2A12铝合金微弧氧化膜的高温氧化性能

对2A12铝合金表面的微弧氧化膜进行了高温氧化实验研究。结果表明：微弧氧化膜层的高温抗氧化性能随着温度的升高而降低,但氧化指数均在2以上,说明微弧氧化膜层对于2A12铝合金起到了保护作用,有效地阻止了高温氧化时的氧扩散。微弧氧化膜层抗空冷热震性能要优于抗水冷热震性能,在60次热震循环后,水冷热震的合金边角处出现膜层脱落现象,而空冷热震的合金只在表面出现裂纹,没有膜层脱落现象出现。微弧氧化膜热震失效主要由膜层与基体热膨胀系数不同、膜层与H₂O、氧气反应分别生成氢氧化物与氧化物所导致;膜层内部的CeO₂起到减小孔径的作用,在热震反应初期能够有效地降低热震对膜层的影响,但随着循环次数增多,生成碱式碳酸盐和氢氧化物,导致微弧氧化膜失效。     

声场对气固流化床气泡动力学特性的影响

气泡行为对气固流化床的流体力学特性和热质传递特性起着决定性作用,气泡的动力学特性是气固鼓泡流化床反应器模拟计算及设计放大的重要参数.将声场引入传统流化床,利用声波能量促进颗粒运动和气泡破碎,以改变气泡的动力学行为,从而达到改善床层流化状态,强化传热传质的目的.因此,研究声波对气泡动力学特性的影响是把握声场流化床的关键....     

基于均匀设计法的燃烧型焊条立焊配方优化

手工自蔓延焊接技术因在野战应急抢修方面的独特优越性而受到广泛关注.主要针对因自蔓延燃烧型焊条焊接原理的特殊性及配方各组分之间的复杂相互作用而使得应用普通自蔓延焊条施行立焊作业的焊接状况较差的实际情况,提出应用均匀设计方法对自蔓延燃烧型焊条的配方进行优化设计,通过借鉴燃烧型焊条焊接性能快速评价表对实验结果进行评价,并利用均匀设计软件对所得实验结果进行回归分析,经过适当的调整和添加其他添加剂后获得适用于立焊的燃烧型焊条优化配方.实验表明,应用经优化配方后的焊条施行立焊作业时,焊接效果较普通燃烧型焊条得到大幅提高,使手工自蔓延焊接技术的应用领域得到进一步推广.     

磁铁矿对超高密度水泥浆体系性能的影响

针对钻探深井超深井过程中的高温高压固井问题,研制一套抗高温超高密度水泥浆体系。该水泥浆体系由磁铁矿粉、降失水剂FS-23L、分散剂SXY-2、缓凝剂HX-31L配制而成。通过对超高密度水泥浆流变性、流动度、沉降稳定性和抗压强度等的评价,得到磁铁矿加重剂的优选加量范围,以及适应循环温度150℃的综合性能良好的水泥浆配方。     

液态金属高温热管传热极限研究

热管作为一种高效可靠、可进行长距离传热的非能动设备,在核能领域有着广泛的应用。本文针对工质为钠、充液量为158 g与208 g的毛细驱动热管,对其传热极限开展实验和理论研究。实验方面,设计搭建了高温热管传热极限测试分析实验平台,研究了液态金属高温热管在不同水平倾角和不同加热功率下传热功率的变化。理论方面,验证了连续流动极限与夹带极限理论模型的正确性,总结了两种极限的发生规律。研究发现,热管连续流动极限影响热管的启动;由于水平夹角较大时转变温度较高,因此大角度下的热管更容易发生连续流动极限,小角度下经验模型的预测误差在6.58%以内,大角度下误差超过28%。夹带极限发生时热管蒸发段温度骤升且冷凝段温度出现波动,热管倾角越大夹带极限越容易发生,经验模型在不同角度下均存在误差,大角度下误差超过100%。本文总结了连续流动极限与夹带极限的发生规律,为先进核反应堆系统中热管的设计提供参考。     

