Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Researcher finds faster, more efficient technique for creating high-density ceramics

Abstract:
"New mechanism for field-assisted processing and flash sintering of materials"

Author: Jay Narayan, North Carolina State University

Published: Online February 2013, Scripta Materialia

Abstract: We propose a unified mechanism for field-assisted phenomena such as enhanced rapid flash sintering, reduction in flow stress and grain growth retardation. It is argued that that defect segregation causes enhanced ionic and electronic transport along dislocations and grain boundaries, which leads to enhanced mobility of dislocations and their selective joule heating. This selective heating, if uncontrolled, can lead to an avalanche and selective melting of grain boundaries, which we propose as the primary mechanism for flash sintering of oxides.

Researcher finds faster, more efficient technique for creating high-density ceramics

Raleigh, NC | Posted on February 27th, 2013

A researcher from North Carolina State University has developed a technique for creating high-density ceramic materials that requires far lower temperatures than current techniques - and takes less than a second, as opposed to hours. Ceramics are used in a wide variety of technologies, including body armor, fuel cells, spark plugs, nuclear rods and superconductors.

At issue is a process known as "sintering," which is when ceramic powders (such as zirconia) are compressed into a desired shape and exposed to high heat until the powder particles are bound together into a solid, but slightly porous, material. But new research from Dr. Jay Narayan, John C. Fan Distinguished Chair Professor of Materials Science and Engineering at NC State, may revolutionize the sintering process.

Narayan's new technique, selective-melt sintering, allows sintering of yttria-stabilized zirconia at 800 degrees Celsius (C) - instead of the conventional 1450 C. In addition, using the selective-melt sintering technique, it is possible to sinter zirconia at 800 C in less than a second, and create a material with no porosity at all. In contrast, traditional sintering techniques take four to five hours at 1450 C.

"This technique allows you to achieve ‘theoretical density,' meaning it eliminates all of the porosity in the material," Narayan says. "This increases the strength of the ceramic, as well as improving its optical, magnetic and other properties."

The key to Narayan's approach is the application of an electric field, at approximately 100 volts per centimeter, to the material. When this field is applied, it creates subtle changes in the material's "grain boundaries" - where atoms from different crystals meet in the material. Namely, the field draws "defects" to the grain boundary. These defects consist of vacancies (missing atoms) which can carry charges. The defects are negatively charged and draw current from the electric field to the area - which raises the temperature along the grain boundary.

Raising the temperature along the grain boundary means that the material can be sintered at a much lower temperature, because sintering is done by selectively melting the grain boundaries to fuse the crystals together.

Normally you would have to apply enough heat to raise the mass of all the material to the melting point, even though you only need to melt the grain boundary. "Pre-heating" the grain boundary with an electric field is what allowed Narayan to lower the sintering temperature from 1450 C to 800 C and sinter the material much more quickly.

####

For more information, please click here

Contacts:
Matt Shipman

919-515-6386

Dr. Jay Narayan

919.515.7874

Copyright © North Carolina State University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

n invited viewpoint paper describing the work, “New mechanism for field-assisted processing and flash sintering of materials,” is published online in Scripta Materialia. Narayan is the sole author:

Related News Press

News and information

NanoScience: Giants of the Infinitesimal July 31st, 2014

University of Manchester selects Anasys AFM-IR for coatings and corrosion research July 30th, 2014

Nature inspires a greener way to make colorful plastics July 30th, 2014

Analytical solutions from Malvern Instruments support University of Wisconsin-Milwaukee researchers in understanding environmental effects of nanomaterials July 30th, 2014

Superconductivity

UCF Nanotech Spinout Developing Revolutionary Battery Technology: Power the Next Generation of Electronics with Carbon July 23rd, 2014

Flashes of light on the superconductor: Using light to modulate the properties of a copper-based superconductor July 15th, 2014

Iranian researchers Produce High-Temperature Superconductive Nanorods July 7th, 2014

Bending the rules: A UCSB postdoctoral scholar in physics discovers a counterintuitive phenomenon: the coexistence of superconductivity with dissipation June 29th, 2014

Discoveries

New imaging agent provides better picture of the gut July 30th, 2014

Watching Schrödinger's cat die (or come to life): Steering quantum evolution & using probes to conduct continuous error correction in quantum computers July 30th, 2014

From Narrow to Broad July 30th, 2014

A new way to make microstructured surfaces: Method can produce strong, lightweight materials with specific surface properties July 29th, 2014

Materials/Metamaterials

From Narrow to Broad July 30th, 2014

Nature inspires a greener way to make colorful plastics July 30th, 2014

Tough foam from tiny sheets: Rice University lab uses atom-thick materials to make ultralight foam July 29th, 2014

A new way to make microstructured surfaces: Method can produce strong, lightweight materials with specific surface properties July 29th, 2014

Announcements

NanoScience: Giants of the Infinitesimal July 31st, 2014

Nature inspires a greener way to make colorful plastics July 30th, 2014

Analytical solutions from Malvern Instruments support University of Wisconsin-Milwaukee researchers in understanding environmental effects of nanomaterials July 30th, 2014

FEI Unveils New Solutions for Faster Time-to-Analysis in Metals Research July 30th, 2014

Military

New imaging agent provides better picture of the gut July 30th, 2014

Watching Schrödinger's cat die (or come to life): Steering quantum evolution & using probes to conduct continuous error correction in quantum computers July 30th, 2014

Tough foam from tiny sheets: Rice University lab uses atom-thick materials to make ultralight foam July 29th, 2014

A new way to make microstructured surfaces: Method can produce strong, lightweight materials with specific surface properties July 29th, 2014

Energy

From Narrow to Broad July 30th, 2014

Oregon chemists eye improved thin films with metal substitution: Solution-based inorganic process could drive more efficient electronics and solar devices July 21st, 2014

Steam from the sun: New spongelike structure converts solar energy into steam July 21st, 2014

3-D nanostructure could benefit nanoelectronics, gas storage: Rice U. researchers predict functional advantages of 3-D boron nitride July 15th, 2014

Automotive/Transportation

Stanford team achieves 'holy grail' of battery design: A stable lithium anode - Engineers use carbon nanospheres to protect lithium from the reactive and expansive problems that have restricted its use as an anode July 27th, 2014

Nano-supercapacitors for electric cars July 25th, 2014

Using Sand to Improve Battery Performance: Researchers develop low cost, environmentally friendly way to produce sand-based lithium ion batteries that outperform standard by three times July 8th, 2014

Up in Flames: Evidence Confirms Combustion Theory: Berkeley Lab and University of Hawaii research outlines the story of soot, with implications for cleaner-burning fuels July 1st, 2014

Fuel Cells

Media Advisory: Minister Rempel to Announce Support for Alberta's Nanotechnology Sector June 20th, 2014

Evolution of a Bimetallic Nanocatalyst June 6th, 2014

University of Surrey collaborates with India and Tata Steel to revolutionise renewable energy March 26th, 2014

Novel membrane reveals water molecules will bounce off a liquid surface: Study may lead to more efficient water-desalination systems, fundamental understanding of fluid flow March 16th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE