熱量傳輸與凝固行為
(1. 北京科技大學材料科學與工程學院，北京100083;
2.寧夏大學物理與電氣信息工程學院，銀川750021;
3. 鋼鐵研究總院，北京100081)
摘 要: 建立了在等離子旋轉電極霧化（PREP）制取合金粉末的過程中霧化熔滴的軌道運動方程，討論了霧化熔滴在凝固過程中的熱量傳輸與凝固行為，并確定了定量計算換熱系數(shù)所需的霧化熔滴初始速度。用數(shù)值求解方法計算了FGH95高溫合金霧化熔滴在PREP過程中的速度及其在凝固過程中的溫度、固相分數(shù)、冷卻速率等凝固參數(shù)。結果表明：在作者提出的工藝參數(shù)下，F(xiàn)GH95合金熔滴的冷卻速率達104K/s量級以上,合金過熱度對冷卻速率的影響主要在全液態(tài)階段， 而冷卻速率和固相分數(shù)對氬氦氣體的混合比例極其敏感。
關鍵字: 等離子旋轉電極法；快速凝固；FGH95合金粉末；數(shù)值計算
behavior ofdroplets during plasma rotating electrode processing
（1. University of Science & Technology Beijing，
Beijing 100083，China;
2. Ningxia University，Yinchuan 750021，China;
3. Central Iron and Steel Research Institute，
Beijing 100081，China）
Abstract:A mathematical model to describe flight trace of droplets atomized by plasma rotating electrode processing PREP was established, and the heat transfer and solidification behavior of the droplets during PREP discussed was based on Newtonian heat transfer formulation coupled with the classical heterogeneous nucleation. With the application of the differential method of Newton fluid dynamics，the initial velocities of droplets correlated to the heat transfer coefficients were determined. Using numerical method，the droplet velocity，droplet temperature，and fractional solidification with flight time about FGH95 superalloy droplet were predicted based on mathematical model. The results show that the cooling rate of FGH95 superalloy droplet reaches above 104K/s order of magnitude，and the effect of droplet superheat taking on the droplet solidification behavior is mainly in the fully liquid stage，while the cooling rate of the droplet is sensitive to the proportion of mixed cooling gas.
Key words: plasma rotating electrode process;rapid solidification; FGH95 droplet；numerical analysis
