Investigation of density dependence of silica nonwoven materials on specific load value

The article presents the results of the study investigating the dependence of the density of silica nonwoven fibrous materials on the value of specific load. Nonwoven fibrous materials, in the form of mats, are extensively used across various industries. Among fiber materials, heat-insulating high-temperature silica materials hold a special place. The fibrous canvases are composed of silica fibers (KV-11) with a diameter of 7.5 microns and a length of 60 mm. Needle-punched mats are produced from a portion of these canvases using a needle-punching machine. Canvases produced by the mechanical method exhibit pronounced orientation of fibers. Consequently, samples of mats made from canvases with both longitudinal and longitudinal-transverse fiber orientations were prepared for experiments. The aim of the work is to investigate the dependence of the change in density of silica nonwoven fiber mats on the specific load. The experimental methodology was to determine the thickness of samples when loaded with weights. Needle-punched mats exhibit more stable parameters under compressive loads compared to mats made from mechanically formed canvases. Low initial density of needle-punched mats can lead to additional costs to achieve the specified values of heat shield density. The density of heat shields should be range between 100–200 kg/m3. From the available on the market fiber materials with the above parameters for the thermal screen needle-punching mats Supersilica with density ranging from 120 to 170 kg/m3 were selected. The conducted studies revealed that the correlation coefficient between specific load and thickness change, as a percentage of the initial thickness of the specimens, is higher for the specimens made from Supersilika mats. Therefore, the use of Supersilika needle-punched mats in thermal shields with double-sided silica fabric lining is more preferable.