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 Intelligent wheelchairs, predictive prostheses
20.12.2017 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA

nachricht Jelly with memory – predicting the leveling of com-mercial paints
15.12.2017 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>