Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Study may expand applied benefits of super-hard ceramics

Abstract:
Using atomic-scale simulations, the team observed for the first time how atoms moved and interacted as a super-hard ceramic deformed under stress

Study may expand applied benefits of super-hard ceramics

Atlanta, GA | August 04, 2005

A discovery reported in the August 5 issue of Science could speed the design of materials that approach the hardness of diamond yet remain supple enough to be worked like metal.

In a massive computer simulation involving 128 computer processors and nearly 19 million atoms, materials scientist Izabela Szlufarska of the University of Wisconsin-Madison and colleagues at University of Southern California demonstrated the precise atomic mechanisms that explain why "nanostructured" ceramic materials-some of the hardest substances known-also exhibit unusual pliability.

Unlike other exceptionally hard materials, these advanced ceramics tend to bend rather than break, meaning they could be shaped into extremely long-lasting yet lightweight parts for everything from automobile engines and high-speed machining tools to medical implants in the body.

But they are also notoriously difficult to engineer, because as their name implies they possess a grain structure that falls into the nano-size range of molecules and atoms.

"How to optimize their design is an open question," says Szlufarska, who is also a professor of engineering physics. "People have used a trial and error approach to make these materials harder. But there is still much to be understood as to why they are harder."

Simulations can help to answer this by providing a level of detail unavailable to experiments. Using atomic-scale simulations, the team observed for the first time how atoms moved and interacted as a super-hard ceramic deformed under stress. The advance has not only provided unprecedented insight into the properties of these materials, but also a tool that researchers can use to systematically nano-engineer them.

"This study is just the first step," says Szlufarska. "The goal is to design the strongest material possible."

The particular nanostructured ceramic Szlufarska focuses on, called nanocrystalline silicon carbide, is also exceptionally resistant to high temperature and radiation, which has NASA eyeing it as a coating for the space shuttle. Another important application is micro-electro mechanical systems (MEMS), tiny machines that are currently made of silicon.

"Today's MEMS can't have two surfaces rubbing against one another because the silicon is brittle and tends to break," says Szlufarska. "If we could instead make MEMS out of silicon carbide, the sky would be the limit in terms of applications."

Normal ceramics, like clays, become brittle when fired. But when ceramic is made from particles spanning mere atoms in diameter, the material exhibits dramatically improved ductility after bonding at high temperature and pressure.

This unusual combination of strength and suppleness is derived from the material's two-phase nature. In nanocrystalline silicon carbide, says Szlufarska, highly ordered, crystalline grains are surrounded by a more disordered, or amorphous, matrix of grain boundaries-much like tiny stones cemented by a semi-fluid mortar. And the volume of grain boundaries exceeds that in other nanostructured materials such as metals.

To understand, at the atomic scale, how nanocrystalline silicon carbide deforms under force, the team performed a simulation in which they pressed a tiny, virtual probe, called an indenter, into the material's surface and watched how the atoms moved in response. Initially, the grains deformed and then sprang back as a unit, an illustration of the material's hardness.

"At this point, the grains all moved together because the grain boundaries held them together like glue," says Szlufarska.

But as the probe pressed deeper and exerted greater pressure, the researchers witnessed a surprising shift in the material's response. At a specific indentation depth, the grain boundaries began to yield, allowing individual grains to rotate and glide independently under the probe's force.

"Because the grain boundaries are flowing, the material is more ductile than normal ceramic would be," says Szlufarska. "And the grain boundaries initially take part of the deformation, so in essence they protect the grains from breaking."

In contrast, nano-structured metals go through no such phase; instead their grains take the brunt of the force, immediately developing defects, like tiny cracks, when the material begins to yield.

"Once defects occur in the system, the system is just weaker and it's going to break," says Szlufarska.

This crossover in response-from cooperative grain movement and hardness, to individual movement and ductility-is unique to nano-structured ceramics, she says. The researchers next want to learn how to control the crossover point so as to engineer greater hardness into nano-crystalline silicon carbide without compromising pliability. For example, they could vary the volume of the grain boundaries or the size of the grains. Impurities, or dopants, might also be added to the grain boundaries to make the material stronger.

Key to it all is the enormous computing power that allows scientists to simulate the material's atomic details.

"The experiments and devices have become smaller and smaller, while the simulations have grown larger and larger," says Szlufarska. "This is a unique time when the leading edge of materials design is exactly at the same length scale where fully atomic simulations are possible."

