2.1 antifouling coatings for ships
At present, the main types of antifouling coatings are: ① self-polishing antifouling coatings without organic tin; ② Abrasive antifouling coatings in Wuxi; ③ Non-toxic antifouling coatings (low surface energy coatings, biological antifouling coatings); ④ Conductive antifouling paint. Among them, low-toxic or non-toxic antifouling coatings without organic tin are the main research and development goals, and Wuxi self-polishing or abrasive antifouling coatings are the fastest to develop. Wuxi self-polishing antifouling paint has the characteristics of long-term antifouling, resistance reduction and energy saving, and meets the requirements of environmental protection, which is of great practical significance both economically and militarily.
Low surface energy antifouling coatings are commonly known as "non-stick" coatings. It uses the physical properties of low surface energy on the coating surface to make it difficult for marine organisms to adhere or even if they adhere to it, the adhesive force is very small, and it is easy to be removed by the shear force of seawater when the ship sails at low speed. The existing low surface energy antifouling coatings are mainly based on silicone and organic fluorine resin, and are made by using the low surface energy characteristics of organic silicon and organic fluorine. This kind of antifouling paint has been applied in practice, and the longest antifouling period can reach 5 years.
The natural antifouling agent for biological antifouling coatings is a natural substance extracted from various marine animals and plants and land plants by biotechnology to prevent marine organisms from being polluted, mainly including the antifouling agent for macrophylla, the antifouling agent for Malus angustifolia, the antifouling agent for acylated emodin mussel, the antifouling agent for horseradish, the antifouling agent for sponge fatty acid, and the antifouling agent containing decomposing protease. Bionic antifouling coatings use the principle of bionics. There are two main directions: ① extracting natural active substances from the ocean as antifouling agents; ② Simulate the epidermis structure of large marine animals to prevent pollution. Biotechnology is a high-output industry. Using biotechnology to produce the above-mentioned antifouling agents is harmless to human body, environment and marine life, and developing this field will produce great social and economic benefits.
conductive antifouling paint is to coat several layers of conductive paint on the hull surface. When tiny direct current is applied to the surface coated with conductive paint, seawater will be electrolyzed to produce sodium hypochlorite, so as to prevent marine organisms from adhering to the hull surface. There are usually three ways to realize low VOC antifouling coatings: ① water-based antifouling coatings; ② Powder antifouling paint; ③ High solid content antifouling paint. At present, the research and development of low VOC antifouling coatings at home and abroad are only reported in the field of water-based antifouling coatings.
Marine antifouling coatings are one of the most important marine coatings, which have a direct impact on the interests of ship owners and the marine environment. Therefore, researchers and coating suppliers strive to develop more environmentally friendly, better performance and more competitive marine antifouling coatings.
Anti-fouling technology also includes electrochemical anti-fouling method, new methods to control corrosive microorganisms-electrochemical sterilization and applied potential anti-fouling method.
2.2 antirust coatings for ship hull
At present, the varieties of antirust coatings for ship bottom can be roughly divided into three categories: ① traditional asphalt system and oily system; (2) High-performance anti-rust coating for ship bottom with epoxy, ethylene, epoxy asphalt, ethylene asphalt and chlorinated rubber resin as the main body; ③ New high-performance antirust coatings for ship bottoms, mainly including modified epoxy, glass flake coatings and fluororesin coatings.
2.3 special functional coatings for ships
special coating materials for ships are an indispensable part of ship equipment. It involves fields such as high temperature resistance, heat insulation, fire prevention, sound absorption and damping, wave absorption, optical camouflage, etc. It mainly includes radar absorbing stealth coatings, sonar absorbing stealth coatings, infrared stealth coatings, anti-thermal radiation coatings, flight deck anti-skid coatings, high temperature resistant coatings, etc. Although the amount is not large, it is an indispensable and alternative supporting material for ships, and with the acceleration of modernization of weapons and equipment, special coating materials are playing an increasingly important role in various parts of ships.
3 absorbing coating
absorbing coating is a kind of material that can absorb electromagnetic wave energy projected on its surface and convert it into heat energy through material loss. The absorbing coating is mainly composed of absorbent and binder. Among them, the absorbent containing specific electromagnetic parameters is the key to the absorbing coating, which determines the absorbing performance of the absorbing coating; Binder is the film-forming substance of coating, and it is the main substance that makes the coating firmly adhere to the surface of the coated object and form a continuous film. Generally, according to different absorbents, radar absorbing coatings can be divided into the following categories: ferrite radar absorbing coatings, carbonyl iron radar absorbing coatings, metal ultrafine powder or metal oxide magnetic ultrafine powder radar absorbing coatings, ceramic radar absorbing coatings, nano radar absorbing coatings, radioisotope radar absorbing coatings, conductive polymer radar absorbing coatings, retinyl Schiff base salt radar absorbing coatings, chiral radar absorbing coatings, radar absorbing coatings doped with high loss substances and rare earth elements radar absorbing coatings.
