On the thermal impact on the excavation damaged zone around deep radioactive waste disposal

Clays and claystones are considered in some countries （including Belgium, France and Switzerland） as a potential host rock for high activity long lived radioactive waste disposal at great depth. One of the aspects to deal with when assessing the performance of the disposal is related to the effects of the temperature elevation due to the placement of exothermic wastes on the host rock. The potential effects of the thermal impact on the excavation damaged zone （EDZ） in the near field are another important issue that was the goal of the TIMODAZ European research project. In this paper, some principles of waste disposal in clayey host rocks at great depth are first presented and a series of experimental investigations carried out on specific equipment specially developed to face the problem are presented. Both drained and undrained tests have been carried out to investigate the drained thermal volume changes of clays and claystone and the thermal pressurization occurring around the galleries. The importance of proper initial saturation （under in situ stresses） and of satisfactory drainage conditions （in spite of the significantly low perme- ability of claystones） is emphasized, leading to the development of a new hollow cylinder apparatus. It is observed that claystones cannot be considered as overconsolidated clays given that they can exhibit, as the Callovo-Oxfordian claystone does, a thermoplastic contraction. Mechanical and thermal hardenings are however observed, extending the knowledge already gained on clays to claystones. A new method of determining the thermal pressurization coefficient in the laboratory is described and the data obtained allow completing existing data in the field. Finally, the hollow cylinder apparatus makes it possible to demonstrate that the good self-sealing properties of clays and claystones can be extended to temperature effects, an important conclusion in terms of performance assessment.

Synthesis and Characterization of Novel Sulphanilamide/Epoxy Resin Modified Polyester for Thermal Stability and Impact Strength

The synthesis of thermally stable Tetra-di-glycidyl ether bisphenol-A (TDGEBA) Epoxy resin and Sulphanilamide (SAA) have been synthesized from (SAA) and TDGEBA by in situ polymerization technique to obtain Te-tra-di-glycidyl ether bisphenol-A Sulphanilamide (TDGEBA/SAA) Epoxy resin and modified with various per-centages of polyester (PE) to obtain Tetra diglycidyl ether bisphenol-A Sulphanilamide polyester (TDGEBA/SAA-PE), highly cross-linked thermosetting polymer network. These materials were cured with triethylenetetramine TETA (hardener) to obtain highly cross-linked thermosetting resin. The physical properties of the resulting blends were evaluated by measuring the impact strength of (TDGEBA/SAA-PE) (increased more than 30% than the unmodified epoxy resin) and hardness that is found to be higher than unmodified epoxy resin. Differential scanning calorimetry (DSC) and thermo gravimetric (TGA) analysis were also cured to assess the thermal behavior of the samples. DSC of the (TDGEBA/SAA) Epoxy resin cured with TETA showed exothermic reactions and the glass transition temperature (Tg) shifted from 350℃ to 400℃compared with uncured epoxy and the thermal stability of the TDGEBA/SAA epoxy resin modified increased with increasing of PE. Scanning Electron Microscopy (SEM) studied the morphology of the samples after unnotched impacts on fracture surfaces. These materials exhibited a higher degree of solvent resistance.

Effects of Temperature Induced Thermal Expansion and Oxidation on the Charpy Impact Property of C/C Composites

C/C composites are the emerging materials of choice for aero-engine hot-end components that will bear impact loading in thermal-oxidizing environments. For the components run for extended periods, the safe operation of components depends on how to evaluate damages under a dynamic load. In this study, Charpy impact tests at a temperature range of 25 to l 200 ＂C were carried out on C/C composites to verify the effects of temperature induced thermal expansion and oxidation on their impact performance. Below 800 ℃, oxidation was negligible and composites expanding played a leading role, resulting in the remarkable increase in fiber/ matrix interface strength and impact energy. However, when the temperature was above 800 ℃, the release of CO or CO2 due to oxidation resulted in a lower impact energy.

Thermal and Thermo-oxidative Degradation of Flame Retardant High Impact Polystyrene with Triphenyl Phosphate and Novolac Epoxy Resin

Thermal and thermo-oxidative decomposition and decomposition kinetics of flame retardant high impact polystyrene （HIPS） with triphenyl phosphate （TPP） and novolac type epoxy resin （NE） were characterized using thermo-gravimetric experiment. And the flammability was determined by limited oxygen indices （LOI）. The LOI results show that TPP and NE had a good synthetic effect on the flame retardancy of HIPS. Compared with pure HIPS, the LOI values of HIPS/NE and HIPS/TPP only increased by about 5%, and the LOI value of HIPS/TPP/NE reached 42.3%, nearly 23% above that of HIPS. All materials showed one main decomposition step, as radical HIPS scission predominated during anaerobic decomposition. TPP increased the activity energy effectively while NE affected the thermal-oxidative degradation more with the help of the char formation. With both TPP and NE, the materials could have a comparable good result of both thermal and thermal-oxidative degradation, which could contribute to their effect on the flame retardancy.

