Study On The Heating Characteristics Of Microwave Sensitive Coatings For Interface Deicing Of Engineering Structures

Compared with traditional deicing methods,microwave deicing,as a non-contact deicing method,has the advantages of high energy utilization rate,good deicing effect,environmental protection,and economy.At present,the application of microwave deicing technology is mainly limited by the weak absorption of engineering structures.In order to improve the microwave heating performance of engineering structures and promote the application of microwave deicing technology,it is proposed to modify the microwave absorbing ability of structures by applying microwave-sensitive coatings with high microwave loss on the surface of the structures.The key to the microwave-sensitive coating deicing lies in the heat conduction at the ice-coating interface.The microwave heating performance of the coating is the most important indicator for its practical application.And,due to the imitation of the test period,the heating characteristics and response laws of microwave-sensitive coatings under multiple influencing factors were researched.It will provide a basis for the parameterized design of coatings and development of deicing equipment in the future.First,based on the principle of microwave deicing,the heating characteristic index of microwave sensitive coating in the non-icing state that can reflect the microwave deicing efficiency of the coating was planned;the heating process mechanism of microwave sensitive coating was also studied,and the factors influencing the heating characteristic of the coating included microwave conditions,coating characteristics and coating substrate were defined.Then,carbon black（CB）and ferroferric oxide（Fe₃O₄）were determined as the absorber of the coating,and the epoxy resin was determined as matrix to prepare the microwave-sensitive coatings for deicing applications.After that,microwave heating physical experiment and COMSOL Multiphysics numerical simulation were used for the research of the coat heating characteristics under microwave conditions（microwave power,heating time,irradiation distance,microwave frequency,incident angle,antenna type）,coating characteristics（type of absorber,coating ratio,coating thickness,curved surface）,and coating substrate（ideal medium,wave-transmitting medium,ideal electric conductor）.Finally,the feasibility of coating deicing was verified.The main conclusions are as follows:（1）The heating performance of the coating was positively correlated with the microwave power and heating time and also influenced by the microwave heating path.With the same microwave energy,the heating performance of the coating under the action of high power and short time was better than that of low power and long time.Considering the heating rate and heating uniformity,the optimal irradiation distance of the coating in this study was 3cm-5cm.The heating rate of the coating was positively correlated with the microwave frequency,but the increase of the microwave power will also reduce the heating uniformity.2.45GHz was recommended as the deicing frequency of the microwave sensitive coating.There was no obvious effect on the heating characteristics of the coating when oblique incidence was within a certain incident angle.As the angle of incidence increases,the maximum temperature rise of the coating increased,which shifted in the incident plane along the long side of the antenna.Compared with standard waveguide antennas,horn antennas had obvious advantages in terms of long distance,large area and heating uniformity.（2）The heating performance of the coating was positively correlated with the coating ratio.The coating thickness in the range of 1mm-5mm had little effect on the heating performance of the coating.In practical applications,the coating thickness need not be strictly controlled,and the thickness should be kept as large as possible.The curved surface form of the coating had a higher heating rate and a smaller area of the influenced zone,and the high temperature area overlaps with the area to be deiced.Therefore,it can be inferred that the microwave sensitive coating deicing is suitable for curved structures such as cables and wires.The heating performance of the coating was not only controlled by the microwave heating performance of the absorber,but also related to the volume filling rate.The microwave heating performance of Fe₃O₄ powder per unit mass was weaker than that of CB powder,but the limit volume filling rate of Fe₃O₄ powder in epoxy resin was much greater than that of CB powder.Therefore,the Fe₃O₄ coating can achieve better heating performance through a higher ratio,but there was also a problem of larger specific gravity at this time.（3）The heating characteristics of the coating were influenced greatly by coating substrate.The heating performance of CB coatings with different substrate ranged from high to low:ideal medium（air）,wave-transmitting medium（PTFE）and ideal electrical conductor（aluminum）;the heating performance of Fe₃O₄ coatings ranged from high to low:ideal electrical conductor,wave-transmitting medium,ideal medium.Among them,ideal electrical conductor was significantly higher than wave-transmitting medium and ideal medium.Fe₃O₄ coatings can be combined with dense metal mesh to improve the heating performance and mechanical properties...