SCHOTT solutions no. 1/2013 > Technical Tubing

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Materials at the Limit

Materials can be analyzed in many different ways with weathering devices from the global market leader Atlas Material Testing Technology. Here, tube filters from SCHOTT allow for stress tests to be performed that imitate exposure to real solar radiation.

Thomas H. Loewe

From the dashboard to the tires: a four by four’s components are made to last – no matter if it’s driven in the desert, a subtropical climate or an alpine region. The same applies to a tent, a sleeping bag or hiking shoes. To guarantee a product’s durability, researchers around the world are always busy developing new materials. Atlas provides weathering machines that help predict the wearing properties of materials ranging from textiles and synthetics to car finishes and other coatings.

”All materials, not just human skin, are affected by sunlight,” explains Rainer Eichholz, Lead Developer Glass, Melting and Drawing Technology for the SCHOTT Business Segment Tubing. Even varnishes, seat covers or synthetics age with constant exposure to sunlight. ”In the past, an entire car was simply placed under the Floridian sun for a period of time,” says Eichholz. Nowadays, these tests can be sped up with weathering machines. For this, Eichholz and his colleagues developed special glass tubes. They filter the light from a xenon lamp inside the machine to simulate the sun’s rays. And a built-in humidifier helps reproduce a climate that resembles the natural environment. ”Weathering machines reduce trial times considerably and help accelerate the development and marketability of new products,” says Eichholz.
Simulated environment: The xenon lamp is encased in a tubular filter (center). Over one hundred samples can be mounted on the sample rack inside the test chamber. Temperature and humidity can also be adjusted quite accurately. Photo: ATLAS MATERIAL TESTING TECHNOLOGY LLC
The special filter is necessary because the sun’s natural light spectrum is not entirely identical to what is emitted by a xenon lamp: ”The two light sources differ at very short wavelengths,” ­Michael Frigo, project head at Atlas emphasizes. In nature, the destructive UV spectrum between 280 and 315 nanometers is kept away from the earth’s surface by the atmosphere. The light source in the weathering machine, on the other hand, emits the entire light spectrum at full intensity. ”We have to use a filter to replicate authentic conditions,” says Frigo. For several years, Atlas has relied on SCHOTT to supply the necessary tubular filters that can be exchanged for different tests.

In cooperation with Atlas, Eichholz and his colleagues are continuously enhancing the product. Besides its special trans­missibility, the filter has to have a high life expectancy and other special properties. ”Its qualities must remain stable for as long as possible,” says Eichholz. Michael Frigo and his colleagues are very satisfied: ”We can offer our customers a highly improved and ­diverse product,” he says. ”SCHOTT is the only manufacturer that can develop and guarantee tubular glass filters with the required characteristics.” <

Artificial Sunlight