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1.
本实验采用ZrO_2(MgO)固体电解质氧浓差电池直接测定氧的活度,用放射性测量技术及低温无水电解分离夹杂的方法,考察了电解分离过程中La_2O_2S的稳定性并测定了铁液中溶解态的La含量,对实验数据用平衡值外推法处理得到: 1550℃ K_(La_2O_2S)=3.81×10~(-19) e_S~(La)=-4.1 1600℃ K_(Li_2O_2S)=6.45×10~(-19) e_S~(La)=-4.8 1650℃ K_(Li_2O_2S)=7.41×10~(-19) e_S~(La)=-4.2 La_((1))=[La] △G_(sol)~0=-136700+59.82T,γ_(La)~0=0.33(1873K) 实验结果表明La具有比Ce,Nd,Y更强的脱硫氧能力。  相似文献   

2.
本实验采用ZrO_2(MgO)固体电解质氧浓差电池直接测定氧的活度,用放射性测量技术及低温无水电解分离夹杂的方法,考察了电解分离过程中La_2O_2S的稳定性并测定了铁液中溶解态的La含量,对实验数据用平衡值外推法处理得到: 1550℃ K_(La_2O_2S)=3.81×10~(-19) e_S~(La)=-4.1 1600℃ K_(Li_2O_2S)=6.45×10~(-19) e_S~(La)=-4.8 1650℃ K_(Li_2O_2S)=7.41×10~(-19) e_S~(La)=-4.2 La_((1))=[La] △G_(sol)~0=-136700 59.82T,γ_(La)~0=0.33(1873K) 实验结果表明La具有比Ce,Nd,Y更强的脱硫氧能力。  相似文献   

3.
本文用阳极溶解计时电位法,对稀土金属La在液态Al-Si合金中的扩散系数进行了测定。结果表明,973K,La浓度18.0×10~(-4)mol·cm~(-3)时,La在Al-5.2wt-%Si合金液中的扩散系数平均值DLa(Al-SI)=(0.91±0.01)×10~(-5)cm~2·S~(-1)。在953-1053K温度范围内,求得La在合金液中的扩散系数与温度间存在下列关系: lgDLa(Al-SI)=-1.78×10~(-3)-4909/T同时求得扩散激活能Q=94.00kJ·mol~(-1)。为了便于分析比较,对Sr在某些条件下的扩散系数也进行了测试。通过La,Sr扩散数据的比较,分析了变质元素的扩散对变质过程中出现的潜伏期,临界冷却速度等问题的影响。  相似文献   

4.
用Ag浴等活度法测定了1450℃下Fe-B-Si三元系熔体的两条等活度线;用Si浓差电池EMF法测定了Ag-Si合金(银浴)的α_(Si).由实验测定结果计算了Si的活度系数及活度交互作用系数,得到lnγ_(Si)=-3.19,ε_(Si)~(Si)=7.0,ρ_(Si)~(Si)=6.5, ε_(Si)~B=16.0,ρ_(Si)~B=-12.0,ρ_(Si)~(Si,B)=40.8  相似文献   

5.
用Ag浴等活度法测定了1450℃下Fe-B-Si三元系熔体的两条等活度线;用Si浓差电池EMF法测定了Ag-Si合金(银浴)的α_(Si).由实验测定结果计算了Si的活度系数及活度交互作用系数,得到 lnγ_(Si)=-3.19,ε_(Si)~(Si)=7.0,ρ_(Si)~(Si)=6.5, ε_(Si)~B=16.0,ρ_(Si)~B=-12.0,ρ_(Si)~(Si,B)=40.8  相似文献   

6.
铁液中稀土元素-硫平衡的研究   总被引:6,自引:0,他引:6  
本文应用放射性同位素,通过测定电解液内的稀土元素(RE)含量(排除了夹杂状态存在的稀土量),测定了纯铁液中Ce-S,La-S和Nd-S平衡常数及相互作用系数。在1600℃ K_(CeS)=2.70×10~(-6) e_S~(Ce)=-2.36 K_(LaS)=7.41×10~(-7) e_S~(La)=-1.51 K_(NdS)=2.57×10~(-6) e_S~(Nd)=-1.54 在Fe-Ce-S-C系统中,测定了Ce,S浓度积和[%C]之关系,并测得e_(Ce)~C=-0.43。分析了前人所测平衡常数偏高的原因。  相似文献   

