Papers by Keyword: TiB Precipitation

Abstract: Titanium and its alloys are common in medical implant applications because of their desirable properties, such as relatively low Young’s modulus, good fatigue strength, corrosion resistance, biocompatibility as well as formability and machinability. However, these materials cannot meet all of the clinical requirements. Current research focuses on improving not only the mechanical performance but mostly the biocompatibility of Ti-based systems through variations in alloy composition and surface treatment. One of the methods that allows the change of biological properties of Ti surface is the modification of its chemical composition. In this work plasma surface modification approach was used to improve mechanical properties by synthesis of composite layer structure on a pure titanium surface. The study aims at development of TiB precipitation dispersed uniformly at α-Ti matrix by plasma melting of Ti-2 wt% and Ti-10 wt% B alloy powders composition. Grain size of precursor powders obtained by mechanical alloying method and its homogenization can control the porosity and boron agglomeration tendency of the synthesized layers. Plasma procedure was taken under argon and helium inert atmosphere and surface was obtained by single passage of plasma pillar upon the prepared surface. The Vickers microhardness of obtained surface reached nearly 850HV, which was much higher compared with initial sample of the pure titanium substrate of 160HV. The surface corrosion resistance in 0.9% NaCl solution was nearly the same as for pure titanium, showing stable behaviour of created oxide layer, with no negative effect of dual phase microstructure. In vitro biocompatibility test in static condition was performed. All samples showed good cell growth. Our studies suggests that chemical composition of modified titanium surface by TiB precipitation by plasma alloying process has no negative effect on cytocompatibility.

Abstract: Good mechanical properties with combination of biocompatibility and high corrosion resistance make titanium and its alloys desirable materials for medical applications. A big disadvantage of titanium connects with its poor wear characteristics, however in this work this property was modified by boride microplasma surface alloying. Plasma surface alloying gives a wide range of layer thickness, which is controlled by the amount of the placed powder and process parameters like gas flow, nozzle diameter and current. Formation of TiB phase precipitation was confirmed by XRD analysis. Additionally, the modified microstructure was observed by optical microscopy. The Vickers microhardness was significantly improved from 180HV for original titanium substrate to 900HV in obtained composite layer structure, with a smoth hardness reduction in the cross section profile. Strong heat penetration from microplasma melt-in technique, results in substrate dissolution with formation of stable composite Ti + TiB layer. The surface corrosion resistance in 0.9% NaCl solution was nearly the same as for pure titanium, showing stable behavior of created oxide layer, with no negative effect of dual phase microstructure. Wear resistance of received composite layer structures were significantly improved in comparison with initial titanium samples.