Glass: Characterizing with precision and efficiency

Oct 26, 2012

(Phys.org)—At home, in the car or with industrial processes – glass is a universal material. Its properties are so extraordinary that frequently there are no alternatives to this material. Take, for example, high-temperature fuel cells, in which layers of ceramics and metals are alternately attached to each other: to ensure no explosive hydrogen escapes, the metal and ceramic layers must be firmly bound to each other, and the seam must be sealed tight. Only glass can accomplish this type of seal – and here, we are specifically referring to solder glass. But how does glass behave at such high temperatures? To what extent does it enlarge? Until now, this question was investigated using a push rod, which pushes from the glass onto a cylinder.

If the glass heats up, then it expands and pushes back against the push rod. Were the glass to become molten, however, then it adheres to the push rod and renders it unusable. Even if seeking to create glass with new qualities, scientists need reliable, efficient and simple methods in order to investigate the characteristics of the glass.

Researchers from the Fraunhofer Institute for Silicate Research ISC in Wertheim have just developed a thermooptical measuring device that makes the comprehensive characterization of glass possible. "With our system, we can study all glass characteristics simultaneously for the first time ever – and that on a laboratory scale, in other words, with minimal sample material," says Dr. Andreas Diegeler, head of the Center of Device Development at ISC. This system consists of an oven that a "looks into." This camera enables the researchers to observe the glass during the entire heating process.

The centerpiece for glass characterization is the maximum bubble pressure module, which the scientists can use to measure the viscosity and the of the glass under molten conditions. The principle behind this concept: The glass is heated in a crucible made of quartz glass. Since quartz glass has a higher melting point (about 1600 degrees Celsius) than other glass, the quartz glass crucible remains solid while the study glass slowly melts in it. A quartz glass capillary – in other words, a pipette with an inner diameter of one to three millimeters – is dipped, on a fully-automated basis, into the molten glass through a hole in the roof of the oven. A precisely defined volume of glass is likewise blown on a fully-automated basis through this pipette into the glass melt. The capillaries in the molten glass are like a drinking straw in a glass of soda: Blow air through the drinking straw into the beverage, and bubbles emerge. Do the same thing with yoghurt and you see fewer bubbles. Similarly, the researchers can determine the viscosity (flow resistance) of the glass based on the way in which the bubbles develop, and they can also establish the surface tension of the molten glass. Using the thermooptic measurement principle, they can additionally define other basic qualities of the glass, such as thermal expansion, under application-related conditions.

The process delivers a number of advantages: "On the one hand, it saves time: With the thermooptical system, glass can be characterized at least five times faster than previously. Because instead of having to produce and individually analyze five samples just to study five characteristic viscosity points of the glass, now we only need one sample, which is studied in only one heating operation. In addition, the process helps save on resources. Since we only need one sample instead of five, we spare 80 percent of the material – on a small scale, naturally," Diegeler summarizes. However, this system delivers outstanding services for more than glass alone. It can be used for any type of melting, whether steel or slag. Another interesting alternative: For test purposes, instead of blowing a gas into the glass that does not react with glass, one can also introduce gas that generates a chemical reaction with the glass, thereby changing its characteristics. This could be an alternative way of developing entirely new types of .

The system is already on the market – some customers are already working with it. Researchers will demonstrate the process at the Glasstec trade fair from October 23 to 26 in Düsseldorf (Hall 15, Booth E25).

Explore further: A new, tunable device for spintronics

add to favorites email to friend print save as pdf

Related Stories

AGC creates 15% lighter glass for mobile devices

Apr 25, 2011

(PhysOrg.com) -- Asahi Glass Co. (AGC), a Tokyo-based makers of flat glass, automotive glass, display glass, chemicals and other high-tech materials and components, has announced the creation of a the world's ...

Robot speeds up glass development

Nov 07, 2011

Model by model, the electronics in a car are being moved closer to the engine block. This is why the materials used for the electronics must resist increasing heat – so the glass solder being used as ...

Safety glass - cut to any shape

Oct 25, 2012

If an object slams into the glass façade of a high-rise building, the glass must not shatter and fall down, because it could harm pedestrians below. In addition, the window panes must hold if a person were ...

To boldly go where no glass has gone before

Mar 30, 2012

QUT's first foray into space is bound to be a giant step for mankind. Dr Martin Castillo from Queensland University of Technology's (QUT) Science and Engineering Faculty, and researcher for the university's ...

MU engineers develop safer, blast-resistant glass (w/ Video)

Sep 10, 2009

To protect from potential terrorist attacks, federal buildings and other critical infrastructures are made with special windows that contain blast-resistant glass. However, the glass is thick and expensive. Currently, University ...

Recommended for you

A new, tunable device for spintronics

Aug 28, 2014

Recently, the research group of Professor Jairo Sinova from the Institute of Physics at Johannes Gutenberg University Mainz in collaboration with researchers from the UK, Prague, and Japan, has for the first time realised ...

User comments : 0