聚变堆第一壁涂层材料TiC和TiN的残余应力研究

采用Ｘ衍射法测定了聚变堆第一壁涂层材料ＴｉＣ和ＴｉＮ薄膜的残余应力．对涂层材料不同的制备方法（化学气相沉积ＣＶＤ和物理气相沉积ＰＶＤ）、基体材料（Ｍｏ、石墨和３１６ＬＳＳ）、涂层厚度及沉积温度对残余应力的影响进行了研究．结果表明，ＣＶＤ与ＰＶＤ制备的涂层的残余应力均为压应力，且ＣＶＤ较ＰＶＤ产生的残余应力要低，Ｔｉ／Ｍｏ（ＣＶＤ）随涂层厚度（１４μｍ～６０μｍ）的增加，残余应力增加．ＰＶＤ涂层的残余应力主要为本征应力，高达数ＧＰａ．其值随沉积温度（２００℃～６５０℃）的升高而降低．对残余应力产生的原因作了初步讨论     

Al2O3化学气相沉积工艺研究

采用ＡｌＣｌ３Ｈ２ＣＯ２化学气相沉积（ＣＶＤ）系统，在不同ＣＶＤ工艺条件下，氧化铝被沉积在预涂层ＴｉＣ的３１６ＬＳＳ、石墨和钼基体上。氧化铝涂层经ＳＥＭＸｒａｙ和电子能谱分析表明：该涂层为正化学计量致密Ａｌ２Ｏ３。工艺研究表明：温度升高使Ａｌ２Ｏ３沉积速率迅速增加；ＡｌＣｌ３浓度达２％左右，沉积速率增加缓慢；ＣＯ２浓度小于１０％时，沉积速率迅速下降。     

复合膜对316L不锈钢氚渗透性能的影响

利用物理气相沉积（ＰＶＤ）方法在３１６Ｌ不锈钢表面分别镀制微米量级厚的ＴｉＮ＋ＴｉＣ＋ＴｉＮ、ＴｉＮ＋Ｔｉｃ＋ＳｉＯ２复合膜。扫描电镜观察表明：膜致密,与基体结合牢固,抗氧化,抗热冲击。二次离子质谱（ＳＩＭＳ）和红外光谱（ＩＲ）分析结果证实：ＴｉＣ和ＳｉＯ２的膜在３００℃以上的氢中退火可形成抗氚爱阻挡层。测量了不同温度下氚在带膜３１６Ｌ中的渗透率。在２００～６００℃范围内,镀有ＴｉＮ＋ＴｉＣ＋Ｓｉ     

一个研究聚变中子辐照损伤的蒙特卡罗程序

文章描述计算机模拟聚变中子辐照损伤的蒙特卡罗程序。该程序适用于含轻，重核素的非晶态复合材料及能量低于１５ＭｅＶ的中子和各种能量的离子。文中给出辐照后靶原子Ｆｅ，Ｃｒ，Ｎｉ，Ｍｏ，Ｗ，Ｓｉ，Ｃ的ＤＰＡ截面，ＰＫＡ能谱和发射角分布的计算结果，并给出作为混合堆第一壁材料的３１６ｓｓ，钨，石墨，碳化硅化移损伤率的气体产生率。     

合金添加剂Si和Ti对316不锈钢辐照肿胀作用的研究

用ＨＶＥＭ在１ＭｅＶ和５５０℃下原位研究了Ｓｉ和Ｔｉ对３１６不锈钢照肿胀的影响。含１％Ｓｉ的３１６钢在辐照剂量≤１１ｄｐａ时作含０．１％Ｔｉ的一样，能强烈抑制辐照肿胀。但在〉１１ｄｐａ后，含１％Ｓｉ的３１６钢肿胀率远大于未含添加剂的对比钢样吕，含０．５％Ｔｉ能完全抑制辐照空洞产生，但诱导了Ｔｉ析出物，１％Ｓｉ的３１６钢肿胀率远大于未含添加剂的对比钢样品，含０．５％Ｔｉ能完全抑制辐照空洞产生，但诱导     

聚变中子引起的嬗变α、p粒子研究

计算了聚变堆常用结构材料３１６Ｓ．Ｓ．、ＳｉＣ、石墨及其所含核素的嬗变α、ｐ粒子的产额、气体产生率、氦产生率与原子位移率比值Ｈｅ／ｄｐａ（ｄｐａ－ｄｉｓｐｌａｃｅｍｅｎｔｐｅｒａｔｏｍ）、能谱分布以及它们对材料ｄｐａ的贡献和嬗变α粒子在３１６Ｓ．Ｓ．中的电子能量损失。计算结果表明，嬗变α、ｐ粒子对靶材料ｄｐａ的贡献虽然很小，但α粒子在输运过程中电子能量损失很大。对含轻、重核素不同的材料，它们的能谱分布有明显不同，主要取决于反应能和靶原子量。计算结果将为离子模拟聚变中子辐照损伤提供参数依据。     

