Investigation of the sample preparation and curing treatment effects on mechanical properties and bioactivity of silica rich metakaolin geopolymer

摘要

Inmany biomedical applications both the biological andmechanical behaviours of implants are of relevant interest; in the orthopaedic field, for example, favourable bioactivity and biocompatibility capabilities are necessary, but at the same time the mechanical characteristics of the implants must be such as to allow one to support the body weight. In the present work, the authors have examined the application of geopolymers with composition H_(24)AlK_7Si_(31)O_(79) and ratio Si/Al = 31 to be used in biomedical field, considering two different preparation methods: one of the activators (KOH) has been added as pellets in the potassium silicate solution, in the other as a water solution with 8 M concentration. Moreover, a different water content was used and only some of the synthesized sampleswere heat treated. The chemical andmicrostructural characterizations of those materials have been carried out by Fourier transforminfrared spectroscopy (FT-IR) and scanning electronmicroscopy (SEM). Subsequently, the effects of the adopted preparation on the mechanical and biological properties have been studied: compressive strength tests have demonstrated that more fragile specimens were obtained when KOH was added as a solution. The bioactivity was successfully evaluated with the soaking of the samples in a simulated body fluid (SBF) for 3 weeks. The formation of a layer of hydroxyapatite on the surface of thematerials has been shown both by SEM micrographs and EDS analyses.