Development of single pendulum impact scratch test for evaluating of thermally sprayed coatings

The adhesion of thermally sprayed coatings is an important subject for engineers applying thermal spray process . The single pendulum impact scratch test is the most popular method in the tribological investigation of modified surfaces of materials. In this paper, the adhesion of thermally sprayed coatings has been investigated using this test method. The key of evaluation for thermally sprayed coatings is the sheer strength of coatings obtained in the test. The results show that the test method is reproducible, reliable and easy to perform, and does not require expensive equipment . The procedure proposed in the test method for evaluating the adhesion of coatings is more reliable and realistic than others.

热输入对高锰钢焊接热影响区微观组织和性能的影响

为了研究不同热输入对高锰钢组织性能的影响,利用GLEEBLE 3500热力模拟试验机对高锰钢进行了不同峰值温度和线能量的热模拟试验,并对热模拟试样进行了微观组织、冲击韧性和显微硬度分布等表征。结果表明,随着线能量的增加,试样冲击韧性和硬度呈现出下降趋势,硬度与平均晶粒尺寸平方根倒数呈现很好的线性相关性。峰值温度T_(m)=1 300℃时,试样中出现的微裂纹是冲击韧性显著降低的主要原因。

The effect of wax coating,aluminum and ammonium perchlorate on impact sensitivity of HMX

Interaction of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)/ammonium perchlorate(AP) and its effect on mechanical sensitivity may result in some restrictions for the application of AP/HMX system in high energetic weapon system. In this work, impact sensitivity test is used to study the effects of wax coating of HMX, AP and aluminum(Al) powder on sensitivity properties of HMX/AP/Al mixtures.Thermogravimetry-differential scanning calorimetry(TG-DSC) analysis has been developed to investigate the mechanism of interaction between HMX and AP during the course of thermal decomposition of HMX/AP/AI mixtures. The results show that severe interaction effect exists between AP and HMX, which causes the impact sensitivity(H_(50)) to become smaller. The impact energy(E_(50)) of mixture can be improved under the circumstances of effective separating HMX from AP by surface coating with Wax. AP may firstly engender low-temperature decomposition under the circumstance of external heat or mechanical impact, which causes the exothermic peak of HMX forward shift about 28 C. The gaseous product releasing from thermal decomposition of HMX accelerates further decomposition of AP. For HMX/AP composite system, the interactive catalysis effect between AP and HMX can be eliminated mostly by adding a great deal of Al powder(i.e. above 30%).

INFLUENCE OF THE SECOND THERMAL CYCLE ON COARSE- GRAINED ZONE TOUGHNESS OF X70 STEEL

The influence of the second thermal cycle on coarse grained zone (CGHAZ) toughness of X70 steel is studied by weld thermal simulation test, scanning electron microscope and electron microprobe. The results show that the CGHAZ toughness is improved after the second thermal cycle but being heated during the intercritical HAZ (ICHAZ). The CGHAZ toughness decreases evidently after being heated during partially transformed zone, which chiefly results from the carbon segregation to the grain boundaries of primal austenite, thus forming high carbon martensite austenite (M A) constituent and bringing serious intercritically reheated coarse grain HAZ (IRCGHAZ) embrittlement.

IMPACT PROPERTIES OF METALLOCENE - CATALYZED ETHYLENE-α-OLEFIN COPOLYMERS

The impact properties of two selected metallocene-catalyzed ethylene-butene copolymers and one conventionalcopolymer were evaluated using Izod impact test. It is found that the metallocene-catalyzed copolymer shows superior impactproperties. This result was explained on the basis of the more homogeneous inter-molecular composition distribution andnarrower molecular weight distribution, which leads to more homogeneous morphology with fewer defects. Stepwisecrystallization improves the impact properties, especially in the crack propagation process, to a large extent. This is due to thedecrease of entanglements by stepwise crystallization, which is advantageous for the chain slip and shear. The polymer withheterogeneous intra-molecular composition distribution exhibits a more evident improvement of impact properties understepwise crystallization.

Effect of Thermal Cycle on Microstructure and Fracture Morphology in HAZ of HQ130 Steel

The effect of different peak temperature(Tp) and cooling time (t8/5) on microstructure, hardness, impact toughness and fracture morphology in the heat-affected zone (HAZ) of HQ130 steel was studied by using weld thermo-simulation test. Experimental results indicate that the impact toughness and hardness decrease with the decrease of Tpor increase of t8/5 under the condition of a single thermal cycle. There is a brittle zone in the vicinity of Tp= 800℃, where the impact toughness is considerably low. There is a softened zone in the vicinity of Tp=700℃, where the hardness decreases but the toughness increases. In the practical application of multi-layer and multipass welding, the welding heat input should be strictly limited (t8/5≤20s) so as to reduce the softness and brittleness in the HAZ of-HQ130 steel.