7.
本文应用放射性同位素,通过测定电解液内的稀土元素(RE)含量(排除了夹杂状态存在的稀土量),测定了纯铁液中Ce-S,La-S和Nd-S平衡常数及相互作用系数。 在1600℃ K_(CeS)=2.70×10~(-6) e_S~(Ce)=-2.36 K_(LaS)=7.41×10~(-7) e_S~(La)=-1.51 K_(NdS)=2.57×10~(-6) e_S~(Nd)=-1.54 在Fe-Ce-S-C系统中,测定了Ce,S浓度积和[%C]之关系,并测得e_(Ce)~C=-0.43。分析了前人所测平衡常数偏高的原因。  相似文献   

8.
含有微量O,S,C的Fe—Nb—Ce溶液热力学性质的研究   总被引:2,自引:0,他引:2  
周谦莉  杜挺 《金属学报》1989,25(1):91-95
利用下列组装的固体电解质定氧电池Mo/Cr,Cr_2O_3//ZrO_2(MgO)//[O],Ce_2O_2S/Mo+ZrO_2金属陶瓷,Mo.在1600℃温度下对含微量C的Fe-Nb-Ce溶液进行热力学性质的研究。实验测得1600℃时Fe液中反应Ce_2O_2S=2[Ce]+2[O]+[S]的平衡常数和Ce_2O_2S的标准生成自由能分别为K=4.395×10~(-15),ΔG°_(Ce_2O_2S)=-514.786kJ·mol~(-1);Ce与Nb的活度相互作用系数为e_(Nb)~(Ce)=-2.306,e_(Ce)~(Nb)=-3.481。 随着Nb含量的增加,在微量碳含量的条件下,产物中存在NbC化合物,本文对NbC的生成问题进行了探讨,并得到1600℃时,Fe液中NbC的标准生成自由能为ΔG°_(NbC)=-87.111kJ·mol~(-1)。  相似文献   

9.
采用金属溶液-固相产物直接平衡法,研究了铝基溶液中铈与锰、铈与锌的相互作用。结果表明,800℃时,铝-铈-锰溶液体系中有平衔产物 AlCe_2Mn_3存在,其标准生成自由能为△G_(AlCe2Mn3)~0=-159.3kJ/mol;反应 AlCe_2Mn_(3(s))=Al_(1)+2[Ce]+3[Mn]的平衡常数为 K_(AlCe2Mn3)=1.76×10~(-8);铈与锰的相互作用系数为 e_(Ce)~(Mn)=-5.19,e_(Mn)~(Ce)=-2.03,ε_(Ce)~(Mn)=ε_(Mn)~(Ce)=-2430。700℃时,铝-铈-锌溶液体系中存在两种平衡产物:Al_2CeZn_2和Ce_3Al_(11),前者的标准生成自由能为△Gu_(Al2CeZn2)~0=-81.0kJ/mol,平衡反应 Al_2CeZn_(2(s))=2Al_(1)+[Ce]+2[Zn]的平衡常数为 K_(Al2CeZn2)=4.48×10~(-5),铈与锌的相互作用系数为 e_(Ce)~(Zn)=-5.54,e_(Zn)~(Ce)=-2.59,ε_(Ce)~(Zn)=ε_(Zn)~(Ce)=-3088。  相似文献   

10.
利用电化学方法测定高温银液中氧的扩散系数   总被引:2,自引:0,他引:2  
采用圆柱体状氧化锆基固体电解质原电池:(+)Pt|air|ZrO_2(MgO)[O]_(Ag(l))|Ir(-),利用恒电压法测定了1473-1773 K银液中氧的扩散系数.通过外加恒电压后测定的电池外电路总电流,获得随时间变化的穿过固体电解质的氧离子电流,进而计算得到银液中氧的扩散系数.在假定符合Arrhenius公式的基础上,实验结果经最小二乘法处理确定的在1473—1773 K扩散系数与温度的关系为:D_O=(1.11±0.04)×10~(-3)exp((-25573±1718)/RT).实验测得的银液中氧的扩散系数值与基于前人低温测定结果外推到本实验温度下的值比较接近.利用该公式计算得到1773 K下银液中氧的扩散系数D_O=(1.96±0.28)×10~(-4)cm~2/s.  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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