本文分别采用聚合物先驱体转化法和硼酸-尿素法在纤维表面制取C(碳)涂层和BN(氮化硼)涂层，接着通过粉末冶金方法(模压成型+无压烧结)制备了短C纤维及其C涂层或BN涂层(简写为C/BN涂层)形式的弱界面涂覆碳纤维增强的TiCN基金属陶瓷基体复合材料(Cf/TiCN复合材料)。研究了浸渍液浓度、浸渍次数、裂解温度对C纤维表面涂层沉积效果的影响。通过对复合材料组织结构以及性能等的深入表征、分析，探究了弱界面层的引入对C纤维复合的TiCN基金属陶瓷材料的增韧机理与断裂机制的影响。研究结果表明： (1)优化的C涂层制备工艺为：40 g/L的酚醛树脂浸渍液、最终700 ℃保温1 h裂解，此工艺制备的C涂层可覆盖于纤维的大部分表面上，C纤维表面上的缺陷大大地减少，涂层均匀、致密，与纤维结合良好，显示出优良的沉积保护效果，纤维的分散状态也比较良好。优化后的BN涂层制备工艺为：2 mol/L的浸渍液浸渍2次、最终950 ℃保温2 h裂解，此条件下所得的BN涂层可覆盖纤维的大部分表面，碳纤维表面的缺陷大大减少，涂层均匀、致密，与纤维结合良好，涂覆保护效果良好。 (2)未添加C纤维的金属陶瓷主要由TiCN、Ni、(Cr,Mo,W,Ti)(CN)、W2C和Mo2C相组成。添加4 wt.%未涂覆涂层的C纤维后，材料主要由TiCN、(Cr,Mo,W,Ti)(CN)与Ni相组成，并且除C纤维以非晶形式存在外，其余的相均以晶态的形式存在。而添加C涂层、BN涂层涂覆的C纤维后，材料组织中分别出现了少量新相Ni3C、BCN。 (3)未添加纤维的试样，其断口组织大多表现为沿晶的脆性断裂，而添加纤维以及涂层改性纤维的试样断口出现大量的穿晶型的韧性断裂，其中添加C涂层改性纤维的试样断口组织有一定程度上的粗化，BN涂层改性纤维的试样断口组织却比较细小、致密。在添加有未涂覆涂层碳纤维的试样中没有发现明显的纤维状组织，而在添加涂层碳纤维的试样中发现明显的纤维组织，这说明C涂层和BN涂层确实对碳纤维起到了一定的弱界面层保护作用，使得用其所增强的复合材料在断裂时消耗更多的断裂能，最终改善了材料的强韧性能。在1480 ℃条件下烧结的试样，其中添加BN涂层改性纤维的T-BN1试样的抗弯强度为1073.31 MPa，综合强韧性能优于1500 ℃条件下制备的试样。

The C and BN (or C/BN in short) surface coatings were coated by precursor infiltration and pyrolysis (PIP) and boric acid-urea method, respectively, and then the titanium carbonitride-based (TiCN-based) cermet composites (Cf/TiCN composites) reinforced by short carbon fiber (Cf) and the coated Cf weak interfacial layer were prepared by powder metallurgy method (compression moulding forming + pressureless sintering) in the present research. The effects of dipping solution concentration, dipping times and pyrolysis temperature on the quality of the coatings deposited on Cf were studied. Besides, the influence of the weak interfacial layer which had been introduced onto Cf on the toughening mechanism and fracture mechanism of Cf/TiCN composites was explored, by in-depth analyzing the density, porosity, microstructure, phase composition, and mechanical properties of the Cf/TiCN composite, The main results of this research are as follows. (1)The optimized C coating preparation process was finally determined as: 40 g/L phenolic resin impregnation solution, final pyrolysis temperature of 700 ℃ (1 h). And the C coating prepared with this process could be covered on the majority of the fiber surface, with excellent coating uniformity and compactness as well as fine interface bonding between the C coating and the fiber, the defects on the Cf surface were greatly reduced , and the fiber dispersion was relatively good, showing a better protective deposition effect. While, the optimized BN coating preparation process should be 2-mol/L impregnating solution impregnated for two times and finally pyrolysised at 950 ℃ for 2 h, and then BN coating could be covered on the majority of the fiber surface, with excellent coating uniformity and compactness and fine interface bonding between and the fiber, and the defects on the Cf surface were greatly reduced, showing a better protective deposition effect. (2)The cermet composite without Cf was mainly composed of phases like TiCN, Ni, (Cr, Mo, W, Ti) (CN), W2C, and Mo2C. The composite contained 4 wt.% non-coated Cf was composed of main phases including TiCN, (Cr, Mo, C, W, Ti) (CN) and metallic phase Ni, and the remaining phases existed in the form of crystalline form while carbon fiber in the amorphous form. Whereas, a small amount of new phase Ni3C, BCN formed separately in the composites with C- and BN- coated Cf introducing. (3)The fracture microstructure level sense of the cermet composite without adding fiber was not obvious, ans most of the fracture showed brittle intercrystalline fracture. However, lots of flexible transgranular fracture formed at the fracture of the composite adding Cf and C and BN coating modified Cf, among which the fracture of the composite with C-coated Cf had a certain degree of coarsening while the fracture of the composite with BN-coated fiber was relatively small and dense. No evident fibrous microstructure was found at the fracture of the composites without Cf, while carbon fibers could be remarkably observed at the fracture of the composites with coated Cf, illustrating that the C and BN coating indeed played a excellent protective effect on the carbon fiber, specifically worked as the weak interface layer, and thus the composites with coated Cf would consume more fracture energy when the composites were broke, and ultimately the strength and toughness of the composites were improved. The comprehensive strength and toughness performance of those specimens sintered at 1480 ℃, among which the composite with BN-coated Cf (T-BN1) presented the flexural strength of 1073.31 MPa, was better than that of those sintered at 1500 ℃.