| Due to its excellent sealing performance,the dry gas seal has developed into the preferred shaft end seal form for the new large-unit new machine projects.Among them,the spiral groove dry gas seal is particularly widely used.Due to the dynamic pressure effect of the spiral groove and good dynamic followability,a layer of gas film can be formed on both end surfaces during the sealing operation so as to ensure non-contact of the sealing end surface.However,in the start-stop phase of the dry gas seal,the start-up rotation speed is low,and the dynamic pressure effect is insufficient.There is significant contact and friction between the two end faces,causing unavoidable wear on the end face.Many studies have shown that in dry gas seals,both contact friction during start-up and shut-down,or contact friction that sometimes occurs during operation,the two seal faces will be in a dry friction state,and random contact and collision will occur between the micro-convex bodies.As a result,friction and wear will significantly reduce the life of the dry gas seal,and even lead to seal failure in severe cases.At present,the research on the performance of low-speed spiral groove dry gas seals,especially the friction properties of the end surfaces,is very lacking.This paper adopts experimental research methods to conduct a comprehensive and systematic analysis and discussion on the conditions affecting the friction coefficient of the spiral groove dry gas seal face.Tests were conducted on a face-to-face friction and wear tester to investigate the effects of different frictional materials,different end face machining methods,helical groove geometry parameters,and operating condition parameters on the friction coefficient at both ends.In the contact of the end face,the friction coefficient must be considered in the material of the friction pair and the machining pattern of the sealing ring surface.At present,DLC film is widely used as a good wear-resistance material in dry gas seals,but there are different opinions about the anti-friction properties of surface textures.This paper focuses on the surface coating and surface texture ring.The tribological properties were compared and it was found that the DLC film doped with tungsten on the Si C substrate compared to the graphite ring can indeed reduce the friction and wear between the two ends and reduce the friction coefficient between the two rings;the surface texture is only Under certain working conditions,the friction performance is better than that of the DLC film.The geometric parameters of the texture are one of the important factors affecting the friction characteristics and lubricating effect.Only in the proper range can the excellent lubrication be obtained.Effect,otherwise it will backfire.The main find in gs of this paper are as follows:First,in helical groove dry gas seals,the overall friction performance of the 16~°helix angle is better than 18~°under dry friction conditions.During the entire test,the fluctuation of the friction coefficient of the 16~°helix angle seal ring is less than 18~°.The wear scar is less than 18~°.Second,different friction materials have different influences on the friction performance between the two ends of the spiral groove dry gas seal.The friction performance of the“hard-to-hard”friction pair is better than that of the“soft-touch-hard”friction property,but the Si C ring is brittle and has a high load.Rotation of the end face of the ring easily occurs at the rotation speed.Third,compared with the friction properties of the coated SiC ring,the friction performance of the textured ring is not prominent.Even under some conditions,the friction coefficient of the two ends of the ring is greater than the friction coefficient of both ends of the coating ring. |
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