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1

Efficiency of additives of the polysaccharide type on physical properties of bentonite mixtures

100%

Beňo J. , Jelínek P. , Špirutová N. , Mikšovský F.

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2011

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tom Vol. 11, iss. 1

5-8

EN

The addition of polysaccharide additives generally aims at improving some important physical properties of bentonite mixtures, above all the stability of moulds against the water loss and prevention of surface defects of castings. Polysaccharide products of inland and foreign production were checked in mixtures of two bentonites of the Czech provenance with the same montmorillonite content. The attention was paid in particular to the abrasion resistance of mixtures during storing them under constant climatic conditions. Conclusions have shown the substantial influence of: the amount of the added additive, the kind and structural composition of the additive (pH of the water extract, electric conductance).

2

Surface quality of foundry pattern manufactured by FDM method - rapid prototyping

100%

Hanus A. , Špirutová N. , Beňo J.

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tom Vol. 11, iss. 1s

15-20

EN

The goal of this paper was to verify the possibilities of using 3D models produced by means of the FDM technology for actual foundry production. Experimental models were produced using Dimension sst 768 3D printer. Two types of castings (type I - simple plates, type II - jewellery) were cast in plaster moulds. The models were burnt out at 500 oC. The goal of the experiment was to verify the effect of modifications upon surface quality of the resulting casting. The ABS model was tested with unmodified surface, chemically treated surface, blasted surface and blasted and etched surface together. The results of the experiment have confirmed the assumed effect of both mechanical and chemical modifications of the model surface on casting surface quality.

3

Influence green sand system by core sand additions

88%

Špirutová N. , Beňo J. , Bednářová V. , Kříž J. , Kandrnál M.

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tom Vol. 12, iss. 1

105-110

EN

Today, about two thirds of iron alloys casting (especially for graphitizing alloys of iron) are produced into green sand systems with usually organically bonded cores. Separation of core sands from the green sand mixture is very difficult, after pouring. The core sand concentration increase due to circulation of green sand mixture in a closed circulation system. Furthermore in some foundries, core sands have been adding to green sand systems as a replacement for new sands. The goal of this contribution is: 'How the green sand systems are influenced by core sands?" This effect is considered by determination of selected technological properties and degree of green sand system re-bonding. From the studies, which have been published yet, there is not consistent opinion on influence of core sand dilution on green sand system properties. In order to simulation of the effect of core sands on the technological properties of green sands, there were applied the most common used technologies of cores production, which are based on bonding with phenolic resin. Core sand concentration added to green sand system, was up to 50%. Influence of core sand dilution on basic properties of green sand systems was determined by evaluation of basic industrial properties: moisture, green compression strength and splitting strength, wet tensile strength, mixture stability against staling and physical-chemistry properties (pH, conductivity, and loss of ignition). Ratio of active betonite by Methylene blue test was also determined.

4

Mechanical Properties of Two Manganese Steels

75%

Cagala M. , Lichý P. , Beňo J. , Mazancová E. , Břuska M. , Špirutová N.

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5

Mechanical properties of two manganese steels

75%

Cagala M. , Mazancová E. , Lichý P. , Beňo J. , Břuska M. , Špirutová N.

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tom Vol. 12, iss. 1

9-12

EN

The article is focused on thermomechanical and plastic properties of two high-manganese TRIPLEX type steels with an internal marking 1043 and 1045. Tensile tests at ambient temperature and at a temperature interval 600 C to 1100 C were performed for these heats with a different chemical composition. After the samples having been ruptured, ductility was observed which was expressed by reduction of material after the tensile test. Then the stacking fault energy was calculated and dilatation of both high-manganese steels was measured. At ambient temperature (20 C), 1043 heat featured higher tensile strength by 66MPa than 1045 heat. Microhardness was higher by 8HV0,2 for 1045 steel than for 1043 steel (203HV0,2). At 20 C, ductility only differed by 3% for the both heats. Decrease of tensile properties occurred at higher temperatures of 600 up to 1100 C. This tensile properties decrease at high temperatures is evident for most of metals. The strength level difference of the both heats in the temperature range 20 C up to 1100 C corresponded to 83 MPa, while between 600 C and 1100 C the difference was only 18 MPa. In the temperature range 600 C to 800 C, a decrease in ductility values down to 14 % (1045 heat), or 22 % (1043 heat), was noticed. This decrease was accompanied with occurrence of complex Aluminium oxides in a superposition with detected AlN particles. Further ductility decrease was only noted for 1043 heat where higher occurrence of shrinkage porosity was observed which might have contributed to a slight decrease in reduction of area values in the temperature range 900 C to 1100 C, in contrast to 1045 heat matrix.