It is the main direction for the future development of high-performance and wide-band absorbing coatings to broaden the effective frequency band and achieve multi-spectrum stealth effect. At the same time, various new absorbents are studied and the new absorbing mechanism is discussed to meet the goal of "thin, light, wide and strong" pursued by the absorbing coating.
absorbing coating is one of the main invisible materials in military, and it is also widely used in civil products, such as human safety protection, electromagnetic interference elimination of microwave darkroom equipment and communication and navigation systems, security information confidentiality, improvement of overall performance, improvement of signal-to-noise ratio and electromagnetic compatibility, electromagnetic radiation protection of waveguide or coaxial absorbing elements, radio and television transmitting stations, electromagnetic radiation protection of industrial science and medical equipment, electromagnetic radiation protection of microwave ovens and mobile phones for daily use, and many other aspects. [Page]
4-nanometer stealth coating
Stealth coating is a kind of stealth material which is fixedly covered on the structure of weapon system. According to its functions, it can be divided into radar stealth coating, infrared stealth coating, visible stealth coating, laser stealth coating, sonar stealth coating and multifunctional stealth coating. Nano-coatings are generally composed of nano-materials and organic coatings, which should be called nano-composite coatings more scientifically. After decades of development, stealth coatings, as one of the key technologies of stealth technology, have not only been used in flying missiles and other aircraft. The latest development is that several major industrialized countries and military powers have begun to apply stealth coatings technology to naval vessels, stealth armored vehicles, stealth mines, stealth artillery, stealth tanks, stealth vehicles, stealth radars, stealth communication systems, stealth projects, stealth fortifications, stealth robots, stealth combat suits and infrared stealth flares.
the application fields of nano-materials in marine coatings are as follows: ① radar wave absorbing coatings. (2) Ship infrared stealth coating: The composite powder of nano-alumina, iron oxide, silicon oxide and titanium oxide combined with polymer fiber has a strong absorption performance in the mid-infrared band, and this composite has a good shielding effect on infrared detectors in this band, which not only has excellent radar wave absorption characteristics, but also has good infrared absorption and dissipation performance, and has obvious stealth function. ③ Submarine camouflage coating: The key technology of submarine camouflage coating is its wet reflectivity and aging resistance. The application of nano-scale dark pigment is one of the effective ways to reduce the wet reflectivity and improve the aging resistance of camouflage coatings. ④ Super weather-resistant hull paint: Nano-titanium dioxide can absorb ultraviolet rays, which can improve the aging resistance of the paint. They can be used as one of the main additives in the future. ⑤ Anti-mildew coating for ship cabin: Nano-titanium dioxide, nano-zinc oxide and other nano-materials can be used as antibacterial agents with non-toxicity, wide antibacterial range and excellent thermal stability. The antibacterial effect of nano-materials can be used to prepare new efficient antibacterial and mildew-proof materials and coatings in the cabin. ⑥ New efficient antifouling coatings for ship bottoms: It may be an effective way to adopt nano antifouling agents, such as nano cuprous oxide and nano zinc oxide, or microcapsule technology. ⑦ Ship flame retardant materials and coatings: Some nano-particles have flame retardant function, for example, nano-zinc oxide can be added as a flame retardant to the interior decoration materials of the ship cabin or made into flame retardant coatings to improve the fire resistance of non-metallic decoration materials and flame retardant coatings of the ship.
5 automotive coatings
automotive coatings include coatings used in automobile manufacturing and maintenance. The main varieties are automotive primer, automotive topcoat, finish varnish, automotive intermediate coating and automotive repair paint. Automobile coating has become a special coating. In the developed countries of automobile industry, the output of automobile coatings accounts for about 21% of the total output of coatings.
5.1 primer
cathodic electrophoretic paint is widely used in automobile primers all over the world. The future development direction of cathodic electrophoretic paint is high durability, high swimming penetration, low pigment content, low VOC, low odor, low smoke, no heavy metal, less CO2 generation, light weight and energy saving. Lead-free cathodic electrophoretic coatings and low-temperature curing electrophoretic coatings have also been applied in Europe, America and Japan.
5.2 middle paint
putty, secondary primer and sealing paint are all intermediate layers of the matching coating, that is, middle paint. The development of middle coat and top coat focuses on water-based coatings, powder coatings and high solid coatings.
5.3 topcoat
The topcoat for automobile plays a major role in decoration and protection in the whole coating system, which determines the durability and appearance of the coating. At present, some western developed countries have adopted water-based automobile topcoat on new automobile painting lines, and solvent-based topcoat is mainly used in China. The main variety of automobile topcoat is enamel, which generally has bright colors, good mechanical properties and weather resistance.
5.4 metallic flash primer
The so-called metallic flash primer is the coating used as the coating between the intermediate coating and the topcoat. Its main functions are coloring, covering and decoration. The reason why metallic glitter background paint has this special decorative effect is that metallic aluminum powder or pearlescent powder and other effect pigments are added to the paint.
5.5 plastic coatings
automotive plastic coatings are similar to those used for other metal parts, and can also be divided into primer, primer, varnish or topcoat.