紧凑 Tokamak(球形环)聚变堆第一壁及中心导体柱上中子负荷及核热计算与分析

采用通用蒙特卡罗粒子输运程序ＭＣＮＰ／３８计算低环径比Ｔｏｋａｍａｋ（紧凑环或球形环）聚变堆第一壁及中心导体上的中子壁负荷分布和核热沉积分布，并与常规Ｔｏｋａｍａｋ堆第一壁上中子壁负荷分布和核热沉积分布进行比较、分析。结果表明，在中子壁负荷归一化为１ＭＷ／ｍ２时，与常规Ｔｏｋａｍａｋ相比，在低环径比Ｔｏｋａｍａｋ堆第一壁及中心柱表面上中子壁负荷分布峰值并不比常规Ｔｏｋａｍａｋ堆第一壁上的峰值高，而且低于低环径比Ｔｏｋａｍａｋ堆整个第一壁上的平均值，而中心柱上的核热沉积峰值稍高于常规Ｔｏｋａｍａｋ堆第一壁上的核热沉积峰值，但对较高中子壁负荷情况，中心导体柱上的核热沉积和辐照损伤仍可能是比较严重和值得特别研究的问题。     

CMOS运算放大器在不同辐射环境下的辐照响应

介绍了ＬＦ７６５０ ＣＭＯＳ运算放大器在＾６０Ｃｏγ射线,１ＭｅＶ电子了４,７,３０ＭｅＶ不同能量质子辐照环境中的响应规律及＾６０Ｃｏγ射线和１ＭｅＶ电子辐照损伤在室温和１００℃高温条件下的退火特性,探讨了引起ＣＭＯＳ运放在不同辐射环境中辐照响应出现差异的损伤机理,并对ＣＭＯＳ运放电路在不同辐射环境中表现出的与ＣＭＯＳ数字电路不同的响应特征给予了解释。     

CMOS 运算放大器的总剂量辐射响应和时间退火特性

对ＣＭＯＳ运算放大器ＬＦ７６５０进行了１ＭｅＶ电子的电离辐照实验，研究了ＬＦ７６５０的总剂量电离辐射响应特性和抗总剂量辐射水平，并通过研究其辐照后在室温和１００℃高温条件下电离辐照敏感参数随时间的变化关系，分析了在电离辐射环境下ＣＭＯＳ运算放大器的损伤机制及参数失效机理。     

CMOS运算放大器的部剂量辐射响应和时间退火特性

对ＣＭＯＳ运算放大器ＬＦ７６５０进行了１ＭｅＶ电子的电离辐照实验，研究了ＬＦ７６５０的总剂量辐射响应牧场生和抗总剂量辐射水平，并通过研究其照后在室温和１００℃高温条件下电离辐照敏感参数随时间的变化关系，分析了在电离辐射环境下ＣＭＯＳ运算放大器的损伤机制及参数失效机理。     

The formation of tritium permeation barriers by CVD

The effectiveness as permeation barriers of the following CVD coatings have been investigated: TiC (1 to 2 μm in thickness); a bi-layer of TiN on TiC (3 μm total thickness) and CVD A1₂O₃ on a TiN/TiC bi-layer. The substrate materials were TZM (a Mo alloy) and 316L stainless steel in the form of discs of diameter 48 mm and thickness 0.1 or 1 mm. Permeation measurements were performed in the temperature range 515–742 K using deuterium at pressures in the range 1–50 kPa. CVD layers were shown to form reasonably effective permeation barriers. At a temperature of 673 K TiC is around 6000 times less permeable to deuterium than 316L stainless steel.     

Simulation of thermal stress in Er2O3 and Al2O3 tritium penetration barriers by finite-element analysis

The physical vapor deposition method is an effective way to deposit Al2O3 and Er2O3 on 316L stainless steel substrates acting as tritium permeation barriers in a fusion reactor.The distribution of residual thermal stress is calculated both in Al2O3 and Er2O3 coating systems with planar and rough substrates using finite element analysis.The parameters influencing the thermal stress in the sputter process are analyzed,such as coating and substrate properties,temperature and Young's modulus.This work shows that the thermal stress in Al2O3 and Er2O3 coating systems exhibit a linear relationship with substrate thickness,temperature and Young's modulus.However,this relationship is inversed with coating thickness.In addition,the rough substrate surface can increase the thermal stress in the process of coating deposition.The adhesive strength between the coating and the substrate is evaluated by the shear stress.Due to the higher compressive shear stress,the Al2O3 coating has a better adhesive strength with a 316L stainless steel substrate than the Er2O3 coating.Furthermore,the analysis shows that it is a useful way to improve adhesive strength with increasing interface roughness.     

