Enhancement of Thermal Strength and Corrosive Resistance for Rotating Cylindrical Tubes Made of FGC and FGM Using CVD-SiC and T91 When Subjected to High-temperature Sources of Gaussian Laser Boundaries

旋轉圓管熱焠火工藝應用於碳化矽與T91合金傳統功能複合材料與功能材料強化結構之抗熱強度與抗腐蝕提升

Hsin-Yi Lai(賴新一) ； Kai-Chien Lo(羅凱謙)

《中國機械工程學刊》 44卷2期 (2023/04) Pp. 121-132

摘要

Materials such as CVD-SiC and T91 martensitic-ferritic are widely used as nuclear fuel cladding base material for LWRs (light water reactors) due to their excellent high temperature and corrosive resistance under critical environmental conditions. This study is geared towards investigation of the functional graded composites (FGC) of CVD-SiC-Fe_(12)Cr_2Si and the functional graded material (FGM) of T91-Fe_(12)Cr_2Si, respectively, to meet the needs of thermal impact of LWR industry. The work-piece in a wide range of high temperature environment from 20°C to 1200°C is implemented and simulated using a 3D rotating cylindrical tube and a 2D cylindrical model with a laser quenching boundary. The linear rule of mixture and Wakashima-Tsukamoto estimate are the main algorithms of FGM in this study. The continuous material property distribution of FGM material can prevent stress concentration and non-continuous problem of diffusion in the rotating cylindrical tube and the associated 2D cylindrical model. Moreover, the silicon concentration of the 2D cylindrical model on the inner surface can be transformed to an oxidized layer, which enhances the corrosive resistance of FGC and FGM models. The margin of safety calculated by the tresca stress is also promoted when the volume mixture number of FGM material is increased, and the materials are designed based on the Fe_(12)Cr_2Si- SiC model. This result shows the Fe_(12)Cr_2Si-SiC FGM model with a volume mixture number of three is an ideal material component for nowadays fuel cladding design being aware of LBLOCA problem.

關鍵字

functionally graded material ； maximum shear stress ； corrosion resistance

並列摘要

CVD-碳化矽和T91馬氏體－鐵素體合金被廣泛認為是輕水型反應堆（LWR）的核燃料管道不可或缺之重要基材。由於在該材料高溫環境下具有優異的高溫和耐腐蝕性。本文旨在分別研究CVD-碳化矽- Fe_(12)Cr_2Si和T91-Fe_(12)Cr_2Si功能性梯度複合材料（FGC）和功能性梯度資料（FGM）。應用於具有雷射淬火邊界的3D旋轉圓柱結構與高溫致1200℃的2D圓柱模型用以模擬在20℃～1200℃環境中的核反應爐管道工作情形。在本研究中，線性體積分率法與Wakashima-Tsukamoto演算法是FGM之主要演算法。FGM材料的連續性分佈可以防止旋轉圓柱管和二維圓柱模型中的應力集中和不連續擴散係數與濃度分布問題。二維圓柱模型管內表面的矽濃度可以轉化為氧化層，從而防止LBE等冷卻液在通過原管內部時進一步侵蝕FGC和FGM模型的內層結構。當FGM的體積分率值逐漸增加並且結構為Fe_(12)Cr_2Si-SiC之設計時，由最大剪應力理論計算的安全裕度也隨之提高。根據研究成果顯示，體積分率值為3的情況下Fe_(12)Cr_2Si-SiC的功能性材料模型是當今輕水型核反應爐管道設計的理想結構組合，該研究成果亦考慮到了LBLOCA意外發生時超過1000℃高溫之問題。