5. 6 damping coatings
In recent years, automobile damping coatings are generally a solvent-free PVC series coating with PVC as the main binder, and its solid content can generally reach 111%. This PVC coating has good hardness, elongation, shear strength and tensile strength, which can well meet the performance requirements of damping coatings.
5.7 powder coatings
powder coatings for automobiles include epoxy polyester hybrid, polyester, polyurethane and acrylic. In the future, the development of powder coatings for automobiles will strive to further improve weather resistance, ultraviolet resistance, low-temperature curing, filming and decoration.
5.8 application of nano-materials in automobile coatings
the application of nano-materials in automobile coatings mainly includes nano-topcoat, nano-glass coating, collision discoloration coating, stone impact resistant coating, antistatic coating, deodorizing coating, etc. Using its special properties, developing excellent automobile coatings has broad development prospects.
6 Other New Coatings
6. 1 Anti-skid coating
The anti-skid coating on the deck of carrier-based aircraft mainly refers to the special anti-skid coating on the landing and berthing aircraft of warships such as aircraft carriers and large destroyers. According to the different materials used, it can be divided into resin-based anti-slip coating and metal-based anti-slip coating; According to different painting methods, it can be divided into spray deck anti-skid coating and roll deck anti-skid coating.
6.2 submarine characteristic signal control coating [Page]
submarine acoustic characteristic control technology is a comprehensive application technology. Acoustic stealth coatings have damping, sound insulation and noise elimination functions. At present, there are sound insulation materials and noise elimination materials polyurethane acoustic stealth coatings.
6.3 New photocatalyst coating
Recently, the Institute of Physical and Chemical Technology of Chinese Academy of Sciences has successfully developed a new photocatalyst coating with multiple functions such as antibacterial, antifogging, self-cleaning and photocatalytic decomposition of pollutants. The main functional components in the coating are TiO2 and its silver-based complex. This coating can be used on the surfaces of various materials, such as glass, ceramics, plastics, etc., giving these materials multiple functions such as antibacterial, antifogging, mildew prevention, self-cleaning and photocatalytic decomposition of pollutants. Therefore, this coating can be used in many occasions, such as automobile rearview mirrors, automobile glass, glass curtain walls, road traffic signs, billboards, automobile bodies and train bodies. The Institute of Physics and Chemistry has applied for a national invention patent for this technology.
6.4 new paint for purifying automobile exhaust
Happiness Times Chemical Company in Britain recently invented a paint, which can absorb most harmful gases in automobile exhaust when applied to the exhaust pipe of an automobile. In addition to purifying automobile exhaust, the company also hopes that this coating can become a new weapon for construction engineers and urban planners to eliminate environmental pollution. This coating is a polysiloxane-based coating, in which a large number of spherical particles of titanium dioxide and calcium carbonate with a diameter of about 31 nm are distributed.
6.5 new coating for protecting optical discs from abrasion
El this TDK company has developed a new coating for optical discs with strong abrasion resistance. After CD, DVD and other optical discs are coated with this coating, the trouble that the data cannot be read after the surface of the optical disc is worn can be effectively avoided. This new coating adopts a double-layer manufacturing process. TDK said that this new coating is not only tougher and more wear-resistant than the single-layer coating developed by the company two years ago, but also transparent in the visible range, which can protect the surface of color LCD screen from damage.
6.6 New reversible color-changing coating at room temperature
A color-changing coating with cobalt salt as color-changing crystal and water-absorbent material as water vapor balancer. This coating can effectively overcome the influence of environmental humidity and film-forming materials on the color change point temperature, and the color change point of the color-changing coating can be limited to 31 ~ 32℃. At the same time, adding other inert pigments can form a color-changing coating with a variety of harmonious colors.
6.7 New thermal protective coating
An external thermal protective coating for supersonic aircraft was studied. Thermal protective coatings should have the characteristics of low density, low thermal conductivity, high specific heat capacity, low pyrolysis temperature, high latent heat of pyrolysis, high gasification fraction, high specific heat capacity of pyrolysis gas, high radiation coefficient and good adhesion with aircraft surface. E-type epoxy modified by phenyl silicone resin has good properties, and the coating material based on it has better properties.
6.8 thermal barrier coating and sol-gel coating
at present, the most feasible and economical way to improve the working temperature of gas turbines is to adopt thermal barrier coating on the premise of using advanced superalloy materials and cooling technology. Using thermal barrier coating can reduce the heat transfer from gas to metal parts, and reduce the working temperature of metal parts by 51 ~ 81℃, which can be reduced by 1.41℃ in a short time. The thermal barrier coating consists of two parts: the inner oxidation-resistant alloy layer (intermediate layer) and the outer insulating ceramic layer (surface layer).
Sol-gel coating technology is applied to metal surface, which endows the metal surface with higher oxidation resistance and corrosion resistance, and has a wide application prospect. With the development of sol-gel coating technology and control technology, it will make greater contributions to improving the corrosion resistance of metals.