Core Tip: In the industrial field, coated powder material is a surface engineering application material, which is coated on the surface of the substrate to resist wear, corrosion, high temperature, oxidation, and aging, and meets light, electricity, and Special effects or functions such as magnetism.
In the industrial field, the coated powder material is a surface engineering application material, which is coated on the surface of the substrate to resist wear, corrosion, high temperature, oxidation and aging, and meets special requirements of light, electricity and magnetism. Function or function. As some products become more and more elaborate and the service conditions become more and more demanding, the requirements for surface coating materials are also higher. It has been found that when the characteristic scale of a material is reduced to the nanometer scale, it is significantly different from the properties of the material in the macroscopic world due to small size effects, quantum effects, interfaces or surface effects. This also prompted scientists to combine nanotechnology with surface engineering.
Surface engineering is a special field. It is an industry that combines materials and processes. It is impossible to carry out only materials, but the coating process is not good or economical. Thermal spraying is a relatively mature technology, its use is the most popular, and the cost performance is also the highest. How to use thermal spray technology to spray nanomaterials has been a difficult problem. Because the nanoparticles are a tiny particle, if it is operated by thermal spraying, the nanoparticles will be ablated or blown away in an instant, and the material will not reach the substrate, making it impossible to form an effective functional coating. The solution is to agglomerate the nanoparticles to form micron-sized particles. In this way, both the special effects of the nanomaterials and the thermal spraying process can be implemented.
To this end, American scientists began research in the 1990s, and Chinese scientists later joined the research team and achieved success. In 2000, the first product in the United States nano-materials company - nano-aluminum-titanium powder coated powder material, its density reached 95% ~ 98%, combined strength increased by 2 to 3 times, wear resistance It has increased by 3 to 8 times, and now the company's products are exclusively for US Navy applications. At present, this nano-agglomeration technology has matured, and more products can be developed through this technology.
Nano coating materials are widely used
Nano-coating applications are very extensive, especially in the application of aero-engine and gas turbine (two-machine) hot end components, which is of more significance. Because the two-machine equipment is not only an important symbol of a country's science and technology, industry, and economy, it is known as the treasure of the town, the "crown pearl of the modern industry", and the two-machine equipment is in an important strategic position in the national defense construction of our country. Experts predict that in the next 10 years, China's aviation market will exceed one trillion yuan. Therefore, our country has a more urgent need for two-machine equipment and its key materials, including coating materials.
In November 2014, the National Natural Science Foundation of China held the Shuangqing Forum on the theme of “Challenging Scientific Issues in Aeroengine Thermal Barrier Coating Technology and Applicationâ€. Experts pointed out that thermal barrier coating technology is one of the key technologies of aviation promotion programs in various countries around the world, and has great application prospects. The world's aerospace powers such as the United States, Britain, France, and Russia have applied thermal barrier coating technology to the aerospace and aerospace industries, and further expanded to the power and energy industries.
For high-performance aero engines, the hardest part of their development is in materials and manufacturing processes, because performance requirements beyond the limits are ultimately implemented to develop cutting-edge materials and manufacturing processes. Experts pointed out that the difficulties and performance gaps in the development of aero-engines in China are mainly reflected in the turbine blades and the materials and processes of the turbine disks. The most basic requirement of modern aviation turbine engines for turbine performance is reliable and stable operation under high temperature, high pressure and high speed conditions. Among them, high-performance blades integrate advanced materials, advanced molding technology, advanced cooling technology and advanced coating.
At present, the life of China's aviation engines, especially military engine thermal barrier coatings, is lower than the advanced level in foreign countries. At the same time, as the engine's thrust-to-weight ratio increases, the temperature of the combustion chamber, turbine and compressor is also greatly increased, even with advanced directional solidification superalloys and single-crystal superalloys for turbine blades, supplemented by advanced cooling technology. It also cannot meet the requirements of heat insulation, corrosion resistance and oxidation resistance. Therefore, high-temperature protective coating materials are developing in the direction of long life, low thermal conductivity, and good thermal radiation shielding, and its research and development will become a top priority in China's aviation industry.
