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Abstract

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In this study, a powder blend representing 6061 Al-alloy was first mixed with Al 2 O 3 ceramic particles and then foamed by using the powder compact melting method. 6061-Al 2 O 3 foams and control specimens 6061 foams (without ceramic reinforcement) were produced. The effects of both different ratios of Al 2 O 3 particle addition and different kinds of heat treatment on hardenability, structure and mechanical behavior of the final foams were investigated. Foams that were fully heat treated had the highest hardness values, and they performed best with an increase in collapse strength up to 100% over the untreated samples. Improved cell structure and decreased drainage were obtained when the Al 2 O 3 addition was not more than 5 vol%. The compression test results were interpreted in terms of the foam's microstructure, and correlations were made relating to the unloading modulus and compression strength of the foams to the relative density.

In this study, porous hydroxyapatite structures were produced by using urea particles of 600-850 mm size. Samples with two different urea composition (25 and 50 wt%) were prepared along with samples without any urea content by adding urea to commercially available hydroxyapatite in its as purchased and calcined states. The produced pellets were sintered at 1100 C and 1200 C for 2 h. Compression tests and microhardness measurements were conducted and changes in density values were examined in order to determine the effect of the calcination state of the prior hydroxyapatite powder, the sintering temperature and the amount of urea added. Also X-ray diffraction, Fourier transform infrared, and scanning electron microscopy analyses were conducted to determine the phase stability, functional groups, and pore morphology, respectively. Calcination is found to negatively affect the densification and sinterability of the produced samples, resulting in a decrease of compressive strength and microhardness. With the control of the urea content and sintering temperature uncalcined hydroxyapatite can successfully be used to tailor the density and mechanical properties of the final porous structures.