High-activity submicron boron carbide ceramic powder and low-temperature in-situ preparation method thereof

Abstract

The invention provides a high-activity submicron boron carbide ceramic powder and a low-temperature in-situ preparation method thereof, and belongs to the field of preparation of boron carbide powder.The preparation method comprises the following steps: proportioning boric acid, petroleum coke and a rare earth oxide additive, drying, carrying out high-energy ball milling, crushing, and dry-pressmolding, and carrying out low-temperature carbon thermal reduction in an ultralow-frequency heating furnace to in-situ prepare the high-activity submicron boron carbide ceramic powder. According to the method, preparation and crushing are integrated, submicron B4C powder can be directly prepared, and subsequent tedious crushing and purifying are not needed. The rare earth oxide can reduce the carbon thermal reduction temperature, inhibit the growth of B4C grains and prevent the coarsening of grains. Meanwhile, due to the addition of the rare earth oxide, a second phase for promoting subsequentB4C ceramic sintering can be generated through an in-situ reaction, and the sintering activity of the ceramic powder is greatly improved. Compared with the prior art, the method has the advantages oflow reaction temperature, short reaction time, low cost, environment friendliness, energy conservation, consumption reduction and the like, and the process is simple and feasible and can be suitablefor industrial large-scale popularization.

Description

technical field [0001] The invention belongs to the field of preparation of boron carbide ceramic materials, and in particular relates to a submicron boron carbide ceramic powder and a low-temperature in-situ preparation method thereof. Background technique [0002] Boron carbide (B 4 C) is an important special ceramic material with high hardness (Mohs hardness 9.36, second only to diamond and cubic boron nitride), low density (theoretical density is only 2.52g / cm 3 ), excellent thermal neutron absorption performance (neutron absorption cross section up to 347×10 -24 cm 2 ), high melting point (2450°C), stable chemical properties and high temperature resistance, it is widely used as high-end military bulletproof armor materials, nuclear industry shielding and control materials, advanced abrasive materials, engineering ceramics and advanced refractory materials, etc., among which High-end military bulletproof armor and nuclear shielding materials require B 4 C ceramics ha...

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Problems solved by technology

And, B 4 C crystal blocks have disadvantages such as high energy consumption, low output rate and heavy environmental pollution during production; 4 C hardness is extremely high, resulting in serious material loss, long processing cycle, and serious waste of water resources.

[0005] Patent announcement number CN101570438B has announced a kind of superfine B 4 The preparation method of C powder, this production method consumes a lot of energy, the production efficiency is low, and the average particle size of the original powder obtained is relatively large, between 20 and 40 μm, and the crushing process needs to be added before sintering, which greatly increases the production cost.

The patent application with the patent publication number CN106006644A uses graphene as the carbon source, boron powder, boron oxide or boric acid as the boron source, and synthesizes nano-B by carbothermal reduction reaction at 900-2500°C under an inert protective atmosphere. 4 C powder, this method uses graphene as a raw material, which is expensive and rare, and needs to be carried out under an inert protective atmosphere, making it difficult to implement industrial production

The patent application whose patent publication number is CN105314636A discloses a kind of plasma preparation of high-purity ultra-fine B 4 The method of C powder needs to use methane as the reaction gas and argon as the carrier, the equipment is expensive, the operation is complicated, the cost is high, and the output is low

The patent application of patent publication number CN105541332A discloses a kind of micron B 4 C The preparation method of bulletproof ceramic powder, using boron carbide powder with a thickness of 45-106 μm as the raw material, undergoes two processes of crushing, pickling to remove impurities, multiple washings, pressure filtration, hydraulic classification, microwave drying and other processes to obtain micro-nano-scale B 4 C powder, the process is long and complicated, and it needs to be pickled and purified, which seriously pollutes the environment and wastes water resources

In recent years, B 4 There are self-propagating high-temperature synthesis methods, mechanical alloying methods, sol-gel carbothermal reduction methods, and chemical vapor deposition in the preparation of C powder. However, due to their own limitations, the above methods are difficult to implement in large-scale industrial production.

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