Tenacidad a la fractura de compuestos cermets 3Al2O3*2SiO2/Ag manufacturados por molienda de alta energía

Abstract

RESUMENLa fabricación de materiales compuestos de matriz cerámica reforzados con partículas metálicas han propiciado la formación de nuevos materiales conocidos como compuestos CERMETS, materiales que debido a sus elementos precursores poseen propiedades distintas a las de los materiales convencionales. En este trabajo se establece la ruta de fabricación de materiales compuestos cermets base 3Al 2 O 3 *2SiO 2 reforzados con partículas metálicas de Ag a partir de la formación de la composición química en peso de polvos de 3Al 2 O 3 *2SiO 2 / 1% Ag en busca de un aumento en la tenacidad a la fractura con respecto al cerámico base. La composición química de polvos es sometida a un proceso de mezcla molienda de alta energía en seco en un molino tipo planetario por 2 horas a 200 rpm. Los polvos posteriormente son conformados en muestras cilíndricas de 20 mm de diámetro y 3 mm de espesor mediante la aplicación de carga uniaxial en frío de 200 MPa. Las muestras son sinterizadas a 1500°C y 1600°C por una y dos horas en un horno de resistencia eléc-trica en atmósfera controlada de gas nitrógeno. Los compuestos fabricados son analizados microestructuralmente por microscopia óptica y electrónica de barrido. Se determina la densidad y las propiedades mecánicas de dureza y tenacidad a la fractura, las dos últimas por el método de indentación. Los resultados muestran la viabilidad de fabricación de materiales compuestos cermets así como los cambios en la densidad, la dureza y la tenacidad a la fractura, con respecto al cerámico 3Al 2 O 3 *2SiO 2 sin refuerzo metálico.Palabras clave: Tenacidad a la fractura, cermets, metalurgia de polvos, molienda ABSTRACTThe composites known as CERMETS are a combination between ceramics and metallic materials. The properties of these materials are different in comparison to conventional materials and their derivatives. The processing methodology of 3Al 2 O 3 *2SiO 2 reinforced with silver metallic particles (CERMET) was established and discussed in this research. The final chemical composition of the powder mixture obtained by high energy mechanical milling technology was 3Al 2 O 3 *2SiO 2 / 1 wt.% Ag in order to improve the fracture toughness aptitude as related to the ceramic base material. The milling was carried out for 2 hours at 200 rpm in dry. The powders were uniaxially pressed into cylindrical samples at a pressure of 200 MPa and then were subjected to a sintering treatment at 1500°C and 1600°C for 1 and 2 hours respectively using an electric furnace with nitrogen gas atmosphere. The resulted materials were microstructurally analyzed by using optical and scanning electron microscopy techniques. The density and the mechanical properties of hardness and fracture toughness were also evaluated, these last two were obtained by using the indentation method. The results

Physical, mechanical properties and antimicrobial analysis of a novel CaO·Al2O3 compound reinforced with Al or Ag particles

“…Thus, the increase in metallic inclusions affects the crack propagation path due to there existing a high probability to collide with any Al or Ag particle that acts as barriers and promotes the crack to stop (Tahaa et al, 2017). The cracks can have a loss of energy that prevents its growth because the metal particle absorbs this energy, forcing the cracks to move around the inclusions, increasing the fracture toughness (Naga et al, 2019;Tahaa et al, 2017;José et al, 2016). Finally, the shear modulus or transversal elastic modulus determined in the synthesized materials are 55 ± 2 GPa, 64 ± 1 GPa and 69 ± 1 GPa for pure calcium aluminate, calcium aluminate-Al and calcium aluminate-Ag, respectively (see Table 3).…”

“…Considering the temperature effect during the synthesis process (Miranda Hernández et al, 2018), it was found that the calcium aluminate material synthesized by an in-situ solid state reaction between Al 2 O 3 and CaCO 3 obtained from snail shells is feasible, but the results show that this material is brittle. However, there are several investigations showing that the incorporation of metallic or ceramic particles into the matrix of the ceramic materials modified their physical properties and mechanical properties, such as hardness, fracture toughness, elastic modulus, and fatigue strength (Naga et al, 2019;Tahaa et al, 2017;Granados et al, 2017;José et al, 2016;Sergejev and Antonov, 2006;Moradkhani et al, 2013;Pramanick, 2015;González-Morán et al, 2017;Shukla et al, 2010;Dapievea et al, 2018). In other works, the effect of silver particles with calcium aluminate was studied and it was found that with silver particles, calcium aluminate has favorable conditions as an endodontic sealer, that presents improved antibiofilm properties with a positive effect on antimicrobial behavior (Almeida et al, 2018).…”

REFRACTORY CERAMICS SYNTHESIS BY SOLID-STATE REACTION BETWEEN CaCO₃ (MOLLUSK SHELL) AND Al₂O₃ POWDERS

“…As is known, if the fracture toughness value is low for any material, this material is sensitive to mechanical flaws when is submitted to mechanical stresses such as tension, vibration, and impact. The values of K IC presented in Table 2 for both materials, namely 0.49 MPa•m 1/2 for the material sintered at 1450°C and 0.43 MPa•m 1/2 for the material sintered at 1500°C, are average values of the fracture toughness determined by all these mathematical models [35][36][37][38]. The low K IC values indicate that the synthesized materials are very brittle and sensitive to mechanical flaws.…”