Surface Texturing For SiC Mechanical Seals By Multi-phase Micro-abrasive Jet Machining Technique

Mechanical seals are essential shaft sealing components in rotating machineries.They are widely used in petroleum,chemical industry,metallurgy,atomic energy and aviation industry because of their good sealing performance,long service life,low power consumption and other advantages.Non-contact mechanical seal technology,which is represented by micro texture end face mechanical seal,dry gas seal and upstream pumping seal,has been proved to be an effective means to improve mechanical seal performance by fabricate micro texture or spiral grooves on the sealing face.However,the existing processing technologies have some limitations and deficiencies to fabricate microstructure on the commonly used silicon carbide(SiC)mechanical seals that limit the engineering application and related research of surface texture on the face of mechanical seals.Therefore,on the basis of multi-phase micro-abrasive jet machining(M-MAJM)technology,the new M-MAJM technology for improving the surface texture processing efficiency and machining quality of SiC is studied.The optimal design and experimental study of the machining equipment,the processing flow and the processing parameters are also carried out,and the following works have been done:(1)The design of M-MAJM system is optimized,including the design of overall project,nozzle,machining platform and jet angle control device.The designed machining system in this paper could transform the abrasive particles into multi-phase micro-abrasive jet under conditions of relative low air pressure,which has the ability to process micro texture on the surface of SiC rings,and has the advantages of simple structure,convenient maintenance and high reliability.(2)The processing flow of M-MAJM is determined.By using the mask to protect the surface of the workpiece which is not needed to be processed,the micro structure with special position,shape and size can be machined on the surface of SiC.Firstly,the mask manufacturing method of laser processing stainless steel sheet is studied,and then on the basis of the selection of micro abrasive,processing feed scheme,the jet distance,the specific processing flow and the matters needing attention are clarified.(3)The processing technology of two kinds of M-MAJM is studied by using green silicon carbide and artificial diamond as micro abrasive.The effects of jet distance,jet pressure,micro-abrasive concentration,micro-abrasive particle size and jet angle on the groove depth and the roughness of the bottom surface are studied to evaluate the processing efficiency and quality.(4)In order to solve the problem of low efficiency and poor processing consistency in the processing of SiC by green silicon carbide M-MAJM,the processing technology of the green silicon carbide M-MAJM with appropriate reduction of jet angle and the optimized synthetic diamond M-MAJM are proposed,which can effectively improve the machining efficiency and machining consistency of micro grooves on the surface of SiC.(5)The experimental results show that under the same processing conditions,the processing efficiency of synthetic diamond M-MAJM is about 150 times higher than that of the green silicon carbide M-MAJM,while the bottom surface roughness is only 40% of the latter one,which means the synthetic diamond M-MAJM has strong application value in engineering.