Diamond is the hardest super abrasive wear-resistant interface in processing industry, the most effective heat dissipation material in electronic industry, the best semiconductor chip, the highest frequency filter in communication components, the diaphragm with the most fax sound, the most transparent radome for flying objects, the most scratch-resistant protective film for glasses, the most stable anticorrosive coating for parts and so on. Diamond has many advantages that other materials do not have, and it has undoubtedly become the most popular and useful engineering and functional material. With the diversification of synthetic technology, superhard materials (mainly diamond, but also cubic boron nitride) have more and more opportunities to be applied and selected in modern science and technology and modern industry, making greater and greater contributions to the rapid growth of China's economic benefits, and showing its kingly demeanor in improving the technical level of traditional industries. The development prospect of such excellent materials will be bright and beautiful!
Both conventional diamond films and nano-diamond films can be obtained by CVD. CVD diamond film has good mechanical, thermal, optical and electrical properties as single crystal diamond prepared by static high pressure and high catalyst method. At present, it has been widely used in various fields and will become the mainstream of diamond material development in the future, which will not only bring huge economic benefits, but more importantly, give full play to the all-round characteristics of diamond materials. Nano-diamond films will become the focus of CVD diamond research.
Graphite products maintains the original chemical properties of flake graphite, namely, acid resistance, corrosion resistance and physical properties, namely, high temperature resistance of 3000℃ and low temperature resistance of -204℃. Its compressive strength is more than 800kg/Cm2, it is oxidation resistant, its weight loss rate is 1%, its rebound rate is 15-50% (density is 1.65438), and it also has strong self-lubricating performance. Therefore, graphite products has been widely used in metallurgy, chemical industry, petrochemical industry, high-energy physics, aerospace, electronics and other fields.
People make use of the characteristics of graphite and skillfully manufacture different types of products according to the needs of engineering, such as high purity graphite products, flexible graphite products, composite graphite products and so on. In order to improve the service performance, graphite, fiber (including synthetic fiber), metal wire, metal mesh and metal processing plate are made into composite graphite products, which greatly increases its strength and elasticity. Composite graphite products is mainly made of resin, synthetic rubber and plastic (PTFE, ethylene, propylene, etc.) by cold pressing or heat sealing. ) and liquid graphite products (graphite emulsion, etc.). ) and semi-liquid graphite products (graphite grease, etc. Graphite products plays an important role in sealing, temperature resistance, corrosion resistance, electrical conductivity, heat insulation, pressure resistance, wear resistance and oxidation resistance, which has attracted the attention of experts at home and abroad. Of course, graphite products are also quietly entering modern office supplies. For example, an archival supplies factory in Jiangxi province uses graphite to expand and process it into insect-proof discs, which can absorb drugs for one year without losing their medicinal properties. There is also a graphite lubricating belt produced by Beishu graphite mine, which solves the problem of urgently needed sander (mostly imported sander) accessories in domestic wood processing industry and fills the gap of similar products in China. In a word, graphite products has been increasingly used by various industrial sectors, and graphite products has a vast market.
The most important use of artificial graphite is to make electrodes for arc steelmaking furnaces. Artificial graphite electrode is also used to electrolyze salt solution to produce chlorine and sodium hydroxide. Graphite does not react with acid, alkali, organic solvent or inorganic solvent, which makes it widely used in various process equipment in food, chemical industry, petroleum and other industries. Graphite is also used in nuclear reactors.
If some man-made fibers are mixed with plastic resin and heated under pressure, they can become carbon fibers. The carbon in these fibers exists in the form of graphite. The density of carbon fiber is lower than that of steel, but its strength and hardness are better. They are used for decks and folding wings of radios, as well as meteorological satellites and communication satellites. In sporting goods, carbon fiber is used to make golf clubs, tennis rackets, fishing rods and tripods for bicycles.
Carbon black-application
Mainly used as reinforcing agent and filler of rubber, the dosage is about half of rubber. Carbon black for rubber accounts for 94% of the total carbon black, of which about 60% is used in tire manufacturing. In addition, it is also used as a colorant for ink, paint and plastics, and as an ultraviolet shielding agent for plastic products. It is also an important additive for many other products, such as electrodes, dry batteries, resistors, explosives, cosmetics and polishing paste.
Furnace black is mainly used for rubber products. The finer the particle size of carbon black, the better its reinforcement performance. The higher the structural degree of carbon black, the higher its modulus and modulus. Fine-grained reinforcement varieties are mainly used for tire treads, giving tires excellent wear resistance. Other parts of the tire, such as sidewall, cord fabric, belt buffer layer and inner liner, require the rubber compound to be resistant to flex cracking, ozone oxidation, good resilience and low heat generation performance. Generally, semi-reinforced furnace black is selected with coarse particle size (specific surface area is less than 40m2/g).
