Status Quo is Not an Option

My research interest are reflected in my 18 years of experience in experimental materials science. On the synthesis of materials (mainly metals and ceramics) my research has taking me to the use of vacuum furnaces, hot presses, chemical vapor deposition, induction heating, and many other techniques. On the materials characterization side, my research has taken me to the use of x-ray diffraction (phase identification, structure determination, pole figures, inverse pole figures, Laue single crystal, crystallite size determination, etc), transmission electron microscopy (BF, DF, DP, EDS, EELS, CBD, ZOLZ, HOLZ, etc), electron probe micro-analyzer (EDS, WDS - 4 crystals, mapping and line scan), scanning electron microscopy (morphology, EDS, elemental mapping, ZAF, Bence-Albee, crystallographic orientation, LN2 cooling of samples, etc), scanning auger microscopy (Auger chemical composition, elemental mapping, surface analysis), scanning probe microscopy, x-ray fluorescence and other techniques. Some of this research has been published while others are still in development. Here are some examples.

Photo: Reduced Magnetite - Topotacticity (30-50nm Fe crystallites)

Development of nanocrystallite porous agglomerates by Direct Reduction.

Objective: To develop porous agglomerates made of nanocrystallites with controlled porosity.

During reduction of high purity fused magnetite Fe3O4 in a hydrogen atmosphere, Fe crystallites will form. The initial size of these Fe crystallites depends mainly on the reduction temperature, lower temperatures will produce smaller crystallites. However, even at lower temperatures, sintering is a competitive process and crystallite coalescence will take place, changing not only the crystallite size but also the porosity and available surface area.

Smaller amounts of unreducible impurities in the Fe3O4, such as Al2O3 or MgO can readily form a solid solution (dissolve) with fused magnetite and during hydrogen reduction, they will segregate at the Fe intercrystallite regions. This has a three-fold effect on the material: (a) it will cause an increase in the reduction temperature; (b) it will inhibit crystallite coalescence, i.e. smaller Fe crystallites and higher porosity are possible and (c) it will generate solid network of Fe crystallites joined together by regions of unreducible oxide.  Click here for more information.......    

Photo: MMC of W particles (bimodal) in a Cu-Ag matrix

Objective: To develop microstructures that allow us the independent control of  the material properties.

Many material properties are interrelated, for example strength and hardness, hardness and wear, electrical and thermal conductivity, etc. However, MMC gives us the opportunity to control and tailor the microstructure to optimize an specific material property. We have demonstrated this ability of the MMC by controlling the wear properties of the material using infiltration techniques. The wear results were independent of the strength of the material.

We are trying to extend this concepts in the independent control of electrical and thermal properties of MCC's.  Click here for more information...... 

Photo: Spaghetti-type carbon nanotubes

Objective: Determine the effect of Catalyst Composition ob the Synthesis of Carbon Nanotubes.

Carbon nanotubes are synthezised using the vapor-liquid-solid (VLS) mechanism where a nanosize transition metal particle serves as a catalysts for the formation of carbon nanotubes. The TM particle locates itself at the tip of the nanotube and the catalyst dynamics determines the growth rate, dimensions and morphology of the carbon nanotube. We have prepared  catalyst samples with large compositional gradient of nanoparticles using Fe, Ni and Co  samples and exposed them to reactive gases for the formation of carbon nanotubes. Click here for more information.......    

Photo: Microtwinning

Objective: Determine the conditions for microtwinning and shear band formation in deformed Cu-Ni alloys and their relationship to the development of texture.

We have investigated the development of deformation and annealed textures in different Cu-Ni alloys. The alloys were synthesized under vacuum techniques and contained impurities such as Mn, Fe and C. The alloys  were deformed from 50 to 99%. The development of Cu-type and brass-type texture was studied using inverse pole figures, pole figures and transmission electron microscopy. Some of the samples were annealed to temperatures in the range 400-800oC. The formation of a retained rolling texture after annealing and cube texture was studied and related to the deformation texture. Click here for more information.......    

Photo: AlN whisker

Objective: Determine the parameters for the low temperature synthesis of 1-D nitrides such as AlN, BN, GaN and others using the VLS technique.

We have synthesizes AlN whiskers at high temperature using the  carbothermal reaction and a catalyst. The whisker varied in size from the micro to the nanometer scale. The growth direction was characterized using SEM and TEM techniques. The catalyst was found at the root of the whiskers rather than at its tip. Click here for more information.......    

Photo: HK40 failure along primary carbides

Objective: Various cases of failure analysis are illustrated.

(a) Failure analysis of a HK40 alloy. (b) Failure analysis of a rail train (c) . Click here for more information.......    

Photo: Huge Carbon tubes

Objective: Illustrate small and exploratory research.

We have been involved in many other small and exploratory research. Some of the findings and images are illustrated here. Click here for more information.......