THISYS
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THISYS APPARATUS FOR THERMAL CONDUCTIVITY MEASUREMENT OF THIN SAMPLES THISYS offers an accurate, fast and uncomplicated measurement of the thermal conductivity of thin samples of high thermal conductivity materials. Typical samples are sheet materials of metals, alloys and high conductivity plastics with various filler materials. Metal samples are ideally in the thickness range of 0.1 mm and less, plastic samples typically in the thickness range of 6 mm, composites in between. THISYS is a combination of a Thin Sample Instrument (THI01) and a Measurement and Control Unit (MCU). The measurement essentially determines the temperature gradient across the sample when it is heated, in the plane of the sample itself. Employing a specially designed high accuracy thermopile sensor THI01 can handle thin sample materials (less than 0.01 to 6 mm) usually in the thermal conductivity range to 200 W/mK. Following this method, problems with contact resistance are avoided. The method is a good alternative when procedures according to ASTM D5470 are failing. Using a climate chamber a large temperature range can be covered, performing measurements at regular intervals. THISYS is fully PC controlled. For use with low thermal conductivity materials a different model, type THASYS, is available. Figure 1 THISYS consists of the Thin Sample Instrument (THI01), (1) and a Measurement and Control Unit (MCU), (2). It is PC controlled though RS232 (4, 5). The PC is not included. The measurement result appears on screen automatically. The THI01 housing contains two heat sinks in a bath of glycerol. It has a slot on top through which the sample is inserted. The sample is heated on two sides. One heater also contains the hot joints of the thermopile sensor. The sample plus heater are then pressed together with the heat sinks using a screw on the side, creating a perfectly symmetrical setup. The glycerol fluid eliminates the problem of contact resistance. INTRODUCTION The measurement of thin materials with relatively high thermal conductivity is a classic problem. Commonly used methods like ASTM D 5470 – 01 (Standard Test Method for Thermal Transmission Properties of Thin Thermally Conductive Solid Electrical Insulation Materials) have shown to be highly sensitive to contact resistance, and not applicable with high conductivity materials. THISYS offers a solution to this problem. THISYS essentially measures the temperature gradient from centre to side across the sample when mounted across a well insulated cavity, and heated with a known uniform flux. By measuring the flux φ (derived from heater power), the differential temperature across the sample, ∆Tamp, and the sample thickness, H, it is straightforward to calculate the relative thermal conductivity λrel: λrel ~ φ / H ∆Tamp The measurement is performed relative to a known reference material. Version 0817 (page 1 of 3) Hukseflux reserve the right to alter specifications without prior notice HUKSEFLUX™ THERMAL SENSORS . WWW.HUKSEFLUX.COM . INFO@HUKSEFLUX.COM

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Figure 2 THI01 geometry: heat sinks (7, 9). sample material (8), air filled cavities (17), heaters (4). Heat generated by the heaters first flows in the plane of the sample and only after that into the heatsinks (14). thermal conductivity: deviation from literature value % Figure 3 Test results with THISYS: Measurements were performed with Pyrex 7740 (2 to 7 mm), Perspex reference standard from NPL (5.62 mm) and Stainless Steel type 304L (stacked from 0.1 to 0.7 mm). The test shows a remarkable accuracy level of +/- 6% relative to literature values (1.086, 0.188 and 14.34 W/mK...

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THI01 DESIGN The Hukseflux THI01 employs two aluminium "heat sinks”. Each of these contains a heater that is mounted over an air-filled, insulating cavity. The sample is installed over the cavities. The resulting temperature gradient (centre-edge) is measured. Apart from the new design, the technological novelties are a thin thermocouple thermopile (proprietary Hukseflux design) performing an accurate and ultra-sensitive differential ∆T measurement, and the fact that the measurement is performed in a bath of glycerol. The THI01 can handle samples of less than 0.01 to 6 mm thickness. Samples...

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THISYS 3Pages

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THISYS
3Pages