ZrB₂‐ZrC_x composites were produced using Zr:B₄C powder mixtures in the molar ratios of 3:1, 3.5:1, 4:1, and 5:1 by reactive hot pressing (RHP) at 4‐7 MPa, 1200°C for 60 minutes. X‐ray diffraction analyses confirmed the formation of nonstoichiometric zirconium carbide (ZrC_x) with different lattice parameters and enhanced carbide formation by increasing the Zr mole fraction. An increase in applied pressure from 4 to 7 MPa was responsible for the improved relative density (RD) of 4Zr:B₄C composition from 86% to 99%. Microstructural studies on Zr‐rich composites showed a reduction in unreacted B₄C particles and enriched elongated ZrB₂ platelets. Reaction and densification mechanism in 4Zr:B₄C composition were studied as a function of temperature increased from 600 to 1200°C at an applied constant pressure of 7 MPa. After 1000°C, <40 vol.% of unreacted Zr was observed during the densification process. Concurrently, low energies of carbon diffusion and carbon vacancy formation were found to enhance nonstoichiometric ZrC_x formation, which was found to be responsible for the completion of the reaction. The plastic deformation of unreacted Zr was responsible for the densification of the ZrB₂‐ZrC_x composite. The results clearly showed that the applied pressure is five times lower than the reported values. Moreover, a temperature of 1200°C was sufficient to produce dense ZrB₂‐ZrC_x composites. The improved microhardness, flexural strength, fracture toughness, and specific wear rate were 8.2‐15 GPa, 265‐590 MPa, 2.82‐6.33 MPa.m^1/2, and 1.43‐0.376 × 10⁻² mm²/N, respectively.

中文翻译：

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反应热压制备的ZrB2-ZrCx复合材料的致密化，力学和摩擦学性能

使用Zr：B ₄ C粉末混合物以3：1、3.5 ：1、4：1和5：1的摩尔比通过4-7 MPa的反应热压（RHP）生产ZrB ₂ -ZrC _x复合材料， 1200°C持续60分钟。X射线衍射分析证实了具有不同晶格参数的非化学计量碳化锆（ZrC _x）的形成，并且通过增加Zr摩尔分数提高了碳化物的形成。施加压力从4 MPa增加到7 MPa可以使4Zr：B ₄ C组成的相对密度（RD）从86％提高到99％。对富含Zr的复合材料的微观结构研究表明，未反应的B ₄ C颗粒减少，而伸长的ZrB ₂富集血小板。研究了在施加7 MPa恒定压力下，温度从600升高到1200°C时4Zr：B ₄ C组成中的反应和致密化机理。在1000℃之后，在致密化过程中观察到＜40vol。％的未反应的Zr。同时，发现低能量的碳扩散和碳空位形成增强了非化学计量的ZrC _x形成，这被认为是反应完成的原因。未反应的Zr的塑性变形是ZrB ₂ -ZrC _x致密化的原因综合。结果清楚地表明，施加的压力比报告的值低五倍。此外，1200°C的温度足以生产致密的ZrB ₂ -ZrC _x复合材料。改善后的显微硬度，抗弯强度，断裂韧性和比磨损率分别为8.2-15 GPa，265-590 MPa，2.82-6.33 MPa.m ^1/2和1.43-0.376×10 ^-2 mm ² / N。