Why nanomaterials need to be surface modified

Steel is a low-cost structural material that is irreplaceable for its importance and universal functionality. However, the corrosion problem of steel materials is the Achilles' heel of this type of structural material--- in the environment of water and oxygen, corrosion occurs at an irrepressible rate, and eventually leads to the rapid failure of the material. Especially in the marine environment, chloride ions.

and marine organisms are more rapidly corrosive to iron. The combination of high temperatures, high salinity, biomass and water currents accelerates the corrosion of iron materials, causing catastrophic failure and damage to ships, platforms and other marine structures. In order to change the corrosivity of iron in the water-oxygen environment, technicians invented various coatings, platings, and even used toxic substances to cope with the corrosion of steel in the ocean.

However, to date, there is no effective method that can be applied on a large scale to solve the problem of corrosion of steel materials in harsh sea conditions. In recent years, scientific and technological workers have extended the technical path of anti-corrosion of marine materials to the field of high-temperature metallurgyA new technology that uses the first-class passivation principle combined with the interfacial melting process to modify the surface of iron-based materials, and then produces a micron-scale nano-passivation layer. The inventor of the technology, borrowed from powder metallurgy.

principle, and from the laser spraying and supersonic spraying technology to get inspiration, screen out a number of nano powders and their slurries, on the surface of steel or steel structures to form a triple anti-corrosion effect"Nanolayer"…Its corrosion resistance function is the same as other coatings or coatings, from physical isolation, sacrificial anode and dense passivation film, its uniqueness is that the first surface layer produced by this technology has an abnormal combination with iron-based materials, and its bonding zone achieves unprecedented metallurgical interfusion with the help of melting-solidification. Solidly, this technique is called"Micrometallurgical miscibility"Also known as"Interfacial micrometallurgy"Mutual miscibility.

According to the results of the disclosed tests, its corrosion resistance has reached an extraordinary level....Neutral salt spray corrosion time can exceed 25,000 hours. At the same time, the steel and structures treated in this method can effectively alleviate the adhesion of marine organisms and the catastrophic corrosion caused by them. It is reported that a company in Shanghai has introduced this technology.

Industry insiders expect that this technology can be applied and promoted to truly solve the problem of steel material failure under marine conditions.

According to the application of various industries,. The specific surface area of the nanomaterial itself.

Big. There are five major effects of nanomaterials, 1, volume effect 2, surface effect 3, quantum size 4, quantum tunneling 5, and dielectric confinement.

Because nanomaterials are characterized by their small size, complex structure, and strong interaction, substances made of nanomaterials may produce new physical and chemical phenomena that we cannot imagine. At the nanoscale scale, substances possess properties that are very different from those they would in their normal state.

First of all, the surface of ultrafine particles is very different from the surface of large objects, these particles have no fixed form, and will automatically form various shapes (such as cubic octahedron, decahedron, icosahedral crystallization, etc.) with the change of time, so the substance is not only different from the general solid, but also different from the liquid, and is a quasi-solid.

Second, the surface of ultrafine particles is highly active, and metal ultrafine particles will oxidize rapidly and burn in the air.

Thirdly, it has special optical properties. The reflectivity of light from ultrafine metal particles is very low, usually less than 1.

Fourth, it has special thermal properties. The melting point of solid matter is fixed when it is large in size, but it is found that its melting point will be significantly reduced after ultra-fineization, especially when the particles are less than 10 nanometers. For example, the conventional melting point of silver is 670 degrees Celsius, while the melting point of ultrafine silver particles can be below 100 degrees Celsius.

Fifth, it has special magnetic properties. It has been found that there are ultra-fine magnetic particles in organisms such as pigeons, dolphins, butterflies, bees, and magnetotactic bacteria living in water, so that these organisms can discern the direction under the guidance of the geomagnetic field and have the ability to return. The magnetic ultrafine particle is essentially a biomagnetic compass that magnetotactic bacteria living in the water rely on to swim to the nutrient-rich bottom.

Sixth, it has special mechanical properties. Ceramic materials are generally brittle, but nano-ceramic materials made of nano-ultrafine particles have good toughness. Because nanomaterials have a large interface, the atomic arrangement of the interface is quite chaotic, and the atoms are easy to migrate under the condition of external force deformation, so they show excellent toughness and certain ductility, so that the ceramic materials have novel mechanical properties.

Studies have shown that the human tooth has a high strength because it is made of nanomaterials such as calcium phosphate. In addition, some nanomaterials have special properties such as superconductivity.

