Preparation method of TiB2 (titanium diboride) gradient ceramic with hard surface and tough core

Abstract

The invention relates to a preparation method of TiB2 (titanium diboride) gradient ceramic with a hard surface and a tough core. The surface layer of the TiB2 gradient ceramic is rich in B4C (boron carbide). Titanium dioxide (TiO2) powder, boron (B) powder, boracic acid (HBO3), and citric acid (C6H8O7) are used as raw materials, and are prepared by a two-step sintering and middle impregnation technology. The preparation method comprises the following steps of firstly, mixing the TiO2 powder and the B powder according to the mass fraction ratio of (62-76%):(24-38%), drying, heating to 600-1200 DEG C, maintaining the temperature for 0.5-10h, and obtaining a TiB2-B2O3 (boric oxide) presintering body; putting the presintering body into a saturated solution of the HBO3 and the C6H8O7 with the mass ratio of (25-35%):(65-75%); performing multiple times of impregnation; finally, rising the temperature of the impregnated presintering body to 1400-1800 DEG C in an Ar (argon) atmosphere, maintaining the temperature for 0.5-5h, continuously rising to 1800-2000 DEG C, maintaining the temperature for 0.5-4h, performing hot pressing sintering, and maintaining the pressure to 10-50MPa, so as to obtain the TiB2 gradient ceramic with the surface rich in B4C. The TiB2 gradient ceramic has the advantages that at the surface layer of the ceramic, the hardness is 25-40GPa, and the fracture toughness is 3-6MPa m1 / 2; at the core of the ceramic, the hardness is 20-30GPa, and the fracture toughness is 5-10MPa m1 / 2; by utilizing the gradient change of the B4C content in the surface layer, the excellent property of hard surface and tough core of the TiB2 ceramic is realized.

Description

technical field [0001] The invention relates to the field of non-oxide-based ceramic materials, and specifically discloses a method for preparing TiB with a hard surface and a tough core. 2 Gradient ceramics approach. Background technique [0002] B 4 C ceramics have excellent properties such as wear resistance, high temperature resistance, high thermal conductivity, low density, and high hardness. They are widely used in journal bearings, high-pressure wear-resistant nozzles, corrosion-resistant high-temperature gas turbines, bulletproof armor, etc., but B 4 C ceramic has high hardness but high brittleness and low fracture toughness, which limits its application range. [0003] TiB 2 Ceramics have good toughness and high strength, and are widely used in various structural parts, but TiB 2 Ceramics have poor wear resistance and low hardness, so it is difficult to apply to occasions requiring high wear resistance. [0004] in TiB 2 The addition of high-hardness material...

AI Technical Summary

Problems solved by technology

Another way is in TiB 2 Ceramics are used as the surface coating, which is evenly coated with a layer of high-hardness material, but the combination between this hard coating and the substrate is difficult to tighten, and it is easy to fall off

[0005] Although different composite materials and methods have different functions, it is necessary to basically preserve the TiB 2 The mechanical properties of ceramics ensure good fracture toughness and hardness, and traditional preparation methods still cannot solve the problem.

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