稀土加入量对硼砂型固体渗硼效果的影响

在硼砂型渗硼剂中加入适量的稀土有利于45钢渗硼层质量、厚度及性能的提高．稀土加入量的最佳值为10％。     

稀土在渗硼中渗入机制和作用机理的讨论

研究了45钢表面硼稀土共渗，讨论了稀土元素的渗入机制、催渗机理及稀土催渗效果出现最佳值的原因。在硼砂型渗硼剂中加入适量的稀土有利于45钢渗硼层质量、厚度及性能的提高，稀土加入量的最佳值为10％。     

硼砂—石墨型粒状渗硼剂

1．前言硼砂型渗硼剂的应用结果表明，用廉价的棚砂取代B4C、B－Fe作为供硼剂是可行的[1～2]。本研究用含结晶水硼砂、石墨等廉价材料取代B4C、B－Fe、SiC和KBF4等较贵材料制作粒状渗硼剂，在大大降低成本的同时，提高渗硼速度和渗棚层质量以及渗后工件表面质量；45钢经950℃×6h的渗硼可得到大于300μm的致密渗硼层，使渗硼工艺能应用于承受强烈磨粒磨损的工件及难以渗硼的钢铁材料；由于渗速快，在较低的温度和较短时间内就能得到较厚的渗硼层，因此也能应用于变形要求严格的工件。本文同时对厚度大于300μm的渗硼层的耐磨性和耐腐…     

稀土在渗硼中渗入机制和作用机理的讨论

研究了45钢表面硼稀土共渗,讨论了稀土元素的渗入机制、催渗机理及稀土催渗效果出现最佳值的原因。在硼砂型渗硼剂中加入适量的稀土有利于45钢渗硼层质量、厚度及性能的提高,稀土加入量的最佳值为10%。     

稀土硼砂型渗硼剂中硅、铝还原剂对渗层组织的影响

对稀土硼砂型渗硼剂中加入硅铁或铝铁作为还原剂时所组成的渗剂对渗硼能力的影响进行了研究,结果表明,硅铁作为还原剂渗硼可以比铝铁得到更厚的渗层,但用铝铁还原时所获得的硼化物更为致密,此外,渗剂中还原剂的合适加入量与钢种有关。     

45钢渗硼工艺对渗层组织与性能的影响

研究了渗硼温度、保温时间和渗硼剂配方对45钢渗硼层组织和性能的影响.结果表明:在给定实验条件下,渗硼层组织致密,硼化物呈针齿状楔入基体,与基体结合牢固;渗硼层厚度随渗硼温度的升高、保温时间的延长而增加.相比而言,温度对渗硼层厚度的影响大于时间的影响;渗硼层中FeB相使表面硬度显著提高:渗硼层抗盐酸、硫酸、氢氧化钠腐蚀性优良.     

自保护硼铝共渗膏剂研究

试验以价格低廉的硼砂为供硼剂，采用膏剂自保护技术进行了硼铝共渗试验，试样渗后表而光洁，解决了硼砂引起的粘结问题。试学命结果表明：粘结剂的含量对膏剂表面状态有很大影响，调整还原剂和硼砂的比例或者降低硼砂含量可以避免硼砂粘结。为获得耐蚀耐磨性能，综合考虑致密性、相组成和渗层厚度的影响，在保证致密性及相组成的情况下，渗层只要具有一定的厚度就可以，其结果为研制一种新型能耗低、效率高的硼铝共渗工艺提供了基础。     

稀土La2O3对45钢渗硼层性能的影响

目的研究渗硼剂中稀土氧化物La_2O_3的添加量对45#钢渗硼层厚度及性能的影响。方法通过在渗硼剂中添加质量分数为0%、5%、10%的La_2O_3,对45#钢在850℃进行4h渗硼处理,利用金相显微镜观察渗硼层的形貌并测试其厚度,利用XRD分析渗硼层的物相结构,利用显微硬度计、磨损试验机、电化学工作站对渗硼层的硬度、耐磨性、耐腐蚀性以及脆性进行测定及衡量。结果 45#钢渗硼后,硬度显著提高,且在渗剂中加入5%和10%的La_2O_3进行渗硼后,渗硼层厚度及硬度较渗剂中不加La_2O_3均有明显增加。在渗剂中添加不同含量的La_2O_3对渗硼层的耐磨性、耐蚀性以及脆性影响不同。添加5%La_2O_3进行渗硼后,渗硼层的耐磨性、耐蚀性最佳,脆性最小;添加10%La_2O_3进行渗硼后,渗硼层的耐磨性和脆性都比未加La_2O_3的要差,但耐腐蚀性较未加La_2O_3的要好。结论综合渗硼层的厚度、硬度、耐磨性、耐腐蚀性以及脆性指标,在渗硼剂中加入5%La_2O_3时,45#钢渗硼层厚度适中,性能最佳。     

硼砂型膏剂渗硼剂的研制

使用硼砂作为渗硼膏剂的供硼剂，对7种活化剂的活化效果进行了研究，发现活化剂的类型和自身熔点的高低对活化效果有影响，氟化物活化效果好于氯化物，熔点高的活化剂活化效果较好，几种活化剂配合使用渗速明显高于单独使用一种活化剂的渗速，利用正交试验法，确定了CaF2,MgCl2和Na3AlF6三种活化剂的最佳配比，所研制的MSG膏剂渗速快，渗层质量好，对碳钢和低合金钢均有良好的渗硼能力。     

Q345B钢膏剂渗硼工艺的试验研究

利用正交试验法研究了膏剂厚度、渗硼温度和时间对Q345B钢渗硼层厚度的影响.结果表明:在给定的试验条件下,各因素对渗硼层厚度的影响顺序是膏剂厚度、渗硼时间、渗硼温度,并确定了最佳膏剂渗硼工艺方案为膏剂厚度6 mm,渗硼温度900℃,渗硼时间7h.     

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.     

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.     

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.