Study On Elastic Heater Based On Liquid Metal And Its Failure Mechanism

Nowadays,graphene,carbon nanotubes and other carbon-based materials are considered to be one of the most promising conductive materials for the development of flexible heaters.However,the carbon-based conductive materials' tensile properties are limited,and it is hard to be used to prepare elastic heaters,which limits its application in human's wrists,joints and other parts that are susceptible to cold easily.Therefore,the key to the research of flexible heater is to find the intrinsic tensile conductive materials with good tensile properties.Because liquid metal(Ga In Sn)is liquid at room temperature,it can be turned into arbitrarily shape.Besides,liquid metal can be patterned through micro-oxidation treatment and screen printing,which can be used as the core material of elastic heaters.However,a certain amount of air will be mixed in the micro-oxidation process,and the effect on the failure phenomenon and stability of the liquid metal elastic heater is not clear.Therefore,this paper identifies the failure mechanism of the liquid metal elastic heater through qualitative analysis and quantitative characterization,and put forward an optimization plan clearly.The main studies carried out are as follows:(1)Based on the optimization of substrate and preparation process,the flexible heater based on liquid metal was made by screen printing.The failure mechanism of the flexible heater based on liquid metal was studied and proposed.Failure mechanism:the heat accumulation of the liquid metal heater under the condition of large current,when the local temperature is higher than 140-150?,the microscopic morphology and structure of the liquid metal are locally changed,the internal gas escapes,and changes from a continuous conductive connection body to Non-uniform network-shaped connecting body,the mechanical properties are reduced;in the stretched state,especially when it is stretched back and forth,it is easy to break,resulting in the failure of liquid metal elastic heater.(2)Optimization and performance test of working conditions and preparation process of liquid metal elastic heater.When the current of the liquid metal heater is controlled at 0.6-0.7 A,the heating rate can reach 0.41-0.43 ?/s,and the average temperature in the heating area can reach 40-45?,which is higher than the human body temperature,and has a good heating effect;and After the liquid metal conductive circuit is packaged on the cloth-based flexible substrate,the heat is more uniform.The annealing process makes the heating rate and stability of the liquid metal heater as a whole higher than that of the unannealed heater.When the energizing current reaches 0.7 A,the heating rate can reach 1.96 ?/s,and the temperature can be stably maintained at a constant current.(3)Study on the cycle and fatigue characteristics of liquid metal elastic heaters.It is found that the liquid metal flexible heater has a heating rate of 0.36? per second under the current of 0.3 A.Under this condition,the fatigue test is performed,and the tensile temperature is stretched from 0% to 20%.The average temperature is stable at40?.It shows that liquid metal elastic heater has important value in practical application.