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Ł. Jamrozowicz

Abstract

The results of gas pressure measurements in intergranular spaces of fast-setting sands hardened by active gaseous factor are presented in the paper. The research stand and the measuring methodology are described. Investigations concern the determination and recording gas pressure changes in the core sand along the hardened core, in three measuring points. The hardening gas was introduced both in a continuous and impulse way (gas-pause) at a constant pressure. The determined pressure changes of the active gas, which takes part in the chemical reaction of the hardening process, are compared with pressure changes of the neutral gas. The influence of the impulse way of a gas dosage on the core sand strength properties is presented as well as methods of limiting the active gas consumption are shown.

Open access

J. Zych, J. Mocek, T. Snopkiewicz and Ł. Jamrozowicz

Abstract

The investigation results of the thermal conductivity of the selected group of moulding sands with chemical binders, mainly organic, are presented in the hereby paper. Studies encompassed also moulding sands into which additions improving the thermal conductivity were introduced. Two testing methods were applied, i.e. investigations at a steady and unsteady temperature zone. For investigations at a steady temperature zone the new original experimental stand was designed and built, adapted also for testing moulding sands with binders undergoing destruction at relatively low temperatures.

Open access

J. Kolczyk, Ł. Jamrozowicz and N. Kaźnica

Abstract

The results of investigations of the rheological properties of typical ceramic slurries used in the investment casting technology - the lost wax technology are presented in the paper. Flow curves in the wide range of shear velocity were made. Moreover, viscosity of ceramic slurries depending on shearing stresses was specified. Tests were performed under conditions of three different temperatures 25, 30 and 35°C, which are typical and important in the viewpoint of making ceramic slurries in the investment casting technology.

In the light of the performed investigations can be said that the belonging in group of Newtonian or Non - Newtonian fluid is dependent on content of solid phase (addition of aluminum oxide) in the whole composition of liquid ceramic slurries.

Open access

J. Kolczyk, J. Zych and Ł. Jamrozowicz

Abstract

The investigation results of the kinetics of binding ceramic moulds, in dependence on the solid phase content in the liquid ceramic slurries being 67, 68 and 69% - respectively, made on the basis of the aqueous binding agents Ludox AM and SK. The ultrasonic method was used for assessing the kinetics of strengthening of the multilayer ceramic mould. Due to this method, it is possible to determine the ceramic mould strength at individual stages of its production. Currently self-supporting moulds, which must have the relevant strength during pouring with liquid metal, are mainly produced. A few various factors influence this mould strength. One of them is the ceramic slurry viscosity, which influences a thickness of individual layers deposited on the wax model in the investment casting technology. Depositing of layers causes increasing the total mould thickness. Therefore, it is important to determine the drying time of each deposited layer in order to prevent the mould cracking due to insufficient drying of layers and thus the weakening of the multilayer mould structure.

Open access

Ł. Jamrozowicz, J. Kolczyk, N. Kaźnica and Z. Pyziak

Abstract

Measurements of the hardening process of the selected self-setting sands are presented in the hereby paper. Moulding sands were prepared on the matrix of „Szczakowa” sand of the Sibelco Company. Two resins: phenol-formaldehyde-furfuryl (FF/AF) and urea-formaldehydefurfuryl (MF/AF) were used for making moulding sands. - Methylbenzene-sulphonic acid was applied as a hardener for the moulding sand on FF/AF resin, while paratoluene-sulphonic acid for the moulding sand on MF/AF resin. Both hardeners were used in two concentrations: low - the so-called ‘slow’ hardener and high - ‘fast’ hardener. During investigations, the courses of the hardening process were determined, more accurately changes of the velocity of the ultrasound wave passage through the moulding sand cL = f(t) and changes of the moulding sand hardening degree versus time, Sx = f(t). In addition, the kinetics of the hardening process was determined. Measurements were performed on the research stand for ultrasound investigations.