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The influence of the zirconium diboride content and the method of initial material preparation on the corrosion properties of the composite on the 316L stainless steel matrix were determined. The powders were prepared in a Turbula mixer and a planetary mill. The corrosion properties were estimated on the basis of electrochemical tests, including open-circuit potential measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy. The presence of the ceramic phase changes the corrosion resistance of the tested materials due to porosity, which affects the corrosion mechanism. The standard potentiodynamic tests do not reveal poor corrosion resistance of porous materials, and only 24 h tests reveal accurate corrosion resistance of composite materials. Composites cannot go into a stable passive state because of the penetration of electrolytes into the pores and tend to oxidize systematically. 24-h corrosion tests indicate that samples prepared in a planetary mill show better corrosion resistance than those prepared in a Turbula mixer. [ABSTRACT FROM AUTHOR]

Composites reinforced with 8 vol% TiB were subjected to the consolidation process by spark plasma sintering (SPS). The results show that the addition of boron (1 vol%) introduced to the steel matrix has a significant effect on the composite microstructure, as well as physical, mechanical and tribological properties. The full density of 97-99% was obtained in the composites sintered at a temperature of 1100C. The steel-8% TiB-1% B composite sintered at 1100C for 30 min was characterized by the highest microhardness (465 HV0.3) and Young's modulus (229 GPa), combined with the best compressive strength (1150 MPa) and abrasive wear resistance ( μ = 0.25 and W = 207.78 × 10 mm Nm). The microstructure and chemical composition were examined by scanning electron microscopy and transmission electron microscopy. The examinations have revealed the presence of numerous fine complex borides in the microstructure of the steel-8% TiB and steel-8% TiB-1% B composites. [ABSTRACT FROM AUTHOR]

The subject of the work was to study the effect of Si alloying addition to the aluminum on the bond strength properties, wettability, and structure of interface in the AlSi11/Al2O3 .joints. Taking advantage of the sessile drop method, the wetting of alumina substrates by liquid AlSi11 alloy or Al was studied. The sessile drop tests were carried out in the temperature range between 1023 and 1223 K, under a vacuum of 0.2 mPa for 30 or 120 minutes of contact. The shear strength results demonstrated significant improvement of shear strength of AlSi11/Al2O3 joints due to the application of silicon as an alloying addition to aluminum. Microstructural investigations of interface indicated that the silicon crystals were formed at the AlSi11/Al2O3 interface, which influenced the strengthening of these joints. A conclusion could be drawn, that the interface structure influenced the increase of the shear strength of AlSi11/Al2O3 joints. [ABSTRACT FROM AUTHOR]