Thermodynamic properties and heat capacity of Ru metal in HCP,FCC,BCC and liquid state

Isometric heat capacity cv and isobar heat capacity cp of Ru metal in HCP,FCC,BCC and liquid state were calculated by using pure element systematic theory.The results are in good agreement with joint army-navy-air force(JANAF) experimental value and the calculation result by first-principle(FP) method.But the results have great differences in contrast to Scientific Group Thermodata Europe(SGTE) database.The cause is found that it cannot neglect the electron devotion to heat capacity to adjust cp in one-atom(OA) method.The disparity between OA method and SGTE database was discussed.The main cause is that OA method adopts the crosspoint with iso-Ec-line and iso-a-line in hybritriangle to determine the properties,but SGTE database is obtained by extrapolation from activity measurements and critical assessment of data from a large number of binary system.Thermodynamic properties of Ru metal in HCP,FCC,BCC and liquid state,such as entropy S,enthalpy H and Gibbs energy G were calculated.Therefore,the full description of thermodynamic properties from 0 K to random temperature is implemented.

Tin-based metal bath heat treatment: an efficient and recyclable green approach for Pinus massoniana wood modification

Pinus massoniana L. was thermally treated with low melting point alloy as heating medium to investigate the strength properties changes. Contact angle, color and scanning electron microscopy were recorded to assess the effectiveness of the treatment. Samples were pre-treated in a micro-wave for 5 min followed by metal bath heat treatment at 150, 180, and 210 °C for 2, 4, and 8 h,respectively. Strength properties of metal bath treated wood were decreased with increase temperature and time.Density, modulus of rupture, impact bending, modulus of elasticity were reduced for all treatments. Maximum compressive strength slightly increased at 150 °C for 4 h followed by gradual reduction. The Janka hardness was reduced in the tangential and radial directions. Treatment of the wood at 210 °C for 8 h caused the wood to become brittle and rupture. The contact angle was considerably higher after thermal treatment. The color of the wood became darker with increasing temperature of thermal treatment. Micrographs of the heat-treated samples showed damage to the cell wall with increase in temperature. Metal bath heat treatment of wood was carried out successfully and some strength properties were reduced.

Carburization of ferrochromium metals in chromium ore fines containing coal during voluminal reduction by microwave heating

Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the conditions of COFCC with n(O)-n(C) (molar ratio) as 1.00-0.84 and n(SiO2)-n(CaO) as 1.00-0.39, the samples were heated by 10 kW microwave power to reach the given temperatures and held for different times respectively. The results show that the low-C-Cr ferrochromium metal phase in the reduced materials forms before the high-C-Cr ferrochromium metal phase does. With increasing temperature the C content of ferrochromium metals is in a positive correlation with the content of Cr. The C content of ferrochromium metal in reduced materials is 0-10.07% with an average value of 4.68%. With the increase of holding time the Cr content in ferrochromium metals is in a negative correlation with the content of C, while the content of Fe changes in the contrary way. In the microwave field the kinetic conditions of carburization are closely related with the temperature of microwave heating, holding time and carbon fitting ratio.

Effect of Heat Treatment on the Mechanical Properties of FeCoZrWB Bulk Metallic Glass

A Fe61Co10Zr5W4B20 bulk metallic glass （BMG） with a diameter of 2 mm was prepared by using copper mould suction casting. The X-ray diffraction （XRD）, differential scanning calorimetry （DSC）, micro-hardness and compression tests were adopted to investigate the structure, thermal stability, especially, the effect of heat treatment on the micro-hardness and compression strength of this BMG. The BMG exhibits micro-hardness of about 1 207 Hv and compression fracture strength of about 1 707.6 MPa. After being annealed below the onset of crystallization temperature, the micro-hardness almost keeps constant. But after being annealed above the peak of crystallization temperature, the micro-hardness increases firstly and then declines gradually with the elongation of annealing time. However, annealed for the same period of time, the micro-hardness will increase with the rise of annealing temperature, while the compression fracture strength will apparently decrease.

