Abstract: A bearing mat for supporting an exhaust gas catalyst is configured as a binding agent-free, multi-layered flat structure made of thermally stable threads mechanically reinforced by quilting seams. The threads consist of a crimped yarn composed of filaments and are fixed in the flat structure by the quilting seams under tensile stress. The quilting seams are sewn using a thread whose thermal stability is lower than the mat's operating temperature. A process for producing the mat is also provided, in which crimped yarn composed of thermally stable filaments is withdrawn from rolls in several strands and placed under tension on a transporting device moving transversely to the take-off direction in order to form a multi-layered flat structure. The flat structure moved forward by the transporting device is mechanically reinforced with quilting seams so that the threads remain under tension after the flat structure is removed from the transporting device.

Abstract: A yarn that expands upon heating comprises a plurality of voluminous, thermally stable individual threads or filaments, which are compacted to form a bundle and aligned in parallel, and a casing for the bundle made of a material having a lower thermal stability than the individual filaments, which decomposes upon heating. A method for producing the yarn is also provided.