Composite materials are composed of two or more materials with different properties, which have excellent mechanical properties and functional characteristics and are widely used in fields such as aeronautics and astronautics, automotive manufacturing, and civil engineering. In composite materials, the bonding strength between the matrix and reinforcing material is one of the key factors affecting their overall performance. Improving bonding strength can not only enhance the load-bearing capacity of the material but also improve its fatigue resistance, crack propagation resistance, and other properties. This article will discuss how to improve the bonding strength of composite materials from aspects such as interface optimization, surface treatment, material matching, and process improvement.



Firstly, optimizing the interface between the reinforcing material and the matrix is one of the key methods to improve bonding strength. The failure of composite materials often originates from delamination at the interface, so good interface bonding is crucial for the effective transmission of stress. By introducing an interface layer, such as a coating or coupling agent, the wettability and chemical compatibility between the matrix and reinforcing material can be improved. For example, in the carbon fiber/epoxy resin system, the use of sizing agent or silane coupling agent to treat the surface of carbon fibers can significantly improve their bonding strength to the resin matrix.



Secondly, surface treatment of the reinforcing material is an effective method to enhance bonding strength. Reinforcing materials such as carbon fibers, glass fibers, ceramic particles, etc., usually require chemical or physical treatment to increase their surface activity and roughness, thereby improving the mechanical interlocking force and chemical bonding force with the matrix. Common surface treatment methods include oxidation treatment, plasma treatment, acid pickling, electrochemical treatment, etc.



Thirdly, selecting matrix and reinforcing material with matching properties is also an important factor in improving bonding strength. An ideal composite material should have good thermal expansion coefficient matching, chemical stability, and physical compatibility between the matrix and reinforcing material. For example, in metal matrix composite materials, if there is a large difference in thermal expansion coefficient between the reinforcing material and the matrix, it is easy to produce residual stress and cause interface cracking during the temperature change process.



Finally, optimizing the preparation process conditions is also an important way to improve bonding strength. Parameters such as temperature, pressure, and curing time during the preparation process will affect the quality of interface bonding. For example, in the molding of resin-based composite materials, appropriate pressure timing and temperature control can help reduce bubbles and defects, improve the wettability of the resin to the reinforcing material, and thus obtain better bonding strength.



In summary, improving the bonding strength of composite materials requires comprehensive consideration from multiple aspects such as interface design, surface treatment, material matching, and process control. With the development of materials science, it is expected that new technologies such as nanointerface engineering and intelligent process control will further enhance the interface properties of composite materials in the future, thereby promoting their wider application in high-end fields.