【摘要】 石墨铸造模具因其高熔点、低热膨胀系数、良好导热性、化学稳定性强，在铸造生产中得到了广泛的应用，但裸石墨内壁在服役过程中普遍存在高温氧化、碳扩散、熔融金属或气体渗透、机械强度与耐磨性不足等一些问题，因此在石墨内壁引入防护涂层（Graphite Barrier Coating,GBC）成为提升其服役寿命和可靠性的关键技术路径。然而在进行内壁喷涂过程中，由于空间封闭，热源集中且热量不易逸散，这使得内壁喷涂过程中的温度场控制变得尤为关键。由于通过实验测量很难捕捉喷涂过程中石墨模具的全场温度分布，因此本文采用有限元方法构建了石墨模具在高能长层流等离子喷涂三次加热过程中的数值传热模型，计算得到了三次扫描下基体的瞬态温度场分布。在三次加热过程中，石墨管模型最高温度分别达到414、483、502℃，石墨管内径45 mm时径向温度梯度最大为4.45℃，石墨管长度200 mm时轴向温度梯度最大为199℃。同时将本次数值模拟的温度场变化与实际实验过程中的两次温度变化进行对比，误差分别为1.58%和3.97%，随后对数值计算模拟与实际实验过程中的误差来源进行了分析。通过对内壁喷涂温度场进行系统的数值模拟，为以后喷涂参数优化、基体保护及高可靠涂层制备提供了理论依据。更多还原

【Abstract】 Graphite casting molds have been extensively utilized in casting production due to their high melting point,low coefficient of thermal expansion,favorable thermal conductivity,and robust chemical stability. However,bare graphite inner walls commonly encounter several issues during service,including high-temperature oxidation,carbon diffusion,penetration by molten metals or gases,and inadequate mechanical strength and wear resistance. Consequently,introducing barrier coatings onto graphite inner walls has emerged as a key technical pathway for enhancing service life and reliability. Nevertheless,during internal wall spraying processes,the enclosed space,concentrated heat source,and hindered heat dissipation render temperature field control particularly crucial. Given that experimental measurements struggle to capture the full-field temperature distribution of graphite tubes during the spraying process,this study employed the finite element method to develop a numerical heat transfer model of the graphite tubes subjected to the three-pass heating process in high-energy long laminar-flow plasma spraying. The transient temperature-field distribution of the graphite tube during three scanning passes were calculated. During the three heating processes,the peak temperatures of the graphite tube model reached 414 ℃,483 ℃ and 502 ℃,respectively. The maximum radial temperature gradient of the graphite tube reaches 4. 45 ℃ at an inner diameter of 45 mm,while the maximum axial temperature gradient reaches 199 ℃ at a tube length of 200 mm. Furthermore,the temperature field evolution obtained from this numerical simulation was concurrently compared with two temperature variations measured during the actual experimental process,yielding discrepancies of 1. 58% and 3. 97%,respectively. Subsequently,an analysis of the error sources between the numerical simulation and the experimental process was conducted. Through the systematic numerical simulation of the temperature field during internal diameter spraying,a theoretical foundation has been established for future optimization of spray parameters,substrate protection,and fabrication of highreliability coatings.更多还原