Concepts of textile composites for short- and long-term applications at high temperatures

摘要

One important application of textile composites is their use as components in modern machinery and transport systems. Present developments in these areas increase the demand for textiles capable of withstanding high temperatures, in excess of 200°C Besides constructing the composite completely of thermally-stable components, an alternative solution is to have a heat-resistant and insulating layer only on top of a conventional construction, e.g., a low-cost support fabric made of poly(ethylene terephthalate) (PET), In order to investigate this latter concept, in the present study textile fabrics of varying construction and made of various organic and inorganic fibers were characterized with regard to their potential to act as insulating layers by time-dependent temperature measurements. With constant 'hot side' temperatures of 200°C and 300°C, the initial heating rate and the maximum temperature on the 'cold side' of the samples were measured over long periods of time. The analysis of the data indicated a correlation of these parameters with the sample thickness. No correlation was found with physical parameters of the various fiber materials, indicating that the heat transport was governed by the included air volume, A model composite consisting of a PET fabric, a polyimide (PI) felt as insulating layer, and a PI film (to create a smooth surface) was designed and application tested to temperatures up to 300°C and pressures up to 3 105 N/m2., Thermal stress with a dynamic, i.e., time-dependent, temperature function on the 'hot side' was simulated by applying hot metal blocks on top of the sample with surface temperatures exceeding 350°C for a short time The results indicated that non-wovens made of A12O3 offer high insulating characteristics Composites according to these concepts were fabricated on a laboratory scale and were found to be able to withstand the extreme thermal conditions.