Examples of nanomaterial applications can be cited to many. For example, chemical fiber clothes often produce annoying static electricity when worn on the body. A small inconspicuous electrostatic spark can cause ** and fire on some special occasions.

If a small amount of metal nanoparticles is added in the production of chemical fiber fabrics, then the chemical fiber fabrics made of pure vertical fabrics will no longer have the phenomenon of rubbing trouser finger rubbing. Another example is adding some nanoparticles to textiles such as socks, which can deodorize and sterilize. At present, nano washing machines, air conditioners and sterile tableware that can remove odors, antibacterial gauze, etc., have appeared on the market, and nanomaterials are used in these products.

Nowadays, scientific and technological progress is advancing with each passing day. Many people already have some understanding of high-tech such as "Internet" and "genes". In recent years, new terms such as "nano", "nanotechnology" and "nanomaterials" have become louder and louder.

For many teenagers, the term "nano" seems unfamiliar, and nanotechnology is even more magical and incomprehensible. In fact, nanotechnology has long been quietly integrated into our lives.

A nanometer is a unit of length, and one nanometer is equal to one billionth of a meter, which is really small. How small is it? To use an analogy:

Make a red plastic ball with a diameter of one nanometer (of course, invisible to the naked eye) and place it on a ping-pong ball as if you were putting a ping-pong ball on the earth. Electron microscopy is required to observe the shape and topography of nanomaterials.

The so-called "nanomaterials" and "nanotechnology", simply put, are some ordinary materials made into nano to hundreds of nanometers of particle materials, which are extremely small in size, but have a large surface area and special structure, which will produce a kind of magic and special properties, and apply them. Scientists have summarized the special properties of nanomaterials into four major effects: small size effect, surface effect, interface effect, and macroscopic quantum tunneling effect.

Examples of nanomaterial applications can be cited to many. For example, chemical fiber clothes often produce annoying static electricity when worn on the body. A small inconspicuous electrostatic spark can cause ** and fire on some special occasions.

If a small amount of metal nanoparticles is added to the chemical fiber cloth in the production of chemical fiber fabrics, then the frictional electricity generation phenomenon will no longer occur in the chemical fiber fabrics. Another example is adding some nanoparticles to textiles such as socks, which can deodorize and sterilize. At present, nano washing machines, air conditioners and sterile tableware that can remove odors, antibacterial gauze, etc., have appeared on the market, and nanomaterials are used in these products.

Scientists pointed out that nanotechnology is the common basis for the further development of information and life science technology, a key point in the future development of science and technology, a technological revolution, and will also give rise to another industrial revolution in the 21 st century, which will have a huge and far-reaching impact on human society.

Nanomaterials have a number of unique properties, including but not limited to:

Size effect: Nanomaterials are typically between 1-100 nanometers in size, which makes their physical and chemical properties very different from those of macroscopic materials.

Surface effects: Since the surface area of nanomaterials is very large relative to their volume, the surface effect has a great influence on their dusty properties. For example, nanomaterials have higher surface energies, resulting in enhanced surface activity.

Quantum effects: At the nanoscale, electrons and photons behave very differently from the macroscopic world, resulting in many quantum effects, such as quantum size effect, quantum tunneling effect, etc.

Mechanical properties: Nanomaterials generally have better mechanical properties than macroscopic materials, such as strength, toughness, and hardness.

Optical properties: The optical properties of nanomaterials are also very unique, such as the color, absorption, scattering, and transmission they exhibit.

In conclusion, the special properties of nanomaterials make them have potential applications in many fields, such as electronics, materials science, energy science, biomedicine, etc.

This question is a bit general, and there are at least two understandings.

First, the material itself is already nanoscale, and its modification is generally adjusted in terms of structure, such as crystal doping, nanoparticle shape change, spherical, potato-shaped, rod-shaped or capsule-shaped, nanotube-like, etc., and the other is to pack these nanoparticles in a certain way to form dense or porous materials, etc., depending on the purpose.

Second, it is to deposit or coat nanoparticles on the surface of non-nanoparticles, so that the material has some characteristics that only nanomaterials have. In fact, some examples of most applications today are using this method, such as self-cleaning tablecloths, etc., and all materials are made of nanomaterials. That's sky-high, just a small amount of nano-TiO2 is deposited on the surface of the fiber.

As for the deposition method, there are too many methods, whether it is the method of forming chemical bonds between each other, or the method of using the physical surface energy between two phases.