Cold Uniaxial Pressing of PTFE-Based Composite Materials with Functional TiC and TiB₂ Additives

The possibilities of a solid-phase technology to produce composite materials based on polymer mixtures of PN-90 polytetrafluoroethylene (PTFE) with functional additives of titanium carbide and diboride synthesized by self-propagating high-temperature synthesis (SHS) are studied. The pressing of bulk-density composite powders into compact billets in a special mold by loading at a constant speed is studied. Rheological stress σ–strain ε curves are obtained and used to determine the time of the beginning of a progressive increase in stress inside a sample. The experimental results are compared with the data obtained for samples without additives (pure PTFE) and for compositions with a basalt fiber (BF). At a stress of 171–177 MPa, the density corresponding to a calculated compact density of 2.24–2.25 g/cm³ is shown to be achieved. The density difference throughout the volume of a compact sample is investigated, and a comparative analysis of compressibility moduli G after uniaxial cold pressing is performed.