Experimental Study On Anti-icing Performance Of Hydrophobic Coating On Surface Of Ice Drill

The ice core located in deep polar ice sheets record a large amount of ancient climate and environment information,which has important research value.Therefore,in recent years,countries around the world have carried out deep ice core drilling.When drilling at a certain depth using cable-suspended elecromechanical coring drill,it will encounter the "warm ice" layer with low melting point and high temperature.And the warm ice is brittle and viscous.During the drilling process,ice chips tends to gather and stick to the surface of the drill bit and cutting tool.Meanwhile,The heat from rotary cutting can easily melts the ice chips,and after melting,the water is easy to freeze again on the surface of the drill,causing the occurrence of accidents such as sticking the drill.Based on the above questions,it is necessary to study the anti-icing technology on the surface of drill for ice drilling.It can reduce the bonding strength of ice on the surface,improve drilling efficiency,avoid the occurrence of stuck drill and ensure the safety in warm ice drilling.In other fields,hydrophobic anti-icing coating is one of the most common anti-icing strategies on the surface of solid materials.Hydrophobic coating can not only delay and even completely prevent frost from accumulating on the solid surface,but more importantly,it can greatly reduce the adhesion and freezing force of ice on the surface.So that it can make the ice adhering to the surface of the drill easy to fall off under the action of external forces,and effectively avoids the occurrence of stuck drill and other accidents.Therefore,this paper put forward that hydrophobic coating is applied to the surface of drilling tool to make it has anti-icing performance.And the efficiency of warm ice drilling will be greatly improved.In this paper,the anti-ice mechanism of hydrophobic coating was analyzed at first.Through the research on the wettability of solid material surface,it is found that the main reason for the anti-ice mechanism of hydrophobic coating is that it can greatly reduce the contact area between ice and surface.So that it can reduce the adhesion and freezing force of ice on its surface.By analyzing the factors influencing the bond strength between ice and solid materials,it is found that hydrophobic coating materials containing organic fluorine and organic silicon are beneficial to the anti-icing performance.Therefore,four fluorine-based and silicon-based commercial hydrophobic coatings are selected in this paper.Their main components are: polytrifluoroethylene silicon and fluorocarbon resin mixture,modified polytetrafluoroethylene,silicon-based emulsion and acrylic-based copolymer coating,respectively.And from experimental testing their water contact angles were 107°,101°,114° and 95°,respectively.Then an experimental system is designed to test the freezing force of ice sticking on the planar and curved surface respectively.The experimental test was conducted in a cryogenic container within a temperature range of –10? to –30°C,and the measured force directions were normal and shear directions respectively.The experimental results show that the four hydrophobic coatings can effectively reduce the adhesion and freezing force of ice on the surface,and the lower the temperature,the more obvious the reduction effect.The coating of an acrylic-based copolymer,in particular,can reduce the average tensile strength and the shear strength of the ice adhesion by 87.08% and 97.11% on planar surfaces at-30°C,and by 98.06% and 96.15% on a curved surface,respectively.The durability of the coating is an important property to determine whether it can be widely used in polar ice drill.Therefore,finally the durability of the four coatings is tested and analyzed.The durability is mainly divided into two aspects: friction test and usage test.In the friction test,the four hydrophobic coatings gradually lose their hydrophobic properties with the increase of friction times.The water contact angle of acrylic-based copolymer coating was lower than 90° after 140 cycles of abrasion.In the usage test,the four hydrophobic surfaces were destroyed gradually with the increase of the times of icing and de-icing cycles,and gradually lost their anti-icing performance.The shear strength of ice adhered on curved surfaces coated with acrylic-based copolymer will approach that achieved on uncoated surfaces after 11 cycles of icing and de-icing tests.In conclusion,the acrylic-based copolymer coating has excellent anti-icing performance and good endurance performance.Meanwhile,it has the characteristics of simple construction and easy maintenance.So it can be applied to the surface of the drilling tools in ice drilling and make it has anti-icing performance.