水分对三乙胺法冷芯盒砂芯强度及断裂的影响

Influence of Moisture on Strength and Fracture of Cores Produced with Triethylamine Cold-Box Process

研究了水基涂料和环境湿度对三乙胺法冷芯盒砂芯强度的影响,并利用扫描电镜分析了砂芯断口。结果表明：（1）水基涂料使砂芯24h终强度显著下降,下降幅度随树脂加入量的增加而减少;存放1~6h后浸涂的砂芯强度低于即时浸涂强度和24h浸涂的砂芯强度。（2）在常温高湿环境下,随着砂芯存放时间的延长,砂芯强度出现显著的下降;在40℃、RH100%的环境下,砂芯的强度在5h达到最大值,随后砂芯的强度随放置时间的延长迅速下降。（3）低湿环境树脂粘结桥断口为以内聚断裂为主的复合断裂;而高湿环境里存放的砂芯,水分使树脂粘结桥出现裂纹、砂芯呈附着断裂。

The influence of water-base coating and environmental moisture on the strength of the cores produced with triethylamine cold box process was investigated, and the fracture of cores was analyzed with SEM. The result showed： （1）The water base coating caused obvious strength decreasing of the cores held for 24 h and the decreasing extent reduced with increasing of the resin addition. The strength of the cores soaking-coated after 1～6 h helding was lower than the strength of the cores soaking-coated without helding and after 24 h helding.（2）Under the environment of high temperature and high Influence of Moisture on Strength and Fracture of Cores Produced with Triethylamine Cold-Box Process YU Guang-yuan1,CAI Qi-zhou1,ZHU Xiao-long2,ZHOU Chu-qing2,YU Chang-jian2 （1.State Key Laboratory of Material Processing and Die Mould Technology of Huazhong University of Science Technology,Wuhan 430074,China; 2.No.1 Foundry Plant,Dongfeng Motor Co. Ltd., Shiyan 442048,China） Abstract： The influence of water-base coating and environmental moisture on the strength of the cores produced with triethylamine cold box process was investigated, and the fracture of cores was analyzed with SEM. The result showed： （1）The water base coating caused obvious strength decreasing of the cores held for 24 h and the decreasing extent reduced with increasing of the resin addition. The strength of the cores soaking-coated after 1～6 h helding was lower than the strength of the cores soaking-coated without helding and after 24 h helding.（2）Under the environment of high temperature and high humidity the core strength obviously decreased with prolonging of its holding time： under the environment of 40 ℃ and RH 100%, the core strength reached maximum at 5 h, and then the strength rapidly decreased with prolonging of holding time. （3）under low humidity environment, the fracture of the adhesive bridge of the resin was presented as composite fracture with cohesive fracture as its main part; whereas, for the sand cores held under high humidity environment, the moisture caused crack in the adhesive bridge of the resin, and the core presented adhere fracture.