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Silicon-incorporated diamond-like coatings for Si3N4 mechanical seals
Camargo Junior, S. S.; Gomes, J. R.; Carrapichano, J. M.; Silva, R. F.; Achete, C. A.Amorphous silicon carbide (a-SiC) and silicon-incorporated diamond-like carbon films (DLC-Si) were evaluated as protective and friction reduction coatings onto Si3N4 rings. Unlubricated tribological tests were performed with a pin-on-disk apparatus against stainless steel pins with loads ranging from 3 N to 55 N and sliding velocities from 0.2 m/s to 1.0 m/s under ambient air and 50-60% relative humidity. At th...
Functionality diagrams for hybrid mechanical seals with silicon nitride rings
Carrapichano, J. M.; Oliveira, F. J.; Silva, R. F.; Gomes, J. R.Ring-on-ring tribological experiments were performed with hybrid mechanical seals with silicon nitride (Si3N4) rings. The K x PV product, where K is the wear coefficient, P the sealing pressure, and V the linear speed, is proposed as a novel parameter to characterize the total working range of a mechanical seal system, with the advantage of directly indicating the thickness reduction for a certain time of servic...
Si3N4 and Si3N4/SiC composite rings for dynamic sealing of circulating fluids
Carrapichano, J. M.; Gomes, J. R.; Oliveira, F. J.; Silva, R. F.Silicon nitride (Si3N4) and silicon itride/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 ≈ 4ms−1 of linear speed, in the range of 0.3–1 kN of applied load, under a pressure of 2 × 105 Pa of a mixture of 20 vol.% of hydrogen peroxide in deionised wa...
Tribological behaviour of Si3N4–BN ceramic materials for dry sliding applications
Carrapichano, J. M.; Gomes, J. R.; Silva, R. F.The main objective of this paper is to help on the clarification of the lack of consensus in the bibliographic data concerning the tribological behaviour of Si3N4–BN omposites. Unlubricated sliding tests by pin-on-disc were carried out with three grades of composite materials with 10, 18 and 25 vol.% of BN. The addition of BN to the Si3N4 matrix resulted in a slight reduction of the friction coefficient, which ...
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