In materials science and engineering, there is a demand in new materials for radiation shielding in the transport of radiopharmaceuticals used in the diagnosis and therapy of cancer, justifying the interest in developing this work. The obtained lignin kraft and tungsten form the precursors used for metal-organic composite. Tungsten metal has diverse applications in the nuclear sector presents an enormous mechanical strength and an excellent cross section with thermal neutrons. The aim of this study is to analyse the microstructural evolution of metal-organic composite using the kraft lignin and tungsten, using analysis of scanning electron microscopy (SEM), microhardness test and x-ray diffraction (XRD). Microscopic analysis showed the granulometry of the precursors separate and composite morphology, observing the formation of alpha (α) and beta (β) phases and absence of oxidation process for different heat treatment temperatures. The spectra of x-ray diffraction identified the structures of each phase formed and micro hardness measures showed an increase of mechanical resistance with temperature. The results of the microstructural characterization of metal-organic composite, will contribute in the next steps of attenuation measurements of gamma radiation.Keywords: Tungsten; Composite; Lignin Kraft. ResumoNa ciência dos materiais e na engenharia, há uma demanda em novos materiais para proteção contra radiação no transporte de radiofármacos utilizados no diagnóstico e terapia do câncer, justificando o interesse em desenvolver este trabalho. A lignina kraft obtida e o tungstênio formam os precursores utilizados para o composto metal-orgânico. O metal de tungstênio tem diversas aplicações no setor nuclear, apresenta uma enorme resistência mecânica e uma excelente seção transversal com neutrons térmicos. O objetivo deste estudo é analisar a evolução microestrutural do composto metal-orgânico utilizando a lignina kraft e tungstênio, utilizando análise de microscopia eletrônica de varredura (SEM), teste de micro dureza e difração de raios X (XRD). A análise microscópica mostrou a granulometria dos precursores separada e morfologia compósita, observando a formação de fases alfa (α) e beta (β) e ausência de processo de oxidação para diferentes temperaturas de tratamento térmico. Os espectros de difração de raios X identificaram as estruturas de cada fase formada e as medidas de micro dureza mostraram um aumento da resistência mecânica com a temperatura. Os resultados da caracterização microestrutural de compostos metálicos e orgânicos contribuirão nos próximos passos das medidas de atenuação da radiação gama.

This research has been carried on to analyze the capability of a new composite to be effectively used as shielding of gamma radiation. The preparation of a metal-organic composite formed by tungsten and Kraft lignin is presented. Samples have been characterized through X-rays and scanning electron microscopy measurements. The results led to the study of the different phase formations. The microscopic analyzes indicate that two different phases are present in the composite. The absence of oxidation in the process even after the temperature treatment imposed to form the sample has also been noticed. Measurements of the attenuation have been performed to study its ability to absorb gamma radiation. A sample of cobalt 60 (Co-60), for which the peak energies are at 1173 keV and 1332 keV, was used as a source of gamma radiation in the experiment of attenuation. The measured attenuation of gamma radiations when the composite is placed to act as a shield is only 16% smaller than the attenuation obtained for standard pure tungsten. This is a clear indication that the new metal-organic composite is suitable for the fabrication of devices dedicated to shielding radiation, with the advantage of being easier to manipulate.