Current status of nanomaterials

The basic theoretical research of nanotechnology and the application research of new material development have been developed rapidly, and have been widely used in traditional materials, medical equipment, electronic equipment, coatings and other industries. In terms of industrial development, in addition to the initial large-scale production of nano powder materials in the United States, Japan, China and a few other countries, nano biological materials, nano electronic device materials, nano medical diagnostic materials and other products are still in the development stage. In 2010, the global market size of new nano materials reached US $2.23 billion, with an annual growth rate of 14.8%. In the next few years, as countries increase their investment in nanotechnology application research, the industrialization process of new nano materials will be greatly accelerated, and the market scale will grow in a large scale. The nano calcium carbonate, nano zinc oxide, nano silicon oxide and other products in the nano powder materials have formed a certain market scale; The widely used nano ceramic materials, nano textile materials, nano modified coatings and other materials have also been successfully developed, and the industrialization of production has been preliminarily realized. The application of nano powder particles in medical diagnostic agents and microelectronics is accelerating the transfer from experimental research results to industrial production.

Five effects of nanomaterials

When the size of nano particles is equal to or smaller than the de Broglie wave of conducting electrons, the periodic boundary conditions will be destroyed, and the magnetism, internal pressure, light absorption, thermal resistance, chemical activity, catalysis and melting point have changed greatly compared with ordinary particles, which is the volume effect of nano particles. The following effects of nanoparticles and their various applications are based on their volume effects. For example, the melting point of nano particles can be far lower than the bulk, which provides a new process for the powder metallurgy industry; Using the property that the plasma resonance frequency shift changes with the particle size, the particle size can be changed, the absorption displacement can be controlled, and a microwave absorbing nano material with a bandwidth can be manufactured for electromagnetic shielding, stealth aircraft, etc

Research achievements of nanomaterials

As an emerging science and technology with the most market application potential, the potential importance of nanotechnology is beyond doubt. Some developed countries have invested a lot of money in research. For example, the United States was the first to set up a nanotechnology research center, and the Japanese Ministry of Culture, Education and Science listed nanotechnology as one of the four key research and development projects in materials science. In Germany, the University of Hamburg and the University of Mainz are the research centers of nanotechnology, and the government invests 65 million dollars every year to support the research of microsystems. In China, many scientific research institutions and colleges and universities also organize scientific research forces to carry out research on nanotechnology, and have made certain research achievements, mainly as follows:

Preparation methods of nanomaterials

Evaporation condensation method under inert gas. It is usually formed by high-pressure forming of particles with a clean surface and a particle size of 1-100nm. Nanoceramics also need to be sintered. A variety of nano solid materials, including metals and alloys, ceramics, ionic crystals, amorphous and semiconductors, have been successfully developed abroad using the above inert gas evaporation and vacuum in-situ pressurization methods. China has also successfully used this method to make metal, semiconductor, ceramic and other nano materials.

Classification of nanomaterials

Nanomaterials can be roughly divided into four categories: nano powder, nano fiber, nano film and nano block. Among them, nano powder has the longest development time and the most mature technology, which is the basis for the production of other three types of products.

Nanometer new material formula

The nano new material formula is a new nano material project created by directly sequencing atoms and molecules through natural changes in the space of 100 nanometers. Nanometer new materials and this field are the starting point of modern power and modern technological innovation. The discovery of new laws and principles and the creation of new ideas provide basic science with new opportunities, which will become an important new driving force for reform in many fields. Due to the small size of SAIZU, nano new material formula has many unique properties. In 1988, Baibich et al. found for the first time that the change rate of magnetoresistance in nano Fe/Cr MS reached 50%, which was a level higher than that of general ME, and was negative in all directions, called GMR. After that, giant ME was also found in nano systems, tunnel junctions, Perovskite structures and granular films. The Perovskite structure was found in 1993 and has a large ME, called CMR, and the TMR is found in the tunnel junction.

Application scope of nanomaterials

Sea turtles lay eggs on the coast of Florida in the United States, but young sea turtles after birth have to swim to the waters near the United Kingdom to survive and grow up in order to find food. Finally, the turtle will return to the coast of Florida to lay eggs. It takes about 5 to 6 years to go back and forth. Why can sea turtles travel tens of thousands of kilometers? They rely on nano magnetic materials in their heads to guide them accurately.

Nanostructure

Nanostructure is a new system based on nano scale material units and according to certain rules. It includes nano array system, mesoporous assembly system and film mosaic system. The research on nano array system focuses on the binary system formed by the orderly arrangement of metal nanoparticles or semiconductor nanoparticles on an insulating substrate. The assembly system of nano particles and mesoporous solids has become a research hotspot due to the characteristics of the particles themselves and some new effects generated by coupling with the matrix at the interface. According to the type of support, it can be divided into inorganic mesoporous complex and polymer mesoporous complex, and according to the state of support, it can be divided into ordered mesoporous complex and disordered mesoporous complex. In the film mosaic system, the main research on the nanoparticle film is based on the electrical and magnetic properties of the system. American scientists use self-assembly technology to make hundreds of single-walled carbon nanotubes into crystal rope "Ropes". This rope has metal characteristics, and its resistivity at room temperature is less than 0.0001 Ω/m; Nanometer lead triiodide was assembled on nylon - 11, which had photoconductivity under X - ray irradiation. This property laid a foundation for the development of digital radiography.

Development of nanomaterials

The two cooperation projects of "Functionalization of nano composite polyurethane synthetic leather materials" and "Application of nano materials in vacuum insulation panels" have made great progress. The polyurethane synthetic leather with anion release function and a release amount of more than 2000 conforms to the strategic upgrading direction of ecological and environmental protection synthetic leather, and a pilot scale study is to be carried out recently.