Influência de cargas de talco nas propriedades microestruturais e mecânicas na matriz de carbetos de silício em compósitos de matriz cerâmica

Abstract

Ceramic Matrix Composites (CMC) are the most recent materials in field composites. The main factors for the good acting of these materials are the choice: of the matrix material, of the reinforcement, of the processing and chemical composition. Ceramic materials possess elastic module very loud, low density, and can support temperatures very discharges, even so they present low toughness. The introduction of a ductile metallic phase in the ceramic can improve its toughness to for frature. The SiC stands among the materials used in the ceramic matrix. Among the metals stands out the aluminum. The infiltration under pressure of a melted (Squeeze Casting) it is one of the methods more used in the production of CMC, being the focus of many searchs. The mechanical properties of a composite varies in function of the ligants addition and addictive in for pre-form. In this work it was obtained CMC of SiC-Talc/AI by "Squeeze Casting" method and investigated the influence of the talc as addictive in the mechanical properties of the ceramic matrix with controlled sizes of particles, intending improvement its mechanical properties of composites obtained. Rectangular test bodies of SiC were made with proportions from 10 to 50% in talc mass. The samples went burned partially at 1100°C, characterized and later infiltrated with aluminum melted at 850°C under pressure. The composites were characterized by optical microscopy and scanning electronic microscopy (SEM), where the different sizes of particles of matrix and the complete infiltration of the channels by melted metal was observed. They were also analyzed by X-ray difraction, showing the presence of phases SiC, Al, Si, SiO2, and MgAl2O4. The result of the flexural module at three points obtained for the proportions of 10 to 50% of talc show the influence of the proportions of addictive in the values of the mechanical properties of these composites.