Metal fibers generally reach micron level, such as Stainless steel fiber Generally, the diameter is about 10 μ m, and the average diameter of fine stainless steel fiber supplied in the market is 4 μ m. Metal fiber has good mechanical properties, not only Specific breaking strength And tensile specific modulus is high, and bending resistance and toughness are good; It has good conductivity and can prevent static electricity. For example, tungsten fiber is used as the filament of incandescent bulb, and it is also an important material for preventing electromagnetic radiation, conducting electricity and transmitting electrical signals; High temperature resistance; Stainless steel fiber, gold fiber and nickel fiber also have good chemical corrosion resistance and are not easy to oxidize in the air. The metal fiber has the following characteristics:
(1) Metal fiber can operate at 500~590 ℃ (930~1100 ℃), and may be used in more complex systems in the future.
(2) Metal fiber is superior to ceramic filter material in terms of its ability to withstand high pressure drop, purification capacity and stability at high temperature.
(3) Metal fiber has irregular cross section and conventional surface area, which makes it have very large specific surface area. [2]
Metal fibre （1） Metal foil and organic fiber composite fiber
The aluminum/polyester composite fiber produced in China belongs to this category and is also a representative one. Aluminum has good thermal conductivity, conductivity, oxidation resistance, low density, and good ductility of cooked aluminum. It can be made into film filament and compounded with polyester filament. Aluminum foil wire was originally used in inlay decoration or industry, and is known as "gold and silver wire" in China. Our military "81" camouflage net is woven with polyester aluminum foil composite silk thread with basic cloth towel for anti radar reconnaissance. Through reasonably designed basic layout, radar wave can be controlled after netting transmissivity It can also resist external adverse conditions and play a protective role. （2） Metallized fibre
Organic fibre The surface is plated with nickel, copper, diamond and other metals, and Acrylic acid Class, etc resin The protective film is called metallized fiber in Japan. It is reported that 1 × 10 shielding cloth is made by weaving ten ～3×10 ten The shielding rate of Hz can reach 99.90%~99.99%. Because of its conductivity, it can also be used to make anti-static fabrics. However, the fastness of metal film still exists, especially the corresponding washing resistance. （3） Pure metal fiber
The metal fiber with essential significance is all used Metallic materials Fabricated fibers, such as those made of lead, copper, aluminum, stainless steel, etc., are the basis for application and development. The lead fiber made of lead is soft and dense, and has a wide range of applications, such as sound insulation, vibration control, radiation protection and battery materials. Copper fiber has excellent conductivity and thermal conductivity, which can be used to prepare conductive fabrics, conductive clothing and other products. Stainless steel fiber Yes Stainless steel wire The drawn fiber is the fastest developed and most widely used metal fiber in the world. Stainless steel fiber drawing is a long tow, each bundle contains thousands to tens of thousands of stainless steel fibers. Stainless steel fiber has good flexibility. The flexibility of stainless steel fiber with a diameter of 8m is better than that of stainless steel fiber with a diameter of 13m Bast fibre Equivalent; It has good mechanical properties and corrosion resistance, and is completely resistant to nitric acid, phosphoric acid, alkali and organic chemical solvents; Good heat resistance. It can be used continuously at 600 ℃ in oxygen atmosphere and has good performance High temperature resistant material 。 The resistance of the fabric woven from stainless steel fiber decreases with the increase of temperature, which has good textile application performance. [3] Metal fibers can be prepared by drawing, spinning, cutting, grinding and sintering with coated metal.
1) Drawing method
The ordinary single wire drawing can obtain extremely fine fibers, and its section shape and surface state can reach the best state, with smooth surface and accurate size. However, the production efficiency is low and the mold cost is high, so the price is very expensive. The cluster drawing method is used to draw dozens or even hundreds of wires on a mold at the same time, which greatly improves the production efficiency and reduces the cost. Bundle drawing is to pull the raw metal wire in a sheath (such as a copper sheath) for many times, with an additional annealing process in the middle. When it reaches a certain diameter, it is cut into sections and combined together. After it is installed in the sheath material, it continues to pull until the required fiber diameter is obtained. The sheathing material can be dissolved with acid (such as nitric acid) to obtain the required metal fiber.
2) Spinning process
Spinning can be carried out from liquid metal Direct production of metal fiber has low cost, but requires special equipment. For example, after melting the metal, use mechanical force or gas pressure to make the molten liquid flow out of the small hole at the bottom of the container and solidify in a proper atmosphere. After the molten metal flows out of the fine metal L, just after solidification, the bonding force between the metal fiber grains is very weak and has "thermal brittleness", so a small force can cut the metal fiber into short fibers. Therefore, the metal short fibers with the same length can be obtained by adding a certain amount of shear force to the falling metal fibers. Shear force It can be produced by the impact of metal plate inclined to the metal fiber. This method has simple process, fast speed, no oil, water and other pollution, and no residue stress 。 3) Cutting method
The cutting method uses solid metal as raw material and tools cutting Fibroblast chips. The method is simple, the production cycle is short, and the cost is low, but it is difficult to obtain fibers with uniform and smooth cross section, which are mainly used to produce short metal fibers. 4) Grinding method
Install some kind of Abrasive materials (high hardness material) Grinding machine The metal fiber with the required diameter can be obtained by adjusting the biting amount, feeding amount and selecting the abrasive particle size on the grinder. The thickness of metal fiber is affected by many factors. For example, the larger the feeding amount is, the finer the metal fiber is obtained, and the coarser the abrasive particle size is, the coarser the metal fiber is obtained. In this way, fine nickel or nickel alloy wires and Ferronickel A class of strong and tough metal fibers. 5) Plated metal sintering method
stay Organic fibre Electroless metal plating Vacuum evaporation Soak with the metal slurry, or conduct conductive treatment on the surface of the organic fiber before electroplating Reductive atmosphere Hollow metal fibers can be obtained by pyrolysis to remove organics and sintering, or by decomposing (or pyrolysis) organics in the atmosphere and reducing annealing to remove oxides. 6) Other methods
Put metal powder or metallic oxide plus Organic binder The metal fiber can also be obtained by mixing the slurry, extruding the fiber from the microporous spinneret, removing the binder at high temperature, sintering in the reducing atmosphere, or directly pyrolysis in the reducing atmosphere to remove the binder. Also, if Ni (OH) is used two The nickel fiber can be prepared by extruding the powder, binder and paste into fiber, and then reducing sintering. [4] (1) It is used as a wire for power transmission and electrical signal transmission in smart clothing.
(2) If the antistatic materials in general functional clothing are blended with metal short fibers, the weight blending ratio is less than 10%; If the metal fiber filament is used and the weight blending ratio is less than 2.5%, all kinds of friction, induction and other static electricity can be completely eliminated. This is applicable to the production enterprises of oil, gas fields and flammable and explosive products, the transportation process of flammable and explosive materials such as oil, natural hot gas, and electrical safety operation sites.
(3) The metal fiber embedded in the fabric can achieve good electromagnetic shielding effect. It is widely used in military, aviation, communication and confidential shielding environment.
(4) Chemical agents, processing materials, filter screens for waste liquid and wastewater filtration, filter screens for high-temperature dust filters, and materials that require high strength, wear resistance, and conductive conveyor belts.
(5) Metal composite Reinforcements in, such as Explosion proof tire 、 automobile engine Connecting rod, etc. (6) Other special materials, such as conductive paper, filament of incandescent bulb, etc. [1]
