Because of the small diameter, large aspect ratio, high strength, high modulus and excellent heat resistance, silicon carbide whiskers play a unique role in the modification of polymer materials. Epoxy resin has been widely used in various fields of the national economy because of its high strength, good adhesion, good thermal stability, high strength, and small shrinkage. SiC whisker modified epoxy resin can further improve its mechanical properties (strengthening and toughening), friction and wear resistance and antistatic properties.
Epoxy resin (EP) is one of the most widely used thermosetting polymer materials. It has excellent adhesion, thermal stability, electrical insulation, chemical resistance, high strength, small shrinkage, and low price and it’s widely used in various fields such as coatings, adhesives, light industry, construction, machinery, aerospace, electronic and electrical insulation materials, and advanced composite materials. However, due to the shortcomings of epoxy resin cured products such as high brittleness, low impact strength, easy cracking, and poor antistatic performance, its further applications are limited.
Epoxy resin glue is prepared by epoxy resin plus curing agent, filler and so on. It has the characteristics of high bonding strength, high hardness, good rigidity, acid, alkali, oil and organic solution resistance, and small curing shrinkage. At present, the bonding strength of epoxy adhesive is relatively high, but there are still some deficiencies in the bonding of some high-strength structures, and the bonding strength needs to be further improved.
Whiskers are fibers with extremely small diameters grown in the form of single crystals under special conditions. They have a highly ordered atomic arrangement structure, so they can approach the theoretical strength of valence bonds between atoms, and have great potential for strengthening epoxy adhesives. Many research results show that filling whiskers into epoxy resin matrix can effectively solve these shortcomings and greatly improve the comprehensive performance of epoxy resin.
Silicon carbide whisker is a cubic whisker whose crystal form is the same as that of diamond. It is currently the whisker with the highest hardness, the largest modulus, and the best heat resistance among whiskers. The crystal form is β-type, which has higher hardness, better comprehensive properties such as toughness and thermal conductivity, and is also one of the best reinforcing and toughening materials. It can significantly improve the toughness, flexural strength, hardness, wear resistance, and high temperature resistance, oxidation resistance, thermal conductivity, structural stability, thermal shock resistance, etc..
The silicon carbide whiskers treated with the coupling agent can be well and stably dispersed in the matrix, the whiskers are well infiltrated by the matrix, and the interface bonding strength is increased. Through this interface, the matrix and whiskers are connected as a whole. When the matrix is subjected to external force, the stress can be uniformly transmitted through this interface and absorb a large amount of energy. On the one hand, when a crack appears in the matrix, the whiskers bridge the surface of the broken crack, which can hinder the further development of the crack; on the other hand, if the crack encounters silicon carbide powders, if it wants to develop further, the crystal must be destroyed or removed. Whiskers have high strength and high modulus, and it takes a lot of energy to destroy or pull out the whiskers, and when the crack bypasses the whiskers, it develops further and causes more microcracks. And because the whiskers have a relatively large L/D, more energy needs to be absorbed, thereby significantly increasing the strength and toughness of the EP matrix.