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Nascimento, Sergio F. do. Silicon nitride ceramics with silicon, strontium and aluminum oxides for bone replacements. 2019. 100p. Dissertation (Master in Nuclear Technology) Institute of Nuclear and Energy Research IPEN-CNEN / SP. São Paulo. Silicon nitride (Si3N4) is a structural ceramic with excellent mechanical properties such as high flexural and fracture resistances, high fluence and high wear resistance. These properties are owing to the processing techniques and the additives used to promote the liquid sintering. The mechanical properties of silicon nitride ceramics combined to the osseointegration ability increase their potential to applications as structural implants. In this study, the densification, microstructure, mechanical properties and in vitro biological behavior of silicon nitride with additions of silicon, strontium and aluminum oxides were investigated. Different compositions were prepared by means of the conventional sintering at 1815 °C for 1 hour under N2 atmosphere. SEM analyses showed that the final microstructures of the samples were formed by β-Si3N4 grains dispersed in a secondary amorphous phase formed by the sintering aids. The results showed that the samples reached relative densities of 97% and total →-Si3N4 transformation, proving the efficiency of the sintering aids.The values of hardness and fracture toughness were about 10 GPa e 7 MPa.m, respectively. All samples were non-cytotoxic and induced the formation of apatite in their surfaces after 8 days of immersion in SBF. The results proved the materials ability to proliferate MG63 cells whose differences were detected using Analysis of Variance (ANOVA) and Tukey ́s test. The results suggest the more promising sample was that with high amount of strontium due to their great mechanical properties, higher ability to promote apatite formation in reactivity and cell proliferation tests.

Cerâmicas de nitreto de silício contendo óxidos de silício, estrôncio e alumínio para substituições ósseas