Papers by Author: Hubert Matysiak

Abstract: X-ray micro-computed tomography system has been used for visualization in two- (2-D) and three dimensions (3-D) of the dendrite structure and pores in single-crystals fabricated by Bridgman investment casting technique. The system described in the paper reconstructs 3-D geometry from a set of 2-D images obtained by multiple slicing of an X-ray radiography image. The results obtained in this study demonstrate the effect of withdrawal rate on the primary dendrite arm spacing and porosity in single-crystal made of CMSX-4 alloy.

Abstract: The paper presents results of the study on the rheology modifiers of ceramic slurries used in the investment casting. The ceramic slurries used in the study were based on aluminum oxide powder in silica sol binder. Following modifiers were used as thickening agents: mpj, locust bean and xanthan gums. The influence of the substances on the slurry viscosity were tested with a silica sol binder before application to the ceramic slurries. The viscosity measurements were carried out with the use of ARES and Brookfield rheometres. The results obtained demonstrate the potential of employing the investigated substances as rheology modifiers for ceramic slurries used in the investment casting.

Abstract: The paper presents results of investigations into the structure and corrosion resistance of Ti-Al diffusion layers produced on two phase (a+b) Ti6Al4V alloy by Chemical Vapour Deposition (CVD). The process was carried out in aluminium chloride (AlCl3) mixed with argon atmosphere. Surface topography and microstructure characterization of the coatings were examined by scanning electron microscopy (SEM). The local chemical composition witch 1 μm lateral resolution was measured via EDS. The phase content was investigated by X-ray diffraction and analysis of the chemical composition of the surface by XPS. Corrosion resistance was tested using the potentiodynamic method in 0.1M Na2SO4 and 0.1M H2SO4 solutions at the room temperature. Their resistance to high temperature at atmospheric pressure was tested by 24-hours cycling to 700°C. The results indicate that the layers produced on the Ti6Al4V titanium alloy exhibit a very good adhesion combined with exceptional corrosion resistance, especially high at high temperatures.