Pigment tank black is widely used in ink, coatings and plastics. Ink, especially news ink, mainly uses black pigment tank. In the process of coating manufacturing, high pigment groove black gives high-grade automobile topcoat excellent blackness and luster, while the pigment groove black is used in general industrial coatings. In addition, medium pigment tank black is also often used as an ultraviolet shielding agent for polyolefins to improve the weather resistance of plastic products. Groove black for rubber is mainly used for tires, especially for cross-country and bias tires, which gives the tread high strength and good wear resistance.
Pyrolysis carbon black is mainly used for rubber products. Because of its coarse particle size and poor reinforcement performance, it is only used in occasions where the maximum filling increment is needed, such as manufacturing rubber pads, rubber hoses, sponge products, sealing rings, tire liners, bead rubber and insulating products.
Activated carbon is a porous carbonized substance, which is the product of incomplete combustion of wood materials such as wood, coal and fruit shells. Wood materials, such as wood, sawdust, coal, stones and shells, are heated to a suitable temperature in a carbonization device for thermal decomposition. In the process of thermal decomposition, a series of complex chemical reactions will occur, and its structure will change and become a dense and porous black substance-activated carbon.
Activated carbon, worthy of the name, is a carbonized substance full of adsorption activity. Besides carbon, it also contains a small amount of hydrogen, oxygen and nitrogen. Under the microscope, we can see that its surface is covered with irregular hexagonal pores, just like a black sponge. In fact, the pores of activated carbon are much smaller and the density is much larger than that of sponge. The minimum pore size of activated carbon can reach 150 nm, and the maximum pore size is 20000 nm. One nanometer is only one billionth of a meter, which is one ten thousandth of the thickness of hair. That is to say, the pores on activated carbon are only 1% of the thickness of hair. This is also the reason why activated carbon has strong adsorption.
In addition to physical adsorption, activated carbon also has the function of chemical adsorption. The pores of activated carbon can produce strong attraction to adsorb water and air, while the carbon and oxygen in the pores of activated carbon can react with substances in water and air and adsorb to the pore surface. In this way, most harmful substances in water and air are imprisoned by activated carbon, and water and air become clean and hygienic.
Scientific detection shows that activated carbon has a huge surface area because it is covered with numerous interconnected pores. If all the pores in one gram of activated carbon are elongated, its surface area can reach 1000 square meter, which greatly exceeds people's imagination. The huge surface area means that activated carbon can fully contact with all kinds of gases and liquids and capture the adsorbed substances to the maximum extent, so its purification function is incomparable to others.
The peculiar properties of activated carbon make it widely used in air purification, drinking water purification, sewage treatment and waste gas treatment, and even in food processing and industrial production, it is very active.
We often drink pure water. In fact, pure water comes from the purification of activated carbon. After the water source is filtered by activated carbon, impurities remain in it, and clean and delicious pure water comes out. Activated carbon played an extremely important role in the Songhua River water pollution accident in the previous stage. It effectively adsorbs harmful chemicals and brings people completely safe drinking water. Similarly, in sewage treatment, activated carbon can still show its talents, and their purification efficiency is very high. Moreover, people also found that putting activated carbon into fish tanks can ensure the cleanliness of water and make fish healthier.
At present, more and more families begin to contact activated carbon and use it in their own lives.
In addition to putting packaged activated carbon directly at home to absorb harmful gases, some factories also put activated carbon in air conditioners, and some cities install activated carbon on the exhaust system of automobile engines, which effectively purifies air pollution.
In addition, the dense and porous characteristics of activated carbon enable it to absorb some electromagnetic radiation, and people make it into mobile phone chains, mouse pads and so on. Reduce the harm of electromagnetic waves to the body.
199 1 year, Hebard et al. proposed for the first time that K-doped C60 was superconducting, and its superconducting starting temperature was 18 K, which broke the record of 12.8 K for organic superconductor (Et)2Cu[N(CN)2]Cl. Soon, superconductor Rb3C60 was prepared with an initial superconducting temperature of 29 K. Table 6- 1 lists the synthesized C60-doped superconductors and their initial temperatures, indicating that C60-doped superconductors have entered the ranks of high-temperature superconductors. China has also made great achievements in this field. In cooperation with the Institute of Physics of Chinese Academy of Sciences, Peking University successfully synthesized K3C60 and Rb3C60 superconductors with starting temperatures of 8 K and 28 K, respectively. Some scientists predict that if C240 and C540 are doped, it is possible to synthesize superconductors with higher starting temperature.
Besides superconductivity, C60 also has a wide application prospect in the following aspects.
