AlN和AlN/BN层状复合陶瓷的高温氧化行为

采用循环氧化法对单相AlN和层状AlN/h-BN复合陶瓷在1000及1300℃空气中的氧化动力学曲线进行研究.结果指出,在1000℃时,层状AlN/h-BN复合陶瓷的氧化增量低于单相AlN陶瓷;在1300℃时,其氧化动力学曲线分为缓慢增重、快速氧化增重和抛物线增重3个阶段,由xRD分析及扫描电镜观察发现,在1300℃氧化30 h后,试样已不存在BN相,并且由于界面层BN的氧化挥发而残留有微孔.     

铁铬铝合金电热元件设计的探讨

通过对电热元件表面负荷的分析与计算提出高温热处理电阻炉(炉温1000—1300℃)的铁铬铝合金电热元件的设计方法。在预选表面负荷时，采用了较低的黑度值(εl＝0．41)，计算结果与经验值接近。实践证明，结合采用波纹形加热器的结构形式，电炉使用效果好，元件服役寿命长。     

纳米AlN对低温陶瓷结合剂性能的影响

本文探讨了纳米AlN对Na2O-B2O3-SiO2硼硅酸盐玻璃体系陶瓷结合剂性能的影响。利用差热分析仪、X-射线衍射仪等仪器,在不同烧成温度及气氛条件下,测试陶瓷结合剂的热性能、XRD、耐火度、抗折强度,以及线膨胀系数等性能,结果表明：在氩气气氛下纳米AlN会促使陶瓷结合剂中产生析晶;添加纳米AlN质量分数w为6%时,结合剂的烧结温度范围增加30℃;氩气气氛下,烧成温度为710℃,添加纳米AlN质量分数w为6%时,结合剂的抗折强度最大,达到35.64 MPa;纳米AlN加入使结合剂的线膨胀系数下降,添加质量分数w（AlN）为6%时,结合剂的平均线膨胀系数最小为4.99×10^-6℃^-1。     

SiC泡沫陶瓷材料的高温氧化行为

采用可控熔渗反应烧结法制备具有宏观三维连通结构的SiC泡沫陶瓷,研究了SiC泡沫在不同温度的氧气中的氧化行为.结果表明:在800～1300 ℃温度范围内,SiC泡沫陶瓷与块体SiC陶瓷类似,其氧化动力学曲线符合抛物线规律,氧化过程受氧化剂在氧化膜中的扩散控制,氧化膜结晶后材料的氧化速率显著降低.     

SiC电热元件的高温失效分析

对炉用ＳｉＣ电热元件在空气介质中于１０００℃－１５８０℃范围的高温失效行为进行了试验分析。元件表面在高温下形成熔融态ＳｉＯ２薄层。由于在氧化反应中生成气体而产生气泡,气泡破裂后材料表面失去保护层,导致了高温氧化的加剧。文中对ＳｉＣ电热元件在不同温度下的脱落物进行了分析,对ＳｉＣ电热元件高温失效的原因进行了综合讨论。     

二硅化钼电热元件在热处理炉中的应用

二硅化钼电热元件在热处理炉中的应用浙江长兴高温元件电炉厂（浙江长兴３１３１００）李锦桥二硅化钼电热元件（以下简称元件）是由高纯硅、钼采用陶瓷工艺制造的特种功能陶瓷元件，在氧化气氛的高温下工作时表面生长出致密的ＳｉＯ２保护膜，具有优良的抗氧化性能，主要...     

碳化硅磨料在陶瓷磨具中氧化性能的研究

碳化硅磨料在陶瓷磨具中的氧化性能对碳化硅细粒度陶瓷磨具的黑心有直接的影响，也是行业一直关注的问题；本文通过试验、结合化学动力学计算和扫描电镜分析，对碳化硅磨料在陶瓷磨具中的氧化性能进行了初步的研究。试验的计算结果表明：碳化硅磨料在现行的烧成制度下，氧化反应是不可避免的，氧化产物SiO2也不会在SiC磨料表面形成致密保护层；碳化硅磨具产生黑心原因关键在于陶瓷结合剂的性质。陶瓷结合剂的完全烧结温度若略高于烧成温度或能始终保持结合剂的适当开口气孔率，就可能避免产品黑心的产生。     

SiC多孔陶瓷的气孔率和强度

选用ＳｉＣ作为骨料，长石和粘土组成的陶瓷结合剂和活性Ｃ作为成孔剂，对不同的烧成温度下ＳｉＣ多孔陶瓷的气孔率和强度进行了研究，温度的提高使ＳｉＣ多孔陶瓷的显气孔率陶低，而体气也民率增大；气孔形状随陶瓷结合剂的高温性能变化而变化，１２８０℃烧成时的气孔形状多为圆形，尺寸分布较均匀；１２４０℃烧成时出现经度极大值，温度提高使固体气孔率增大而强度降低，但在大于１３００℃时，由于ＳｉＣ的高温氧化产物参与晶界     

钟罩炉

该钟罩炉是磨料磨具行业用于烧成金属结合剂金刚石磨具的专用烧成设备,建成后用于第二砂轮厂。炉最高使用温度为1150℃,采用电加热。电热元件是Φ6的康太尔电热丝。炉子总功率小于100KW。炉子钟罩部分重量小于2吨。为保证制品在加热过程中不被氧化,采用炉胆,制品装在炉胆内烧成。经过试验采用发生炉煤气直接充入炉内做保护气体。     

AlN陶瓷/Cu异质材料低温过渡液相扩散连接

为了实现AlN陶瓷与Cu的低温连接、高温服役的目标,满足高温功率器件的服役需求,设计了一种连接方法,在350?℃的大气环境下采用超声辅助熔焊的方式在AlN陶瓷表面熔覆了Sn-Al-Cu活性钎料层,之后将熔覆活性钎料的AlN陶瓷与Cu在保温温度300?℃下进行过渡液相(transient?liquid?phase,?TL...     

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.     

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.     

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。     

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.     

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality of the slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in mold.This technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, thereby controlling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle and partly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structure and angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower than that without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at the top surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial to the growth of equiaxed crystal and decreased element segregation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).