Carbon fiber of automotive materials

What is carbon fiber?

Carbon fiber, with both the inherent characteristics of hard carbon materials and the processing characteristics of soft textile fibers, is known as the king of materials.

It is often used in aircraft, rockets, and bulletproof cars. Carbon fiber was first used in automobiles in Formula 1 cars, but now it is also used in civilian cars.     

In 1880, Edison discovered carbon fiber when he was experimenting with filaments. After more than 100 years of development, BMW used carbon fiber in the i3 and i8 in 2010, which opened the application of carbon fiber in automobiles. Carbon fiber for automobiles has several advantages.

Lightweight: carbon fiber composite material is 3/4 lighter than steel and 1/3 lighter than aluminum, making it more energy efficient.

Comfort: The soft tensile property of carbon fiber has a good improvement on the noise and vibration control of the whole car, which will significantly improve the comfort of the car.

Reliability: Carbon fiber has higher fatigue strength and good collision energy absorption, which can preserve strength and safety while reducing the weight of the vehicle, reducing the safety risk factor brought by the light weight.

Improved life span: Carbon fiber does not have corrosion and rust problems, which enhances the life span of car parts.

How exactly is carbon fiber made?

Pulling fine wire: the raw material is heated, it is reinforcing material: reinforcing material for winding and molding, mainly various fiber yarns: such as alkali-free glass fiber yarn, medium alkali glass fiber yarn, carbon fiber yarn, high strength glass fiber yarn, aramid fiber yarn and surface felt, etc. Resin matrix, and a variety of fillers. The plastic fibers are made up of thousands of fine filaments, which are extruded to form gel-shaped filaments.

Stabilization: After 400 degrees of heating and oxidation, the thermoplastic macromolecule is converted into a heat-resistant structure. So that it does not melt or burn at high temperature, keep the fiber shape, thermal in a stable state carbonization: heating 1,000-2,000 degrees to drive away the non-carbon atoms, with high temperature oxidation into black, and then through the carbonization furnace carbon atoms combined in the fiber.

Graphitization: parallel filaments after charged corrosion of the surface for better absorption of resin, with hundreds of fibers to form a fiber network, resin coating and fiber network at the same time into the machine heating resin adsorbed on the fiber network, through the extrusion of resin penetration into the fiber network filaments, after cooling the liquid resin into a gel.

How does BMW apply carbon fiber?

BMW quotes a lot of carbon fiber materials: carbon fiber wheels, center mesh, luggage rack, front lip, side skirts, rear diffuser, outside mirror cover, air conditioning vents, lower center console panel, etc.

BMW applies CFRP (Carbon Fibre Reinforced Plastic) carbon fiber components in the main skeleton of the car to reduce the weight and strengthen the body.

As we all know, carbon fiber is a very expensive material, and the production process is complicated, resulting in insufficient production. According to the relevant statistics, the cost of carbon fiber is $20 per kilogram, compared to the traditional steel material cost less than $1 per kilogram, how to reduce costs and mass production is the biggest problem.

In order to produce carbon fiber, BMW set up a joint venture with SGL Carbon SE in Germany as early as 2009 to produce carbon fiber parts. 2014, the two companies invested an additional $200 million to triple the annual production of carbon fiber. The annual capacity of carbon fiber was increased from 3,000 tons in two production lines to 9,000 tons in six production lines, with the extra capacity being absorbed by the BMW 7 Series, a model with extremely high sales volume.

Due to the strategic importance of the project, BMW made the rare move of securing its influence in the Wiesbaden-based manufacturer by purchasing a 16% stake against the 10% stake purchased by Volkswagen. Susanne Klatten, a member of the Quant family (BMW's majority shareholder), also bought a 27% stake in SGL, so BMW has far more control over this company than its competitors.