Research On The Effect Of Rigid Particles On The Thermal Conductivity Of Silica-based Thermal Conductive Composites

With the increasing application of thermal conductive materials,people have put forward many new requirements for thermal conductive materials.Such as good weather resistance,corrosion resistance,lightweight and easy processing and other comprehensive properties.So the researchers conducted research on the thermal conductive materials in response to these requirements.With the deepening of the research,the polymer-based thermal conductive composite material immediately entered the researchers’ vision.Its unique electrical insulation,high temperature resistance,corrosion resistance,Lightweight and other advantages make it possible to replace metal materials in many fields and become a new type of heat conduction and heat dissipation materials.Researchers usually add thermally conductive metals,inorganic or carbon-based thermally conductive fillers to polymers to build thermally conductive networks to make polymer-based thermally conductive composite materials to improve the thermal conductivity of materials.However,many difficulties were encountered in the research process.Similarly,the construction of a filler network can greatly improve the electrical conductivity of the composite material,while the thermal conductivity network has little effect on the improvement of thermal conductivity.Professor Wu Daming boldly conceived this problem.A new idea for forming thermal conductive composite materials-"stone canal conversion mechanism",transforms the low-efficiency heat conduction network,"sand canal",into an efficient heat transfer network,"stone canal",and has been verified by experiments The rationality and feasibility of this transformation mechanism.In this paper,the "stone channel conversion mechanism" is used to prepare silica-based thermally conductive composite materials,and the main aspects of the optimization of the preparation process and the effects of the types of rigid particles involved in the conversion mechanism on the thermal conductivity of the composite material are discussed.content.Committed to preparing silica-based thermally conductive composites with low filler content,high thermal conductivity,and excellent mechanical properties.Specific research contents include:(1)The three types of silica gels E620,2225,and 184 were compared and analyzed from the three aspects of operating performance,curing temperature range,and impact on the thermal conductivity of the composite material.The analysis results show that 184 is the most suitable substrate choice.(2)Explore the process parameters in the preparation process of SCFNA method including the effect of mixing speed,mixing time and imprinting temperature on the thermal conductivity and mechanical properties of thermally conductive composite materials,and finally determine the mixing speed of 2000r/min,mixing time 2min,imprinting The temperature of 120℃is the optimal preparation process parameter of SCFNA method.(3)Design experiments to add rigid particles with different self thermal conductivity and different physical shapes into the PDMS/30wt%SCF mixed system,continuously change the volume ratio of rigid particles,and explore the thermal conductivity and physical properties of rigid particles The influence of shape and added amount on the thermal conductivity of silica-based thermal conductive composites.The experimental results show that spherical hollow glass beads with lower thermal conductivity than the polymer matrix are most suitable for filling the composite with low content to improve the thermal conductivity of the thermally conductive composite.(4)Using the L9(34)orthogonal test design,the four factors of the thickness of the composite material,the content of SCF filler,the content of hollow glass beads,and the particle size of the hollow glass beads on the thermal conductivity of the thermally conductive composite were compared and analyzed.influences.The influence degree of the four factors on the thermal conductivity of the final composite material from large to small is the SCF content,the content of the hollow glass microbeads,the thickness of the composite sheet,and the particle size of the hollow glass microbeads.According to the analysis of the final range data,the best raw material selection,mixing ratio and process conditions that can achieve the highest thermal conductivity of the composite material are:SCF content 40wt%,hollow glass microbead content 8vol%,hollow glass microbeads The diameter is 20μm,the thickness of the sheet is 0.1mm,and the thermal conductivity of the thermally conductive composite material at this time is 23.325W/(mK).