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Preparation Methods And Application of Aluminum Carbide

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Update time : 2019-12-27 16:16:56

Aluminum is the most abundant metal element in the earth's crust. It is widely used in industry because of its lightweight and good formability. However, aluminum and its alloys are faced with the development problems of low strength, wear-resistance, and poor high-temperature performance. Aluminum carbide (Al4C3) is an ionic compound with a diamond-hexahedral structure, which has high hardness, shear strength, and melting point, making it an ideal second-phase strengthening material for aluminum-based materials.
 

Aluminum carbide gold hexagonal flake crystal. The relative density was 2.36, stable at 1400℃, and decomposed above 2200℃. In the case of water decomposition to form methane, storage in dry shade, insoluble in acetone, dilute acid decomposition. It is made by heating pure aluminum powder with pure carbon. At present, the preparation methods of aluminum carbide mainly include direct metal carbonization, carbon thermal reduction, sol-gel, microwave synthesis, and high-energy mechanical ball grinding.
 

 

Metal direct carbonization and carbon thermal reduction are the earliest synthetic methods, and some of the technologies have been applied to industrial production. However, the disadvantages of these two methods are high synthesis temperature, long reaction time, and large particle size. However, in the known high-energy ball grinding method, the focus is mainly on the in-situ synthesis of a small amount of Al4C3 to enhance the aluminum-based materials, rather than the high-purity synthesis of Al4C3. At the same time, the high energy ball mill itself has such disadvantages as the ball grinding time is too long, the energy consumption is large, the powder particle is not uniform, and so on.

 

A method for preparing aluminum carbide powder by plasma ball grinding includes the following steps:

(1) Aluminum powder and graphite powder were mixed simply and evenly, and the powder was ground (refined and activated) by plasma ball mill under the protection of argon to obtain the mixed powder; The proportion of the mass of the stone toner in the mixed powder is 35%, and the residue is aluminum powder; Conditions for ball grinding: the rotating speed is 960rpm, the discharge current is 1.5a, the pellet material ratio is 50:1, and the ball grinding time is 1h(excluding the stopping time). The operation mode is to restart alternately for 30 minutes and stop for 30 minutes (ball grinding for 30 minutes, then stop ball grinding for 30 minutes, then ball grinding for 30 minutes, and so on);
 

(2) After the ball mill mixing powder inside with cover alumina crucible, place the pot in a vacuum tube furnace, vacuum furnace tube, using vacuum pump to 10 pa, argon gas is piped in, then repeat after keep the argon gas flow in the tube furnace (flow rate of 100 ml/min), with ten ℃ / min temperature heating rate will rise to 1000 ℃ and the four h heat preservation, then air cooling tube furnace (cool to room temperature within 100 min), at the end of the aluminum carbide. SEM diagram of aluminum carbide powder is as follows:

 

 

Aluminum carbide is often used as an additive to enhance the strength of three-component aluminum-based materials (al-si-Al4C3, al-alti-Al4C3). In addition, Al4C3 is an important compound in the technical field of the aluminum metal industry, which is used in reducing metal oxides in the metallurgical industry, chemical reaction catalysts in the chemical industry, and advanced ceramic materials such as high temperature, cutting and mold in the ceramic industry. As an ionic compound, carbon atoms exist as separate C atoms in the lattice structure of Al4C3. C has strong alkalinity. During hydrolysis, methane is produced by C+4H→CH, so Al4C3 is also used as a methanogen and desiccant. It is this unique structure that makes one-dimensional Al4C3 nanowires a potential cold electron emitter.
 

1) preparation of aluminum nitride powder based on aluminum carbide, including (b) aluminum carbide is heated to a predetermined temperature in the flowing ammonia or nitrogen gas and kept warm for a period of time. Aluminum carbide reacts with ammonia or nitrogen gas in a high-temperature environment to produce aluminum nitride. Through the invention, aluminum nitride powder can be prepared at a relatively low temperature, and the powder prepared has high purity, small particle size and uniform particle size distribution, high thermal conductivity and excellent thermal and mechanical properties, which can be widely used in the substrate materials of integrated circuits.
 

2) preparation of an aluminum carbide nanoribbon. The crucible containing al-si alloy was placed in the furnace, the door was closed, and the crucible was vacuumed to 50Pa~ 10-3pa, then it was filled with protective gas argon, then the temperature was raised to 700℃~1600℃, and the heat was kept for 1-20 hours, then it was naturally cooled to normal temperature, and many yellow aluminum carbide nano boards were generated on the surface of the alloy and the inner wall of the graphite crucible. The aluminum carbide nanoribbon prepared by the invention is thin in thickness and has fewer impurities; Aluminum carbide nanoribbons are long in length and can reach several millimeters; The cost of growing aluminum carbide nanoribbons is very low; No environmental pollution, sample preparation equipment.

 

Aluminum carbide contact with water will soon release flammable gas methane, in case of heat or fire can cause combustion and explosion. It can react violently with acids.Therefore, it should be stored in a cool, ventilated warehouse. Keep away from fire and heat sources. The relative humidity is kept below 75%. The packaging is sealed. It should be stored separately from acids and so on. The storage area should be equipped with suitable materials to contain spills.