Interfacial heat transfer behavior at metal/die in finger-plated casting during high pressure die casting process

Heat transfer at the metal-die interface has a great influence on the solidification process and casting structure. As thin-wall components are extensively produced by high pressure die casting process(HPDC), the B390 alloy finger-plate casting was cast against an H13 steel die on a cold-chamber HPDC machine. The interfacial heat transfer behavior at different positions of the die was carefully studied using an inverse approach based on the temperature measurements inside the die. Furthermore, the filling process and the solidification rate in different finger-plates were also given to explain the distribution of interfacial heat flux(q) and interfacial heat transfer coefficient(h). Measurement results at the side of sprue indicates that qmax and hmax could reach 9.2 MW·m^(-2) and 64.3 kW ·m^(-2)·K^(-1), respectively. The simulation of melt flow in the die reveals that the thinnest(T_1) finger plate could accelerate the melt flow from 50 m·s^(-1) to 110 m·s^(-1). Due to this high velocity, the interfacial heat flux at the end of T_1 could firstly reach a highest value 7.92 MW·m^(-2) among the ends of T_n(n=2,3,4,5). In addition, the q_(max) and h_(max) values of T_2, T_4 and T_5 finger-plates increase with the increasing thickness of the finger plate. Finally, at the rapid decreasing stage of interfacial heat transfer coefficient(h), the decreasing rate of h has an exponential relationship with the increasing rate of solid fraction(f).

The Morphology of Patterning with Pseudoplastic Metal Nanoparticle Fluids during Heat Treatment

A pseudoplastic metal nanoparticle fluid （PMNF） is used in nanoimprint to fabricate semiconductors and func- tional devices. The evaporation of the solvent and the sintering of the Au PMNF are investigated. The key parameters, which influence the morphology of patterning, such as the radius of metal particles, the concentra- tion of metal particles, the Hamaker constant of the solvent, viscosity of the fluids and the evaporation velocity, are analyzed. Based on a two-sphere sintering model, the equations are derived, which represent the relationships between the relative shrinkage and radius of the metal particles, sintering temperature and time. The optimal parameters for the heat treatment are provided in nanoimprint.

Heat treatment optimization for tensile properties of 8011 Al/15% SiCp metal matrix composite using response surface methodology

In this study,a mathematical model was developed to optimize the heat treatment process for maximum tensile strength and ductility of aluminum(8011) silicon carbide particulate composites.The process parameters are solutionizing time,aging temperature,and aging time.The experiments were performed on an universal testing machine according to centre rotatable design matrix.A mathematical model was developed with the main and interactive effects of the parameters considered.The analysis of variance technique was used to check the adequacy of the developed model.The optimum parameters were obtained for maximum tensile strength.Fractographic examination shows the cracks and dimples on the fractured surfaces of heat-treated specimen.

Preparation and characterizations of heat storage material combining porous metal with molten salt

A new type of heat storage materials combining high temperature molten salts phases change latent heat thermal storage materials, PCM with porous metals sensible heat thermal storage materials was developed. The process was expressed as following: firstly, it is necessary to heat up the molten salts phases change materials to molten; and then the porous metals are put into the molten bath; after being held for 13 h, the composite heat thermal storage materials lumps are taken out of the molten bath and cooled to atmospheric temperature; the last step is to electrodeposit a layer metal coat on the surface of the material lumps. The new type of heat storage material integrates the advantages of both solid sensible heat thermal storage materials and high temperature phases change latent heat thermal storage materials. The metal base heat storage materials enjoy some favorable characteristics such as higher heat charge discharge rate, higher heat storage density and better mechanical strength.

