vacuum sintering furnace for boron carbide bullet proof

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With the large-scale development of modern war lethality weapons, the early bulletproof materials can not meet the performance requirements of bulletproof materials. It is of great strategic significance for national defense to seek for bulletproof materials with superior performance. As early bulletproof materials, metal materials are easy to be broken down by bullets and have low bulletproof coefficient. Moreover, the density of metal is large, and the thickness of metal can not be increased at will, otherwise the combat ability of soldiers will decline in a straight line. Alumina is the most commonly used bulletproof material for ceramic materials. It has the advantages of good sintering performance, mature technology, stable product size, low production cost and rich raw materials. However, its bulletproof ability is slightly lower and its density is larger, which can not meet the bullet proof requirements of high performance.

The interceptor’s bullet proof vest in the United States is made of pure boron carbide by hot pressing sintering. Its bullet proof performance is superior, but its raw materials are scarce and sintering process is difficult, which makes the manufacturing cost very high, so it is not suitable for large-scale military deployment.

In order to overcome the shortcomings of the prior art, a bulletproof boron carbide / silicon carbide composite ceramic preparation method is provided. The bulletproof material has the advantages of small density, good bulletproof performance and high cost performance.

The preparation method of bulletproof boron carbide / silicon carbide composite ceramic comprises the following steps:

Step 1: mix the materials evenly, weigh the four components of silicon carbide powder, nano carbon black, phenolic resin and boron carbide powder according to the weight ratio of 24:5:4: (1.7-27), mix the three solids of silicon carbide powder, boron carbide powder and nano carbon black in the mortar, mix the phenolic resin with alcohol while mixing until the phenolic resin is fully dissolved, add them to the mortar, and put them into the ball milling mixture. Fully mix in the machine for 24 hours;

Step 2: granulate, pressurize the mixed powder with a pressure of 60MPa for half a minute, and then granulate through 80 mesh screen;

Step 3: molding, weighing 25.0og particles, evenly filling in 50X50mm abrasive tools, pressing with semi-automatic pressure forming machine under 120MPa pressure to make green billets, and pressing mode is bidirectional;

Step 4: dry and solidify, put the green body into the oven for drying and solidifying, keep it at 80 ° C for 4 hours, then heat it up to 100 ° C, then keep it for 4 hours, and finally keep it at 140 ° C for 8 hours at 2 ° C per minute;

Step 5: reaction sintering of siliconizing, adding 5 μ silicon particles with the same weight as the total weight of green body and graphite paper into the graphite crucible, placing the solidified green body on the metal silicon, putting it into the high temperature vacuum sintering furnace together with the graphite crucible for sintering, after the vacuum resistance furnace is preheated for 30 minutes, vacuumizing is started, and then the heating voltage is increased every half an hour, when the furnace temperature reaches 13500c Stop vacuumizing, continue to heat up to 1600 ° C, keep at this temperature for 30 minutes, then stop heating and cool down to room temperature with furnace temperature.

The particle size of the silicon carbide powder is 14 μ M.
The best particle size of the boron carbide powder is 14 μ m, and the fracture toughness is the largest. The decrease of boron carbide particle size is easy to produce agglomeration, and the particle distribution is not uniform; the increase of boron carbide particle size has an effect on the crack growth, but the amount of residual silicon becomes more, and the hardness of the material decreases.

The best weight fraction of boron carbide is 15% (wt%), and the composite ceramics have the highest bending strength and fracture toughness. Adding boron carbide can improve the hardness of composite ceramics and reduce the amount of residual silicon when it reacts with silicon. However, when the content of boron carbide reaches a certain amount, the agglomeration of boron carbide will become uneven, the gap between the structures will become larger and the amount of residual silicon will become more, which will affect the mechanical properties of composite ceramics.

Based on the principle of reaction sintering, boron carbide particles with high hardness and low density were added into the green body, and the bulletproof material prepared by the particle reinforcement mechanism has the advantages of low density (2.70-3.05g / cm3), good bulletproof performance (the lowest depression depth of trunk mold is 15.0mm, which is lower than the national military standard by 25mm), and high cost performance.

Bullet proof sheet, silicon carbide, boron carbide bullet proof clothing, sintering, reaction sintering, vacuum sintering furnace.