金属锂还原罐内化学反应与传热耦合特性

为了分析真空热还原制取金属锂的还原效率和还原率,综合考虑罐内球团传热和化学反应,建立了传热与反应动力学耦合模型.利用该模型对单球团和还原罐内球团还原过程进行数值模拟,得到了球团温度及还原率的时间分布,并分析了罐外换热系数对球团还原过程的影响.结果表明:球团低导热率和反应等效热汇是影响还原过程的主要因素,罐中心区域和罐壁处的温度和反应速率存在较大差值;还原初期传热为还原过程的主要控制因素,而反应后期化学反应为主要控制因素;罐外换热系数对还原过程影响不大,增强罐内传热是提高还原效率的有效途径.     

稀土对提高炼镁还原罐抗氧化性能的概述

分析了硅热法炼镁用的还原罐的工作条件、失效型式及失效原因。根据稀土元素在钢中作用的机理,阐述了钢中加入稀土元素后,提高耐热钢还原罐的抗氧化性能,以提高其使用寿命。     

炼镁还原罐早期失效分析

对炼镁还原罐的失效形式及原因进行了理认和实验分析，研究发现还原罐的早期失效与化学成分及组织的控制不当直接相关，铬的不足导致还原罐的严重氧化；碳量过高导致晶界碳化物网的形成，为高温氧化及裂纹的扩展提供了通道；对回炉料控制不当带来的夹杂物也严重地影响了还原罐的使用寿命     

球团预制-硅热还原炼镁还原罐内传热

为了解决皮江法还原罐内传热慢的问题，提出将白云石粉、硅铁、萤石混合，加入黏结剂先造球再煅烧，煅烧后的热球团直接用于还原的炼镁新技术.采用数值方法研究预制球团在还原罐内的传热规律.结果表明:提高硅铁添加量、增加球团直径、减小床层密度均有利于热量向还原罐内部传递;将边界温度由1473K提高至1498K，还原罐中心区域达到1473K的时间由300min缩短至178min;当还原罐直径为300mm时，对于直径为25mm的预制球团，还原罐中心点加热至1473K的时间为90min，而对于皮江法球团则需要288min.     

炼镁还原罐早期失效分析

对炼镁还原罐的失效形式及原因进行了理论和实验分析，研究发现还原罐的早期失效与化学成分及组织的控制不当直接相关。铬的不足导致还原的严重氧化；碳量过高导致晶界碳化物网的形成。     

基于经典PID控制双罐选择性催化还原系统的仿真研究

选择性催化还原系统(SCR)能够有效去除机动车尾气中的氮氧化物,该文介绍了选择性催化还原系统(SCR)的反应原理,基于SCR反应原理建立了双罐SCR系统建模,然后设计经典PID控制器应用于双罐SCR系统,仿真结果表明,经典PID对双罐SCR系统有一定的控制作用,但是不能充分体现双罐SCR系统的优势。     

RM—1型炼镁还原罐专用焊条性能的研究

用电弧参数分析仪、扫描电镜等手段，对合金系统为Ｃｒ２６Ｎｉ１６的ＲＭ－１型炼镁还原罐专用焊条的工艺性、抗高温氧化及硫化腐蚀性能进行了研究。实际运行结果表明，用该焊条所时焊焊缝的性能可满足炼镁还原罐的使用要求．     

固体碳还原铁鳞采用密封还原罐工艺的热力学分析

文本根据现场工艺实验的比较,用热力学观点分析讨论了用固体碳还原铁鳞时采用还原罐密封工艺的不合理性,及还原罐密封工艺对产品质量的影响和不必要的工序增加材料消耗造成的经济损失。     

炼镁还原罐内传热与化学反应的耦合特性

为了综合分析还原罐内传热过程及化学反应过程对Pidgeon炼镁工艺中产镁速率和反应转换率的影响机理,建立了具有耦合特征的传热和反应动力学模型。利用该模型对炼镁过程进行了数值模拟,获得了还原罐内的温度和产镁速率的空间分布和时间分布,并分析了罐外等效换热系数对上述结果的影响。结果表明:罐中心区域与罐壁处的温度及反应速率存在较大差值;球团的吸热反应特性及导热热阻是影响产镁速率和反应转换率的主要原因,而等效换热系数在达到一定数值后,对罐内的工作过程影响不大。     

储罐制造中几个常见变形的控制

对罐底、罐顶、罐壁的变形进行了分析,并提出了有效的控制措施,收到了良好的效果。     

Mechanical properties and microstructure of 3D-printed high Co-Ni secondary hardening steel fabricated by laser melting deposition

The mechanical properties and microstructure of the 3D-printed high Co-Ni secondary hardening steel fabricated by the laser melting deposition technique was investigated using a material testing machine and electron microscopy. A microstructure investigation revealed that the samples consist of martensite laths, fine dispersed precipitates, and reverted austenite films at the martensite lath boundaries. The precipitates are enriched with Co and Mo. Because the sample tempered at 486℃ has smaller precipitates and a higher number of precipitates per unit area, it exhibits better mechanical properties than the sample tempered at 498℃. Although the 3D-printed samples have the same phase constituents as AerMet 100 steel, the mechanical properties are slightly worse than those of the commercial wrought AerMet 100 steel because of the presence of voids.     

