SiC/(W,Ti)C梯度陶瓷喷嘴材料的制备及其冲蚀磨损机理研究

针对陶瓷喷嘴磨损特点,在喷嘴材料的设计和制造中提出运用梯度功能材料理论,通过控制陶瓷喷嘴材料的成分分布以实现其力学性能的合理梯度变化,将梯度陶瓷喷嘴材料制备过程中所产生的残余压应力引入喷嘴入口以提高喷嘴入口的力学性能,从而缓解喷嘴入口的高应力,提高其抗冲蚀磨损能力.采用热压烧结工艺制备SiC/(W,Ti)C梯度陶瓷喷嘴材料并分析其冲蚀磨损机理.结果表明,在相同冲蚀磨损条件下,梯度陶瓷喷嘴材料的抗冲蚀磨损性能较非梯度陶瓷喷嘴材料显著提高,这是由于梯度陶瓷喷嘴应力状态的改善及其力学性能提高的缘故.梯度陶瓷喷嘴材料的磨损机制为入口处呈现疲劳断裂、中间呈现微切削、出口处呈现疲劳断裂和脆性断裂特征.

Development of SiC/(W,Ti)C Gradient Ceramic Nozzle and Study on Its Erosion Mechanism

Idea of functionally gradient material(FGM) theory was used to the design of ceramic nozzle.The purpose was to reduce the stress at the entrance of the nozzle during abrasive jet machining process.The stress states of the nozzle were analyzed by finite element method.Results show that the minimum stress appeared in entrance area of the gradient ceramic nozzle,and so SiC/(W,Ti)C gradient ceramic nozzle were produced.The erosion behavior of the SiC/(W,Ti)C gradient ceramic nozzle was investigated in comparison with common ceramic nozzles.The SiC/(W,Ti)C gradient ceramic nozzles exhibited an apparent increase in erosion wear resistance over the common ceramic nozzles under the same test conditions.This is because that the stress state at gradient ceramic nozzle was changed and its mechanical properties were improved.The wear mechanism of gradient ceramic nozzle was fatigue and fracture at nozzle entrance,micro-cutting between extrance and exit,and fracture due to fatigue and brittle fracture.