Bone cements of poly (methyl methacrylate) (PMMA) have been used for about 40 years to fix artificial prosthesis to bone structure. The aim of this study was to evaluate the absorption, solubility, degradation and bioactivity of novel formulations of PMMA/Ca 2+ bone cements. These properties were evaluated using a fractional experimental design. Hydrolytic parameters were determined, from which we found that 7/8 of the formulations for absorption and 6/8 for solubility fulfill the ISO 4049:2000 requirements. The final degradation values ranged between 1 and 5%, except for one of the formulations. Besides, some formulations showed bioactivity after seven days of immersion in SBF solution.
The chromium carbide coatings are widely used in the mechanical industry due to its corrosion resistance and mechanical properties. In this work, we evaluated a new source of chromium and silicon with micro-additions of boron on the deposition of multi-component coatings of chromium carbides in W108 steel. The coatings were obtained by the pack cementation method, using a simultaneous deposition at 1000 o C for 4h. The coatings were analyzed by X-ray diffraction, X-ray energy dispersive spectroscopy, optical microscopy, microhardness test method and pin-on-disc wear test. It was found that the coatings formed on W108 steel were mainly constituted by (Cr,Fe) 23 C 6 , (Cr,Fe) 7 C 3 , Cr 5-x Si 3-x C x+z , Cr 3 B 0,44 C 1,4 and (or) Cr 7 BC 4 . The carbide layers showed thicknesses between 14 and 15 µm and maximum values of microhardness between 15.8 and 18.8 GPa. Also, the micro-additions of boron to the mixtures showed statistically significant influence on the thickness, microhardness and abrasive wear resistance of the carbide coatings.
The biomimetic method is used for the deposition of calcium phosphate coatings (Ca -P) on the surface of different biomaterials. However, the application of this method requires long exposure times in order to obtain a suitable layer thickness for its use in medical devices. In this paper, we present a fast approach to obtain apatite coatings on titanium, using a combination of supersaturated calcification solution (SCS) with chemical modification of the titanium surface. Also, it was evaluated the effect of four different surface treatments on the apatite deposition rate. Commercially pure titanium plates were activated by chemical or thermochemical treatments. Then, the activated samples were immersed in a solution with high content of calcium and phosphate ions at 37 °C for 24 h, mimicking the physiological conditions. The coatings were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The use of SCS solutions allowed the formation of crystalline hydroxyapatite coatings within a period of 24 h with a thickness between 1 and 5.3 μm. Besides, precipitates of hydroxyapatite nanoparticles with a globular configuration, forming aggregates with submicrometer size, were found in SCS solutions.
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