Si复合Al2O3-SiC材料热机械性能的研究

通过应力-应变关系、高温抗折强度等高温试验,研究了金属硅复合Al2O3-SiC材料的热机械性能,结合SEM和XRD,对金属硅复合Al2O3-SiC材料高温显微结构和物相进行分析.结果表明:金属硅作为一个组元,不仅能缓解Al2O3-SiC材料由于热膨胀系数不匹配产生的内应力,而且使Al2O3-SiC材料兼具有金属塑性的特点,从而改善了Al2O3-SiC无机材料热机械性能.     

Si复合Al_2O_3-SiC材料高温氧化行为研究

通过在不同条件下的氧化试验,结合SEM,研究了金属Si复合Al2O3-SiC材料的高温氧化行为。结果表明,金属Si优先SiC氧化有利于生成玻璃状薄膜,形成结构致密的保护层,保护了碳化硅不被氧化,同时使得内部金属Si保存下来;Si复合Al2O3-SiC材料的1350℃氧化过程包括前期化学反应控制和后期扩散控制两个阶段,扩散控制阶段反应符合Ginsterlinger扩散动力学关系。同Al2O3-SiC材料相比,Si复合Al2O3-SiC材料的氧化更早进入扩散控制反应阶段。     

复合料浆热压滤法制备空间网络复合涂层及其高温氧化行为

采用复合料浆热压滤法制备出厚度在数十微米到数百微米之间可控的YSZ/YSZ、Al2O3/YSZ、Al2O3/YSZ-Al2O3和Al2O3/Al2O3复合涂层。微观形貌显示复合涂层由具有空间网络结构的YSZ或Al2O3包覆颗粒状YSZ或/和Al2O3组成。高温氧化实验结果显示,含有适量YSZ颗粒的Al2O3/YSZ-Al2O3复合涂层具有优异的抗高温氧化性能。为通过氧元素在复合涂层中的扩散行为深入分析其抗高温氧化性能,本文还基于复合涂层的微观结构及高温氧化行为表现,建立与之相对应的简化模型。     

强化处理对Al2O3/SiO2陶瓷型芯高温变形的影响

研究了强化处理对Al2O3／SiO2纳米复合陶瓷型芯高温变形的影响规律，结果表明：强化处理对Al2O3／SiO2纳米复合陶瓷型芯高温变形的影响很大，1550℃保温1h的高温挠度由强化前的7mm降至强化后的1mm。强化剂的浓度对陶瓷型芯高温变形的影响不明显，强化次数对陶瓷型芯高温变形的影响相对较大。强化后的陶瓷型芯中出现了莫来石新生片状晶，减少了型芯的高温变形。     

纳米Al2O3在聚酰亚胺胶粘剂高温固化过程中的偏析现象

纳米Al2O3对聚酰亚胺粘接材料的性能具有显著的提升,当纳米Al2O3添加质量分数为8%～12%时,粘接材料的剪切强度由22 MPa提高到35 MPa,粘接面积超过60%。分析发现,Al元素在粘接材料与被粘物界面出现了明显的富集现象,表明纳米Al2O3在复合粘接材料高温固化过程中产生界面偏析现象,这对提高接头的强度十分有利。     

ZrO2-SiC复合材料的合成及其添加对Al2O3-C质耐火材料抗氧化性能的影响

以锆英石和碳黑为原料,利用碳热还原反应在氩气气氛下合成了ZrO2-SiC复合材料,并将其添加到Al2O3-C质耐火材料中.研究了加热温度对ZrO2-SiC复合材料合成的影响以及添加ZrO2-SiC对耐火材料抗氧化性能的影响.采用XRD分析合成材料的相组成,利用SEM观察材料的显微结构.研究表明,提高加热温度有利于ZrO2-SiC复合材料的合成,在本实验条件下合成该材料的适宜温度为1873 K.通过添加合成的复合材料,明显改善了Al2O3-C质耐火材料的抗氧化性能,且当添加6%(ZrO2-SiC)复合材料时,耐火材料的抗氧化性能最佳.     

自蔓延高温合成TiB2／Al2O3复合材料的力学性能

以普通商用TiO2为原料，与铝粉、碳化硼进行自蔓延（SHS）高温合成TiB2／Al2O3复合材料，通过差热和X射线衍射分析，确定了TiO2、Al及B4C的反应机制，得到了生成TiB2／Al2O3复合粉体的最佳工艺条件。测定了TiB2／Al2O3复合粉体相关的力学性能，得到材料的抗压强度为87．2MPa，抗弯曲强度为104．3MPa。SEM观察发现生成相中存在大量的气相或气孔，生成物微观区域不太均匀，材料的断裂形式主要为脆性断裂，生成物的颗粒尺寸为亚微米级。     

AI2O3/Cu复合材料制备工艺的优化

新型颗粒增强铜基复合电极材料Al2O3/Cu能较好地解决电阻点焊镀锌钢板时普通电极材料做电极寿命较短的问题。为了获得优化的Al2O3/Cu复合电极材料制备工艺,采用粉末冶金法制备Al2O3/Cu复合电极材料,通过改变制备过程中的工艺参数,以密度、显微维氏硬度、电导率、显微组织为检测内容,探讨压制力和烧结温度对Al2O3/Cu复合电极材料物理机械性能和显微组织的影响。结果表明,综合性能最优时的Al2O3/Cu复合电极材料制备工艺为:Cu-Al2O3混合粉末制坯压制力100 kN,烧结温度940℃。     

NiAl微晶涂层对两种NiAl基共晶合金高温氧化性能的影响

研究了磁控溅NiAl微晶涂层对NiAl－28Cr-5Mo-1Hf和NiAl－33.5Cr-0.5Zr两种共晶合金在1000－1150℃静态空气中氧化性能的影响，添加Cr,Mo,Hf,Zr等元素使NiAl合金由单相转变为多相结构，高温氧化后表面分别形成抗氧化性能较差的Al2O3 CrO3 HfO2和Al2O3 Cr2O3 ZrO2复合氧化膜，并且发生严重的内氧化。施加NiAl微晶涂层后，高温下表面形成致密的单一氧化物Al2O3，抗氧化性能得到明显提高。     

Al和Co对K4169合金950℃高温氧化行为的影响

利用热重分析法、X射线衍射、扫描电镜和能谱分析研究了Al和Co含量对K4169高温合金950℃高温氧化行为的影响,结果表明:合金氧化动力学符合抛物线规律;添加Al和Co的合金氧化产物颗粒比原始成分合金的细小;Al含量的增加增强了合金的高温抗氧化能力,而Co含量的增加降低了合金的高温抗氧化性能。当Al含量为1.45 wt%、Co含量为0.3 wt%时,合金的高温抗氧化性能最好,而原始成分合金的高温抗氧化性能最差。不同Al、Co含量K4169合金氧化膜都分为3层:外层主要是疏松的Cr2O3和TiO2的混合层,还含有少量的NiO和NiCr2O4尖晶石相;中间层是Cr2O3保护层;内氧化物层是Al2O3。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。