耐热球墨铸铁模具材料的研究现状与发展趋势

对耐热球墨铸铁模具材料的研究现状进行了综合评述.讨论了合金元素对球墨铸铁耐热性的影响、耐热球墨铸铁的耐热机理以及耐热球墨铸铁模具材料的应用领域,在此基础上提出了耐热球墨铸铁模具材料未来的发展趋势.     

贵金属复合材料的成就与展望:(Ⅱ)贵金属复合材料体系

贵金属及其合金作为组元材料,可与其他金属、陶瓷、碳、化学化合物、金属间化合物以及聚合物结合,构成贵金属复合材料.在贵金属复合材料中,贵金属及其合金可作为基体材料,为纤维状或颗粒状的其他材料强化;亦可以涂层、纤维和颗粒等形式作为功能相材料分布在其他基体材料中.本文是“贵金属复合材料的成就与展望”系列文章的第二部分,总结了贵金属复合材料的种类,包括层状复合、纤维复合和颗粒复合材料;列举了贵金属复合材料的主要体系及其应用;讨论了一些贵金属复合材料的结构特征及其今后研究的新课题.     

SiC_P/Cu梯度复合材料的制备及性能研究

采用粉末冶金方法制备了SiCP/Cu均质复合材料及梯度复合材料,并对复合材料的显微组织、硬度、导电率和耐磨性进行了研究。结果表明:均质复合材料中SiC颗粒含量越多,导电率越小,耐磨性越好;梯度复合材料基体连续,组织及硬度呈梯度分布且其耐磨性优于基体Cu材料;磨损机理是微切削磨损和磨粒磨损的复合作用。     

贵金属复合材料的成就与展望:(II)贵金属复合材料体系

贵金属及其合金作为组元材料,可与其他金属、陶瓷、碳、化学化合物、金属间化合物以及聚合物结合,构成贵金属复合材料。在贵金属复合材料中,贵金属及其合金可作为基体材料,为纤维状或颗粒状的其他材料强化;亦可以涂层、纤维和颗粒等形式作为功能相材料分布在其他基体材料中。本文是“贵金属复合材料的成就与展望”系列文章的第二部分,总结了贵金属复合材料的种类,包括层状复合、纤维复合和颗粒复合材料;列举了贵金属复合材料的主要体系及其应用;讨论了一些贵金属复合材料的结构特征及其今后研究的新课题。     

知识窗

机械工程材料是指用于制造各类机械零件、构件的材料和在机械制造过程中所应用的工艺材料。按属性分有金属材料和非金属材料两大类。此外,还有由两类或两类以上的不同材料组合而成的复合材料。由于其各种组成材料在性能上能互相取长补短,产生协同效应,使复合材料的综合性能优于原组成材料而满足各种不同的要求,成为了一类新型的工程材料。机械工程材料按用途分类,有结构材料 (结构钢 )、工模具材料 (工具钢 )、耐蚀材料 (不锈钢 )、耐热材料 (耐热钢 )、耐磨材料 (耐磨钢 )和减摩材料等。 　　复合材料的组成包括基体和增强材料两个部…     

注模凝胶热压法制备Al2O3(YAG)/LaPO4层状陶瓷复合材料

选择Al2O3(YAG)作为基体片层材料,LaPO4作为界面层材料.采用凝胶注模成型技术制备出基体层材料的坯片,然后在基体层坯片上采用浸渍或喷涂工艺附着界面层材料,最后将坯片叠置于模具中热压烧结.制备的陶瓷复合材料微观结构均匀,基体片层厚度为110 μm～150 μm,界面层厚度为10 μm～30 μm,实测层厚比为11.重点研究了工艺参数及界面层成分对层状陶瓷复合材料室温性能的影响.结果表明氧化物基层状陶瓷复合材料的抗弯强度比基体材料略有下降,但室温断裂韧性达到了13.52 MPa.m1/2,是基体材料断裂韧性的3倍.还对比了氧化物基层状陶瓷复合材料与基体材料在断裂过程中裂纹扩展路径的差异.     

WC颗粒增强钢基复合材料辊环的研究

用离心铸造工艺制备了WCp/钢基复合材料辊环,并对所制备的复合材料进行了分析与性能测试.结果表明:离心铸造工艺制备的复合材料辊环表面复合层与芯部基体结合良好,表面复合层硬度达到63～65 HRC,WC颗粒发生了溶解-析出作用,复合层的最大厚度为3.9 mm,复合材料的耐磨性较基体材料提高了3倍.     

陶瓷模具材料的表面改性技术及应用

全面综述了表面镀层、表面复合、表面涂覆等表面改性技术在各类陶瓷模具中应用、研究的现状.指出:表面改性技术既能发挥陶瓷材料的高硬度、高耐磨和耐高温等的优势,又能发挥金属基体高强度、高韧性的特点,从而使得陶瓷模具材料具有良好的使用性能,具有广阔的应用前景.今后研究的重点是如何通过表面改性工艺的控制和复合层材料的合理选择和设计,使得所形成的陶瓷复合层与金属基体结合强度高,硬度高,既减摩又耐磨.     

高铬表面复合材料的冲击磨损性能研究

以高碳铬铁为主要增强材料,采用铸造方法制备了三种不同成分的高铬表面复合材料。观察了表面复合层的组织及其与基体的结合状态,使用MLD-10型动载磨料磨损试验机进行了材料的冲击磨损试验。磨损试验结束后,使用扫描电镜观察了表面复合材料的磨损面及其正切面形貌,分析了材料的磨损机理。结果表明:在所制备的三种材料中,增强颗粒中高碳铬铁含量为40%的表面复合材料耐磨性最好,其耐磨性是基体材料的10倍以上;所制备表面复合材料的主要磨损失效方式为反复塑性变形和疲劳剥落。     

合金元素对球墨铸铁抗热疲劳性能的影响

研究了合金元素对球墨铸铁抗热疲劳性能的影响。结果表明,就抗热疲劳性能而言,在本研究范围内,耐热球墨铸铁模具材料的较佳成分配比w为:5.0%Si、0.5%Mn0、.5%Mo、1.2%Cr。Si是影响材料热疲劳抗力的重要元素,对耐热球墨铸铁模具材料的抗热疲劳性能起着决定性作用,它的含量直接决定了耐热球墨铸铁模具材料热疲劳抗力的总体水平。Mo元素的加入能够使晶粒细化,其含量越多,则晶粒越细小,材料对热疲劳裂纹萌生和扩展的抗力就越强。     

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.