喷雾干燥法制备钼合金微粉的研究

钼合金的制备过程广泛采用原料粉末混匀、坯料压制、烧结成型的粉末冶金方法,因此原料粉末混合的均匀程度、纯度、粉末粒径和形貌对钼合金制品的性能有重要影响。本文采用溶液喷雾干燥法制备前驱体粉末,再将前驱体粉末在氢气气氛下进行高温还原制备钼钨合金粉和钼钌镍复合粉,研究了喷雾干燥工艺参数（溶液浓度、进料速度、干燥温度等）和还原热处理工艺参数（还原气氛、温度、时间等）对钼合金微粉粒径、成分和形貌的影响,此外还分析了钼钨合金化和钼钌镍复合粉钎焊性能。结果表明,采用溶液喷雾干燥结合还原热处理工艺,可获得粒径0.5~3μm的球形钼钨固溶体合金粉和0.5~2μm的球形钼钌镍复合粉,且钼钌镍复合粉在钼板上钎焊时具有优异的润湿性。     

喷雾干燥结合微波煅烧法制备微米级球形钼粉的研究

本文以仲钼酸铵(优级纯)为原料,通过结合气流式雾化干燥法和微波煅烧氢还原法制备出球形、微米级、比表面积大、分散性好的钼粉。重点研究雾化造粒过程和微波煅烧氢还原阶段的升温速率对最终Mo粉的形貌、粒度以及比表面积的影响及规律。研究结果表明,控制一定的参数可以制备出球形、微米级、分散性好的钼酸铵前驱体粉末;最终Mo粉的微观形貌受升温速率的影响,升温速率越低制备的Mo粉破碎越严重,且有少量团聚现象,升温速率越高制备的Mo粉球形度越高,分散性越好;升温速率也直接影响平均粒度和比表面积,升温速率越低,平均粒度越小,而比表面积越大,升温速率越高,平均粒度相应增大,比表面减小。     

喷雾干燥结合微波煅烧氢还原法制备微米级球形钼粉

以仲钼酸铵(优级纯)为原料,通过气流式雾化干燥结合微波煅烧氢还原法制备出微米级球形钼粉。重点研究雾化造粒过程和微波煅烧氢还原阶段的升温速率对最终Mo粉的形貌、粒度以及比表面积的影响及规律。结果表明,控制一定的工艺参数可以制备出微米级球形、分散性好的钼酸铵前驱体粉末。微波煅烧氢还原的升温速率越低,制备的Mo粉破碎越严重,且有少量团聚现象。升温速率越高,制备的Mo粉球形度越高,分散性越好。升温速率也直接影响平均粒度和比表面积,升温速率越低,平均粒度越小,而比表面积越大;升温速率越高,平均粒度相应越大,比表面越小。     

WC-Co复合粉形貌遗传特性及粒度分布研究

以偏钨酸铵、可溶钴盐、有机碳为原料,经喷雾转化、煅烧、低温还原碳化制备WC-Co复合粉。对前驱体、复合粉物相组成、WC晶粒度、微观形貌、平均粒度及分布进行研究。结果表明:复合粉由WC和Co两相组成,WC晶粒度约为60 nm;前驱体粉末呈空壳球形结构,部分颗粒破裂;经煅烧后,形貌未发生明显变化;再经还原碳化处理,颗粒表面产生大量孔隙,形貌与前驱体相似,具有很好的形貌结构遗传特性;复合粉平均粒度比前驱体略有减小且粒度分布更窄;溶液浓度、给料速度越大,离心转速越小,则平均粒度越大;进气温度对粒度影响很小。     

球形氧化锆及氧化锆/镍复合粉体的制备

采用化学沉淀法分别制备球形氧化锆及镍/氧化锆复合微球粉体。考察加料速度、加料方式和反应器结构等因素对粒径分布、结晶状态及形貌的影响,初步得到优化工艺条件,并在优化条件下制得粒径分布均匀的球形氧化锆粉体和镍包裹氧化锆复合粉体。利用扫描电镜、能谱及X射线衍射仪分别对前驱体及热处理产物的形貌和物相进行分析,利用激光粒度分析仪检测球形氧化锆前驱体的粒径分布。研究表明,采用化学沉淀法,通过优化制备工艺条件,可以制备粒径分布较均匀的球形氧化锆粉体;利用非均相化学沉淀包裹技术制备的金属镍包裹氧化锆微球粉体,球形氧化锆颗粒表面作为异相成核的场所,通过控制颗粒浓度、加料速度以及添加表面活性剂等工艺条件,可以调控包裹层厚度、表面均匀度以及表面裂纹等。     

