多组元陶瓷相协同增韧WC的机理及其两步烧结制备技术研究

This project will explore a novel type of fine-grained binderless WC with high hardness, excellent strength, good toughness and resistence to elevated temperature. Synergistical toughening for pure WC will be carried out by in-situ Si3N4 whisker, phase-transformation ZrO2 and non phase-transformation Cr3C2/VC. To obtain desired microstructure and outstanding properties, a distinctive two-step sintering will also be developed and adopted. The study focuses on composition design of high property WC material, revolution and mechanism of microstructure during sintering, effect and mechanism of microstructure on property. The synergistically toughening mechanism of in-situ Si3N4 whisker, phase-transformation ZrO2 and non phase-transformation Cr3C2/VC will be investigated in detail. Meanwhile we will penetrate into the formation mechanism of in-situ Si3N4 whisker and t-ZrO2, the sintering densification mechanism of WC material, the formation and growth of Si3N4 whisker, and the evolution of WC grain. Then, the influences of composition and processing parameters on properties will be clarified. Finally, the material composition and preparation technique will be determined by optimization. The study will supply theory for composition design of binderless WC with high properties, optimization of sintering, and precise controlling of microstructure and property of sintered material. It will also help exploration of a new preparation route of good performance WC material.

本项目以WC为研究材料对象，以探索通过原位自生Si3N4晶须、相变ZrO2以及非相变Cr3C2或VC陶瓷等多组元协同增韧的无粘结相、细晶、高硬、高强韧、耐高温WC材料的两步烧结制备技术为研究主线，以具有优异综合性能的WC材料的成份与组织设计、粉末烧结过程中的组织变化规律及机理、组织对性能的影响规律和机理等为核心研究内容。重点研究原位自生Si3N4晶须、相变ZrO2以及非相变Cr3C2或VC陶瓷等多组元协同增韧WC的机理、WC基体中原位自生Si3N4晶须和t-ZrO2陶瓷增韧相的形成机理、陶瓷增韧WC材料的烧结致密化机理以及Si3N4晶须形成与发展、WC晶粒生长等组织演变规律，进而明确材料成份、制备工艺参数等对WC材料性能的影响规律，优化成份和制备工艺。为高性能无粘相WC材料的成份设计、烧结技术优化和精确控制烧结材料的组织与性能提供理论依据，并为高性能WC材料的制备探索新途径。

本项目以WC为研究材料对象，探索通过原位自生Si3N4晶须、相变ZrO2以及非相变Al2O3或VC陶瓷等多组元协同增韧制备具有无粘结相、细晶、高硬、高韧、耐高温等特点的WC材料，以期提高WC材料的使用性能和拓展其应用空间。主要开展了无粘相WC材料的成份与组织设计、粉末烧结过程中的组织变化规律及机理、组织对性能的影响规律和机理等研究内容。揭示了原位自生Si3N4晶须、相变ZrO2以及非相变陶瓷等多组元协同增韧WC的机理、WC基体中原位自生Si3N4晶须和t-ZrO2陶瓷增韧相的形成机理、陶瓷增韧WC材料的烧结致密化机理以及Si3N4晶须形成与发展、WC晶粒生长等组织演变规律，进而明确了无粘结相WC材料的成份、制备工艺参数等对WC材料性能的影响规律，优化了相应材料的成份和制备工艺。通过多组元陶瓷相协同改性WC材料，在获得高硬度和良好断裂韧性的同时，还有助于降低材料的烧结致密化温度。从而为高性能无粘相WC材料的成份设计、烧结技术优化和精确控制烧结材料的组织与性能提供了理论参考，并为高性能WC材料的制备探索了新途径。