Gas desorption properties of TiC/C compositionally graded coatings on doped graphite

To mitigate carbon contamination from doped graphite (1% B, 2.5% Si, 7.5% Ti) by irradiation of plasma, TiC/C compositionally graded coatings (CGCs) were prepared by chemical vapor deposition. Scanning electron microscopy (SEM) results indicated that the TiC/C CGCs were characterized by avoidances of cracks and loosely bonded particles. Gas desorption results suggested that out gas amount increased with the increase of temperatures. However, it was much lower than that of pure TiC coatings after irradiation for 300 s.     

Development of refractory armored silicon carbide by infrared transient liquid phase processing

Tungsten (W) and molybdenum (Mo) were coated on silicon carbide (SiC) for use as a refractory armor using a high power plasma arc lamp at powers up to 23.5 MW/m² in an argon flow environment. Both tungsten powder and molybdenum powder melted and formed coating layers on silicon carbide within a few seconds. The effect of substrate pre-treatment (vapor deposition of titanium (Ti) and tungsten, and annealing) and sample heating conditions on microstructure of the coating and coating/substrate interface were investigated. The microstructure was observed by scanning electron microscopy (SEM) and optical microscopy (OM). The mechanical properties of the coated materials were evaluated by four-point flexural tests. A strong tungsten coating was successfully applied to the silicon carbide substrate. Tungsten vapor deposition and pre-heating at 5.2 MW/m² made for a refractory layer containing no cracks propagating into the silicon carbide substrate. The tungsten coating was formed without the thick reaction layer. For this study, small tungsten carbide grains were observed adjacent to the interface in all conditions. In addition, relatively large, widely scattered tungsten carbide grains and a eutectic structure of tungsten and silicon were observed through the thickness in the coatings formed at lower powers and longer heating times. The strength of the silicon carbide substrate was somewhat decreased as a result of the processing. Vapor deposition of tungsten prior to powder coating helped prevent this degradation. In contrast, molybdenum coating was more challenging than tungsten coating due to the larger coefficient of thermal expansion (CTE) mismatch as compared to tungsten and silicon carbide. From this work it is concluded that refractory armoring of silicon carbide by Infrared Transient Liquid Phase Processing is possible. The tungsten armored silicon carbide samples proved uniform, strong, and capable of withstanding thermal fatigue testing.     

SiC coating as hydrogen permeation reduction and oxidation resistance for nuclear fuel cladding

Silicon carbide (SiC) coating is one of the countermeasures for the prevention of oxidation and hydrogen embrittlement of fuel claddings because SiC has high resistance of oxidation and hydrogen permeation. Hydrogen permeation and oxidation experiments for the cladding materials with SiC coatings were conducted in unirradiated conditions. The sputtering method was employed to make SiC coatings. In the hydrogen permeation experiment, 316 type of stainless steel (SS316) was used as a base material of the coating. SS316 with SiC coatings showed hydrogen permeation reduction by one order of magnitude. In the oxidation experiments, Zircaloy 4 (Zry-4) and SS316 were used as base materials of the coatings. The weight gain of the Zry-4 specimens with a SiC coating decreased by about one-fifth compared to the uncoated ones at 750 °C and 1200°C. This phenomenon was observed for SS316 at 750 °C as well. The peel-off of the coating was observed in several experiments, and it is considered that the peel-off was caused by the difference of the thermal expansions between coatings and base materials. Thicker coatings showed better oxidation resistance, but thinner coatings showed more tolerance of peel-off.     

Potential of direct metal deposition technology for manufacturing thick functionally graded coatings and parts for reactors components

Direct metal deposition (DMD) is an automated 3D deposition process arising from laser cladding technology with co-axial powder injection to refine or refurbish parts. Recently DMD has been extended to manufacture large-size near-net-shape components. When applied for manufacturing new parts (or their refinement), DMD can provide tailored thermal properties, high corrosion resistance, tailored tribology, multifunctional performance and cost savings due to smart material combinations. In repair (refurbishment) operations, DMD can be applied for parts with a wide variety of geometries and sizes. In contrast to the current tool repair techniques such as tungsten inert gas (TIG), metal inert gas (MIG) and plasma welding, laser cladding technology by DMD offers a well-controlled heat-treated zone due to the high energy density of the laser beam. In addition, this technology may be used for preventative maintenance and design changes/up-grading. One of the advantages of DMD is the possibility to build functionally graded coatings (from 1 mm thickness and higher) and 3D multi-material objects (for example, 100 mm-sized monolithic rectangular) in a single-step manufacturing cycle by using up to 4-channel powder feeder. Approved materials are: Fe (including stainless steel), Ni and Co alloys, (Cu,Ni 10%), WC compounds, TiC compounds. The developed coatings/parts are characterized by low porosity (<1%), fine microstructure, and their microhardness is close to the benchmark value of wrought alloys after thermal treatment (Co-based alloy Stellite, Inox 316L, stainless steel 17-4PH). The intended applications concern cooling elements with complex geometry, friction joints under high temperature and load, light-weight mechanical support structures, hermetic joints, tubes with complex geometry, and tailored inside and outside surface properties, etc.     

