Evaluation of bonding strength of porous coatings on high flux heat exchanger tubes
High flux heat exchange tube is a new type of efficient heat exchange element. Its porous coating on the outer surface can significantly enhance the boiling heat transfer characteristics,which is widely used in indus-trial heat exchange such as evaporators and reboilers. If the bonding strength between the porous coating and the base pipe is too low during transportation,installation,and operation erosion,there is a risk of the porous coating peeling off the base pipe,leading to the failure of the porous structure. Therefore,the bonding strength of porous coatings is one of its important performance indicators. At present,there is no unified quantitative testing method that can effectively evaluate the bonding strength of porous coatings. Based on the experimental principle of peel off method,a set of equipment suitable for evaluating the bonding strength of porous coatings on high-throughput heat exchange tubes was designed. The equipment is used to test the coating bonding strength of different types of high-throughput heat exchange tube samples. The results show that this method can achieve rapid and effective quantitative testing of coating bonding strength,and the of the bonding strength test results have good consisten-cy. The sample relative standard deviation (RSD) of the test results is 1.89％;The bonding strength of coatings prepared on sandblasted surfaces under different roughness levels is different too. It is concluded that the bonding strength is optimal when the roughness Ra is between 3-6 μm.
high flux heat exchanger tubeporous coatingbond strengthstripping methodsurface treatment
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