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1

Effect of temperature on the volume of gas emissions

Żółkiewicz Z., Karwiński A.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2012

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Vol. 1, No 2

75-77

EN

In the full mould process, the polystyrene pattern which fills the mould cavity is subjected to pouring of this mould with liquid metal to the effect of high temperature (1600 0C) and passes from the solid state into liquid and gas. During this process some solid and gaseous products of the thermal destruction of the pattern are created. The kinetics of this process depends on the temperature of evaporation and, though to a smaller extent, on the pattern density, which, combined with the mould parameters, parameters of a ceramic coating, i.e. its thickness, permeability, and resistance to the effect of high temperatures, parameters of a granular material filling the mould and parameters of a technological process, including the technique of pouring and design. The mould cavity is filled with a pattern made of foamed polystyrene which on pouring of mould with liquid metal undergoes total destruction.

2

Zawartość wodoru w odlewach z żeliwa szarego wykonanych technologią modeli zgazowanych

Żółkiewicz Z., Żółkiewicz M.

Prace Instytutu Odlewnictwa

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2008

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T. 48, z. 2

42-47

PL

Jednym z podstawowych parametrów, decydujących o prawidłowym przebiegu procesu cieplnego zgazowywania modeli, jest rodzaj oraz objętość gazów wydzielających się z modelu styropianowego w czasie trwania tego procesu. Proces zgazowywania modelu zachodzi w założonym przedziale temperatury. Objętość wydzielonych gazów jest zależna od temperatury, objętości modelu oraz masy modelu. Jednym z gazowych produktów cieplnego rozpadu modelu polistyrenowego jest wodór. Zawartość jego w całkowitej objętości gazów jest zależna od temperatury zgazowania modelu. Maksymalna zawartość wodoru w całkowitej objętości gazów może wynosić nawet około 10%. W badaniach określono wpływ produktów cieplnego rozpadu modelu styropianowego na właściwości metalu, zwłaszcza na zawartość wodoru w metalu. Jego zawartość określano w próbkach z żeliwa szarego wykonywanych metodą modeli cieplnie zgazowywanych. Wstępne wyniki badań przedstawiono na wykresach.

EN

One of the main parameters that determine the correct run of pattern evaporation process is the type and volume of gas evolved from a foamed polystyrene pattern during its evaporation. The process of pattern evaporation takes place within a preset range of temperatures. The volume of the evolved gas depends on the temperature, and on the pattern volume and weight. One of the gaseous products of the foamed polystyrene pattern decomposition is hydrogen. Its content in the total volume of the evolved gas depends on the temperature at which the pattern evaporation takes place. Maximum hydrogen content in the total volume of gas may reach even 10%. In the present studies the effect of the products of the thermal decomposition of a foamed polystyrene pattern on the metal properties, especially on the content of hydrogen in this metal, was determined. The content of hydrogen was determined in grey iron samples obtained by the lost foam process. The tentative results of the investigations were plotted in the form of diagrams.

3

Pattern evaporation process

Żółkiewicz Z., Żółkiewicz M.

Archives of Foundry Engineering

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2007

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Vol. 7, iss. 2

49-52

EN

The paper discusses the process of thermal evaporation of a foundry pattern. At several research-development centres, studies have been carried out to examine the physico-chemical phenomena that take place in foundry mould filled with polystyrene pattern when it is poured with molten metal. In the technique of evaporative patterns, the process of mould filling with molten metal (the said mould holding inside a polystyrene pattern) is interrelated with the process of thermal decomposition of this pattern. The transformation of an evaporative pattern (e.g. made from foamed polystyrene) from the solid into liquid and then gaseous state occurs as a result of the thermal effect that the liquid metal exerts onto this pattern. Consequently, at the liquid metal-pattern-mould phase boundary some physico-chemical phenomena take place, which until now have not been fully explained. When the pattern is evaporating, some solid and gaseous products are evolved, e.g. CO, CO2, H2, N2, and hydrocarbons, e.g. styrene, toluene, ethane, methane, benzene [16, 23]. The process of polystyrene pattern evaporation in foundry mould under the effect of molten metal is of a very complex nature and depends on many different factors, still not fully investigated. The kinetics of pattern evaporation is also affected by the technological properties of foundry mould, e.g. permeability, thermophysical properties, parameters of the gating system, temperature of pouring, properties of pattern material, and the size of pattern-liquid metal contact surface.

4

Oddziaływanie produktów cieplnego zgazowania modelu polistyrenowego na powierzchnię odlewu

Żółkiewicz Z.

Archiwum Odlewnictwa

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2004

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R. 4, nr 11/2

332--337

PL

W trakcie zgazowywania modelu polistyrenowego nad powierzchnią ciekłego metalu gromadzą się produkty zgazowania modelu. Stykają się one z ciekłym metalem oraz z warstwą ceramiczną oddziaływując na nią. Te trzy podstawowe czynniki tj. właściwości metalu, formy oraz właściwości fizyko-chemiczne produktów zgazowania modelu polistyrenowego wpływają na prawidłowy przebieg procesu, na możliwość wystąpienia w odlewie wad np.: niedolewy, pęcherze gazowe, wżarcia, zwiększenie zawartości gazów (wodoru) w metalu. W referacie przedstawiono wpływ procesu technologicznego zgazowywania modelu polistyrenowego na zawartość wodoru i tlenu w żeliwie szarym.

EN

During evaporation of a polystyrene pattern, the products of evaporation are accumulated above the surface of molten metal. They enter into contact with both the liquid metal and the ceramic material, affecting specially the latter one. The three main factors, i.e. the properties of metal, the properties of mould, and the physico-chemical properties of the products of polystyrene pattern evaporation, affect the correct run of the process, and inrease the risk of occurrence of casting defects, like misruns. blowholes, penetrations, and increased gas content (hydrogen) in metal. In the paper an effect of the technological process of polystyrene pattern evaporation on the content of hydrogen and oxygen in grey iron was investigated.