含氮化硼复相陶瓷反应烧结新途径的构建与性能提升

复相含氮化硼陶瓷（BNCC）无压烧结难于致密化，而热压烧结又容易引起BN晶粒各向异性生长，导致加工成本提高和使用可靠性下降，本项目着重研究和解决以上问题。通过新颖的原位反应设计获得产物组分连续可调的BNCC新体系。以过渡金属氮化物为前躯体，通过其硼化过程引发自蔓延反应, 得到氧含量低的BN纳米片包裹的硼化物超细粉体, 来尝试解决其无压烧结致密化困难的问题；通过原位反应烧结BNCC中致密化先于hBN择优取向形成的特点，来尝试解决BNCC压力烧结过程中hBN择优取向带来的材料性能各向异性的问题；通过实现纳米BN在基体晶粒内生长并实现BNCC的强韧化和可加工性。全面评价材料的力学性能、热学性能以及与熔融金属的润湿行为等。该研究不仅会丰富反应烧结的研究内容，也将增强对BNCC制备与服役过程中的基础科学问题的进一步认识，为BNCC在冶金领域的应用提供知识积累和技术支撑，促进基础研究走向应用。

Boride Nitride Containing Ceramics (BNCC) are hard to be densified by presureless sintering. It is feasible to densify BNCC under pressure, however the anisotropic growth of hBN grains normally takes place at the same time. The later will cause the increase of the cost for machining BNCC, which also reduce their reliability during service. The project aims to solve these aforementioned issues. The compositions in BNCC could be tuned by designing a novel reactive sintering system. Using transition metal nitride as an inorganic precursor, potential.Self-propagating high-temperature synthesis (SHS) reactions could be ignited by its boronizing process. Nanosized hBN coated boride powders with extremely low oxygen content could be obtained via this process, this powder is supposed to be useful for enhancing the pressureless densification of BNCC. During reactive sintering, the densification of BNCC could start in prior to the grain alignment of hBN, this feature will be adopted to solve the anisotropic grain growth of hBN in BNCC. The strengthening and machinability of BNCC could be improved by the formation of nanosized hBN in the matrix grains. This research will also evaluate the mechanical and physical properties of BNCC comprehensively, including the wetting ability between BNCC and molten metals. The planned research will not only enrich the scope of reactive sintering, it will strengthen the understanding of the fundamental knowledge on the fabrication of BNCC and its performance during service. The research will provide the knowledge accumulation and technical support for BNCC, especially for its application in metallurgy, and bridge the fundamental research to industrial application.