① storage of gas
Using the unique molecular structure of C60, C60 can be used as a new type of hydrogen absorption material which is more effective than metals and their alloys. There are 30 carbon-carbon double bonds in each C60 molecule, so hydrogen can be absorbed by opening the double bonds in C60 molecules. Known stable C60 hydrides are C60H24, C60H36 and C60H48.
Under the condition of controlling temperature and pressure, the hydride of C60 can be simply made of C60 and hydrogen, which is very stable at room temperature. At 80℃ ~ 2 15℃, the hydride of C60 releases hydrogen, leaving pure C60, which can be recovered 100% and used to prepare the hydride of C60 again. Compared with the hydrogen storage materials of metals or their alloys, the advantages of using C60 for hydrogen storage are lower price, and C60 is lighter than metals and their alloys. Therefore, for the same quality material, C60 stores more hydrogen than metal or its alloy.
C60 can store not only hydrogen but also oxygen. Compared with high-pressure steel cylinder, the pressure of high-pressure steel cylinder is 3.9× 106 Pa, which belongs to high-pressure oxygen storage method, while the pressure of C60 oxygen storage is only 2.3× 105 Pa, which belongs to low-pressure oxygen storage method. Using C60 to store a large amount of oxygen at low pressure will have many uses for medical departments, military departments and even commercial departments.
② Sensors with sensory function.
Because C60 thin film can be used as the base material to make the finger-shaped combined capacitor, the chemical sensor made of C60 thin film has the advantages of small size, simplicity, reproducibility and low price compared with the traditional sensor, and may become an attractive candidate product in the sensor.
③ Reinforcing metal
The strength of metal materials can be improved by alloying, plastic deformation and heat treatment, and one of the ways of strengthening is through geometric interaction. For example, carbon is dispersed in metal and distributed in coke, and carbon and metal exchange positions in lattice, which can cause plastic deformation of metal, and carbon and metal form carbide particles, which can strengthen metal.
In strengthening metal materials, C60 will play a better role than carbon in coke, because the particles of C60 are smaller and more active than carbon. The particle size of carbide dispersion produced by the interaction between C60 and metal is 0.7 nm, while the particle size of carbide dispersion produced by the interaction between carbon and metal is 2 μ m ~5 μ m ~ 5 μ m, which is quite different among reinforced metals.
④ New catalyst
After the discovery of C60, chemists began to explore the possibility of using C60 as catalyst. C60 has the electronic structure of olefin and can form a series of complexes with transition metals (such as platinum group metals and nickel). For example, C60 can combine with platinum and osmium to form coordination compounds such as {[(C2H5) 3p] 2pt} C60 and C60OsO4 (tetra-tert-butylpyridine), which may become efficient catalysts.
Researchers at Toyohashi University of Science and Technology in Japan have synthesized a highly catalytic compound C60Pd6 of palladium and C60. Researchers from Wuhan University in China synthesized Pt(PPh3)2C60(PPh3 is triphenylphosphine), which has high catalytic activity for hydrosilylation.
⑤ Optical application
C60 with unique microstructure has special optical properties, and one of the interesting optical properties is optical confinement, that is, when the incident light intensity increases, C60 will reduce the transmission performance of optical materials.
Limiting light is of great significance to protecting eyes. Based on the optical limitation of C60, a light-limiting product can be developed, which only allows light below the sensitization threshold (that is, below the danger threshold to eyes) to pass through, thus protecting human eyes from strong light.
⑥ Killing effect on cancer cells.
C60 has a high yield of singlet oxygen after light excitation, and singlet oxygen has an important relationship with physiological and biochemical functions, tissue damage, tumor and photochemical treatment technology.
When the lasing intensity of C60 reaches 4 000 lx, cancer cells are almost 100% dead under the action of singlet oxygen, so it can effectively destroy the important structures of cancer cells, such as plasma membrane, mitochondrial endoplasmic reticulum and nuclear membrane, thus leading to cancer cell damage and even death.
Another study pointed out that the antibody of tumor cells can be attached to C60 molecules, and then C60 molecules with antibodies can be introduced into tumors, which can also achieve the purpose of killing tumor cells.
⑦ Other medical functions
C60 derivatives have the function of inhibiting the activity of human immunodeficiency protease. Human immunodeficiency protease is a virus that causes AIDS. Therefore, C60 derivatives may play a role in AIDS prevention and treatment research.
C60 is also suitable as a free radical scavenger and water-soluble antioxidant in biological systems. Free radicals are harmful substances, which can cause some diseases and even tumors. C60 is expected to reduce the concentration of free radicals in patients' blood and inhibit the growth of abnormal and diseased cells.
Simple carbon plays an important role in our production and life.