Papers by Keyword: Vacuum Infiltration (VI)

Abstract: Strong and tough, macroporous alumina/zirconia composites are superior to alumina scaffolds but still biologically inert to bone tissue, leading to poor tissue ingrowth and osteointegration. One way to solve this problem is applying a bioactive coating onto the pore walls of the macroporous composites. In this study, macroporous alumina/zirconia (20vol%) composites (scaffolds) were prepared by a vacuum infiltration method involving the use of strained (10%) compacts of the expanded polystyrene (EPS) beads (typically 1-2.8 mm in diameter). A bioactive glass (58S33C) coating (~ 20 μm) was applied on the pore walls of the macroporous composites by slurry dip coating and sintering at 1200 oC for 1 hour. A top or outer bioactive glass (58S33C) thin layer (< 10 μm) was further applied by sol dip coating and sintering at a low temperature (< 800 °C). The bioactive glass-coated macroporous alumina/zirconia composites had well interconnected pores, relatively large pore sizes (1-2 mm), medium porosities (60-66%), high compressive strengths (7.52 – 5.42 MPa), and high bioactivity (with an apatite layer formed within 24 hours in the simulated body fluid). The combination of the strong and ultrafine (if not nano-structured) macroporous scaffolds with the multiple or graded bioactive coatings represented a new generation of bone substitutes or permanent scaffolds for bone tissue regeneration.

Abstract: In recent years considerable attention has been dedicated to renewal power sources, such as wind power. This work was carried out in order to develop a small wind turbine of 1-10kW power generation capability. This wind turbine is designed to be energetically more efficient by 30-50% and having a lesser specific cost (by 25-30%). This work focused on the development of composite materials for application on the blades in the wind generator. In this paper we present the results of the research work done on the development of flexible technology for the fabrication matrix-epoxy resin based hybrid composites, reinforced with carbon, basalt and glass fibers. These new composite and hybrid materials were fabricated using epoxy matrixes. These matrices were reinforced with basalt and carbon fibers of different content and strengthened by mullite-like crystals. The basalt fibers for composite reinforcing were prepared from raw materials, with chemical composition: SiO2-15.3%; CaO-10.8%; Na2O-4.2%; MgO-8.8%; Fe2O3-12.1%; MnO-0.7%; TiO2-0.7%. The properties of new composites developed depend on the content and architecture of reinforcing components and are: tensile strength-(0.012-1.590)GPa; compression strength-(0.078-0.656)GPa; modulus of elasticity-(8.4-162.9)GPa; Poisson ratio-(0.015-0.559). The variation of strength and elastic characteristics under tension and compression of the new composites are presented.