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

JPK announces expansion of its global sales and service activities in China and USA April 15th, 2014

Nanobiotix Appoints Thierry Otin as Head of Manufacturing and Supply April 15th, 2014

PAM-XIAMEN Offers UV LED wafer April 15th, 2014

Engineers develop new materials for hydrogen storage April 15th, 2014

Superconductivity

Drexel Researchers Open Path to Finding Rare, Polarized Metals April 2nd, 2014

Pseudogap theory puts physicists closer to high temperature superconductors March 20th, 2014

Colored diamonds are a superconductor’s best friend March 6th, 2014

Electronics based on a 2-D electron gas: A new material could open the door to a new kind of electronics: researchers at the Vienna University of Technology have created a stable two-dimensional electron gas in strontium titanate March 3rd, 2014

Discoveries

Engineers develop new materials for hydrogen storage April 15th, 2014

Nanocrystalline cellulose modified into an efficient viral inhibitor April 15th, 2014

Tiny particles could help verify goods: Chemical engineers hope smartphone-readable microparticles could crack down on counterfeiting April 15th, 2014

A molecular approach to solar power: Switchable material could harness the power of the sun — even when it’s not shining April 15th, 2014

Materials/Metamaterials

Engineers develop new materials for hydrogen storage April 15th, 2014

Industrial Nanotech, Inc. Lands First Major Order from Pemex, Mexico’s State-Owned Oil and Gas Company April 14th, 2014

Properties of Coatings Used in Electrical Insulators Modified by Iranian Researchers April 14th, 2014

Graphene Supermarket to offer HDPlas™ by Haydale, a High-Performance Graphene Material April 10th, 2014

Announcements

Tiny particles could help verify goods: Chemical engineers hope smartphone-readable microparticles could crack down on counterfeiting April 15th, 2014

A molecular approach to solar power: Switchable material could harness the power of the sun — even when it’s not shining April 15th, 2014

Targeting cancer with a triple threat: MIT chemists design nanoparticles that can deliver three cancer drugs at a time April 15th, 2014

Biologists Develop Nanosensors to Visualize Movements and Distribution of Plant Stress Hormone April 15th, 2014

Military

Tiny particles could help verify goods: Chemical engineers hope smartphone-readable microparticles could crack down on counterfeiting April 15th, 2014

Targeting cancer with a triple threat: MIT chemists design nanoparticles that can deliver three cancer drugs at a time April 15th, 2014

Scalable CVD process for making 2-D molybdenum diselenide: Rice, NTU scientists unveil CVD production for coveted 2-D semiconductor April 8th, 2014

Rebar technique strengthens case for graphene: Rice University lab makes hybrid nanotube-graphene material that promises to simplify manufacturing April 7th, 2014

Energy

Engineers develop new materials for hydrogen storage April 15th, 2014

A molecular approach to solar power: Switchable material could harness the power of the sun — even when it’s not shining April 15th, 2014

Shiny quantum dots brighten future of solar cells: Photovoltaic solar-panel windows could be next for your house April 14th, 2014

Scientists open door to better solar cells, superconductors and hard-drives: Research enhances understanding of materials interfaces April 14th, 2014

Automotive/Transportation

Tiny particles could help verify goods: Chemical engineers hope smartphone-readable microparticles could crack down on counterfeiting April 15th, 2014

Nanotech Business Review 2013-2014 April 9th, 2014

Heat-conducting polymer cools hot electronic devices at 200 degrees C March 31st, 2014

Nanovations Sets new Benchmark in Automotive Windscreen Coating Durability: Nanovations new automotive glass coating Vision Protect, sets new benchmark in glass coating durability March 23rd, 2014

Fuel Cells

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

Big Step for Next-Generation Fuel Cells and Electrolyzers: Researchers at Berkeley and Argonne National Labs Discover Highly Promising New Class of Nanocatalyst February 27th, 2014

Research and applications of iron oxide nanoparticles February 26th, 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