Effect of heat input and postweld heat treatment on microstructure and toughness of heat-resistant steel E911 deposited metal

The microstructure of E911 deposited metal was observed and the effect of heat input and postweld heat treatment on microstructure and impact toughness was investigated. The microstructure consists of tempered martensite and residual δ- ferrite. The morphology of tempered martensite is columnar and the residual δ-ferrite is polygonal. With the increase in heat input, the width of columnar martensite grain and the size of residual δ-ferrite increased, whereas the volume fraction of residual δ-ferrite varied slightly. The impact toughness decreased as heat input increased. The result reveals that coarsening columnar martensite grain and δ-ferrite have greater effect on impact toughness than volume fraction of residual δ-ferrite. As the time of postweld heat treatment is exceeded 8h, aggregation of M23 C6occurs in some grain boundaries or lath interfaces. The partial aggregation of M23 C6 results in the decrease in impact toughness.

Heat transfer of liquid metal alloy on copper plate deposited with film of different surface free energy

Liquid metal alloys(LMAs) are the potential candidates of thermal interface materials(TIMs) for electronics cooling.In the present work, buffer layers of Ag, Ti, Cu, Ni, Mo, and W were deposited on polished Cu plates by DC magnetron sputtering, the contact angles of de-ionized water and diiodomethane on the buffer layers were measured by an easy drop shape analyzer and the surface free energies(SFEs) of the buffer layers were calculated by the Owens–Wendt–Kaelble equation. Samples were prepared by sandwiching the filmed Cu plates and LMAs. The thermal properties of the samples were measured by laser flash analysis method. The SFE of the buffer layer has a strong influence on the interface heat transfer, whereas the measurement temperature has no obvious effect on the thermal properties of the samples. As the SFE of the buffer layer increases, the wettability, thermal diffusivity, and thermal conductivity are enhanced, and the thermal contact resistance is decreased.

Heat regulating strategy in numerical control end milling for hard metal machining

The trend in die/mold manufacturing at present is towards the hard machining at high speed to replace the electron dis- charge machining. Failure forms of the AlTiN-coated micro-grain carbide endmill when used for the machining of JIS SKD61 (HRC 53), a widely used material in die/mold manufacturing, are investigated. The endmill shows a characteristic that tool life decreases greatly due to the chipping when overload occurs or the rapid increase of wear when over-heat accumulation in cutting edges. As a consequence of the investigation, a strategy to regulate heat generation in the end milling process is proposed. This is accomplished by controlling the cutting arc length, i.e. the length of each flute engaging workpiece in a cutting cycle. Case studies on the slot end milling and comer rounding are conducted. The results show that the proposed strategy suggests the optimal tool path as well as the optimal pitch between successive tool paths under the cutting time criterion.

Conjugate Heat Transfer Analysis of an Ultrasonic Molten Metal Treatment System

In piezoceramic ultrasonic devices,the piezoceramic stacks may fail permanently or function improperly if their working temperatures overstep the Curie temperature of the piezoceramic material.While the end of the horn usually serves near the melting point of the molten metal and is enclosed in an airtight chamber,so that it is difficult to experimentally measure the temperature of the transducer and its variation with time,which bring heavy difficulty to the design of the ultrasonic molten metal treatment system.To find a way out,conjugate heat transfer analysis of an ultrasonic molten metal treatment system is performed with coupled fluid and heat transfer finite element method.In modeling of the system,the RNG model and the SIMPLE algorithm are adopted for turbulence and nonlinear coupling between the momentum equation and the energy equation.Forced air cooling as well as natural air cooling is analyzed to compare the difference of temperature evolution.Numerical results show that,after about 350 s of working time,temperatures in the surface of the ceramic stacks in forced air cooling drop about 7 K compared with that in natural cooling.At 240 s,The molten metal surface emits heat radiation with a maximum rate of about 19 036 W/m2,while the heat insulation disc absorbs heat radiation at a maximum rate of about 7922 W/m2,which indicates the effectiveness of heat insulation of the asbestos pad.Transient heat transfer film coefficient and its distribution,which are difficult to be measured experimentally are also obtained through numerical simulation.At 240 s,the heat transfer film coefficient in the surface of the transducer ranges from–17.86 to 20.17 W/（m2？K）.Compared with the trial and error method based on the test,the proposed research provides a more effective way in the design and analysis of the temperature control of the molten metal treatment system.