EFFECTS OF THERMAL CYCLE ON MECHANICAL PROPERTIES AND FRACTOGRAPHY IN HAZ OF HQ130 STEEL

The effect of different peak temperature T_P) and cooling time (t_(8/5)) on hardness,impact toughness and fracture morphology in the heat--affected zone (HAZ) of HQ130steel was studied by using welding thermo--simulation test. Experimental results showthat the impact toughness and hardness decrease with the decrease of T_P or increase oft_(8/5) under the condition of a single thermal cycle. There is a brittle zone in the vicinityof T_P=800℃, where the impact toughness is considerebly low. There is softened zonein vicinity of T_P=700℃, Where the harkness decreases but the toughness increases. Inthe practical application of multi--layer and multi--pass welding, the welding heat inputshould be strictly limited (t_(8/5)≤20s) so as to reduce the softness and brittleness in theHAZ of HQ130 steel.

Microstructure and mechanical properties of heat-affected zone of 680 MPa grade steel endured thermal cycle of double-wire SAW

Based on the measured thermal cycle of double-wire submerged arc welding （SAW）, the gleeble thermal test was performed. Meanwhile, the Charpy V-notch impact test at -50 ℃ and hardness test at room temperature were carried out after the thermal test. Thermally cycled microstructure and fracture surfaces were observed too. The results indicate that impact toughness of heat-affected zone （HAZ） at -50 ℃ is lower than that of parent metal with different wire spacing and welding speed. The microstracture of coarse-grains heat-affected zone （ CGHAZ ） is mainly made up of lath bainite with serious brittleness. The study also shows that a smaller energy input could be adopted to ensure the toughness of welded joints at the welding process in a common molten pool, while a higher energy input could be exerted to enhance welding efficieney at the welding process in two separate molten pools.

Impacts of Multi-Scale Solar Activity on Climate.Part Ⅰ:Atmospheric Circulation Patterns and Climate Extremes

The impacts of solar activity on climate are explored in this two-part study. Based on the principles of atmospheric dynamics, Part I propose an amplifying mechanism of solar impacts on winter climate extremes through changing the atmospheric circulation patterns. This mechanism is supported by data analysis of the sunspot number up to the predicted Solar Cycle 24, the historical surface temperature data, and atmospheric variables of NCEP/NCAR Reanalysis up to the February 2011 for the Northern Hemisphere winters. For low solar activity, the thermal contrast between the low- and high-latitudes is enhanced, so as the mid-latitude baroclinic ultra-long wave activity. The land-ocean thermal contrast is also enhanced, which amplifies the topographic waves. The enhanced mid-latitude waves in turn enhance the meridional heat transport from the low to high latitudes, making the atmospheric ＂heat engine＂ more efficient than normal. The jets shift southward and the polar vortex is weakened. The Northern Annular Mode （NAM） index tends to be negative. The mid-latitude surface exhibits large-scale convergence and updrafts, which favor extreme weather/climate events to occur. The thermally driven Siberian high is enhanced, which enhances the East Asian winter monsoon （EAWM）. For high solar activity, the mid-latitude circulation patterns are less wavy with less meridional transport. The NAM tends to be positive, and the Siberian high and the EAWM tend to be weaker than normal. Thus the extreme weather/climate events for high solar activity occur in different regions with different severity from those for low solar activity. The solar influence on the mid- to high-latitude surface temperature and circulations can stand out after removing the influence from the E1 Nifio-Southern Oscillation. The atmospheric amplifying mechanism indicates that the solar impacts on climate should not be simply estimated by the magnitude of the change in the solar radiation over solar cycles when it is compared with other external radiative forcings that do not influence the climate in the same way as the sun does.

热冲击高强钢焊接接头的低周疲劳及断裂机理研究

为了研究热冲击下高强钢焊接接头的低周疲劳性能及断裂机理,用电弧焊焊接Q345结构钢,分别在-20~400℃、-40~650℃、-60~900℃下对焊接接头进行循环冲击,用疲劳试验机加载低周疲劳载荷,分析热冲击温度对低周疲劳性能及疲劳强度的影响,并用扫描电子显微镜等分析焊接接头的断裂机理。结果表明:相同疲劳加载次数下,焊接接头的总应变幅值随热冲击循环次数的增加匀速下降;相同热冲击循环次数下,疲劳加载次数越多,焊接接头的应变幅值越小;相同疲劳加载次数和相同热冲击循环次数下,随冲击温度范围的扩大,焊接接头的总应变幅值逐渐减小,但总应变幅值整体变化与冲击温度范围正相关。

