Industrial glue core parameters! How is "high thermal" silicone gel made?

In order to achieve a wide range of applications in industry, good thermal conductivity is essential. At present, the thermal conductivity study of thermally conductive silicone gel is mainly based on filler correction, and the final thermal conductivity of thermal filler depends on the size, shape and surface characteristics of filler particles, the type of filler and the change of heat conductivity of filler with temperature, humidity and pressure. Improving the thermal conductivity of thermally conductive silicone gels is mainly achieved

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I. The reduction of the particle size of thermal filler particle size is conducive to the improvement of thermal conductivity and physical and mechanical properties of thermally conductive silicone gel
, and the comprehensive performance of thermal silicone gel filled with nano-scale alumina fillers significantly exceeds that of thermal silicone gel filled with micron-grade alumina fillers. Therefore, ultra-finer heat-conducting fillers are beneficial to the improvement of thermal conductivity of thermally conductive silicone gel.
Some scholars have found that the particle size of inorder fillers is super-fine, the atomic spacing and structure within the filler particles will change dramatically, and when the particle size reaches the nanoscale, some properties of the filler may even change qualitatively. Especially for some co-priced key type materials, when their particle size is ultra-fine, it will become a metal bond type material, its thermal conductivity will be increased sharply. For example, Concord Chemical Industries of Japan has developed high-purity, fine magnesium oxide by ultra-fine treatment of magnesium oxide materials, which have a thermal conductivity of more than 50W/m. K, equivalent to three times the alumina and four times the silicon oxide. Some data show that the thermal conductivity of conventional aluminum nitriding is relatively low, and can only reach 36W/m. K, while the thermal conductivity of the ultra-fine nano-scale aluminum nitrid has soared several times to a staggering 320W/m. K.
II, thermal conductive filler high orientation
thermal conductive mesh chain formed between the particles of thermal conductive filler has a great impact on the thermal conductivity of the material, the key to improve the thermal conductivity of thermally conductive silicone gel is to form the thermal mesh chain within its system to the maximum extent consistent with the direction of heat flow. Therefore, the high orientation of thermal conductive fillers is also a key way to improve the thermal conductivity of thermally conductive silicone gel. The thermal conductivity of ordinary silicon nitride is generally relatively low, because its sintering structure is unconventional. If the diameter of 1 micron, length of 3 to 4 microns of crystal particles are added to the powder of silicon nitride raw materials, so that the orientation of these species of crystals is arranged, a highly thermally conductive silicon nitride with a high orientation structure can be formed. The thermal conductivity of this silicon nitride is an opposite due to the formation of fibrous structure, and it has been measured by experiments that its thermal conductivity in structural orientation is three times that of ordinary silicon nitride, reaching a staggering 120W/m. K.
Three, thermal filler surface modified
thermal conductivity of the thermally conductive silicone adhesive is closely related to the degree of moistureability of the particle surface of the thermally conductive filler particles, because whether it is the degree of bonding of the filler and substation, or the thermal barrier of the base and filler interface, or the dispersion and filling of the filler itself will be affected by the humidity of the filler surface, which will directly affect the thermal conductivity of the thermal conduction silicone. After surface treatment of thermal fillers, their filling volume, thermal conductivity and compatibility (with silicone gel) are significantly improved, especially for nano-scale fillers, because nano-scale fillers in order to be evenly dispersed in nano-size silicone glue, surface change is an essential process. Studies have shown that if heat-conducting fillers can form an "isolated distribution state" in silicone adhesive through special processes, thermally conductive silicone gels will obtain better thermal conductivity even if they are filled with a small amount of thermal conductive fillers. For example, some experiments have found that if aluminum alumina is surfaced with γ-ampere triethyloxysilane, hexadisilethane, and methyldioxysilane, etc., and then filled into silicone gel, the thermal conductivity of the resulting thermally conductive silicone gel will be improved, and viscosity will be reduced. This shows that surface treatment of thermal fillers can improve the thermal conductivity and processing performance of silicone gel.
4. Heat-conducting filler mixed filling
Many scholars have found through experiments that it is an effective way to improve the thermal conductivity of thermally conductive silicone gel by mixing heat-conducting fillers of different kinds, particle sizes and shapes in an appropriate proportion. Some scholars used a mixture of 0.5 microns, 3 microns and 20 microns of alumina-filled silicone glue, when the ratio of three different particle size alumina is 10:30:15, the thermal conductivity of silicone gel is significantly better than that of single-particle alumina-filled silicone glue. There are also scholars with two different volume fractions and particle size spherical alumina mixed with another non-spherical alumina as a thermal filler filler filler filled into silicone glue, which not only increases the density of filler accumulation, but also keeps the fluidity of the substation, so that the thermal conductivity of the resulting thermal silicone gum is greatly improved, but the hardness is controlled in a lower range.
, optimize the processing process
when the thermal conductive filler is determined, the processing process has become an important factor in determining the thermal conductivity of thermally conductive silicone gel. For example, the thermal conductivity of silicone gels made from solution mixing is significantly better than that of silicone gels made from direct blending, because different processing processes result in different composites of particles and substations. In addition, the filling process and various additives in the feeding order will also greatly affect the thermal conductivity of thermal silicone gel. Patents have specifically studied the effect of the feeding sequence on the thermal conductivity of thermal silicone gel, and the results show that if silicone gel is mixed with alumina of small particle size and then mixed with alumina of large particle size, the thermal conductivity of thermal silicone gel is better, while the thermal conductivity of silicone gel mixed with all alumina is poor.
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