Thermal barrier coating (TBC) is mainly used on aircraft engines, turbines and turbine blades to protect high temperature alloy substrates from high temperature oxidation and corrosion, to insulate, increase engine inlet temperature and increase engine thrust-to-weight ratio. Ceramic coating material. With the improvement of engine and turbine performance, especially the use temperature of military aircraft engine blades is getting higher and higher, the original materials have been unable to adapt, and the development of new coating materials has become an urgent need in the military industry.
In 2014, the Ministry of Industry and Information Technology released the special focus of industrial strong base. Two of the seven coating materials listed in the direction of high-performance coating materials for surface strengthening of industrial parts with high-end equipment basic capacity are related to thermal barrier coating. Layer material, one is a multi-component MCrAlY material as a thermal barrier coating bonding layer, and the other is a multi-phase ceramic material as a thermal barrier coating surface layer.
The same is true for gas turbines. At present, multinational companies control the gas turbine supply and maintenance market. The result of monopoly is the high price paid, not only in the initial investment, but also in the operation and maintenance costs. Taking Shanghai's natural gas power plant as an example, since its completion, between 2009 and 2011, maintenance and maintenance cost an astonishing 383 million yuan. It has exceeded 13% of the total investment. The cost of the Shanghai Lingang gas turbine is even more alarming. The average annual maintenance cost of Siemens is 120 million yuan. In these maintenance projects, hot runner components are generally detached, cracked, and burnt, which accounts for 80% of the total maintenance cost.
Nano-coating materials combined with 3D technology
The Nano Surface Engineering Research Office of Harbin Institute of Technology is aiming at the country's major needs, and has worked hard on thermal barrier coatings and transition alloy layers. They have created several unique alloys and ceramic powder materials with fine composition, high density, good sphericity, narrow particle size distribution and good fluidity, which can be widely used to prepare key core components in two machines. Also expected to be used for 3D printed parts.
They developed a nanostructured zirconate thermal barrier coating powder material through special nano-powder granulation control technology, which provided technical support for the development of high-end engines in China. The nanoceramic coating prepared from this zirconate powder material has a much higher insulating effect than the conventional micron ceramic coating of the same thickness which is now widely used. In addition, the nanostructured double ceramic coating has better thermal shock resistance.
Multi-component MCrAlY series superalloy powder materials are widely used as thermal barriers due to their high resistance to high temperature oxidation and hot corrosion, good plasticity, similar thermal expansion coefficient to matrix, less influence on matrix performance and adjustable composition. The bonding layer of the coating is applied to the aero engine and gas engine as a separate coating. Due to the development of 3D printing technology, this MCrAlY alloy powder is expected to be directly used for printing hot end parts such as engines and turbine blades, thereby changing the multiple processes of re-spraying thermal barrier coatings on high-temperature alloy substrates, directly and quickly printing 3D substrates and Parts such as blades with integrated coating function.
The modified MCrAlY series superalloy powder developed by the Nano Surface Engineering Research Laboratory of Harbin Institute of Technology can significantly improve the strength, hardness, thermal shock resistance, high temperature oxidation and corrosion resistance of the final parts, and when used as a coating. The bonding strength with the substrate reaches 60 MPa or more, which is much higher than the requirements of the Ministry of Industry and Information Technology.
Additive manufacturing is known as the fourth industrial revolution and has grown rapidly in recent years. However, the development of 3D printing in China is facing a serious bottleneck, that is, consumables. Academician Lu Bingheng clearly pointed out that the prospect of additive manufacturing is "creative material." The development of new materials with ultra-high strength, ultra-high temperature resistance, ultra-high toughness, ultra-high corrosion resistance and certain environmental adaptability may become China's breakthrough in the 3D printing market. The profitability of 3D printing materials is the strongest in the industry chain, and the gross profit margin is 60%~80%, which is much higher than other links of 3D printing.
In summary, nano-coated powder materials have great application potential in upgrading China's equipment manufacturing. It is hoped that these products will be applied to China's aero-engine and gas turbine equipment to contribute to our national defense industry.
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