Study On Coating Face Performance Of Mechanical Seal Composite Seal Ring

Mechanical seal composite seal rings are obtained through adding hard wear-resistant coating on steel,copper and other substrate surface by spray,laser-cladding and other surface technique.The excellent properties of coating and substrate materials were synthetically used.In practical engineering,however,when the operating conditions are harsh and the coating structural design is unreasonable,the composite seal ring may cause seal failure due to coating face cracking.Thus,In-depth study had been done from the impact factors of the coating face performance,coating surface cracks,coating face running test and other aspects in this paper.The study is intended to guide the coating face design and development,and promote its engineering application.Accurate coating face numerical analysis models were established based on considering interaction among seal face deformation,film pressure and seal ring face temperature.pbV value and temperature distribution of seal face,stress distribution of coating surface and interface of coating and substrate were obtained.The reasons of coating face cracking ware analyzed.Assessment indexes of coating face performance were confirmed,including maximum pbV value([pbV]max)and maximum temperature(Tmax)of seal face,maximum tension stress of coating surface(?max),maximum shear stress of main interface(?max),maximum shear stress(?cmax)and maximum normal tension stress of side interface(?cmax).The influence of coating face structural parameters and material parameters on coating face performance were analyzed.According to analysis results,it is suggested that thermal expansion coefficient ratio of coating and substrate should be between 0.5 and 1.0,spray angle should be between 15° and 30°,elastic modular ratio of coating and substrate should be btween 1.0 and 2.5,coating thickness should be between 0.4mm and 0.6mm.The influence of process parameters(fluid differential-pressure,rotate speed and media temperature)on coating face performance were researched.Results showed that coating face stress status will get worse dramatically while process parameters are greater than certain application scopes.Coating surface crack numerical analysis model was established.The variation law of coating surface crack stress intensity factor with its characteristic parameters was analyzed.The influence of coating face structural parameters,material property parameters and process parameters on coating surface crack stress intensity factor were analysed.The type of coating surface crack is Mode I crack.The influence of each parameter on coating surface crack K1 value and coating surface maximum tensile stress are consistent.Based on research results,further application reference and suggestion of coating face manufacture and maintenance were put forward.Mechanical seal experiment system was designed and manufactured.Friction torques of the coating face and stationary ring temperature were measured and compared with the numerical results.Lot's of damaged composite seal rings were viewed and measured,and the relationship of coating surface crack character and numerical calculation results were contrasted.The experimental results are in good agreement with the numerical results and the reliability of numerical analysis relusts were well verified.The research content of this paper is helpful to promote its design and development,to generalize its engineering application.And it has important scientific research significance for the study the coating failure mechanism.