Carbon fiber (CF) refers to a fibrous material with a carbon content of 92% or more. Each CF monofilament has a diameter of about 5 microns to 15 microns. Many parallel filaments are combined to form a so-called CF tow. Therefore, the number of tows refers to the number of filaments in each tow. For example, the 24K specification represents 24,000 filaments in a CF tow. Generally, the carbon fiber with a tow size of ≤24,000 is called a small tow carbon fiber, and the tow exceeding 24K filaments is called a large tow carbon fiber.
The small tow carbon fiber has obvious advantages compared with the large tow fiber, which is mainly reflected in the higher tensile strength and higher modulus after laying or braiding into a composite material, so the small tow carbon fiber is mainly used for performance requirements High aerospace and other industries, and the price of small tow carbon fiber is often significantly higher than large tow fiber.
This article analyzes the costs from the precursor PAN precursors required for the preparation of carbon fibers to the complete chain of carbon fibers (CF) and the final carbon fiber reinforced polymer (CFRP). And its composite material chain was analyzed.
01 Carbon fiber and its composite material value chain
The main process steps to convert crude oil into carbon fiber and finally process it into carbon fiber reinforced polymer (CFRP), and mark the value from raw materials, intermediate products to end products. During the preparation of the precursor, the propylene produced by the cracking of crude oil reacts with ammonia to produce acrylonitrile (AN). At present, most domestic and foreign carbon fiber manufacturers purchase AN directly from suppliers. Of course, there are a few companies, such as Mitsubishi Liyang, which also have crude oil refining and cracking capabilities. All carbon fiber manufacturers in the market have their own polymerization and spinning capabilities, so the process and formula for converting PAN precursors from AN to CF precursors are strictly confidential. In addition to AN, some comonomers are added during the polymerization, but their concentration is generally less than 5%. Like AN, these comonomers are usually purchased from suppliers.
Although carbon fibers can be purchased in the market, PAN yarns used for carbon fiber production are not available at all. PAN yarns produced by companies such as Toray in Japan cannot be obtained by any means, which still dominates the industry. Of Japanese manufacturers bring a competitive advantage. Therefore, there have been recent reports that a domestic company producing PAN yarn has been exported overseas, but this does not indicate that the core competitiveness of the company has been improved, because true high-quality PAN yarn is a core secret of the company and will not be sold outside.
The PAN raw silk for carbon fiber production is 3-6 US dollars / kg. However, after pre-oxidation, low-temperature carbonization, high-temperature carbonization, surface treatment, and sizing, the aviation-grade carbon fiber can reach 113 US dollars / kg. On the one hand, the energy consumption of PAN raw yarns is always accompanied by high-temperature heat treatment during the process of conversion to carbon fibers, which is the most critical factor that leads to a significant increase in the cost of carbon fibers. On the other hand, the evolution of PAN precursor to carbon fiber involves microstructure evolution, as shown in Figure 2, and the microstructure, especially defects, is the key factor restricting the performance of carbon fiber. Therefore, the technology of the process of PAN precursor to carbon fiber conversion is also very high. Technical barriers, and domestic and foreign carbon fiber manufacturers attach great importance to the technical protection of PAN precursors into carbon fibers.
Due to a series of high-tech barriers such as PAN raw silk technology and core technology in the preparation of carbon fibers, coupled with high production costs, there are only more than ten carbon fiber suppliers capable of large-scale production at home and abroad and generating benefits.
In order to increase the added value of carbon fiber products, CFRP must be prepared for use. From CF to CFRP, the resin matrix is only added from the raw materials, and the general resin price is relatively low. In addition, CFRP has mature processing technology and equipment. Aerospace-grade carbon fiber is USD 113 / kg made into CFRP and the value can reach USD 332 / kg. In other fields such as automobiles, wind power blades, pressure vessels, etc., the benefits of using carbon fiber to make end products are also considerable.
02 Airline carbon fiber and its composite material supply chain
The small tow carbon fibers required for most aerospace applications are produced by the following five carbon fibers, three of which are Japanese companies, and Japanese carbon fibers have certain applications in Airbus and Boeing aircraft. The United States Hexcel produces carbon fibers mainly for Airbus A350, The A380 is produced, and the American Cytec company was acquired by Solvay in Belgium in 2015, but COMAC's C919 is listed in its supply catalog.
Since Airbus and Boeing have used heavy cargo aircraft to transport wide-body aircraft fuselage parts internationally, the supply chain of these two major aircraft components has been widely distributed around the world. The complete supply chain based on the main carbon fiber suppliers to the prepreg and ultimately the Boeing 787 fuselage is shown in Figure 3. PAN Yarn is produced and processed into carbon fibers at factories in Ehime, Japan and Decatur, Alabama, USA. These carbon fibers are then processed into prepregs in Tacoma, Washington and Ishikawa, Japan. These prepregs are subsequently Shipped to the United States, Japan, Italy, etc. for various sections of production, and finally assembled in Charleston or Everett, Washington.
Although the processing plants are located all over the world, in order to effectively reduce transportation costs, Boeing has selected manufacturers to be adjacent to the airport, such as the Spirit Aerosystems front fuselage facility in Wichita and the Alenia Aermacchi fuselage facility in Grottale, Italy. Adjacent to the main airport. And three Japanese heavy industry companies-Fuji, Mitsubishi and Kawasaki-manufacture wing boxes, wings and fuselage sections, respectively. They are all located in the port of Nagoya and are transported to Chubu Centrair International Airport by barge. The Airbus A350 carbon fiber and its composite material chains are also found in the United States, France, Germany, and Spain.
Through the analysis of the global chain of carbon fiber and its composite materials laid out by the two major international airlines, it can be found that the American domestic carbon fiber company Hexcel serves Airbus aircraft, and the American Boeing aircraft carbon fiber source is mainly from Toray Japan. Europe and Japan are basically on the same front. Through globalization, global advantages can be integrated to further determine the dominant position.