Nanopowder is also called nanoparticles, which generally refers to ultra-fine particles with a size between 1-100nm. Some people call it ultrafine particles. Its size is more significant than atom clusters and smaller than ordinary particles. The shape of the nanoparticles is spherical, plate, rod, horn, sponge, etc. The constituents of nanoparticles can be metals, oxides, or other various compounds.



Properties of nanoparticles:

1. Thermal characteristics

The melting point and sintering temperature of nanoparticles are much lower than that of conventional powders. This is due to surface and interface effects.



For example, the melting point of bulk Pb is 600k, while 288k reduces the melting point of 20nm spherical Pb particles, nano-Ag particles begin to melt below 373k, and the melting point of conventional Ag is much higher than 1173k. In addition, the nano-TiO2 is obviously densified when heated at 773k, and the same densification of large-grain samples needs to be heated up to 873k to achieve this, which is significantly related to the sintering temperature.

2. Optical characteristics

Broadband strong absorption

When the size is reduced to nanoparticles, it becomes almost black, and the reflectance to visible light drops sharply.

Some nanoparticles are like silicon nitride, SiC and alumina have a broadband energetic absorption spectrum for infrared. And ZnO, ferric oxide, and titanium dioxide nanoparticles have a broadband energetic absorption spectrum for ultraviolet light.



Blue and red shift

Compared with bulk materials, nanoparticles generally have a blue shift in the absorption band, that is, the absorption band moves to the short wavelength direction; and under certain conditions, the absorption band shifts to the long-wave direction when the particle size is reduced to the nanometer level, that is, red shift.



3. Chemical properties

Due to the surface effect, it can be used as a catalyst to improve the reaction activity.



Application of nanoparticles:

1. Nano coating

Nano-coating uses surface technology to apply part or all of the nano-powder-containing material to the substrate. Due to the unique surface properties of the nano powder, new features are given to the material.

Nanoparticles can be made into surface coatings to change the optical properties of the material surface, such as optical nonlinearity, light absorption, light reflection, and light transmission. Nanoparticles have good applications in the light bulb industry. For high-pressure sodium lamps, 69% of the electricity of the iodine arc lamp is converted into infrared rays, and only a small amount of light energy is visible light. The heating of the lamp will also reduce the life of the lamp.



The nano-infrared coating has also been studied by many people. After the nano-powder of silicon dioxide, iron oxide and aluminum oxide is compounded, it can strongly absorb infrared rays, and can be made into military clothes. It can avoid the detection of enemy hot bands and reduce weight by 30%.



2. Application in environmental protection

The shortage of mineral energy and environmental pollution have bothered people. The application of nanomaterials in environmental protection, environmental governance, and pollution reduction has shown a thriving scene. Nanoparticles can be antibacterial, anticorrosive, deodorant, purify the air, optimize the environment, and facilitate degradation. In addition, they can also absorb heavy metal ions to purify water, adsorb bacteria, viruses, and toxic ions.



3. Photocatalysis of nanoparticles

Photocatalysis can be used for environmental protection, degradation of pesticides, organic matter, etc. Due to the small particle diameter, large specific surface area, and high photocatalytic efficiency; besides, most of the electrons and holes generated by the nanoparticles will not recombine when they reach the surface, so the holes are low, and the chemical reaction activity is high.



The iron nanoparticles, nickel nanoparticles, copper nanoparticles, titanium nanoparticles, etc., produced by Luoyang Tongrun Nano Technology Co.,Ltd has the excellent performance due to its high purity, uniform particle size distribution, easy to disperse use. These nanoparticles can be widely used in lubricating, ceramics, wear-resistant, photoelectric, etc. industries.