## 3 Results and Discussion  
It is well known that the structure of composites has a significant effect on their properties: the interaction between the matrix and the fillers and the fillers distribution determine the mechanical, tribological, and thermal behavior of the composites. The method for producing composites should provide good adhesion between the components and the uniform filler distribution. The microstructure of the carbonized composites is shown in Figure 2.  
It was found that the CFs during the mixing are crushed, and their length in the composites was in a range of 150-300 \(\upmu\)m, regardless of the initial length. At CFs content up to 50 PHR, a uniform distribution of the fibers is provided, and a good interfacial interaction between the rubber and the CFs is observed. It can also be seen that mixing uniformly distributes the fillers in the rubber matrix. Frequently, high filler content levels result in a decrease in the properties caused by an increase in the tendency of the fillers to aggregate and form larger particles [16]. This causes a reduction of the aspect ratio of the filler and of the interaction surface area between the matrix and the filler. In our case, for the manufactured composites, a uniform filler distribution was achieved, which yielded materials with a homogeneous structure and high-performance properties. Figure 1: Prototypes of the products (impellers for electric centrifugal pumps) from the carbonized composites (view from both sides). Figure 2: The microstructure of the carbonized composites: (**a**) T2; (**b**) T2-2; (**c**) SiC-1; (**d**) SiC-4 compounds. A critical aspect of using the composite materials is their performance in moisture and chemical environments. The absorbed water usually affects mechanical performance and long-term durability of high-performance composites [17; 18]. The water absorption of the carbonized composites after 70 days is shown in Figure 3a. It was found that the water absorption values lie quite close to each other (0.45-0.61 wt %). Some difference can be related to the nature of the fillers; so the moisture permeability of SiC-reinforced composites is lower than that of for T2 and T2-2 SiC-free compounds that do not contain SiC. Therefore, it can be concluded that the SiC-reinforced composites have a smaller volume of open porosity. The contact angle (CA), which characterizes the hydrophobicity important for the performance of pump parts, decreases from 110-106\({}^{\circ}\) for the vulcanized composites to 62-70\({}^{\circ}\) for the carbonized ones (Table 1). This is due to the presence of a large amount of oxygen-containing functional groups on the surface of the materials after carbonization. Moreover, the SiC-reinforced composites have smaller values of CA, because SiC itself has a more hydrophilic nature than that of carbon. Since the NBR and its composites are not resistant to oxidizing chemicals [19], the effects of immersion in liquid chemicals are also a critical performance aspect of using the obtained composite materials. The change in mass of the SiC-1 composites exposed to various liquids during 35 days is shown in Figure 3b. These curves show time dependences of the composite's mass changes; they are typical for all composites and have similar behavior. Table 1 summarizes the data on a change in mass after exposure to various liquids after 35 days. It was found that, for T2 and T2-2, the change in mass after exposure to liquid chemicals, as well as after exposure to water, was higher than that of for SiC-1 and SiC-4 due to lower porosity of the latter. It was found that the noticeable changes are observed for samples exposed in HNO\({}_{3}\). For all compositions, a noticeable increase in mass occurs, indicating that HNO\({}_{3}\) has a rather high permeability. The analysis of the effect of HCl showed a similar tendency