等离子弧堆焊WC增强型高铬铸铁的组织和性能

采用等离子弧粉末堆焊技术在Q235钢表面分别堆焊高铬铸铁和WC增强型高铬铸铁,通过对各堆焊层的显微组织、化学成分、显微硬度、耐磨性和耐蚀性进行对比分析,揭示WC颗粒对高铬铸铁堆焊层的影响。结果表明,高铬铸铁堆焊层显微组织由初生(Fe,Cr)7C3和共晶组织组成,WC增强型高铬铸铁堆焊层由初生碳化物、WC颗粒和共晶组织组成。与高铬铸铁相比,WC增强型高铬铸铁由于WC的加入,初生碳化物面积分数非常高,共晶组织数量相应减少;WC增强型高铬铸铁的硬度,耐电解腐蚀性和耐热腐蚀性均优于高铬铸铁。两种堆焊层熔合线处的硬度陡降,结合线扫描结果说明,WC的加入不影响WC增强型高铬铸铁堆焊层与基体界面处的冶金结合和堆焊质量。     

Fe-C-Cr-V高铬堆焊合金的M7C3型碳化物及耐磨性

采用药芯焊丝埋弧堆焊方法制备含有0.9%~3.0%C,15%~20%Cr,2.0%~3.0%V的高铬合金.借助光学显微镜、扫描电镜和X射线衍射等手段,研究其显微组织及碳化物分布形貌.结果表明,其显微组织由马氏体+铁素体+奥氏体+初生M7C3+(Fe,Cr)3C+TiC等相组成.通过优化药芯焊丝组份及调整堆焊速度,获得了沿堆焊表面垂直方向定向分布的初生M7C3型碳化物,电子能谱分析显示该碳化物为(Fe,Cr,V)7C3.此外,考察了碳含量对高铬堆焊合金硬度及耐磨粒磨损性能的影响.表明其耐磨性优良,其中15~25μm M7C3型初生碳化物颗粒有效阻碍磨粒的显微切削运动,显著改善了耐磨性.     

VC-90药芯焊丝堆焊组织性能研究

采用埋弧堆焊技术对药芯焊丝VC-90进行四层堆焊,借助金相显微镜、扫描电子显微镜、EDS能谱仪、X射线衍射仪、维氏硬度计及磨损试验机等对堆焊合金微观组织及耐磨性能进行测试和分析。结果表明,堆焊合金的基体组织为马氏体和残余奥氏体,基体上分布着初生碳化物和共晶碳化物,碳化物的类型均为M7C3型。初生碳化物主要呈不完整的六边形,中间有空洞。堆焊金属的相结构为C0.055Fe1.945+(Fe,Cr)7C3+CFe15.1。堆焊合金层的耐磨性是Q235钢的27.20倍,抵抗低应力的磨料磨损效果良好。     

CO2气体保护药芯焊丝喷粉堆焊层组织及其耐磨性

采用CO2气体保护焊方法,使用高铬铸铁药芯焊丝,喷射优化设计的Cr-Ti-Mn-B系粉体形成耐磨堆焊层。利用XRD及金相显微镜分析堆焊层组织结构,并测定堆焊层的硬度和磨损性能。结果表明:与单纯高铬铸铁芯堆焊层相比,喷射粉体后堆焊层的洛氏硬度HRC增加,当Mn铁、Cr铁、B铁、Ti铁质量分数比为4.3∶52.2∶3.9∶39.6时,堆焊层硬度和耐磨性最高。喷射粉体堆焊层以马氏体为主,并有(Cr,Fe)7C3,FeMn2等相产生,从而提高堆焊层硬度和耐磨性。     

高铬铸铁芯焊条堆焊层组织分析

基于焊芯过渡合金元素的技术思路,研制了高铬合金铸铁同质堆焊焊条．分析了不同药皮堆焊焊条的堆焊层组织及性能,定量表征了合金元素的过渡系数．结果表明,通过焊芯过渡合金元素的高铬合金铸铁堆焊焊条可获得组织和性能均匀的堆焊层．合金过渡系数高于85％．碱性药皮堆焊焊条堆焊层为亚共晶成分高铬合金铸铁,组织由奥氏体γ＋马氏体M＋碳化物Cr7C3组成．堆焊层硬度为44．5～56．5HRC．碱性石墨化型药皮堆焊焊条堆焊层组织由初生碳化物Cr7C3＋马氏体M＋碳化物Fe7C3＋少量石墨G组成,堆焊层硬度可达59～67HRC．     

铝对高铬合金埋弧堆焊层组织和耐磨性的影响

采用合金粉末与实心焊丝埋弧堆焊相结合的方法,在Q235钢表面堆焊含铝和不含铝的高铬合金堆焊层,使用扫描电镜、能谱仪和磨粒磨损机等手段研究铝对高铬合金堆焊层的组织和耐磨性的影响。结果表明,未加铝粉的堆焊层中主要有含(Fe,Cr)_3C型碳化物,含3%Al的堆焊层中主要有M_7C_3碳化物和黑色小块状氧化铝硬质相存在;两种堆焊层磨损形貌均呈凿槽或犁沟形态,碳化物形成耐磨骨架。加3%Al堆焊层中的氧化铝硬度高,能有效减少磨粒的显微切削运动,堆焊层犁削划痕比未加铝粉的浅而细小,耐磨性较好。     

