Si3N4 and Si3N4/SiC composite rings for dynamic sealing of circulating fluids


Silicon nitride (Si3N4) and silicon nitride/silicon carbide (Si3N4/30 wt.% SiC) seal rings were tested as self-mated pairs and dissimilar sealing systems against grey cast iron. The tribological experiments were conducted in a ring-on-ring tribometer at V approximate to 4 in s(-1) of linear speed, in the range of 0.3-1 kN of applied load, under a pressure of 2 x 10(5) Pa of a mixture of 20 vol.% of hydrogen peroxide in deionised water, which gives an effective pressure (P) between 0.2 and 1.3 MPa. The homologous tribosystems are ineffective to seal due to catastrophic abrasive wear. The system with better performance is the dissimilar pair Si3N4/grey cast iron, that presented wear coefficient values of K = 4.2 x 10(-8) mm(3) N-1 m(-1) for the ceramic ring and K = 1.3 x 10(-7) mm(3) N-1 m(-1) for the metallic ring, in tests driven for about 60 h and 890 kin, with full sealing. An amorphous passivating film of silica protects the ceramic surface. This system still presents an excellent combination K x PV approximate to 0.1 mum h(-1), this product being a measure of the surface loss of a machine component for a given time of service. (C) 2003 Elsevier Science B.V. All rights reserved.



subject category

Engineering; Materials Science


Carrapichano, JM; Gomes, JR; Oliveira, FJ; Silva, RF

our authors

Share this project:

Related Publications

We use cookies for marketing activities and to offer you a better experience. By clicking “Accept Cookies” you agree with our cookie policy. Read about how we use cookies by clicking "Privacy and Cookie Policy".