L. Bejar

Nanoparticle and Intermetallic Formation in Dissimilar Friction Welds Produced with Silver Interlayers

The introduction of a silver interlayer during MMC/AISI 304 stainless steel friction welding promoted the formation of intermetallic compounds and silver nanoparticles. It is suggested that nanocrystal formation and the formation of Ag3Al intermetallics regions resulted from mechanical mixing during the friction welding operation. The nanoparticles were analyzed by a Philips FEG Tecnai F20. Experimental Procedure The chemical compositions of the MMC and AISI 304 stainless steel base materials are indicated in Table 1. All dissimilar friction welds were made using 19-mm bars 0f diameter of AISI 304 stainless steel and Al 6061/Al2O3 (W6.A.l0A-T6) base material containing 10 vol.% Al2O3 particles. The contacting surfaces of the steel and MMC substrates were machined perpendicular to the axes of the as-received bars. The stainless steel test bars were polished using 1µm diamond particles and coated with 5 µm-thick nickel strike layers.

Synthesis of Mesoporous Zirconia by Using CTAB as Template

1 Instituto de Física y Matematicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, México 2 Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, México 3 Depertamento de Ingeniería Metalúrgia y Materiales. Universidad técnica Federico Santa María. Valparaiso, Chile. 4 Automotive Mechanics Department. Universidad Politécnica de Pachuca. Zempoala, Hidalgo. México

Synthesis of ZnO Crystals Hexagonal Ball Shape

Zinc oxide is an important material due to its many applications. It is a wide band gap semiconductor that is piezoelectric and has catalytic activity [1,2]. These properties make it useful in a variety of applications such as solar cells, piezoelectric and chemical sensors [3]. The crystal structure and macroscopic morphology of the ZnO crystals dictates their properties and, thus, the applications for which they can be used. The ability to tailor both the crystal structure and morphology would allow ZnO crystals to be tuned for specific applications. Based on the reaction conditions used in the synthesis of ZnO structures, nanorods, nanowires, nanorings, nanobelts and nanosprings, among others, can be formed [2]. ZnO ball crystal shape was sinthetized using both Sol – Gel method with a hydrothermal soft treatment. In a first step, two solutions were prepared. The first one was obtained by dissolving 5.9498 g of Zn(NO3)2.6H2O in 21.618 g distilled water. For the second solution, 7.999 g of NaOH was dissolved in 21.618 g distilled water. In a second step, the Na-solution was added slowly (drop by drop) to Zn-solution and stirred at room temperature. The final solution was stirred for 30 min at room temperature to get a material with a molar ratio of Zinc:NaOH:H2O = 1:10:120. The gel obtained was aged in a stainless steel autoclave bottle at 160 °C for 1 day. After the hydrothermal treatment, the sample was washed with 100 ml of distilled water and centrifuged at 12000 rpm during 10 min. After that, the material was dried at room temperature for 1 day. The surface morphology of the samples was analyzed by using a scanning electron microscopy FEG-SEM JEOL JSM 7600. Figure 1 shows an SEM image of several ZnO Crystal hexagonal ball shape showing a diameter about 10 nm and the formation of hexagonal bars with diameters ranged between 1 to 5 μm and length from 3 to 15 μm. Figure 2 shows a zoom of a ZnO crystal hexagonal shape from figure 1 where it is possible to appreciate the form of the ZnO crystal. The results showed that the molar ratio Zn(NO3)2.6H2O / NaOH and hydrothermal treatment temperature could be critical parameters in the formation of hexagonal ball shape. The high amount of NaOH in the synthesis could increase drastically the pH during the formation of the gel. This effect could be the reason for the formation of several hexagonal bar to form a ball shape. The synthesis procedure presented in this research work is easy with a low cost and can be used to synthetize different kinds of material.

Synthesis of Mesopores of Zirconia by Using CTAC as Template

1a Instituto de Investigaciones Metalúrgicas, 1b Instituto de Física y Matemáticas, 1c Facultad de Ciencias Físico y Matemáticas, 1d Facultad de Ingeniería Mecánica, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, México, C.P. 58000 2 Depertamento de Ingeniería Metalúrgica y Materiales. Universidad Técnica Federico Santa María. Av. España 1680, Valparaíso, Chile. 3 Automotive Mechanics Department. Universidad Politécnica de Pachuca. Zempoala, Hidalgo. México

Synthesis of Ti-Nb-Ta-Zr Alloys Foams by Powder Metallurgy

1 Depertamento de Ingeniería Metalúrgica y Materiales. Universidad Técnica Federico Santa María. Av. España 1680, Valparaíso, Chile. 2a Instituto de Investigaciones Metalúrgicas, 2b Facultad de Ingeniería Mecánica, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, México, 58000 3 Departamento de Metalurgia, Universidad de Atacama, Av. España 485, Copiapó, Chile 4 UNAM, Campus Morelia, Antigua carretera a Pátzcuaro 8701, Morelia, Mich., México. 58190.

Synthesis of Ti-Nb-Ta-Mn Alloys by Mechanical Alloying

1 Depertamento de Ingeniería Metalúrgica y Materiales. Universidad Técnica Federico Santa María. Av. España 1680, Valparaíso, Chile. 2a Instituto de Investigaciones Metalúrgicas, 2b Facultad de Ingeniería Mecánica, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, México, 58000 3 Departamento de Metalurgia, Universidad de Atacama, Av. España 485, Copiapó, Chile 4 UNAM, Campus Morelia, Antigua carretera a Pátzcuaro 8701, Morelia, Mich., México. 58190.

Effect Of The Chemical Precipitation Synthesis Parameters On The Morphology And Size Of ZnO Nanoparticles

Universidad Michoacana de San Nicolas de Hidalgo (UMSNH), Ciudad Universitaria, Morelia, Michoacan. 58000. Mexico. Departamento de Ingenieria en Materiales, Instituto Tecnologico Superior de Irapuato (ITESI), Carretera Irapuato-Silao Km. 12.5, Irapuato, Guanajuato, 36821. Mexico. Universidad Politecnica del Valle de Mexico. Avenida Mexiquense S/N, Tultitlan Estado de Mexico. 54910. Mexico. Facultad de Ingenieria, Universidad Autonoma del Carmen, Campus II, Av. Central S/N, Cd. del Carmen, Campeche, 24115. Mexico.