铸渗法制备Mo2FeB2增强钢基表面复合材料

采用反应铸渗法在钢基体表面制备一层三元硼化物金属陶瓷复合材料,研究了三元硼化物钢表面复合材料的硬度、耐磨性,用SEM-EDS研究了铸渗层的微观结构和元素分布.结果表明,通过反应铸渗法制备的三元硼化物钢表面复合材料的洛氏硬度为74.3,维氏硬度为789 N/mm2;磨损主要为磨粒磨损.并对铸渗反应机理进行了初步讨论.     

铸钢表面消失模铸渗层干滑动磨损行为研究

采用消失模铸渗工艺在ZG310-570表面制备了钒铬表面复合层,并考察了其显微组织和干滑动磨损性能.结果表明,所制备的复合层组织致密、无铸造缺陷.在铸渗复合层中存在着几种典型的碳化物形态：条块状、菊花状、短杆状以及团球状.在300～750 N载荷下,铸渗层的磨损量随载荷的增加而增加,当铸渗剂中铬铁、钒铁的质量分数分别为35%、40%时铸渗层的耐磨性能最好,在450 N载荷下是ZG310-570的16.5倍.铸渗层的磨损机理为磨粒磨损及塑性变形和剥落.     

铸钢表面钒铬铸渗层组织及干滑动磨损性能研究

采用消失模铸渗工艺在ZG310-570表面制备了钒铬表面复合层,并考察了其显微组织、显微硬度以及干滑动磨损性能。结果表明,钒碳化物为球状和条状,铬碳化物为块状和板条状。铸渗复合层的硬度沿渗层表面到基体方向先增加后降低,在距表面1.5-2.0 mm处达到最大值。在30-90 kg载荷下,复合材料的磨损失重随着载荷的增加而增加,含V-Fe15%、Cr-Fe60%的渗剂做成的块试样耐磨性最好。复合层的磨损机制主要为磨粒磨损,ZG310-570的磨损机制为塑性变形和剥落。     

铸钢表面钒铬铸渗层的微观分析及干滑动磨损性能研究

采用消失模铸渗工艺在ZG310-570表面制备了钒铬表面复合层,并考察了其显微组织、增强相的结构、基体组织构成、显微硬度以及干滑动磨损性能。结果表明,钒碳化物为条状,铬碳化物为板条状。铸渗复合层中主要存在Cr7C3、V8C7、VC0.75、V2C四种硬质相。1000℃淬火后的铸渗层基体组织为马氏体加奥氏体和少量的贝氏体组织,马氏体包括板条马氏体和孪晶马氏体。在距铸渗层表面0～1mm处的显微硬度要低于距表面1～4mm的显微硬度,在过渡区显微硬度呈递减分布,在大于4．5mm以后的区域显微硬度趋于平稳。在450N载荷下,铸渗复合层的耐磨隆不ZG310-570的13.6倍。     

离子氮化对薄壁铸件铸渗WC、Cr硬质表层组织和性能的影响

研究了薄壁铸件WC、Cr硬质合金层在辉光离子氮化炉中的离子氮化处理工艺;探讨了氮化处理对铸渗层的组织与性能的影响;利用SEM研究了铸渗覆层的微观结构和元素分布,利用硬度计测量了铸渗覆层的硬度分布,利用金相显微镜研究了铸渗覆层的金相组织.结果表明,铸渗层经离子氮化处理后,在基体表面形成了弥散分布的尺寸很小的颗粒状氮化物相(如Fe4N、Fe2N等),表面硬度从710HV0.98提高到1100HV0.98左右,基体耐磨性能因此得以显著提高.由于铸渗层中已存在高硬度WC颗粒相的强化作用,所以复合层的硬度在离子氮化处理后没有明显改善.     

球墨铸铁表面钨铬铸渗层研究

研究了铸渗法制造表面粒子增强复合材料,可以在ＱＴ６００－３基体上获得均匀、致密的铸渗层,厚度为３ｍｍ以上。同时,研究了球墨铸铁铸渗层的铸态组织,硬度和合金成分在铸渗层中的分布规律,并现场试验了粉碎机摆锤耐磨粒磨损性能。     

铸铁表面负压铸渗法Ni/WC复合渗层组织和性能

以制备表面质量良好,硬度较高的铸铁材料为目的,采用负压铸渗法在铸铁表面制备了不同WC含量的Ni基复合渗层,用扫描电镜(SEM)、X射线衍射(XRD)和电子探针(EPMA)等测试手段,分析了渗层的显微结构、相组成、化学成分分布、宏观、显微硬度等.结果表明:渗层中WC颗粒分布均匀,渗层组织致密,界面结合良好;渗层主要由Ni基固溶体、W2C颗粒、NiB和FeB等相组成;显著地提高铸铁表面的硬度.最终在铸铁表面获得了硬度、质量较高的复合渗层,达到制备目的,满足使用要求.     

钒对高铬合金铸渗层组织与性能的影响

通过真空实型铸造工艺(V-EPC)在ZG45钢表面制备不同含钒量的高铬合金复合层,采用扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分析了含钒量对铸渗层组织的影响,使用洛氏硬度计和冲击磨损试验机研究了钒含量对硬度和耐磨性的影响。研究表明,铸渗层组织主要由α-Fe与α-Fe+M₇C₃+VC共晶组织组成,过渡层内各合金元素成梯度分布,C、Cr、V元素自铸渗层向基体发生了扩散,且C、Cr、V元素的分布与碳化物的分布高度重合。随着钒含量的增加,晶粒逐渐细化,共晶碳化物数量逐渐增多,VC也增多,铸渗层硬度和耐磨性显著提高。热处理后有大量二次碳化物析出,随着铸渗层中钒含量增加,热处理后二次硬化效果显著提高。     

ZG310-570表面消失模铸渗层磨粒磨损性能研究

采用消失模铸渗工艺,在廉价的ZG310-570表面形成了一层钒铬复合层。在ML-100型磨粒磨损试验机上研究了四种铸渗层成分不同的试样在不同条件下的抗磨粒磨损性能,并借助于JSM-5610LV扫描电镜研究了铸渗复合层的磨损形貌。结果表明:不同条件下四种成分的铸渗层抗磨粒磨损性能大致相当,均能达到ZG310-570的10倍以上;磨损形式以犁沟和显微切削为主。     

钨铬复合铸渗层的冲击磨损性能研究

采用传统的铸渗工艺在铸钢件表面制备了钨铬复合铸渗层,采用MLD-10型动载磨料磨损试验机研究了几种不同成分表面复合材料的冲击磨损性能.结果表明,钨铬复合渗层的磨损率随铬铁含量的升高先降低后升高,随WC含量的增加而降低,随冲击功的增大先减小后增大;而其磨损机制为塑性变形和剥落.     

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.     

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。     

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.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.