What materials are the body armor purchased in large quantities made of?
Military fans with military knowledge know that there are two types of body armor, soft and hard. The difference between them is that the latter needs to insert a hard bulletproof version on the front and back of the body armor. But regardless of whether they are soft or hard, their foundations are made of Kevlar aramid fiber or high-density polyethylene (HDPE).
Kevlar aramid fiber is as shown in the picture. It was developed by DuPont Company of the United States. It was first used to replace steel to make helmets. The earliest actual combat use was in the "Gulf War" in 1991. At that time, in the US military, almost Everyone wears a Kevlar helmet.
Kevlar aramid fiber has the characteristics of high modulus, ultra-fine fiber, and high weaving density. It also has permanent heat-resistant and flame-retardant properties and permanent anti-static properties (this is very important. I am most afraid of static sparks, and some high-precision electronic equipment are also afraid), acid and alkali and organic solution corrosion, high strength, high wear resistance, pull resistance... and so on so that it can not only make bulletproof vests And the puncture-resistant interlayer of helmets and even military boots.
However, the bulletproof effect of Kevlar made into body armor is somewhat unsatisfactory. The main reason is that it should not be too dense when it is made into body armor. If it is molded as hard as a helmet, the feeling of restraint is very strong after wearing it, which makes people very uncomfortable. ! It has an impact on breathing and body movement, but weaving it to a level acceptable to the human body will greatly reduce the bulletproof effect.
It is impossible to make body armor with aramid fiber by pressing film. It is too hard to wear, so it can only be woven with ultra-long ultra-fine fibers.
Due to the reduction of the protection ability of aramid fibers against relatively powerful bullets, the world's advanced chemical countries currently use high-density polyethylene as the material for body armor. High-density polyethylene is pressurized during the production process to make its molecular arrangement more perfect. Tight, this will significantly improve its willfulness and appropriate hardness. Since the silk thread processed with it is thinner, a higher weave number can be used when weaving body armor, so the bulletproof of the body armor woven with it effect will be better.
However, the production process of high-density polyethylene is very complicated, and it cannot be manufactured in countries with some chemical capabilities. In addition, it is difficult to get the molecular density just right during the synthesis and pressurization process, so its process is not very stable. In the case of different molecular densities in several batches, if high-density polyethylene threads with different densities are used to make bulletproof vests, the bulletproof effect will also be different. Moreover, the ability of this material to withstand the natural environment is worse than that of Kevlar aramid fiber (probably because the molecules are more active), and it will be denatured after a long period of storage, and the bulletproof effect will gradually decrease, so bulletproof vests There is a shelf life (up to 5 years)
A very prominent problem with soft body armor is that although it has good impact resistance and tensile properties, its effect of greatly weakening kinetic energy is not too high, that is to say: it can prevent bullets from entering the human body, but it can The problem is that the kinetic energy (Joules) generated by the propellant propelled by the incoming bullet is also very large, which prevents the local high-pressure effect of the bullet, but cannot release the kinetic energy of the bullet. This is like a sledgehammer, although it cannot penetrate the human body, it will cause strong blunt damage, and the huge impact of kinetic energy will damage bones and internal organs... Therefore, it is necessary to use soft body armor Basically, a hard board is installed.
At present, there are three kinds of body armor and hardboard. The first one is the alumina ceramic in the picture.
Alumina material has high density and is easy to obtain. The production process is simple and the price is cheap. It is currently the most widely used bulletproof plate. Its process flow is to put high-concentration alumina powder slurry (the fineness of the powder should reach the micron level) under high pressure. Injected into the gypsum mold, because the gypsum has good water absorption performance, the alumina slurry will be dehydrated and formed quickly, and then the obtained alumina plate will be calcined at a high temperature after the mold is removed to obtain an alumina bulletproof insert. The process of grouting is relatively simple to produce, and tens of thousands of pieces can be mass-produced within a day, so its price is cheap and the bulletproof effect is also good. It has also become a large number of protective equipment purchased by the military and police.
