A twinned and dispersion-strengthened WC-Ni based cemented carbide and its preparation method

By adding Cr3C2 and VC as grain growth inhibitors to WC-Ni based cemented carbide, combined with high temperature sintering and rapid cooling, small plate-like WC grains and nano-dispersed phases are formed, which solves the problems of WC grain growth and Ni evaporation in the preparation process of WC-Ni based cemented carbide, achieves the improvement of alloy performance with high strength and high toughness, and meets the requirements of nuclear main pump mechanical seal.

CN119372537BActive Publication Date: 2025-09-19CENT SOUTH UNIV
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Patent Information

Application Number
CN202411446881.X
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2024-10-16
Publication Date
2025-09-19
Estimated Expiration
2044-10-16

AI Technical Summary

Technical Problem

During the preparation process of existing WC-Ni based cemented carbide, it is difficult to achieve fine WC grains and uniform microstructure, resulting in hardness, strength and toughness that are difficult to meet the stringent requirements of nuclear main pump mechanical seals, and the evaporation problem of Ni seriously affects the performance of the alloy.

Method used

The composite grain growth inhibitor Cr3C2 and VC is used to regulate the WC grain growth through high temperature sintering and rapid cooling combined with low temperature tempering, forming small plate-like WC grains and nano-dispersed phases, thereby improving the hardness and toughness of the alloy.

Benefits of technology

The alloy's bending strength, Vickers hardness and fracture toughness are significantly improved to meet the performance requirements of nuclear main pump mechanical seals. The alloy's bending strength can reach up to 3945MPa, the Vickers hardness can reach up to 2060kgf/mm2, and the Palmqvist fracture toughness KIC can reach up to 10.81MPa·m1/2.

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Abstract

The present invention discloses a twinned and dispersion-strengthened WC-Ni-based cemented carbide and its preparation method. The alloy is composed of a hard phase component WC, a bonding metal Ni, and supersaturated composite grain growth inhibitors Cr3C2 and VC. The WC hard phase in the alloy is composed of irregular grains with an average grain size of less than 0.5 μm and dispersed small plate-like grains. The typical morphological characteristics of the fine plate-like WC grains in the polished cross-section of the alloy are long strips with an average length of less than 2.2 μm and an average width of less than 0.5 μm. Nano-dispersed phases exist in the Ni-based bonding phase solid solution matrix in the alloy. The present invention uses unsaturated carbon nano-WC powder as raw material, and through ultrafine grain strengthening of the hard phase, strengthening of dispersed fine plate-like crystals, and nano-dispersed phase strengthening of the bonding phase, the alloy is given high hardness, high toughness, and high strength.
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