螺旋金属燃料多物理耦合分析方法与概念设计研究

螺旋金属燃料具有导热系数高、导热路径短、强制旋流交混的特点,可实现更高的堆芯功率密度,进而减小堆芯体积,提高反应堆的安全性和经济性。本文介绍了上海交通大学反应堆热工水力实验室建立的螺旋金属燃料热工水力、中子物理、力学特性分析方法及多物理耦合分析框架。在热工水力方面,基于自研仪器实现了交混及沸腾临界行为精细化测量,建立了三维及精细化子通道分析方法;在中子物理方面,建立了适用于特殊能谱、复杂几何的截面及稳瞬态中子物理特性的分析方法;在力学方面,基于分子动力学方法建立了U-Zr合金燃料基础热物性模型,并开展了辐照条件下螺旋棒宏观力学特性研究。基于热工-物理-力学多物理分析和优化,提出了螺旋金属燃料组件及堆芯设计,具有无硼化、堆芯功率密度高、体积小、换料周期长的特点。

A new post-weld heat treatment to improve toughness of 9Cr-1Mo steel weld metals

9Cr-1Mo ferritic steels have been used in the conventional power generation plants due to their excellent creep resistance. However, one of the main obstacles in welding 9Cr-1Mo steels is the formation of undesirable coarse columnar grains in weld metal whieh ean severely compromise the toughness. A new post-weld heat treatment （PWHT） is developed in the present work. Unlike the conventional processes in which the post-weld heat treatment is carried out below Ac1 , the use of temperatures above the Ac1 of 9Cr-1Mo alloy is considered. The new PWHT at a temperature above Ac1 improves the toughness of 9Cr-1Mo weld metals effectively. The improvement in toughness is mainly due to refinement and homogenization of mierostruetures. Key words

NiCuCoMn电极材料的制备及其储锂性能研究

采用熔炼甩带和化学脱合金相结合的方法制备纳米多孔NiCuCoMn过渡金属氧化物(NiCuCoMn@TMOs),并通过热处理进一步制备R-NiCuCoMn@TMOs。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等测试对材料进行结构表征并对其进行电化学性能测试。作为锂离子电池负极材料,R-NiCuCoMn@TMOs在0.1 A/g的电流密度下,经过200次循环后具有394.9 mAh/g的高比容量,并且表现出97.53%的优异容量保持率。与热处理前相比,热处理后的材料具有更丰富的氧空位、更低的电荷转移电阻(38Ω)和更优异的倍率性能(在2 A/g的电流密度下,比容量为141.1 mAh/g)。其独特的纳米多孔结构提供了丰富的反应活性位点;不同半径、价态和反应电位的多种金属阳离子的协同效应使得该材料有很好的体积容忍度以适应脱嵌锂过程中的体积变化,表现出优异的电化学性能。此外,该电极材料原料储量丰富,价格低廉,易于实现批量化制备。该工作为设计多组元过渡金属氧化物负极材料提供了新的思路。

基于变论域模糊PID的金属热处理过程温度控制方法

为高效且安全地提取金属合金内的可用材质并分析其性能,利用变论域模糊PID技术,实现对热处理过程的温度控制。设定在金属规则状态不变的情况下,论域会随着偏差的缩减出现伸缩,即需要增添新的规则。若偏差率能够支持模糊量化取整,控制器的伸缩因子可能会陷入无法取值的情况。此时,通过二元函数分片双一次插值法计算伸缩因子,在临近分档之间填充新规则,确保伸缩因子取值的连续性。然后,在模糊PID控制过程中加入变论域,依靠控制器实现对金属热处理过程温度的控制。根据实验验证情况可知:该方法有效提高了控制效果,在应用该方法后,缩短了温度控制时间,在100s内就可以是加热温度到达拟定值。

