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1.
以二种中国煤为原料,用射频等离子体法制备洋葱状富勒烯(Onion—like Fullerenes:OLFs),就压力对产物的影响进行厂讨论。OLFs的表征采用高分辨透射电镜(HRTEM)和X射线衍射(XRD)等技术。结果表明:在其它工艺条件相同的情况下,压力为30Pa适合OLFs生长;实验所用煤均可大量制备OLFs,纯度较高,为OLFs的制备开拓了廉价生产的新途径。  相似文献   

2.
以液体苯(C6H6)为放电介质,二茂铁为催化剂,石墨做电极,可大量制备洋葱状富勒烯(Onion-like Fullerenes:OLFs)。本文重点考察了二茂铁对OLFs产量的影响,利用高分辨透射电镜(HRTEM)和X-射线衍射(XRD)对所得产物进行了表征,结果表明:加入二茂铁可提高OLFs的产量;OLFs呈中空椭球状和多面体状,石墨化程度较高,OLFs直径分布可控制在10-30nm范围内。  相似文献   

3.
以脱油沥青(DeoiledAsphalt)作原料,用热处理法制备了内包金属镍的纳米碳洋葱。用X-射线衍射仪(XRD)和高分辨透射电镜(HRTEM)对产物进行表征。结果表明:在2000℃温度下真空热处理后,镍粒子大多被数层碳壳包覆形成内包镍的纳米碳洋葱,颗粒多为准球形结构,尺寸在10.30nm范围,晶化程度较高,结构较完善。为内包镍纳米碳洋葱的制备开拓了廉价生产的新途径。  相似文献   

4.
采用磁控共溅法制备Fe-Mn-Si磁性形状记忆合金薄膜,并将制备薄膜在不同的温度下进行真空热处理,比较了不同热处理温度下薄膜的组织形貌。结果表明,制备薄膜组织成分均匀,热处理前主要为γ(fcc)相,经400℃真空热处理2h后,薄膜含有γ(fcc)和ε(hcp)相。随着热处理温度升高,溅射薄膜颗粒增大,表面粗糙度增加。  相似文献   

5.
研究了在不同电流值条件下纯石墨电极水下电弧放电法制备洋葱状富勒烯(OLFs)的过程和工艺。采用场发射扫描电镜,X射线衍射,高分辨透射电镜对产物的微观结构和形貌进行表征。所得产物是直径约为25nm,外形呈球状并具有一定的空心结构OLFs。研究了放电时的电流值对产物的产量和产率以及对产物石墨化程度的影响,结果表明在20A.50A范围内随着电流强度的增大OLFs的产量和产率都有不同程度的提高。  相似文献   

6.
真空热处理:将工件放置在真空度低于1×105 Pa(通常是10-1~10-3 Pa)的环境中加热的热处理工艺。零件经真空热处理后,畸变小,质量高,且工艺本身操作灵活,无公害。因此真空热处理不仅是某些特殊合金热处理的必要手段,而且在一般工程用钢的热处理中也获得应用,特别是工具、模具和精密耦件等,经真空热处理后使用寿命较一般热处理有较大的提高。例如某些模  相似文献   

7.
序号:178;公开号CN1067684A弹性手许热处理方法:本发明涉及一种弹性零件热处理方法。该热处理方法包括将弹性零件在850℃±10℃温度下淬火,400—500℃温度回火、吹砂、用清洗剂对表面进行清洗,之后放入氨化炉中进行真空脉冲软氨化热处理,真空脉冲软氮化热处理温度400~500℃,热处理时间4~6h,氨化介质为氨气(NH3),之后通入N2保护气体、降温至300℃,出炉油冷,再回火至200℃后空冷。用本发明方法热处理后的弹性零件,具有最佳的硬度值,使用寿命提高3~4倍。序号:1798公开号CN1067685A一种在非金用材料及其制品表面构嵌金属…  相似文献   

8.
以脱油沥青(Deoiled Asphalt)为碳源、二茂铁为催化剂,采用化学气相沉积法(CVD)制备碳纤维(CFs),其裂解后的残渣经真空热处理制得含镍碳纳米胶囊(CNCs)。用场发射扫描电镜(FESEM)、高分辨透射电镜(HRTEM)、X射线衍射仪(XRD)和拉曼光谱(Raman)对产物进行表征。结果表明:碳纤维纯度较高,属中空结构,直径主要分布在200~500 nm范围内;含镍碳纳米胶囊为准球形核壳结构,核为金属镍,壳为石墨化碳,大小在5~30 nm范围,晶化程度较高,结构较完善。  相似文献   

9.
采用真空非自耗 真空自耗电弧熔炼的方法制备了Nb-Cr系多元合金的母合金锭;对母合金进行了1450℃,24h 1000℃,24h的热处理;采用三点弯曲方法测试了合金的室温断裂韧性;进行了950℃不同时间的氧化实验.发现热处理后Nbss基体由树枝晶转变为等轴晶,而Laves相Cr2(Nb,Ti,Hf)则由块状转变为边界圆润的棒状;合金的室温断裂机制由电弧熔炼态的解理断裂转变为热处理后的准解理断裂;950℃的氧化产物为CrNbO4、HfO2、TiO2、CrNb11O29和Ti2Nb10O29.  相似文献   

10.
对采用电子束物理气相沉积(EB-PVD)技术制备Ni基高温合金薄板800℃真空保温过程中微观组织结构与硬度进行了研究。结果表明:制备态NiCrCoAl合金组织为γ-Ni固溶体,组织均匀细化、无沉淀析出相、无位错,存在孪晶,晶粒中出现大量应变条纹:在热处理态800℃,5×10^-3Pa真空保温过程中,合金组织相结构未发生变化,合金的平面和截面组织呈现层片状结构,存在大量亚结构缺陷——孪晶、少量位错,在800℃保温16h,有少量碳化物沉淀析出物;随着合金保温时间的延长,应变条纹随之消除,沿(220)晶面的晶粒择优取向迅速长大。同时,显微硬度随之降低。  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
吴玉梅  熊晓云  靳蓉  孙敬民  杨林  罗晓星 《金属学报》2005,10(10):1100-1103
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。  相似文献   

16.
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).  相似文献   

17.
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.  相似文献   

18.
This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.  相似文献   

19.
Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.  相似文献   

20.
A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.  相似文献   

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