This paper presents a preliminary study on obtaining and characterization of phenolic resin-based composites modified with nanometric silicon carbide. The nanocomposites were prepared by incorporating nanometric silicon carbide (nSiC) into phenolic resin at 0.5, 1 and 2 wt% contents using ultrasonication to ensure uniform dispersion of the nanopowder, followed by heat curing of the phenolic-based materials at controlled temperature profile up to 120 • C. The obtained nanocomposites were characterized by FTIR spectroscopy and scanning electron microscopy analysis and evaluated in terms of mechanical, tribological and thermal stability under load. The results highlight the positive effect of the nanometric silicon carbide addition in phenolic resin on mechanical, thermo-mechanical and tribological performance, improving their strength, stiffness and abrasive properties. The best results were obtained for 1 wt% nSiC, proving that this value is the optimum nanometric silicon carbide content. The results indicate that these materials could be effectively used to obtain ablative or carbon-carbon composites in future studies.

This paper presents the production of carbon-fiber-fabric-reinforced laminated composites based on a polyamide 6 matrix using a multiple-stages technique that involves polymer dissolution in formic acid followed by fabric impregnation and high-temperature pressing. The polyamide/solvent ratio's influence on the interface and mechanical properties is discussed, analyzing three PA6 weight contents of (10, 20, and 30) % in a formic acid solvent. The mechanical behavior of the obtained laminated composites is evaluated using tensile and 3-point bending tests and the fracture cross-section is analyzed using microscopy investigation techniques in order to evaluate the fiber-matrix interface and the composite fracture mechanism. The results show that the best mechanical performance is obtained when using a solution of 20 % mass fraction of polyamide in formic acid, as this leads to the formation of a uniform polymer layer that is able to completely embed the fibers that constitute the fabric and create a strong mechanical interface within the composite. Keywords: polyamide 6, carbon fiber, mechanical properties, polymer/solvent ratio, mechanical interfacê lanek predstavlja izdelavo laminatnega kompozita na osnovi poliamida 6, oja~anega s tkanino iz ogljikovih vlaken, z uporabo ve~stopenjske tehnike, ki vklju~uje raztapljanje poliamida v mravljin~ni kislini ter impregnacijo tkanine in stiskanje pri visoki temperaturi. Razlo`en je vpliv razmerja poliamid/topilo na stik in mehanske lastnosti, z analizo treh masnih vsebnosti PA6 (10, 20, 30) % v mravljin~ni kislini. Mehansko obna{anje dobljenega laminiranega kompozita je ocenjeno z nateznim preizkusom in s 3-to~kovnim upogibnim preizkusom, presek preloma pa je analiziran z mikroskopsko tehniko, da bi ocenili stik z vlaknato osnovo in mehanizem preloma kompozita. Rezultati ka`ejo, da je najbolj{a mehanska zmogljivost dose`ena pri uporabi raztopine z 20 % masnim dele`em poliamida v mravljin~ni kislini, ker to povzro~i nastanek enakomernega polimernega sloja, ki lahko popolnoma obda vlakna tkanine in ustvari mo~an mehanski stik v kompozitu. Klju~ne besede: poliamid 6, ogljikovo vlakno, mehanske lastnosti, razmerje polimer/topilo, mehanski stik

Phenolic-resin composites have attractive properties for applications in various fields from the wood and adhesive industry to the automotive, aeronautics and aerospace industries. The paper presents the obtaining of SiC-nanofilled phenolic-resin-based composites reinforced with a bidimensional fabric. Different contents of nanometric silicon carbide (0.5, 1 and 2) % mass fractions) were dispersed into the phenolic-resin matrix, using the ultrasonication method, to ensure the optimum dispersion. Several layers of the bidimensional fabric were impregnated with the obtained mixtures and the final laminated composites were obtained using high-temperature pressing, followed by a multistage temperature program. The obtained laminated nanocomposites were characterized with FTIR spectroscopy and evaluated in terms of mechanical and tribological properties. After mechanical testing, fracture cross-sections were characterized with SEM and optical microscopy. The results highlight the positive effect of the nanometric silicon-carbide addition to the phenolic-resin matrix of the laminated composites, in terms of mechanical and tribological performance, improving their strength, stiffness and abrasive properties. Keywords: laminated composites, tensile strength, flexural strength, nanometric silicon carbide, nanocomposites, friction coefficient Kompoziti fenolnih smol imajo mo`nosti raznovrstne uporabe na razli~nih podro~jih, tako na podro~ju lesne industrije, v industriji lepil, kot v avtomobilski in letalski industriji. Prispevek predstavlja pridobitev SiC fenolnih kompozitov na osnovi smole, oja~anih z bidimenzionalnimi vlakni. Razli~ne vsebine nanosilicijevega karbida (0,5, 1 in 2) % masnega odstotka, so bile razpr{ene z uporabo ultrazvo~ne metode v matrici, pridobljeni s smolo, da je bila zagotovljena optimalna disperzija. Ve~plasti bidimenzionalnih vlaken je bilo impregniranih s pridobljenimi me{anicami in kon~ni laminirani kompoziti so bili pridobljeni z visokotemperaturnim tla~nim pritiskanjem, kateremu je sledil ve~stopenjski temperaturni program. Pridobljeni laminirani kompoziti so bili preu~evani s FTIR-spektroskopijo in ovrednoteni glede na mehanske in tribolo{ke lastnosti. Presek zloma po mehanskem testiranju je bil preu~evan s SEM-mikroskopijo in opti~no mikroskopijo. Rezultati ka`ejo pozitiven u~inek dodatka nanometri~nih silicijevih karbidov, s smolo pridobljenih matric v ve~plastnih kompozitih, zaradi njihovih mehanskih in tribolo{kih lastnosti, in ker se tako izbolj{a mo~, togost in abrazivne lastnosti.

This paper presents the obtaining of advanced materials based on cork powder as reinforcement and phenolic resin (PR) with silicon carbide (nSiC) nanofiller as matrix with potential applications in aerospace industry. Three formulations were obtained: one control sample PR/cork with no nanofiller, two nanofilled samples with 1 and 2 wt% nSiC loadings into the resin. The materials were tested by flexural and compressive mechanical tests to determine their strength and stiffness, to determine their friction coefficient by tribological tests, to determine their thermal decomposition behaviour by TG-DSC analysis and to evaluate their thermal behaviour by thermal shock tests when subjected to extreme temperature directly from room temperature. The material structure was analysed by SEM visualizing the fracture cross-section after mechanical testing. The test results illustrate that silicon carbide nanoparticles improve flexural and compressive strength, but also stiffness and friction coefficient, delay thermal decomposition onset and improve thermal shock resistance. All these sustain the PR/nSiC/cork materials as potential advanced materials candidates for thermal protection applications.

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