Fabrication and characterization of fine-grained 316L steel with 2.0 mass% TiC

Development of fine grain 316L with small amount of TiC for high radiation-tolerant performance was tried considering the fabrication process of thermo-mechanical treatments. The materials obtained are UFG316L+2.0 mass% TiC with the grain size of 90–270 nm, depending on the final annealing temperature from 700 ℃ to 900 ℃. The materials were examined by transmission electron microscopy observation, X-ray absorption near-edge structure spectroscopy, high voltage electron microscope electron irradiation and stress corrosion cracking by crevice bent beam method in high-temperature water with 8 ppm dissolved oxygen. The test results showed that the material is generally of excellent quality. Especially void swelling induced by the electron irradiation at 400 ℃ is less than 1/10 compared to the commercial SUS316L.     

含硼石墨中甲烷的热解吸行为研究

研究了含硼石墨ＧＢ１１０（１０ｗｔ．％Ｂ）甲烷（ＣＨ４）的热解吸谱,发现甲烷的解吸谱主要由３个峰构成,估算出了ＣＨ４不同峰值的解吸激活能。为了弄清含硼石墨中甲烷的形成与解吸机理,分别对高纯石墨ＩＳＯ８８０Ｕ和Ｂ４Ｃ涂层进行了热解吸实验,同时对材料的微观结构进行了分析。经过比较,表明甲烷在含硼石墨中的形成与解吸有３个过程：氢离子注入导致甲烷沿气孔内壁形成,并通过石墨内部的微通道向表面自由扩散;被石墨中Ｂ４Ｃ析出物所俘获的氢原子与Ｂ４Ｃ化合物中的碳原子反应,从而生成甲烷并解吸出来;以及石墨晶格俘获的氢原子与碳原子化学反应产生的甲烷,通过体扩散过程解吸。其中前后两个过程起主导作用。     

Interaction of Ruthenium Tetroxide with Stainless Steel

Research and development (R&;D) on the selection of molybdenum first wall during FY1975–1976 are described. The JT-60 machine parameters are plasma current of 2.7 MA, toroidal magnetic field of 4.5 T, duration time of 5 to 10 s and additional heating power of 20 to 30 MW. From the viewpoint of first wall design, these parameters are more stringent in JT-60 than in medium size tokamaks. Therefore, R&;D on selection of material and structure of the JT-60 first wall was carried out. Initially, comparison between candidate materials were made regarding material, thermal, mechanical and vacuum properties. Molybdenum, pyrolytic graphite (PyG) and CVD-Sic coated graphite (SiC/C) were primary candidate materials. Of these three materials, full-sized trial productions of the first wall were made. High heat load tests with electron beam were carried out to compare thermal shock and thermal cycle properties. Test conditions were heat fluxes of 350 to 1,000 W/cm², duration of 10 s and cycle numbers from 10 to 320. From the test results, many cracks and “crater-like” damage were observed on the surfaces of PyG and SiC/C, but no damage was observed on the Mo surface. Following evaluation of all properties including these results, Mo was selected as primary first wall material for JT-60. Moreover, a trial production of Mo honeycomb structure was done. However, the honeycomb structure was not applied because of the expensive fabrication cost. After the operation of JT-60, the first wall materials (limiter, armor plates and magnetic limiter plate) were changed to graphite in FY1987 in order to reduce severe plasma contamination.     

R&D progress of Korean HCSB TBM

Several R&Ds are being performed for Korean helium cooled solid breeder (HCSB) test blanket module (TBM) in the field of hydrogen isotopes permeation characteristics measurement in the helium purge line, joining technologies of structural materials, breeder pebble materials development, and the measurement of pebble bed characteristics. Electron beam welding for reduced activated ferritic–martensitic (RAFM) steel is evaluated to find optimal welding conditions. Also, a hydrogen permeation measurement apparatus is newly installed for the evaluation of the permeation barrier characteristics of stainless steel and RAFM steels. Two fabrication methods of lithium orthosilicate pebbles are investigated using slurry droplet methods. As methods of silicon carbide coating on the graphite pebble, microwave coating and chemical vapor deposition coating are evaluated. Two apparatuses are established to assess the thermo-mechanical properties of graphite and breeder pebble beds. The current status of R&D activities on these areas is introduced and the main progresses are addressed in this paper.