Since its emergence in 1958, carbon-carbon composite materials have attracted widespread attention worldwide due to their outstanding performance. Many industrialized countries have invested significant human, material, and financial resources into the research and development of this material, continuously improving its performance and expanding its application scope. Over the past few decades, carbon-carbon composite materials have made significant progress in terms of material composition, manufacturing processes, performance, and engineering applications, and can be divided into four developmental stages.
The first stage, from the invention of carbon-carbon composites to the mid-1960s, was the development phase.
It was recognized that to produce high-performance carbon-carbon composites, high-performance carbon fibers (CF) were first required, making this period a vibrant time for CF research and development. In 1958, the American Union Carbide Company began industrial production of CF and carbon fabrics using artificial silk (regenerated cellulose) and its fabrics, and sold the products commercially. In 1959, Shigeo Shindo produced CF using pure PAN fibers. In the early 1960s, Suguro Ohtani produced asphalt through the thermal decomposition of polyvinyl chloride, followed by melt spinning, and then carbonization in air and an inert gas to produce CF. In 1964, Watt and others at the Royal Aeronautical Research Establishment (RAE) in the UK applied tension to the fibers during the pre-oxidation process, opening up a new approach for producing high-strength and high-modulus CF. Subsequently, companies such as Bristol began producing polyacrylonitrile CF using these technologies. Concurrently, extensive research was conducted on the preparation processes of carbon-carbon composites, and methods for characterizing carbon-carbon composites and various testing techniques were developed. In terms of applications, countries such as the United States and France established a series of application development programs based on carbon-carbon composites, including the “Launch Vehicle Materials Program” and the “Opportunity Program for C/C Nozzles.”
In the second phase, from the mid-1960s to the mid-1970s, as research into carbon-carbon composite materials gradually deepened, the field entered the stage of engineering application research.
In 1969, Japan’s Toray Industries successfully developed a special copolymer PAN fiber and, in collaboration with Union Carbide Corporation’s carbonization technology, produced high-strength, high-modulus CF, significantly advancing the development of carbon-carbon composite materials. Subsequently, we gradually developed weaving techniques for carbon-carbon composite materials and vigorously advanced densification processes. In 1966, LTV Space Company had already applied carbon/carbon composite materials to the thermal protection shield of the optical instruments in the Apollo spacecraft’s control cabin and the nose cone of the X-20 aircraft. In 1971, the carbon/carbon composite material re-entry nose cone developed by Sandia Laboratories was successfully applied. In 1974, the aviation division of British Dunlop Company first developed carbon/carbon composite material aircraft brake discs, and successfully tested them on the Concorde supersonic aircraft, reducing the weight of each aircraft by 544 kg and increasing the service life of the brake discs by 5 to 6 times.
In the third phase, from the mid-1970s to the mid-1980s, research on carbon-carbon composite materials was further deepened. The structural design of preform fabrics and the maturation of multi-directional fabric processing technology successfully addressed the anisotropy issues of carbon-carbon composite materials, and through the proper selection and design of reinforcing fabrics, the requirements of complex structures were met.
Extensive and detailed studies were conducted on the mechanical properties, physical properties, oxidation resistance, and manufacturing processes of carbon-carbon composites, with corresponding databases established. Carbon-carbon composites began to be applied in multi-nozzle systems and next-generation high thrust-to-weight ratio turbine engines, and their application in aircraft brake discs was further expanded. Carbon brake discs were adopted in dozens of military and civilian aircraft, and the application of carbon-carbon composites was extended from aerospace to civilian use. Due to the excellent biocompatibility of carbon-carbon composites, research and development of their biological applications began in the early 1980s both domestically and internationally. Carbon-carbon composite-made artificial heart valves and artificial bone joints have since been put into use.
The fourth stage, from the mid-1980s to the present, marks the period of widespread adoption and application of carbon-carbon composite materials.
Building on the extensive theoretical and practical experience gained in research and application during the first three stages, this period laid the foundation for further development and application in both breadth and depth. The primary objective of this stage was to enhance the performance of carbon/carbon composites while reducing costs. To this end, foreign researchers conducted in-depth studies on densification technologies. Typically, the CVI process requires thousands of hours to densify the green body, and carbon tends to deposit on the surface of the green body, affecting the amount of carbon deposited internally. Under the support of the U.S. Air Force, the Georgia Institute of Technology improved the method for preparing carbon/carbon composite materials, studying the forced gas flow/thermal gradient CVI method, which increased the deposition rate of carbon/carbon composite materials by 30 times. Oak Ridge National Laboratory and the California Phillips Propulsion Laboratory also reported on related rapid densification methods.
Meanwhile, the development of various functional carbon-carbon composite materials has been remarkable. For example, a honeycomb-shaped carbon-carbon composite material developed by Sandia National Laboratories not only has low weight and high strength but also excellent thermal insulation properties. The application areas of carbon-carbon composite materials have rapidly expanded from aerospace to numerous fields such as nuclear energy, metallurgy, medicine, and automobiles.
Additionally, research on the oxidation resistance of carbon-carbon composites during this phase has been a hot topic, as it is a prerequisite for their use as thermal structural and thermal protection components. Numerous research institutions worldwide have developed various oxidation-resistant coating systems and manufacturing processes, effectively enhancing the oxidation resistance of carbon-carbon composites in high-temperature, oxygen-rich environments.