Molybdenum disilicide-silicon nitride bushing nozzles tailor-made for basalt fibers production

Abstract A carefully comparative study of several ceramics compounds allowed the identification of MoSi 2 blended with Si 3 N 4 as a suitable material for the realization of bushing nozzles, specifically designed for basalt fibers production. Degradation static tests were developed and performed to demonstrate the high resistance to oxidation at operating temperature of MoSi 2 -Si 3 N 4 composites with respect to alumina, zirconia stabilized with magnesia or yttria, pure MoSi 2 , pure Si 3 N 4 , and MoSi 2 englobing SiC. Moreover, the MoSi 2 -Si 3 N 4 composites resulted resistant to corrosion and chemical inert with respect to oxidizing components present in basalt melts. Bushings in MoSi 2 -Si 3 N 4 were obtained by using hot isostatic pressing and were processed through mechanical drilling. The basalt fibers produced with the MoSi 2 -Si 3 N 4 bushing showed a constant diameter and a regular surface morphology. The bushing was recovered intact without defects or fractures demonstrating the efficiency of the selected material. Replacing platinum-rhodium bushings with ceramic ones could greatly reduce costs of basaltic fibers production and could encourage the use of these eco-friendly, natural fibers as reinforcement in lightweight polymer composites.