####

Contact:
Izabela Szlufarska
608-234-2622
izabela@engr.wisc.edu

Madeline Fisher
(608) 265-8592
mmfisher@engr.wisc.edu

Copyright © University of Wisconsin-Madison

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 News Press

Possible Futures

GLOBALFOUNDRIES Announces Availability of mmWave and RF/Analog on Leading FDX™ FD-SOI Technology Platform: Technology solution delivers ‘connected intelligence’ to next generation high-volume wireless and IoT applications with lower power and significantly reduced cost September 20th, 2017

GLOBALFOUNDRIES Announces Availability of Embedded MRAM on Leading 22FDX® FD-SOI Platform: Advanced embedded non-volatile memory solution delivers ‘connected intelligence’ by expanding SoC capabilities on the 22nm process node September 20th, 2017

GLOBALFOUNDRIES Unveils Vision and Roadmap for Next-Generation 5G Applications: Technology platforms are uniquely positioned to enable a new era of ‘connected intelligence’ with the transition to 5G September 20th, 2017

GLOBALFOUNDRIES Delivers Custom 14nm FinFET Technology for IBM Systems: Jointly developed 14HP process is world’s only technology that leverages both FinFET and SOI September 20th, 2017

MEMS

First Capacitive Transducer with 13nm Gap July 27th, 2017

Bosch announces high-performance MEMS acceleration sensors for wearables June 27th, 2017

Smart multi-layered magnetic material acts as an electric switch: New study reveals characteristic of islands of magnetic metals between vacuum gaps, displaying tunnelling electric current March 1st, 2017

Engineers shrink microscope to dime-sized device February 17th, 2017

Discoveries

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

Solar-to-fuel system recycles CO2 to make ethanol and ethylene: Berkeley Lab advance is first demonstration of efficient, light-powered production of fuel via artificial photosynthesis September 19th, 2017

A new approach to ultrafast light pulses: Unusual fluorescent materials could be used for rapid light-based communications systems September 19th, 2017

New quantum phenomena in graphene superlattices September 18th, 2017

Materials/Metamaterials

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

New quantum phenomena in graphene superlattices September 18th, 2017

New insights into nanocrystal growth in liquid: Understanding process that creates complex crystals important for energy applications September 14th, 2017

Corrosion in real time: UCSB researchers get a nanoscale glimpse of crevice and pitting corrosion as it happens September 14th, 2017

Announcements

GLOBALFOUNDRIES Delivers 8SW RF SOI Technology for Next-Generation Mobile and 5G Applications: Advanced 8SW 300mm SOI technology enables cost-effective, high-performance RF front-end modules for 4G LTE mobile and sub-6GHz 5G applications September 20th, 2017

GLOBALFOUNDRIES Unveils Vision and Roadmap for Next-Generation 5G Applications: Technology platforms are uniquely positioned to enable a new era of ‘connected intelligence’ with the transition to 5G September 20th, 2017

GLOBALFOUNDRIES Delivers Custom 14nm FinFET Technology for IBM Systems: Jointly developed 14HP process is world’s only technology that leverages both FinFET and SOI September 20th, 2017

GLOBALFOUNDRIES Introduces New 12nm FinFET Technology for High-Performance Applications September 20th, 2017

Tools

Graphene based terahertz absorbers: Printable graphene inks enable ultrafast lasers in the terahertz range September 13th, 2017

Chemical hot spots: Scanning tunneling microscopy measurements identify active sites on catalyst surfaces September 7th, 2017

Phenom-World selects Deben to supply a tensile stage as an accessory to their range of desktop SEMs August 29th, 2017

New results reveal high tunability of 2-D material: Berkeley Lab-led team also provides most precise band gap measurement yet for hotly studied monolayer moly sulfide August 26th, 2017

Aerospace/Space

Leti Develops Proof of Concept to Test Wireless Systems in Aircraft: Will Present Results of Joint Project at AeroTech Conference And Exhibition in Fort Worth, Texas, Sept. 26-28 September 20th, 2017

A revolution in lithium-ion batteries is becoming more realistic September 5th, 2017

The July 23 close fly-by of asteroid 2017 BS5 is explored in a Q&A with Dr. John S. Lewis, chief scientist at Deep Space Industries July 23rd, 2017

National Space Society Governor Scott Pace Named to National Space Council as Executive Secretary July 18th, 2017

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