Effect of stoichiometry and Cu-substitution on the phase structure and hydrogen storage properties of Ml-Mg-Ni-based alloys

To improve the electrochemical properties of rare-earth-Mg-Ni-based hydrogen storage alloys, the effects of stoichiometry and Cu-substitution on the phase structure and thermodynamic properties of the alloys were studied. Nonsubstituted Ml_0.80Mg_0.20(Ni_2.90Co_0.50-Mn_0.30Al_0.30)_x (x=0.68, 0.70, 0.72, 0.74, 0.76) alloys and Cu-substituted Ml_0.80Mg_0.20(Ni_2.90Co_0.50-y Cu_y Mn_0.30Al_0.30)_0.70 (y=0, 0.10, 0.30, 0.50) alloys were prepared by induction melting. Phase structure analysis shows that the nonsubstituted alloys consist of a LaNi₅ phase, a LaNi₃ phase, and a minor La₂Ni₇ phase; in addition, in the case of Cu-substitution, the Nd₂Ni₇ phase appears and the LaNi₃ phase vanishes. Thermodynamic tests show that the enthalpy change in the dehydriding process decreases, indicating that hydride stability decreases with increasing stoichiometry and increasing Cu content. The maximum discharge capacity, kinetic properties, and cycling stability of the alloy electrodes all increase and then decrease with increasing stoichiometry or increasing Cu content. Furthermore, Cu substitution for Co ameliorates the discharge capacity, kinetics, and cycling stability of the alloy electrodes.     

Mg2Si热电材料力学性能的分子动力学模拟研究:纳孔效应

在热电材料里引入纳孔能有效降低材料的热导率从而提高其热电性能,但纳米孔洞的引入也可能影响材料的力学性能。以圆柱孔理想单晶Mg_2Si块体热电材料为研究对象,建立不同孔径、孔隙率以及分布形式的纳孔Mg_2Si材料的原子模型,采用分子动力学模拟方法研究不同模型下材料的拉伸力学性能。结果表明:①纳孔的引入造成Mg_2Si热电材料的极限应力和弹性模量的降低,而纳孔孔隙率、分布形式都会影响到材料的极限应力,而材料的弹性模量主要与孔隙率有关,孔隙率越大,材料的弹性模量越低;②纳孔的引入不仅减小材料的有效荷载面积,更重要的是造成材料内部应力分布不均匀,而材料所能承受的拉伸方向的应力极限是一定的,因而当纳孔Mg_2Si热电材料平均应力远小于完整块体的极限应力时,材料内部最薄弱的地方的应力就已达到其极限应力,造成材料的破坏。     

磁性纤维性能的分析

研究了不同条件下磁性纤维的力学、热性能及其磁化强度等，结果发现：随着磁粉含量分数的升高，纤维的力学性能、结晶度、熔融温度降低，磁化强度增加。随着样品厚度的增加纤维的磁感应强度明显加大。经过水洗后纤维的磁性强度略有下降。     

聚丁二酸丁二醇酯/氢氧化镁生物可降解阻燃复合材料的性能研究

熔融挤出制备了聚丁二酸丁二醇酯/氢氧化镁（PBS/Mg(OH)2）生物可降解阻燃复合材料,并对其熔体流动性、热稳定性、阻燃性能、结晶与熔融行为和力学性能进行研究. 结果表明,加入Mg(OH)2降低了PBS的熔体流动速率,延缓PBS在燃烧过程中的分解,有效提高PBS的极限氧指数和抗滴落性能. Mg(OH)2对PBS结晶具有的异相成核作用,显著提高PBS的结晶温度并改变PBS的熔融行为. 当Mg(OH)2质量分数低于40%时,Mg(OH)2提高PBS的拉伸强度、拉伸模量、弯曲强度和弯曲模量,但降低PBS的断裂伸长率和冲击强度;当Mg(OH)2质量分数大于50%时,由于PBS和Mg(OH)2的相容性较差,PBS/ Mg(OH)2复合材料在拉伸和弯曲过程中均呈现出脆性断裂现象,导致拉伸强度和弯曲强度降低.     

