Atlas Material Testing Technology Gmbh

Atlas Material Technology Gmbh

Artur Schönlein

Peter March

Bernd Rudolph

Bernhard Börner

Martin Dickert

The radiation power emitted from the UV radiation sources () in a weathering apparatus is controlled such that the radiation power of each of the radiation sources () is measured in a predetermined spectral range of the radiation emitted from the radiation sources, with the spectral range being chosen such that the measured radiation power is representative of the radiation power in the UV, an averaged radiation power is calculated from the measured radiation powers, and the averaged radiation power is used for controlling the electrical power to be supplied to the radiation sources (). In particular, the control process can be carried out in such a way that the same electrical power, within a predetermined tolerance bandwidth, is supplied to each of the radiation sources (), and the averaged radiation power is kept constant over time at a desired nominal value.

Control of the UV radiation sources for a weathering apparatus on the basis of the averaged radiation intensity

Weathering apparatus with UV radiation sources and radiation sensors containing a double-calibrated UV sensor A weathering apparatus has one or more UV radiation sources () and one or more first sensors (), which are calibrated for a first spectral sensitivity range. In a first aspect of the invention, the sensor or one of the first sensors () is calibrated in such a way that the radiation power of a spectral range which is located within the first spectral sensitivity range can be determined from its output signal. In a second aspect of the invention, a second sensor () is provided, which is calibrated for a second spectral sensitivity range.

Weathering apparatus with UV radiation sources and radiation sensors containing a double-calibrated UV sensor

A holding frame () is mounted in a weathering chamber () of a weathering tester so that it can be rotated around a xenon radiation source (), which is located on the cylinder or rotation axis, and an infrared filter () placed around it. Samples () to be weathered are fastened to the inside of the holding frame () and are exposed to the radiation from the xenon radiation source (). The surface temperature of the samples () can be recorded directly by a black-body radiation detector such as a pyrometer (), which is aimed at a stationary region of space through which the samples () pass periodically during their rotational movement. The surface temperature can be computed in an evaluation circuit from the detected black-body radiation, together with emissivity values stored for the individual samples ().

Contactless measurement of the surface temperature of naturally or artificially weathered samples

Calibrating temperature sensors of weathering devices by means of contactless temperature measurement A temperature sensor () which is, for example, designed as a black standard sensor and is typically used in apparatuses for artificial weathering of material samples, has in a known way a stainless steel plate () which is provided with a black coating () and is thermally coupled at its rear side to a platinum resistor (). The output signal of the electric measurement transducer circuit connected to the platinum resistor () by means of feeder wires () can be calibrated with the surface temperature measured in a contactless fashion by a pyrometer (). The calibration operation can be carried out under the conditions prevailing in a weathering device, that is to say while applying to the surface of the sensor the optical radiation of a xenon radiation source () and an airstream () parallel to the surface.

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Rüsselsheim, Germany

Artur Schönlein