Superior tribological and sealing performance of micro-crystalline diamond coated silicon carbide seals under dry friction and high load

Abstract

Silicon carbide seals suffer severe wear under the conditions of dry friction and high load, posing a great challenge in achieving a stable performance and a long lifetime. In this work, micro-crystalline diamond coatings were deposited on silicon carbide sealing rings to prevent the failure caused by wear. The deposited micro-crystalline diamond coatings exhibit high-quality crystallinity and strong adhesive strength with the silicon carbide substrate. In sealing tests, the micro-crystalline diamond coated silicon carbide sealing pair demonstrates superior tribological and sealing properties under dry friction and high load of 1800 N, featuring a low coefficient of friction of 0.16, a low wear rate of 4.00 × 10−7 mm3·N−1·m−1 and a high friction limit of 5.24 MPa·m·s−1. Characterizations of morphology, chemical composition and microstructure confirm that the smoothening effect on the contact face and the formation of graphite during the sealing test synergistically contribute to the outstanding tribological and sealing performance.