碳氢协同还原-碳化法制备纳米WC粉的工艺及机理研究

针对传统还原-碳化工艺中WC粉颗粒的长大问题,采用碳氢协同还原-碳化法制备纳米级球形WC粉,研究前驱体配碳比和反应温度对WC粉性能的影响。结果表明,WC的碳含量与前驱体的配碳比密切相关,最佳配碳比（即n(C)/n(W)值）为3.6。W向WC的转变具有结构遗传性,WC的平均粒径与还原温度和碳化温度密切相关。随着还原温度由680 ℃升高至800 ℃,还原水蒸气与碳反应生成CO和H2,显著降低体系中水蒸气的分压,从而抑制中间产物W颗粒的挥发-沉积长大,WC的平均粒径随还原温度升高而减小。碳化过程中的高温促进WC颗粒的晶界迁移和纳米W颗粒之间的烧结合并长大,WC的平均粒径随碳化温度的升高而增大。n(C)/n(W)为3.6的前驱体粉末经800 ℃还原和1100 ℃碳化后,得到平均粒径为87.3 nm的球形WC粉。     

碳氢协同还原-碳化法制备纳米WC粉的工艺及机理

针对传统还原-碳化工艺中WC粉颗粒长大的问题,采用碳氢协同还原-碳化法制备纳米级球形WC粉,研究了前驱体配碳比和反应温度对WC粉性能的影响。结果表明,WC粉的碳含量与前驱体的配碳比密切相关,最佳配碳比(即n(C)/n(W)值)为3.6。W转变为WC具有结构遗传性,WC粉的平均粒径与还原温度和碳化温度密切相关。随着还原温度由680℃升高至800℃,还原水蒸气与碳反应生成CO和H_2,显著降低体系中水蒸气的分压,从而抑制中间产物W颗粒的挥发-沉积长大,WC粉的平均粒径随还原温度升高而减小。碳化过程中的高温促进WC颗粒的晶界迁移和纳米W颗粒之间的烧结合并长大,WC粉的平均粒径随碳化温度的升高而增大。n(C)/n(W)为3.6的前驱体粉末经800℃还原和1100℃碳化后,得到平均粒径为87.3 nm的球形WC粉。     

溶胶-凝胶/高温氢还原工艺制备Mo-Al2O3-La2O3复合粉末

Al₂O₃协同La₂O₃强韧化的钼及钼合金具有优越的综合力学性能，通过粉末冶金方法制备钼及钼合金的关键在于获得超细或纳米Mo-Al₂O₃-La₂O₃粉末。本文以仲钼酸铵、硝酸铝、硝酸镧和柠檬酸为原料，采用溶胶-凝胶-煅烧-高温氢还原工艺制备Mo-Al₂O₃-La₂O₃复合粉末，利用XRD、SEM、EDS和TEM等分析手段对粉末的微观组织结构进行表征。结果表明：当水浴温度为85℃、p H=1、柠檬酸与钼酸铵的质量比为1.7时，形成了网状结构大分子交联的络合物前驱体，这有利于在后续高温还原过程中制备超细或纳米Mo复合粉末。前驱体粉体在550℃煅烧3 h后，粉末主要由MoO₃和Al₂(Mo O₄)₃组成。采用一步高温氢还原时，还原3 h后MoO<...     

纳秒激光加工微凹坑对YG3表面浸润性的影响

研究硬质合金刀具表面浸润性对提高刀具寿命和工件加工表面质量有重要的意义。采用波长1064 nm纳秒脉冲激光在硬质合金YG3表面加工微凹坑阵列,运用光学显微镜、光学轮廓仪和接触角测量仪分别测量微凹坑形貌和表面接触角,研究不同激光功率、扫描次数和微凹坑间距对表面形貌和接触角的影响规律。建立微凹坑几何形貌模型,基于Wenzel理论分析微凹坑形貌变化对表面接触角的影响机理。结果表明:随着平均功率和扫描次数的提高,微凹坑的直径和深度均增大;随着间距的减小,微凹坑分布密度增大。3种条件下表面粗糙度率均增大,表面接触角余弦值随粗糙度率的变化趋势基本一致且成正相关,所以接触角随粗糙度率增加而降低。通过实际接触角与推导接触角的曲线拟合得到了接触角方程。     

还原工艺对钼粉粒度和氧含量的影响

以仲钼酸铵、三氧化钼、二氧化钼和钼粉为原料 ,采用不同的温度和不同的料层厚度进行了还原试验 ,分析了所得钼粉的粒度、氧含量和形貌 ,剖析了同舟内不同层次钼粉的粒度和氧含量的变化规律     

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.     

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.