混合扩链剂对聚氨酯弹性体宏观性能的影响

以4,4′-二苯基甲烷二异氰酸酯（MDI）和聚四氢呋喃均聚醚（PTMG）为原料合成聚氨酯（PU）预聚体（A组分）,三羟基聚醚多元醇（330N）分别与1,4-丁二醇（BDO）或乙二醇（EGO）混合作为扩链剂（B组分）,将A、B组分聚合制备PU弹性体。探讨330N/BDO与330N/EGO不同体系以及各体系不同质量比对PU弹性体热性能和机械性能的影响。结果表明,330N/BDO体系的软段玻璃化转变温度（T_gs）较低,硬段熔融热较高,随着330N/BDO质量比的下降,T_gs 上升,硬段熔融热增加;330N/EGO体系的拉伸强度、硬度稍高,而断裂伸长率和滞后损失（tan δ ）有较大落差,随着330N/EGO质量比的下降,弹性体的拉伸强度和硬度增加,断裂伸长率和滞后损失降低。     

12Cr1MoV连铸钢坯高温力学性能研究

在Gleeble-1500热模拟机上进行了低合金钢12Cr1MoV热模拟实验,测试了从600℃到峰值温度,涵盖了连铸时从结晶器到输出辊道的整个温度范围,得出了12Cr1MoV在不同应变速率不同温度下的流变曲线、强度曲线和热塑性曲线,观察了不同温度下试样的断口形貌组织.实验结果表明:低合金钢12Cr1MoV的ZST为1425℃,ZDT为1400℃.在1100~1300℃范围内,钢的断面收缩率均大于60%,具有良好的塑性;脆性范围为1350℃到熔点和900℃以下.     

轻质保温隔墙板的制备及性能研究

建筑节能理念已受到普遍关注,轻质保温隔墙板作为一种节能材料且多功能化而成为研究开发的热点.由发泡聚苯乙烯(EPS)颗粒保温砂浆制备而成的芯材是轻质保温隔墙板的重要组成部分,对隔墙板性能起决定性作用.现有的保温隔墙板虽质轻,但强度较弱.为获得密度低、抗压强以及粘结性好的EPS保温砂浆芯材,以干表观密度对导热系数和抗压强度的影响为引导,研究了粉煤灰、发泡剂、甲基纤维素醚等对芯材抗压强度及粘结性能的作用规律；对芯材的压缩应力-应变曲线进行了分析,并讨论了增韧原因；初步试生产制得了综合性能良好的轻质保温隔墙板.     

Effects of heat treatment on microstructure and mechanical properties of SLMed Sc-modified AlSi10Mg alloy

The influence of heat treatments on the microstructures and mechanical properties of the selective laser melting manufactured AlSi10Mg alloy modified with Sc was systematically investigated. The results showed that the addition of Sc element introduced primary Al₃Sc, which increased the heterogeneous nucleation during the solidification of AlSi10Mg alloy, and then the ultrafine network eutectic structure was obtained, and hence the tensile strength was improved significantly (nearly 23 ​%). During the heat treatment process, the network eutectic structure transformed from continuous to discontinuous, and the grain refinement was weakened with an increasing heating temperature, both of which affected the mechanical properties of the Sc modified AlSi10Mg alloy. The tensile strength decreased from 438 ​± ​10 ​MPa for the Sc-modified alloy to 208 ​± ​6 ​MPa, while the fracture strain significantly increased from 6 ​± ​0.2 ​% to 30.2 ​± ​1.2 ​% when the Sc-modified alloy was heat-treated at 325 ​°C for 12 ​h. It has been found that the desirable microstructure and mechanical properties of SLM Sc-modified AlSi10Mg alloy can be realized by controlling the heat treatment process parameters.     

High thermal conductivity and high strength magnesium alloy for high pressure die casting ultrathin-walled components

With the rapid development of 3C industries,the demand for high-thermal-conductivity magnesium alloys with high mechanical performance is increasing quickly.However,the thermal conductivities of most common Mg foundry alloys(such as Mg-9wt%-1wt%Zn)are still relatively low.In this study,we developed a high-thermal-conductivity Mg-4Al-4Zn-4RE-1Ca(wt%,AZEX4441)alloy with good mechanical properties for ultrathin-walled cellphone components via high-pressure die casting(HPDC).The HPDC AZEX4441 alloy exhibited a fine homogeneous microstructure(average grain size of 2.8μm)with granular Al₁₁RE₃,fibrous Al₂REZn₂,and networked Ca₆Mg₂Zn₃ phases distributed at the grain boundaries.The room-temperature thermal conductivity of the HPDC AZEX4441 alloy was 94.4 W·m^-1·K^-1,which was much higher than 53.7 W·m^-1·K^-1 of the HPDC AZ91D alloy.Al and Zn in the AZEX4441 alloy were largely consumed by the formation of Al₁₁RE₃,Al₂REZn₂,and Ca₂Mg₆Zn₃ phases because of the addition of RE and Ca.Therefore,the lattice distortion induced by solute atoms of the AZEX4441 alloy(0.171%)was much lower than that of the AZ91D alloy(0.441%),which was responsible for the high thermal conductivity of the AZEX4441 alloy.The AZEX4441 alloy exhibited a high yield strength of~185 MPa,an ultimate tensile strength of~233 MPa,and an elongation of~4.2%.This result indicated that the tensile properties were comparable with those of the AZ91D alloy.Therefore,this study contributed to the development of high-performance Mg alloys with a combination of high thermal conductivity,high strength,and good castability.