微通道内单一/混合流体强化传热研究进展

介绍了近年来微通道换热器内冷却介质强化换热的研究进展。阐述了纳米流体、液态金属以及潜热型功能热流体强化传热的机理;探讨了影响纳米流体传热性能的因素,包括纳米颗粒的种类、体积分数和温度等;讨论了增大液态金属传热系数的方法;分析了微胶囊壁材、相变材料和微胶囊的质量分数等对潜热型功能热流体热容的影响。指出了3种冷却介质目前尚存在的缺陷及相应的改善措施,对高热流密度设备散热问题中冷却介质的选取具有一定的指导意义。

牡丹籽油凝胶乳液的制备及稳定性评估

以辛烯基琥珀酸(octenyl succinic anhydride,OSA)淀粉为乳化剂,植物甾醇-卵磷脂-牡丹籽油凝胶为芯材,制备了4种水包油型牡丹籽油凝胶乳液,其分散相平均粒径在1~4μm,Zeta电位在-31 mV左右。以粒径、Zeta电位为指标,研究了pH值(3~9)、热处理(40~100℃)、盐离子种类(Na^(+)、Ca^(2+)、Al^(3+))及离子强度(100、200、300、400、500 mmol/L)对凝胶乳液稳定性的影响。结果表明,经酸处理后,油凝胶乳液的平均粒径和Zeta电位显著增大(电位绝对值减小),而弱碱条件对乳液粒径无显著影响,Zeta电位则逐渐减小(绝对值增加);在pH 3~9,4种凝胶乳液均表现出良好的稳定性。金属离子(Na^(+)、Ca^(2+)、Al^(3+))及其添加浓度的增加会导致凝胶乳液分散相粒径和Zeta电位增大,其中Al^(3+)的影响最为显著,Ca^(2+)次之,而Na^(+)的影响较弱;金属离子对凝胶乳液稳定性的影响是Zeta电位和分散相粒径变化共同作用的结果,该研究条件下,乳液未发生明显的破乳现象。低温(4~40℃)处理对凝胶乳液分散相粒径和Zeta电位无显著影响;60℃处理30 min,会使乳液粒径增大,Zeta电位绝对值减小,但乳液仍表现出较好的稳定性,未发生破乳现象;高温区(80~100℃)处理30 min,凝胶乳液发生破乳现象。此外,油相中凝胶剂的比例对凝胶乳液稳定性也有一定影响,当m(甾醇)∶m(卵磷脂)=8∶2时,油凝胶的三维网络结构最紧密,凝胶乳液的稳定性最佳。

基于多物理耦合的高温热管流动传热和力学特性研究

研究高温碱金属热管内工质的流动、传热和力学特性,对热管冷却反应堆的安全具有重要意义。本文采用COMSOL Multiphysics有限元软件构建了高温碱金属热管的多物理耦合模型,针对热管内工质的流动传热特性以及管壁的热膨胀效应进行了数值模拟研究。结果表明:本文模型的计算结果与实验值的相对误差小于1%,可准确模拟高温热管的流动传热特性;在额定功率下,沿轴向的压力梯度和温度梯度较小,说明热管具有较好的等温性,但相比于冷态有最大1.75%的总形变;热管的传输功率提高会显著影响热管内工质的运行状态,同时加大热管的形变量。

钛型气保护药芯焊丝工艺质量影响因素综述

综述了涉及钛型气保护药芯焊丝工艺质量的影响因素。结果表明,合理选用药芯添加物,严格控制熔敷金属中主要强化元素C、Mn、Si的含量,可以改善焊丝熔滴过渡形态,获得焊丝熔敷金属满意的力学性能。在Ar+CO_(2)二元混合保护气体中,随着CO_(2)含量增大,熔滴过渡形态从轴向变为非轴向滴状排斥过渡,接头的抗拉强度几乎没有影响,但熔敷金属的冲击吸收能明显下降。热输入较大时,焊丝工艺性变差;热输入居中时,焊丝工艺性较好。热输入对焊丝熔敷金属韧性的影响出现了对热输入敏感和不敏感两种情况。钛型气保护药芯焊丝工艺质量的三个影响因素控制原理各具特色。