Nb和Mo对高碳自保护药芯焊丝熔敷性能

借助光学显微镜、扫描电镜观察Nb,Mo在金相组织中存在的形态,研究了两元素强化机理,分析了硬度和耐磨性存在差异的原因.结果表明,在金相组织中,随Nb.Mo含量的增多,Nb,Mo的初生碳化物数量增多,熔敷金属硬度和耐磨性均增加;在堆焊熔敷金属中,Nb仅生成初生NbC,沉淀强化熔敷金属,强化效果明显,Mo不仅生成初生MO2C,而且还固溶强化初生Cr7C3和基体,通过沉淀和固溶两种形式强化熔敷金属,但强化效果不明显.在高铬铸铁中为得到良好的耐磨性及经济效益须优化合金成分,应同步强化基体和碳化物.     

Mo强化Fe-Cr-C系堆焊材料组织和力学性能分析

在Fe-Cr-C系高Cr铸铁型堆焊焊丝中加入Mo元素制成自保护药芯焊丝,通过热力学平衡计算,理论分析了Mo对高碳高铬系堆焊材料的强化机理。结果表明:Mo元素的添加,可以增加堆焊层中初生碳化物的数量,细化合金组织,在强化碳化物的同时强化基体。通过试验的方法对比分析了Mo元素对高Cr铸铁型堆焊材料显微组织和力学性能的影响,当加入2%Mo时,堆焊熔覆层的质量明显好于不含Mo的材料,同时堆焊层平均硬度值提高了12.5%,添加Mo元素焊丝堆焊制备的复合材料的常温冲击韧性是未添加Mo元素的1.9倍。     

堆焊

20091216Fe-Cr-C系药芯焊丝耐磨堆焊层的组织和性能/肖逸锋…//热加工工艺.-2008,37(11):1~3在Fe-Cr-C系药芯焊丝药芯中添加多种强碳化物形成元素,研究了堆敷金属的显微组织、耐磨性和抗氧化性。结果表明,堆焊层金属中大量呈针状和片状的细小碳化物均匀分布在共晶组织和马氏体基体上,改善堆焊金属的韧性,提高了抗裂性;焊缝金属的硬度为61.7HRC,耐磨性好,其相对耐磨性是市售某药芯焊丝堆焊层金属的3.75倍;堆焊层金属高温稳定性好,抗氧化能力强;焊丝适用于高温低应力磨料磨损环境。图3表4参520091217Fe-Cr-V耐磨堆焊合金/龚建勋…//焊接学报.-2008,29(7):73~76制备了用于埋弧焊药芯焊丝的Fe-Cr-V堆焊合金,其成份(质量分数,%)为C0.9~1.5,Cr13~15,V1.0~2.0。借助光学显微镜、扫描电镜和X射线衍射等手段,研究了其显微组织,并考察V和B4C含量对该堆焊合金性能的影响。Fe-Cr-V堆焊合金的显微组织由铁素体+马氏体+(Cr,Fe)23C6等碳化物组成。电子能谱微区分析显示Cr,V元素晶界含量显著高于晶内,随WC加入量提高,晶界与晶内含量差...     

堆焊

20091216Fe-Cr-C系药芯焊丝耐磨堆焊层的组织和性能/肖逸锋…//热加工工艺.-2008,37(11):1~3在Fe-Cr-C系药芯焊丝药芯中添加多种强碳化物形成元素,研究了堆敷金属的显微组织、耐磨性和抗氧化性。结果表明,堆焊层金属中大量呈针状和片状的细小碳化物均匀分布在共晶组织和马氏体基体上,改善堆焊金属的韧性,提高了抗裂性;焊缝金属的硬度为61.7HRC,耐磨性好,其相对耐磨性是市售某药芯焊丝堆焊层金属的3.75倍;堆焊层金属高温稳定性好,抗氧化能力强;焊丝适用于高温低应力磨料磨损环境。图3表4参520091217Fe-Cr-V耐磨堆焊合金/龚建勋…//焊接学报.-2008,29(7):73~76制备了用于埋弧焊药芯焊丝的Fe-Cr-V堆焊合金,其成份(质量分数,%)为C0.9~1.5,Cr13~15,V1.0~2.0。借助光学显微镜、扫描电镜和X射线衍射等手段,研究了其显微组织,并考察V和B4C含量对该堆焊合金性能的影响。Fe-Cr-V堆焊合金的显微组织由铁素体+马氏体+(Cr,Fe)23C6等碳化物组成。电子能谱微区分析显示Cr,V元素晶界含量显著高于晶内,随WC加入量提高,晶界与晶内含量差...     

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).