Composite material is a material with new properties that is composed of two or more different properties and physically or chemically combined. Due to its excellent mechanical properties, high specific strength and specific modulus, designability, composite materials have been widely used in the aerospace industry. In recent years, the level of chemical industry has been continuously improved, the prices of raw materials such as fibers and resins in composite materials have decreased, the technological level has been continuously improved, and the production capacity of batches has been improved. It has also provided an excellent opportunity for the application of composite materials in the transportation field.
At present, the emphasis on environmental issues and the urgent need for energy conservation and emission reduction have led to increased investment in research and development of composite materials in the automotive and rail transportation sectors. Major companies are also promoting technological innovation and expansion in composite materials applications. The range of composite applications is to increase their competitiveness.
First, the application advantages of composite materials in the automotive field
As a new material, composite materials have been widely used in the aerospace industry due to their unique advantages. For the automotive field, which is increasingly competitive and demanding for lighter weight, composite materials also highlight its advantages in the following aspects. The application advantage of a field.
1. Excellent mechanical properties, anisotropic heterogeneity
Composite materials are characterized by a higher specific strength and specific modulus. The specific strength and specific modulus refer to the ratio of the strength and modulus to the density of the material. When the specific strength is higher, the self-weight of the part is smaller at the same strength. When the specific modulus is higher, the rigidity of the part is higher. Big. Therefore, the improvement of these two properties is of great significance to structural members that require high mechanical properties and operate at high speed, and transportation vehicles that need to reduce their own weight and load carrying capacity. Composite materials are different from traditional materials and have anisotropic characteristics. For example, fiber reinforced composites have a specific strength ratio modulus in the fiber direction that is significantly better than perpendicular to the fiber direction, so they have anisotropy in their mechanical properties. .
2. Performance is designed to achieve integrated design and molding
The structure and corresponding properties of the composite are both designable. Different from the performance of the traditional non-composite, the performance of the composite can be achieved by corresponding design. The selection of the matrix material and the reinforcing material, the selection of the fiber direction, and the design of the layer can all affect the overall performance of the composite material, and the properties of the composite material can be calculated according to the matrix material constituting the composite material and the parameters of the reinforcing material. Compared with the parts made of traditional materials, the joints are connected by riveting, welding, etc., and the composite materials can be integrally formed by reasonable design and appropriate process, which can improve the overall performance of the parts, reduce the cost and reduce the overall quality.
3. Anti-fatigue, shock absorption, noise reduction, corrosion resistance
In addition to good mechanical properties, composite materials also have excellent properties such as fatigue resistance, corrosion resistance and shock absorption. For example, in the widely used fiber reinforced composite material, the applied load is transferred from the substrate to the reinforcing fiber due to the interface between the fiber and the substrate. Moreover, the interface can effectively prevent the expansion of fatigue cracks. For most metal materials, the fatigue strength limit is 30% to 50% of the tensile strength, and the corresponding composite material can reach 60% to 80%. The composite material can absorb energy through the interface of the composite material and the sandwich structure, which can effectively improve the effect of shock absorption and noise reduction, and therefore has a great advantage in the application of ground transportation. In addition, the composite material has strong chemical stability. For example, fiber-reinforced phenolic resin can be used for long-term use in acidic media containing chloride ions. Glass fiber reinforced plastic can be used to produce strong acid, salt and certain solvents. Equipment such as corrosive pumps, valves, vessels and pipes; materials that are compounded with alkali-resistant fibers and plastics and can be used in strong alkaline environments.
4. Structural function integration
The wear resistance of thermoplastics is not excellent, but after adding a small amount of chopped carbon fiber composites, the wear resistance can be increased several times. For example, a polypropylene (PP) composite reinforced with carbon fiber has a wear resistance of 2.5 times that of itself, a corresponding PTFE of 3 times, and a polyvinyl chloride of 3.8 times. When a suitable plastic is used in combination with a steel sheet, a material having excellent properties and being used for producing a wear-resistant article can be obtained. For example, a three-layer composite material made of polytetrafluoroethylene or polyoxymethylene as a surface layer, porous bronze and steel plate as a inner layer is a good material for a sliding bearing.
Therefore, from the perspective of reducing the cost of mold processing, reducing the quality of the parts themselves, increasing the degree of design freedom and the degree of component integration, the application of composite materials has become an important direction for technological innovation and improvement in various countries and major enterprises.
