# rare things are valuable

By [cumquat](https://paragraph.com/@cumquat) · 2023-03-22

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It is said that "rare things are valuable", and everywhere carbon is not "rare" at all. So what is so expensive, and what is so new, about carbon fibre that it is comparable to gold? Carbon fiber, the "star" born in the 1960s, is a new material containing more than 90% carbon made from carbon-containing organic fiber through high temperature carbonization and graphitization. Aerospace is an important field in the application of carbon fiber, which reflects the supporting role of advanced materials for modern cutting-edge technology. In the aerospace field, the most commonly used carbon fiber is PAN based filament high performance carbon fiber. What is PAN based filament high performance carbon fiber? PAN's Chinese name is "polyacrylonitrile", "PAN base" with polyacrylonitrile as carbon containing organic fiber raw material to make carbon fiber. Besides PAN - based carbon fiber, there are asphalt - based, viscose - based and phenolic - based carbon fiber. Due to the relatively simple production process of PAN-based carbon fiber, its finished products have excellent quality and mechanical properties, so it is currently the "popular star" in the field of new materials in the world. Filament is relative to short filament. According to the fiber form, carbon fiber can be divided into filament, staple fiber and cut fiber. They all have specific applications, among which the filament often has better comprehensive properties, and is used in cutting-edge technology. As for "high performance", it is the core requirement of aerospace carbon fiber materials. According to the performance value, PAN-based carbon fiber can be divided into general purpose (GP), high strength (HT), high strength (HM), high strength high model (HP) and other specifications. The high strength and high strength models are promising functional materials in aerospace field. However, carbon fiber is often used in a variety of applications in the form of composite materials. The so-called composite material refers to the multi-component material made of two or more single materials by the composite process. The role of these components is to complement each other, so that the composite material can better meet the needs of specific occasions. Carbon fiber composites usually take resin materials (such as epoxy resin, etc.) as matrix, whose main function is to transfer stress and unite various components as an organic whole, so as to meet the challenges of various loads. As for carbon fiber, its positioning is "reinforced fiber", its main role is to carry the load, that is to pick up the "girder" meaning. Large aircraft has always been the commanding height of international competition, among which composite material has become one of the three key technologies in its manufacture. Using a composite of carbon fibre and resin to make the "outerwear" of a large aircraft is light and easy, consumes less power, has more thrust and is less noisy. For example, the composite material used in Boeing 787 has reached 50%, which can not only effectively overcome the contradiction between weight and safety, but also greatly reduce the energy consumption of the aircraft.

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*Originally published on [cumquat](https://paragraph.com/@cumquat/rare-things-are-valuable)*