Although alumina ceramics are cheap and high-quality, they are relatively heavy, and long-term battles and marches consume a lot of human energy. In order to solve this problem, silicon carbide ceramic bulletproof plates appear. Silicon carbide is what we commonly call "emery". Its density is relatively low, so its weight is also very light, which is almost equivalent to the high-density polyethylene mentioned above, but its price is too expensive, is 4 to 5 times that of the aluminum oxide plate, and the purchase price is too high. It is fully equipped for general troops, and can only be used by special forces with higher operational risks.
Silicon carbide ceramics have excellent normal temperature mechanical properties and excellent oxidation resistance, and also have good corrosion resistance. Its high-temperature mechanical properties are the best among known ceramics...Using it to make bulletproof inserts can also Greatly save energy, the bulletproof plates used by the royal guards of local tyrants may all be made of silicon carbide ceramics.
Better than silicon carbide ceramics is boron carbide ceramics. In the periodic table of chemical elements, the order is hydrogen helium lithium beryllium boron, carbon nitrogen oxygen fluorine neon, sodium magnesium aluminum silicon phosphorus... The density of boron is smaller than that of oxygen. So it will be lighter in weight, but the price of boron carbide is extremely expensive, more than 8 to 10 times that of silicon carbide. The price of a boron carbide bulletproof plate may buy 50 aluminum oxide plates, but its bulletproof performance and silicon carbide The difference is almost the same, this expensive thing can only be used by people at the big boss level.
But no matter what kind of board, after the soft body armor is inserted, it can greatly weaken the kinetic energy of bullets and the impact of shrapnel. The kinetic energy and high pressure will be absorbed and dispersed by the board so that soldiers can better prevent kinetic energy damage and damage. Piercing damage from sharp objects.
Generally speaking, the procurement of bulletproof equipment by the armed forces of major countries should be based on actual needs. Usually, more than two pieces are equipped for each soldier on the battlefield. The bulletproof vest needs to be replaced after being hit by a bullet because its protection ability has declined. If you wear it a lot, you may be really hurt if you continue to wear it. Therefore, it is still necessary to configure a large number of them under the condition of relatively sufficient military expenditure.
Zennison
What materials are the body armor purchased in large quantities made of?
Military fans with military knowledge know that there are two types of body armor, soft and hard. The difference between them is that the latter needs to insert a hard bulletproof version on the front and back of the body armor. But regardless of whether they are soft or hard, their foundations are made of Kevlar aramid fiber or high-density polyethylene (HDPE).
Kevlar aramid fiber is as shown in the picture. It was developed by DuPont Company of the United States. It was first used to replace steel to make helmets. The earliest actual combat use was in the "Gulf War" in 1991. At that time, in the US military, almost Everyone wears a Kevlar helmet.
Kevlar aramid fiber has the characteristics of high modulus, ultra-fine fiber, and high weaving density. It also has permanent heat-resistant and flame-retardant properties and permanent anti-static properties (this is very important. I am most afraid of static sparks, and some high-precision electronic equipment are also afraid), acid and alkali and organic solution corrosion, high strength, high wear resistance, pull resistance... and so on so that it can not only make bulletproof vests And the puncture-resistant interlayer of helmets and even military boots.
However, the bulletproof effect of Kevlar made into body armor is somewhat unsatisfactory. The main reason is that it should not be too dense when it is made into body armor. If it is molded as hard as a helmet, the feeling of restraint is very strong after wearing it, which makes people very uncomfortable. ! It has an impact on breathing and body movement, but weaving it to a level acceptable to the human body will greatly reduce the bulletproof effect.
It is impossible to make body armor with aramid fiber by pressing film. It is too hard to wear, so it can only be woven with ultra-long ultra-fine fibers.
Due to the reduction of the protection ability of aramid fibers against relatively powerful bullets, the world's advanced chemical countries currently use high-density polyethylene as the material for body armor. High-density polyethylene is pressurized during the production process to make its molecular arrangement more perfect. Tight, this will significantly improve its willfulness and appropriate hardness. Since the silk thread processed with it is thinner, a higher weave number can be used when weaving body armor, so the bulletproof of the body armor woven with it effect will be better.