高尺寸稳定性的MgAl2O4/MgO复合陶瓷型芯的制备

本文以镁铝尖晶石(MgAl2O4)为原料,制备了新型MgAl2O4/MgO复合陶瓷型芯。用X射线衍射仪(XRD)分析了样品的相组成,并用扫描电子显微镜(SEM)观察了陶瓷型芯的表面和断面微观形貌。结果表明,陶瓷型芯中的主晶相为镁铝尖晶石,次晶相为方镁石,镁铝尖晶石为陶瓷型芯骨架,骨架大颗粒之间填充有细方镁石颗粒。性能测试证实,添加镁铝尖晶石可抑制氧化镁的液相烧结,降低收缩率,同时可以显著提高陶瓷型芯的显气孔率和高温尺寸稳定性。含有60wt%镁铝尖晶石的MgAl2O4/MgO复合陶瓷型芯显气孔率为38.24%、收缩率为1.99%、室温抗弯强度为25.9 MPa、热膨胀率仅为1.61%。溶出实验结果表明,所制备的MgAl2O4/MgO复合陶瓷型芯能在温和条件下溶出,不对铸件造成化学腐蚀及机械损伤：在溶出液为20wt%有机弱酸乙酸溶液中,90 ℃溶出6 h后,型芯能够完全塌陷成粉末。     

Creep Properties with Short Period Excessive Loadings on a Nickel-Base Heat-Resistant Alloy Hastelloy XR

A series of constant load & temperature creep tests and constant temperature creep tests with short period excessive loadings was carried out on a nickel-base heat-resistant alloy Hastelloy XR, which was developed for applications in the High-Temperature Engineering Test Reactor (HTTR), at temperatures ranging from 900 to 1,000°C. The excessive loading levels were set at the design stress intensity values Sm for Hastelloy XR indicated in the HTTR high-temperature structural design code.

Five to six time excessive loadings did not cause significant changes of the minimum creep rate or the time to onset of tertiary creep. Excessive loadings repeated around ten times did not cause significant changes of the time to rupture or the rupture elongation. The results suggest that the design stress intensity values Sm for Hastelloy XR have been determined reasonably.     

HTR-ESS的堆芯物理仿真方法研究

为满足高温气冷堆工程模拟仿真系统（HTR-ESS）中实时的要求,研究开发了三维圆柱几何堆芯多群中子时空动力学改进准静态方法模拟计算程序,使中子动力学程序满足模拟过程的实时要求。模型利用拟合公式计算宏观截面,使截面可实时反映堆芯状态,与堆芯热工形成反馈。针对高温气冷堆中控制棒的特点,提出使用等效吸收体的方法对控制棒进行等效,等效方法避免了在计算中出现控制棒移动与网格不匹配的问题。最后给出动态过程的简单模拟结果,显示了建立的堆芯物理实时计算模型满足设计条件和要求。     

Development of a Suppression Method for Deposition of Radioactive Cobalt after Chemical Decontamination: (I) Effect of the Ferrite Film Coating on Suppression of Cobalt Deposition

In the last decade, chemical decontamination at the beginning of periodical inspection has been applied to many Japanese BWR plants in order to reduce radiation exposure. However, following the chemical decontamination, a rapid dose rate increase can be seen in some plants after just a few operation cycles. Oxide film, which easily incorporates radioactivity, might be formed after the chemical decontamination. We developed a new way to reduce the recontamination after the chemical decontamination to maintain long-term continued decontamination effects without any chemical injections or chemical controls in reactor water during operation. In our approach, a fine ferrite film is formed by the Hitachi Ferrite Coat process after oxide films formed during the plant operation are removed by the chemical decontamination process.We select Fe(HCOO)₂ aqueous solution, H₂O₂, and N₂H₄ as the treatment chemicals for fine ferrite film formation for suitable BWR plant application. Our laboratory experiment results confirm a ⁶⁰Co deposition reduction effect of 1/5 compared with that of nontreatment for up to 3,100 hours. The fine ferritefilm that was formed on the specimen before the ⁶⁰Co deposition test remains as a film structure after the test. The corrosion amount of the specimen is suppressed to 1/4 through the effect of the fine ferrite film.