Mechanical properties and kinetics of thermally aged Z3CN20.09M cast duplex stainless steel

Cast stainless steels used in nuclear power plants suffer from fracture toughness losses owing to thermal aging after long-term service at temperatures ranging from 280–320°C. To study the thermal aging embrittlement of Z3 CN20.09 M duplex stainless steel produced in China, accelerated thermal aging experiments were carried out at 350, 380, and 400°C for up to 10000 h. Microhardness and Charpy impact energies were measured at different aging times. The microhardness of ferrite increased drastically over the initial aging time of 2000 h at 380 and 400°C and then slowly reached HV0.01 560. In contrast to this observed change in microhardness, Charpy impact energies sharply decreased after initial aging and then gradually reached a minimum value. Taking the microhardness of the ferrite phase as the parameter describing the thermal kinetics of the stainless steel samples, the activation energy of thermal aging was calculated to be 51 kJ/mol. Correlations between the thermal aging parameter, P, and ferrite microhardness and between P and Charpy impact energy were also analyzed. The results showed that the activation energy calculated from the ferrite microhardness is much more reasonable than that obtained using other parameters, such as chemical composition and impact energy.

Re-understanding and Thinking about Environmental Impact of Coal-fired Power Plants under Ultra-low Emission

From the perspective of development background,concepts and related policies of ultra-low emission,according to work practice,some issues and difficulties that need to be paid attention to in the environmental impact assessment of ultra-low-emission thermal power projects were discussed from the aspects of evaluation criteria,evaluation grade and scope,pollution control technical lines,environmental benefit accounting,and total emission control,and corresponding recommendations were put forward.

Thermal aging effect on 2205 duplex stainless steel

： The effect of isothermal aging treatment on the mechanical and corrosion properties of 2205 duplex stainless steel was investigated by means of impact toughness test and micro-hardness measurement in combination with the critical pitting temperature （CPT） technique. The corresponding fractography of the steel was then observed after the impact toughness test. The results demonstrated that, at the critical temperature for precipitation of the sigma （σ） phase, e. g., 850 ℃, the impact toughness decreased rapidly and the micro-hardness increased gradually with increasing aging time. The CPT decreased from 61 to 15 ℃ as the aging time increased from 4 rain to 8 h. In addition, optical microscopy, transmission electron microscope （TEM） and X-ray diffraction studies showed that the ferrite in the steel transformed into secondary austenite and σ phase.

Effect of secondary weld thermal cycle on structure and properties

This paper deals with structure and impact energy of weld HAZ of 10CrNi3MoV steel after secondary weld thermal cycle (t_ 8/5 =8 s ～120 s ; peak temperature T_ m =750 ℃ ～1 300 ℃ ). It is demonstrated that the coarse grain and structure produced by first thermal cycle keep unchanged after secondary thermal cycle above Ac_ 1 critical temperature but below 1 050 ℃ . At the same time the low temperature impact energy decreases obviously with increasing t_ 8/5 . By metallurgical microscope and transmission electron microscope(TEM) , it is revealed that the effect of coarse grain and structure caused by secondary thermal cycle on low temperature impact energy.

Effect of t_(8/5) on the microstructure and properties of the HAZ of ASME SA213-T92 steel by thermal simulation

The relationship between the t8/5 and micro-hardness, impact toughness in the heat affected zone （HAZ） of ASME SA213-792 at peak temperature of 1 350 ℃ was studied by thermal simulation. The result shows that the micro-hardness of HAZ rises at the beginning and then decreases with increasing of t8/5 , whereas the impact toughness presents reverse trend. The distribution of precipitates in substrate has great influence on the impact toughness of HAZ. When the t8/5 is 40 s, chain-like precipitates lower the impact toughness of HAZ seriously.

基于全生命周期的污油泥热脱附处理技术评价

基于全生命周期评价(LCA)软件eFootprint和国内典型污油泥热脱附处理实际,从绿色和可持续性两个方面对污油泥热脱附技术进行评价。结果表明:污油泥热脱附处理过程中,主要评价指标按所产生的环境影响由大到小排列依次为可吸入无机物(RI)、富营养化潜值(EP)、竞争-土地使用(CLU)、臭氧层消耗潜值(ODP)和水资源消耗(WU);回收油和天然气是初级能源消耗(PED)、非生物质资源消耗潜值(ADP)、WU、全球增温潜势(GWP)、ODP等11项评价指标的主要贡献因素,蒸汽是影响RI的最主要因素;污油泥热脱附处理产生的回收油能够抵消热脱附处理过程的部分能源和资源消耗,从而减小PED、ADP、GWP等评价指标的数值;为了进一步提升污油泥热脱附处理技术的绿色和可持续性,建议提高能源效率,减少蒸汽消耗,回收蒸汽余热,优化尾气净化系统和器具清洗系统,减少废水排放和水分挥发。