The application of nano metal powder

Transcription

1 The application of nano metal powder Nano material and nanotechnology respectively belong to the new material and advanced technology that emerged in the late 20 th century. Due to the small size effect, surface effect, quantum size effect and macroscopic quantum tunneling effect, nano material has unique high performance compared with ordinary materials. When the particle size of nano material is in the range of 1-100nm, due to the quantum effect, material locality as well as huge surface and interface effect, it will lead to performance qualitative change and many strange phenomena that are neither same with the macroscopic object nor the single atom. For example, nanocrystalline copper will have excellent superplasticity under normal temperature, which was unimaginable in the past. By using nano materials, some of the process conditions will be greatly improved. For example, by adding 0.1 percent-0.5 percent of mass ratio of superfine nickel particles in the tungsten particles, the sintering temperature can be reduced from 3000 degrees Celsius to degrees Celsius. Besides, the tungsten particles can be sintered into high power semiconductor tube substrate under low temperature. Therefore, nano material and nanotechnology both have drawn a lot of attentions by various countries in the world, especially the developed countries. The application of nano metal powder on missile solid rocket engine As nano metal powder has larger specific area than the ordinary metal powder, it will have strong chemical reaction characteristics and metallurgical reaction ability as well as strong metal particle functional characteristics. Compared with ordinary aluminum powder, nano aluminum powder can burn faster and release more heat, which has become a kind of low

2 cost fuel. By using nano material in the solid propellant, it can effectively improve the combustion performance. When the nano aluminum powder is added in the ballistite, aluminum will be molten on the surface of burny propellant and will form the liquid drop, besides, it will gather in the gap between oxide particles, in which small aluminum droplet will be generated in the small gap and will rapidly enter the airflow, thus it can improve the mobility of propellant as well as improve the reaction speed and efficiency. By adding 1 percent of mass ratio of superfine aluminum or nickel particles in the solid fuel propellant, the combustion heat of per gram of fuel can increase by 1 time. The application of nano metal powder on stealth wave-absorbing materials Metal superfine particle has very low reflectivity to light, which is usually less than 1 percent. Therefore, just only a few microns can completely shadow the light. Nanometer iron nickel alloy has excellent microwave-absorbing property no matter in superhigh frequency band or millimeter wave band, in which the highest absorptivity can even reach percent. The super black powder nano wave absorbing material that was developed by America can even absorb 99 percent of radar wave. Therefore, by using nano material in the missile engine and military aircraft, it can effectively reduce a series of problems that caused by electromagnetic wave or infrared radiation. Besides, nano materials can also be used in solving the radiation protection problems of computer and microwave in the civilian field.

3 metal powder on lubricating oil The application of nano By adding the superfine metal powders (nano copper powders, nano nickel powders and the alloy powders) in the lubricating oil with proper ways, a new kind of lubricating oil that has excellent performance can be obtained. Tribology experiment shows that when the particle size of copper powder is more than 100nm, it can be regarded as a kind of abrasive; when the particle size is less than 50nm, it can largely improve the maximum antiseize duty of lubricating oil. Due to this performance, nano copper powder will have important usages in lubricating oil. After the modification of nano copper powder surface, it can overcome the autophobic phenomenon in the lubricating oil, can evenly and steadily distribute in the lubricating oil as well as can prevent secondary accumulation and precipitation of nano copper powder, thus the nano copper lubricant additive can be obtained. By adding this kind of additive in the automobile engine lubricating oil, it can obviously reduce the starting current of engines and obviously improve cylinder pressure. After the additives have been used in the engines for a period of time, the cylinder sleeve and piston ring will form a layer of protective film. Once the

4 lubricating oil system breaks down, the automobile still can safely operate for a period of time. The application of nano metal material on the electronic field With the sharp decreasing of metal powder particle size, the physical property will be greatly changed. For example, the normal melting point of gold is 1064 degrees Celsius, however, when the particle size is reduced to 10nm, the melting point will reduce by 27 degrees Celsius, besides, the melting point of 2nm gold is only 327 degrees Celsius; the normal melting point of silver is 670 degrees Celsius, while the melting point of superfine silver particles can even be less than 100 degrees Celsius. Therefore, conductive paste that made by nano material can obviously reduce the sintering temperature of ceramics, greatly improve the reliability and yield of chip and reduce production cost. For example, as the conductive paste that made by superfine silver powder can be sintered under low temperature, the part substrate can use plastic instead of high temperature resistant ceramic materials. Nano conductive paste can be widely used in wiring, packaging and connecting in microelectronics industry and will have important effect on the miniaturization of microelectronic device. The application of nano metal powder on magnetic material field Nano metal powder can be widely used in producing nano magnetic recording materials, magnetic liquids, magnetic nanoparticle membrane materials and so on. For example, magnetic liquids that made by nano cobalt, nano iron, nano nickel and other magnetic metal powders can be used in rotary seal, damping device, magnetic liquid printing, mineral separation, precise finish as well as polishing, magnetic drug, magnetic liquid braking and so on. The application of nano metal powder on antibacterial

5 materials According to the research and development in recent years, it can be seen that nano silver particles will have excellent antibacterial activity. According to the report, nano silver fabric that produced by one of the companies in America has higher antibacterial property than the soluble silver ions (such as silver nitrate solution) as well as silver sulfadiazine that has emerged for about more than 60 years as well as has good using effect and no drug resistance in clinical. Drugs that made by this kind of fabric will have good effect on controlling burn and scald infection. The sales volume of this kind of drug was more than 30 million dollars in 2001 and is expected to greatly increase in the next few years. The application of nano metal powder on powder metallurgy field As nano metal powder has high specific area and chemical activity as well as low sintering temperature, it can be used as sintering aids in powder metallurgy so as to shorten the heating period in the sintering process and reduce sintering temperature. In addition, it can be used in producing powder metallurgy coating. For example, powders can be connected on the glass by using laser, or the powder gel can be molten on the matrix.