Jazmín I. González; Diana M. Escobar; Claudia P. Ossa
Abstract
Hydroxyapatite is one of the appropriate materials for hard tissue engineering because it is the inorganic structural constituent of bones and teeth, and hydroxyapatite has been evaluated to compare the mechanical properties, processing as scaffolds to evaluate the influence of porosity, since the elastic ...
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Hydroxyapatite is one of the appropriate materials for hard tissue engineering because it is the inorganic structural constituent of bones and teeth, and hydroxyapatite has been evaluated to compare the mechanical properties, processing as scaffolds to evaluate the influence of porosity, since the elastic modulus of material is influenced by the porosity, it is essential to establish a relationship between the two characteristics to obtain a material with optimum conditions for its implantation. The main objective of this research was to study the mechanical properties of hydroxyapatite scaffolds using compression and nanoindentation tests. The scaffolds were manufactured by gel-casting and gel-casting combined with foam polymer infiltration, in both cases 40 and 50% solids and three different monomers were used. The samples obtained by gel-casting exhibited a compressive strength between 0.93 and 6.15 MPa, an elastic modulus between 11.46 and 27.27 GPa; some of these scaffolds showed very similar values to human trabecular bone reported. In addition, samples produced by gel-casting combined with foam polymer infiltration, it was found that compressive strength was between 0.05 and 0.12 MPa, the elastic modulus between 1.61 and 6.24 GPa, concluding that the gel-casting produces scaffolds with closest to trabecular bone.
Samuel A. Awe; Salem Seifeddine; Anders E. W. Jarfors; Young. C. Lee; Arne K. Dahle
Abstract
In a quest for developing new lightweight metal alloys that can perform excellently at elevated-temperatures (from 300°C to 400 °C), a ternary eutectic Al-Cu-Si alloy was exploited to gain a deeper understanding of the alloy system and its suitability for high temperature applications. The studied ...
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In a quest for developing new lightweight metal alloys that can perform excellently at elevated-temperatures (from 300°C to 400 °C), a ternary eutectic Al-Cu-Si alloy was exploited to gain a deeper understanding of the alloy system and its suitability for high temperature applications. The studied alloys, with chemical composition of Al-27%Cu-5%Si (by weight percent) with Ni addition in the range of 0 to 1.5%wt, were cast in a rapid solidification casting technique. The solidification characteristics of the alloy was studied using the Thermo-Calc software. Microstructures were characterized in a scanning electron microscope coupled with energy dispersive spectrometry (SEM-EDS). Finally, the elevated-temperature tensile properties of the alloys were investigated. Comparing the microstructures and mechanical properties of the Al-Cu-Si(-Ni) alloys with conventional A319 Al- alloy, the refined microstructure with dispersed Ni intermetallic particles formed in the as-cast Al-Cu-Si(-Ni) alloys delivers improved elevated temperature properties. In particular, the yield strength and ultimate tensile strength of the new alloy with 1.5% Ni at 400˚C were observed to be 220% and 309% higher, respectively, than for conventional A319 reference alloy.
G. Ashok Kumar; I. Dinaharan; S. J. Vijay; N. Murugan
Abstract
Friction stir processing (FSP) is a novel solid state technique to refine the microstructure of metallic materials. The objective of this work is to apply FSP to change the morphology and distribution of intermetallic particles and achieve property enhancement. AA6061/8wt. % Al3Zr composite was produced ...
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Friction stir processing (FSP) is a novel solid state technique to refine the microstructure of metallic materials. The objective of this work is to apply FSP to change the morphology and distribution of intermetallic particles and achieve property enhancement. AA6061/8wt. % Al3Zr composite was produced by the in situ reaction of molten aluminum and inorganic salt K2ZrF6. Optical and scanning electron micrographs revealed a uniform distribution of needle shape Al3Zr particles in the aluminum matrix. The Al3Zr particles were located in the inter granular spaces. A double pass FSP was carried out using a tool rotational speed of 1200 rpm, processing speed of 50 mm/min and axial force of 8 kN. A tool made of HCHCr steel; oil hardened to 62 HRC, having a hexagonal profile was used. The needle shape Al3Zr particles were fragmented and converted into a spherical shape subsequent to FSP which resulted an increase in the hardness of the composite.
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