringAGH University of Science and TechnologyMickiewicza Al.3030-059 CraconePoland

Zn-Al alloys constitute an interesting group of foundry alloys. Due to a relatively low melting temperature, they allow a decrease in energy-consumption of the melting process and alloy preparation. The vibration damping ability is one of the most interesting properties of the Zn-Al alloys. Zn-Al alloys are divided into two groups: the low-aluminium and high-aluminium alloys. The investigated Zn-10 wt.% Al(ZnAl10) alloy is representative of the high-aluminium alloys, which, on account of its tendency of forming coarse-grained structures, has rather low plastic properties, including elongation. In order to improve the plastic properties, a modification treatment is usually applied. The dependence of the damping coefficient of the ultrasound wave on the amount of the introduced inoculant was studied. Investigations were performed using the AlT i3C0.15 inoculant as the modifier of the ZnAl10 alloy. It was found that titanium additions, in a range from 25 to 100 ppm in relation to the melted charge mass, can reduce the damping coefficient value. An increase of the inoculant addition causes a rise of the damping coefficient, which is probably related to the scattering of the ultrasound wave on Al_3Ti and TiC particles introduced with the inoculant.

关键词： modification damping damping coefficient zinc alloys ZnAl10 ultrasound wave