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Materials Processing Laboratory
Powder Processing Apparatus
Complete facilities exist in MSE at Georgia Tech for characterization of powders and slurries in support
of hollow sphere development. Powder particle size distributions are measured with a Leeds and Northrup laser particle size analyzer equipped with both a standard range analyzer for sizes 0.7-700 µm and a small
particle analyzer for 0.1-60 µm. Computer control allows data storage and comparison. A Quantachrome Autosorb-1 BET, nitrogen surface area analyzer is available for both surface area and fine pore characterization.
Broad ranges of pore sizes may be measured with a Quantachrome Autoscan, #33 mercury porosimeter. Both the surface area analyzer and the mercury porosimeter are computer-controlled and automatically evaluate a wide
range of analytical models to aid in data interpretation. A Gas permeability Apparatus is also available for measuring the permeability and effective diffusion coefficient of porous materials. Slurry rheologies are
characterized with a Haake RV20 concentric cylinder viscometer which is also computer-controlled and programmed to analyze a wide range of non-Newtonian rheologies. The viscometer can operate over a wide range of
shear rates, 0.1-1000s-1, and automatic temperature control from -20 to 150oC is provided.
{Contact: Dr. Joe Cochran, MSE, Tel: 894-6104}
Hollow Sphere Fabrication
A facility for fabricating hollow spheres from slurries has been developed and refined. It includes a wide selection of concentric nozzles, mass flow controllers for metering inner
jet gas flow, acetone atmosphere flow, and gas pressure for controlling slurry flow rate, Management of sphere free fall velocity is provided by a drop tower equipped with variable air flow control. This increases
free fall residence time for increased shell drying or hardening. A liquid metal hollow sphere fabrication facility has recently been constructed. It has a metal holding tank equipped with a furnace with digital
temperature controller. Atmosphere control is via a glass tube drop tower and gas flow control is by needle valves and rotometers.
{Contact: Dr. Joe Cochran, MSE, Tel: 894-6104}
Melting and Solidification Laboratory
A special furnace has been constructed to independently control and measure both gradient and velocity. The velocity is controlled by placing the specimen on a
weighted platform which can be raised and lowered by a hydraulic pump. A special valving system is then actuated which displaces the specimen through the imposed temperature gradient at a specified rate. The
temperature gradient is maintained through a series of heating and cooling stage. Temperature measurement is performed with a series of thermocouples mounted in thermal wells inside the specimen. Data acquisition is
fully automated with a 16 channel real-time data display and high frequency logging capabilities. The furnace incorporates the same principles as the traditional Bridgeman furnace, but includes more flexibility in
terms of sample size, geometry, and temperature measurement. This furnace permits correlations to be made between alloy composition, cooling rate, and microstructure
{Contact: Dr. Tom Sanders, MSE, Tel: 894-5793}
Impedance Spectroscopy and Electrochemical Analysis and Testing Facilities
Two computerized impedance analysis systems are available for impedance spectroscopy in the frequency range from 1 MHz to
20 MHz: (a) An Electrochemical Interface (Solartron 1286) and a Frequency Response Analyzer (Solartron 1255) interfaced with an IBM/PC/486 computer through software Z-plot and (b) a Potentiostat/Galvanostat
(EG&G PAR 273A) and lock-in amplifier (5208 EC) interfaced with an IBM/PC/486 computer through Model 378 software. for measurements of ionic and electronic conductivities and interfacial properties. The two
systems are also capable of performing various electrochemical or electroanalytic characterization. A Glove box (Vacuum Atmospheres (TS-4000) is used to handle air-sensitive materials like lithium batteries.
{Contact: Dr. Meilin Liu, Tel: 894-2380}
Corrosion Testing
Two electrochemical corrosion testing systems, including EG&G Models 272 and 273 are available
for polarization, potential, and galvanic measurements. An Atomic Absorption Spectrophotometer (AAS) with carbon furnace atomization and mercury cold-vapor accessory (Varian SpectrAA-300 with DTA-96, VGA-76, and
MCA-90) are available for solution analysis for metallic ions.
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