In the late 1960s, United States carbon corporation made sealing materials from expanded graphite, which gave birth to the second generation of sealing materials. In 1971, in order to solve the problem of atomic energy valve leakage, the us rockwell valve engineering design center conducted a comparative test on 64 test sites of l6 different types of sealing fillers produced by nine companies in the us. The results showed that the expanded graphite has a good sealing effect. Since then, the United States, Japan, France, Germany and other developed countries have further in-depth studies, promoting the rapid development of expanded graphite sealing materials, becoming a new type of high-efficiency and energy-saving sealing materials in the world. China began to develop expansive graphite and its products in 1978. Because of the quality of a material soft, compressibility and resilience is strong and other characteristics, so as the sealing material soon received promotion and application in our country, can replace asbestos, rubber, ptfe, the traditional sealing material such as metals, ideal to solve the problem of equipment PaoMaoDiLou, to improve the efficiency of the three, especially the environmental benefits, the role is becoming more and more big.
Two battery material
1. Application in ordinary zinc manganese battery (dry battery)
The electric core of common zinc-manganese battery is mostly used in this century, such as acetylene black used in Germany and the United States. Using high purity expanded graphite instead of acetylene black as electrode, its open circuit voltage, short circuit current and load voltage are all higher than those produced by acetylene black.
2 applications in mercury-free high-energy batteries
Expanded graphite can be used in mercury-free high-energy battery, basic silver oxide high-energy battery. The cathode material of such battery is Ago or Ag O. Currently, it is commonly used to add 5% to 15% of the earthy graphite to the silver oxide cathode as the conductive medium. If you use expanded graphite, it conducts less electricity in the amount used compared to soil-like graphite.
The field of environmental protection is used as adsorbent materials
1. Adsorption of heavy oil and other oil substances
Expanded graphite can be used as a new adsorbent. It has many reticular holes in its interior and large surface area. It has strong adsorption capacity for heavy oil and other petroleum products and its adsorption capacity
The amount is obviously higher than that of activated carbon. It has been reported that 1g of expanded graphite can absorb more than 80g of heavy oil. In 1997, an oil tanker leaked off the coast of fukuoka, Japan. Activated carbon is mainly medium pore, while expanded graphite is mainly large pore, while heavy oil molecules belong to organic macromolecules, which are difficult to enter into the medium pore of activated carbon, and it is difficult to diffuse in activated carbon due to the high viscosity of heavy oil. On the contrary, expansive graphite is mainly medium and large holes, and most of them are connected. As a result, heavy oil molecules are easy to enter and quickly spread through their network system until they are filled with interconnected internal holes. In addition, each other between the expanded graphite worm and worm gear, the formation of table face more, also is advantageous to the macromolecular material adsorption, showed a larger adsorption capacity, which can solve the oil, organic nonpolar substances such as pollution of water environment worse dyeing problem, and this kind of problem is involved in the river, sea, lakes, and the decontamination with water purification, is unable to solve the problem.
2. Absorption of SO and other harmful gases
Expanded graphite also has obvious adsorption effect on s0 gas, and the adsorption effect is more significant at high temperature. Low temperature (room temperature), expanded graphite of s0 mainly physical adsorption, adsorption on the surface of the graphite and s0: at this time the van der Waals force between adsorption, adsorption quantity increases over time into a smooth curve and tend to be saturated adsorption, high temperature (500 ~ C) adsorption is the graphite 丌 electron energy increase, greatly increases the chemical adsorption, when high temperature SO mainly chemical adsorption and adsorption quantity of adsorption is low temperature increase greatly, s0 coal combustion flue gas is the main component, with expanded graphite adsorption SO: to solve the increasingly serious air pollution problem is of great significance.
Make dressings in the medical field instead of medical gauze
Expanded graphite due to the adsorption characteristics of organic and biological macromolecules, in biomedical materials, such as tsinghua university, application of expanded graphite replace medical gauze production of medical dressings, after more than a large number of animal experiments and one hundred cases of clinical trials, prove than traditional gauze, have strong ablility, wound drainage completely, no stimulation, no dark, no absorption, does not affect the characteristics of the wound healing of 171, and have significant resistance to infection, antibacterial, anti-inflammatory effects. At present, this research achievement has obtained the patent right of invention, as a substitute for traditional gauze
Substitution has certain advantages. At present, we are carrying out further industrialization research and comprehensive clinical experiments.