However, the production process of high-density polyethylene is very complicated, and it cannot be manufactured in countries with some chemical capabilities. In addition, it is difficult to get the molecular density just right during the synthesis and pressurization process, so its process is not very stable. In the case of different molecular densities in several batches, if high-density polyethylene threads with different densities are used to make bulletproof vests, the bulletproof effect will also be different. Moreover, the ability of this material to withstand the natural environment is worse than that of Kevlar aramid fiber (probably because the molecules are more active), and it will be denatured after a long period of storage, and the bulletproof effect will gradually decrease, so bulletproof vests There is a shelf life (up to 5 years)
A very prominent problem with soft body armor is that although it has good impact resistance and tensile properties, its effect of greatly weakening kinetic energy is not too high, that is to say: it can prevent bullets from entering the human body, but it can The problem is that the kinetic energy (Joules) generated by the propellant propelled by the incoming bullet is also very large, which prevents the local high-pressure effect of the bullet, but cannot release the kinetic energy of the bullet. This is like a sledgehammer, although it cannot penetrate the human body, it will cause strong blunt damage, and the huge impact of kinetic energy will damage bones and internal organs... Therefore, it is necessary to use soft body armor Basically, a hard board is installed.
At present, there are three kinds of body armor and hardboard. The first one is the alumina ceramic in the picture.
Alumina material has high density and is easy to obtain. The production process is simple and the price is cheap. It is currently the most widely used bulletproof plate. Its process flow is to put high-concentration alumina powder slurry (the fineness of the powder should reach the micron level) under high pressure. Injected into the gypsum mold, because the gypsum has good water absorption performance, the alumina slurry will be dehydrated and formed quickly, and then the obtained alumina plate will be calcined at a high temperature after the mold is removed to obtain an alumina bulletproof insert. The process of grouting is relatively simple to produce, and tens of thousands of pieces can be mass-produced within a day, so its price is cheap and the bulletproof effect is also good. It has also become a large number of protective equipment purchased by the military and police.
Although alumina ceramics are cheap and high-quality, they are relatively heavy, and long-term battles and marches consume a lot of human energy. In order to solve this problem, silicon carbide ceramic bulletproof plates appear. Silicon carbide is what we commonly call "emery". Its density is relatively low, so its weight is also very light, which is almost equivalent to the high-density polyethylene mentioned above, but its price is too expensive, is 4 to 5 times that of the aluminum oxide plate, and the purchase price is too high. It is fully equipped for general troops, and can only be used by special forces with higher operational risks.
Silicon carbide ceramics have excellent normal temperature mechanical properties and excellent oxidation resistance, and also have good corrosion resistance. Its high-temperature mechanical properties are the best among known ceramics...Using it to make bulletproof inserts can also Greatly save energy, the bulletproof plates used by the royal guards of local tyrants may all be made of silicon carbide ceramics.
Better than silicon carbide ceramics is boron carbide ceramics. In the periodic table of chemical elements, the order is hydrogen helium lithium beryllium boron, carbon nitrogen oxygen fluorine neon, sodium magnesium aluminum silicon phosphorus... The density of boron is smaller than that of oxygen. So it will be lighter in weight, but the price of boron carbide is extremely expensive, more than 8 to 10 times that of silicon carbide. The price of a boron carbide bulletproof plate may buy 50 aluminum oxide plates, but its bulletproof performance and silicon carbide The difference is almost the same, this expensive thing can only be used by people at the big boss level.
But no matter what kind of board, after the soft body armor is inserted, it can greatly weaken the kinetic energy of bullets and the impact of shrapnel. The kinetic energy and high pressure will be absorbed and dispersed by the board so that soldiers can better prevent kinetic energy damage and damage. Piercing damage from sharp objects.
Generally speaking, the procurement of bulletproof equipment by the armed forces of major countries should be based on actual needs. Usually, more than two pieces are equipped for each soldier on the battlefield. The bulletproof vest needs to be replaced after being hit by a bullet because its protection ability has declined. If you wear it a lot, you may be really hurt if you continue to wear it. Therefore, it is still necessary to configure a large number of them under the condition of relatively sufficient military expenditure.
1 year ago | [YT] | 1