【摘要】 采用热压烧结工艺制备出口无锥度(直口)和出口带锥度(锥口)2种Al2O3/TiC陶瓷水煤浆喷嘴,在工业锅炉上研究其热冲击行为,采用扫描电子显微镜分析喷嘴磨损表面形貌和微观组织结构,利用有限元法分析喷嘴的温度场和热应力.结果表明:陶瓷水煤浆喷嘴的出口结构对其热冲击行为影响很大,锥口喷嘴因所受热辐射面积小于直口喷嘴,内部的温度梯度和热应力较低,表现出较好的抗热冲击性能;Al2O3/TiC陶瓷喷嘴的温度梯度和热应力由入口到出口逐渐增大,出口部位的较高温度梯度和热应力是导致其磨损失效的主要原因;Al2O3/TiC陶瓷喷嘴的磨损形式表现为脆性断裂、研磨损伤、热裂纹和热崩等特征,其中热裂纹和热崩为主要磨损形式.更多还原

【Abstract】 Al2O3/TiC ceramic coal water slurry(CWS) nozzles were fabricated by hot-pressed technique,and their thermal shock behavior in the CWS industrial boiler was investigated.The eroded bore surface morphologies of the nozzle were examined with scanning electron microscopy.Finite element method was used to study the temperature and thermal stress field.The results showed that exit structure of nozzle played an important role in its thermal shock behavior.The nozzle with taper structure at exit decreased the area facing the elevated temperature environment,result in remarkably decreasing temperature gradient and thermal stresses inside nozzle,and it exhibited better performance over the one without taper in decreasing thermal shock damage.The temperature gradient and thermal stress of Al2O3/TiC ceramic nozzle varied with nozzle zones,while greater temperature gradient and higher thermal stress at exit zone were the main reason that caused the nozzles failure.The wear features of Al2O3/TiC ceramic nozzles consisted of brittle fracture,polishing,thermal cracking and chipping,while the thermal cracking and chipping at exit were the primary wear mechanism of nozzles.更多还原