Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New way to make dense complex-shaped ceramics at lower cost

21.08.2002


A new way researchers have developed to make dense ceramics in complex shapes could lead to light, tough, and hard ceramic parts at lower cost.



The recently patented technique, called "displacive compensation of porosity," or DCP, uses a chemical reaction between molten metal and a porous ceramic to generate a new composite material. The technique fills the tiny pores inside the ceramic with additional ceramic material. The resulting super-dense part retains the shape of the original ceramic.

The technology could be used to produce rocket nozzles, body armor, and manufacturing tools, explained inventor Ken Sandhage, professor of materials science and engineering at Ohio State University. His partner on the patent, former student Pragati Kumar, now works for Novellus Systems Inc., a maker of semiconductor manufacturing equipment in San Jose.


Manufacturers could make hard heat-resistant ceramics cheaper and easier with DCP, since it works at lower temperatures than conventional methods and eliminates the need for post-process machining, Sandhage said. The first step of the process -- creating a porous ceramic shape, or preform -- is well known in industry.

"The same way you form a teacup, you can make one of our preforms," Sandhage said.

Today’s strongest body armor relies on ceramics, because these materials are lighter and harder than metal. For instance, both military armor and commercially available bulletproof vests can contain ceramic plates wedged between layers of fabric.

Sandhage said manufacturers could create thinner, lighter, and stronger body armor if they used very hard ceramics, such as boron carbide, but such materials are difficult to mold into body-friendly shapes.

With DCP, Sandhage and his students were able to create composites containing some of the world’s hardest materials, including boron carbide, zirconium carbide, hafnium carbide, titanium carbide, and zirconium diboride.

In tests, the Ohio State engineers molded a curved object out of tungsten carbide, a fine gray ceramic powder used in machine tools and abrasives. Then they melted a zirconium-copper alloy and let the molten metal seep into the powder.

"The tungsten carbide sucked up the liquid metal like a sponge sucks up water," Sandhage said.

At temperatures of 1,200 C to 1,300 C (2,190 F to 2,370 F), the metal and ceramic reacted with each other chemically inside the porous object, producing a zirconium carbide -- tungsten composite. Normally, this composite material is created at temperatures closer to 2,000 C (3,630 F), and at very high pressures.

Sandhage described some unique features of DCP. "When the reaction is complete, we can have twice as much solid material as we started with. That extra material has to go somewhere, so it fills in the pores of the ceramic, creating a very dense material," he said.

"The composite is very light, too," Sandhage continued. "We’ve made tungsten-bearing composite materials that are 40 percent lighter than plain tungsten."

In another test, the engineers formed a composite of magnesium oxide and plain magnesium at 900 C (1,650 F). Other reactions have taken place at temperatures as low as 750 C (1,382 F), Sandhage said.

One obvious application involves rocket nozzles; two of Sandhage’s former undergraduate students, Matthew Dickerson and Raymond Unocic, won the 2000 National Collegiate Inventors Award for demonstrating that DCP can be used to fabricate composites with ultra-high melting points for applications such as rocket nozzles. Dickerson is now a graduate student in Sandhage’s research group. Unocic will join the group as a graduate student this fall.

Plain tungsten is used to form rocket nozzle liners, because it has the highest melting point of any metal, and won’t oxidize in harsh solid fuel rocket environments. Sandhage said a nozzle made out of a tungsten composite would retain all the good features of plain tungsten, but be much lighter.

Such composites could also be used to form very high quality machine tools and parts for the aerospace, automotive, and manufacturing industries. Because the final part conforms to the shape of the original porous ceramic, there’s no need to reshape the part after processing. This means a potential cost savings for manufacturers, since only expensive diamond tools can shape such parts after they are finished.

Because the DCP process uses lower temperatures than conventional processing, manufacturers could save on electricity costs and use less-expensive furnaces as well, Sandhage said. The DCP process also does not require the use of high pressures -- another potential cost savings.

A start-up company is currently negotiating a license for the process, to further develop it for commercial use.


Contact: Ken Sandhage, (614) 292-6731; Sandhage.1@osu.edu
Written by Pam Frost Gorder, (614) 292-9475; Gorder.1@osu.edu

Ken Sandhage | EurekAlert!

More articles from Process Engineering:

nachricht New technology for ultra-smooth polymer films
28.06.2018 | Fraunhofer-Institut für Organische Elektronik, Elektronenstrahl- und Plasmatechnik FEP

nachricht Diamond watch components
18.06.2018 | Schweizerischer Nationalfonds SNF

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Subaru Telescope helps pinpoint origin of ultra-high energy neutrino

16.07.2018 | Physics and Astronomy

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides

16.07.2018 | Life Sciences

New research calculates capacity of North American forests to sequester carbon

16.07.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>