机械能助渗铝工艺与助渗机理分析

研究了机械能助渗铝工艺,在600℃的低温下,08F钢表面获得200μm以上的渗铝层.研究了温度、保温时间、机械能量等因素对渗铝层厚度的影响,对机械能助渗机理进行了分析.结果表明,温度提高、机械能增大在一定范围内可提高渗铝速度.渗铝层主要是由Fe2Al5相构成.在低温下,渗剂反应产生活性铝原子的过程是渗铝的控制过程.机械能助渗机理是由于机械振动与混合增加了渗件表面处的渗剂反应,提高了活性铝原子浓度,从而加速了渗铝过程.     

以渗铝为主的Q195钢交流电场增强粉末法铝铬共渗特性

在渗铝剂中加入铬粉,对Q195钢在800 ℃进行以渗铝为主的交流电场增强及常规粉末法铝铬共渗。用金相显微观测、X射线衍射分析、显微硬度测试等分析渗层组织、相、厚度及显微硬度沿渗层深度方向的分布。结果表明,相较单一渗铝,添加少量铬粉对常规铝铬共渗层组织和厚度影响不大,但次表层硬度提高;交流电场对单一渗铝和铝铬共渗均有促渗作用,较单一渗铝,添加微量铬粉进一步加快渗速,但对次表层硬度影响不大,随渗剂中铬粉含量增加,渗层厚度先增后减,添加0.1%铬粉时促渗效果最为显著,所得渗层厚约123 μm,而交流电场单一渗铝层厚约50 μm,常规单一渗铝层厚仅约18 μm。     

不锈钢表面镀铝-热氧化处理制备氧化铝膜及其性能

采用无机熔融盐电镀铝、热浸镀铝工艺联合的方法在钢基材表面制备了一层平整、连续的铝镀层,研究了铝镀层在不同氧化时间下的氧化行为。利用X射线衍射仪(XRD)、扫描电镜(SEM)和能谱分析(EDS)对氧化层的形貌和成分进行分析,并考察了氧化层的硬度和耐腐蚀性能。结果表明:将无机熔融盐电镀铝法和热浸镀铝法相结合可获得良好的铝镀层;铝镀层在900℃下热处理20 h后,可获得连续致密的Al2O3膜;Al2O3层有效提高了钢基材的表面硬度和耐腐蚀性能。     

碳钢浸镀扩散渗铝复合渗硼及其表面性能研究

对Q235、45、GCr15钢在720℃±5℃的条件下进行了热浸渗铝,分别扩散1h、2.5h和5h后再进行950℃×6h高温渗硼。利用光学显微镜、扫描电镜、X射线等手段研究了Q235、45钢的热浸渗铝和热浸渗铝复合渗硼层的组织结构。探讨了热浸扩散渗铝复合渗硼中的硼化物的形成机理及硼的迁移机制。采用高温氧化试验和耐热腐蚀试验考察了这两种渗层在高温下的氧化机制,并比较了它们的耐高温氧化性能和耐热腐蚀性能,以及它们在干摩擦条件下的耐磨性。试验结果表明,热浸渗铝经扩散处理后,渗层明显,渗层组织由表及里出现了η相(Fe2Al5)、β1相(Fe3Al)和α相固溶体等组织。热浸渗铝复合渗硼所形成渗层具有与单一渗硼相类似的齿状形态。X射线衍射分析表明,渗层主要由Fe2B、Fe2AlB2及Fe2Al5组成。Q235钢热浸镀铝复合渗硼处理在950℃高温下不具有明显的抗氧化的作用。而热浸渗铝的Q235钢950℃氧化后仍然为扩散处理后的灰色外观。而650℃循环氧化中,这两种渗层的抗氧化能力相当。800℃熔盐腐蚀试验中热浸渗铝与热浸渗铝复合渗硼处理均具有较高的耐蚀胜,比未经处理的试样高10倍左右。在干摩擦条件下,热浸渗铝复合渗硼试样比渗铝扩散处理具有更高的耐磨性。     

化学镀镍-铜-磷三元合金层的制备及其组织与性能研究

对45钢表面用化学镀方法镀镍-铜-磷三元合金层,采用金相显微镜、扫描电镜能谱分析、X射线衍射和显微硬度计研究了镀层的组织、相结构和性能.结果表明,600℃×1 h热处理后,镀层由Ni基固溶体、Ni3P和Cu3P化合物相组成;镀层的硬度随着热处理温度升高先增大后降低,400℃热处理后的硬度最高;在相同的模拟酸性腐蚀条件下,Ni-Cu-P三元合金化学镀层与1Cr18Ni9不锈钢相比,具有更加良好的耐腐蚀性能.     

碳钢表面粉末包埋法渗铝的实验研究

目的 解决粉末包埋渗铝过程中渗剂粘结导致渗铝层表面质量差的问题,在无惰性气体保护气氛中,在Q235钢表面制备出耐高温氧化、耐高温硫化和耐腐蚀的渗铝层。方法 采用粉末包埋渗铝法,通过改变渗剂中填充剂的成分,解决渗剂粘结导致表面质量变差的问题,研究渗铝温度、保温时间对渗层试样表面质量及渗铝层厚度的影响,确定最佳渗铝条件。使用电子显微镜观察渗铝层表面质量并测定渗铝层厚度,采用能谱仪分析渗铝层主要元素分布,采用X射线衍射仪分析渗铝层物相组成,采用显微硬度计检测渗铝层硬度变化。结果 采用成分为15%铝粉+5%氯化铵+75%氧化铝+5%石墨粉的渗剂,在无惰性气体保护下900 ℃保温4 h,获得渗铝层厚度约为370 μm的渗铝试样。渗铝层由外向内依次为铝化物层、过渡层和基体,铝化物层主要含有Al、Fe两种元素,原子百分比保持在7:3左右,主要物相为Fe2Al5,硬度达到896HV0.1,远高于基体硬度。结论 渗剂中添加适量的石墨粉能够改善渗铝层表面质量,增加渗层厚度,过多的石墨粉反而不利于表面质量改善和渗铝层厚度的增长。渗铝层厚度随渗铝温度的升高先增大后减小,与保温时间呈抛物线关系。     

铌基超高温合金包埋渗铝改性硅化物涂层结构

利用包埋渗法在新型铌基超高温合金表面制备了铝改性的硅化物抗氧化涂层,分析了涂层的相组成、结构及其组织形成过程。涂层制备采用先在1150℃包埋渗硅4h,然后再于800-1000℃包埋渗铝4h的方法。结果表明：渗硅后涂层的相组成为（Nb,X）Si2（X代表Ti,Cr和Hf元素）;再于各温度包埋渗铝后,（Nb,X）Si2层中的平均铝含量随包埋渗铝温度的升高而增加,最高可达10.84at%;当包埋渗铝温度为860-1000℃时会在渗硅层与基体间形成新的铌铝金属间化合物层,且渗入（Nb,X）Si2层中的铝会在局部形成Nb3Si5Al2相。     

交流电场对45钢粉末法渗铝的影响

通过设置一对电极,在粉末法渗铝过程中对置于两极间的45钢试样与渗剂施加交流电场,进行交流电场增强粉末法渗铝。通过对渗铝层的生长、组织与相结构特性的观察分析,研究交流电场对45钢粉末法渗铝的影响。结果表明:施加适当的交流电场可以显著促进渗铝过程,促渗作用随电场电流增加而增加;在仅含2%铝粉的渗铝剂中进行电场电流为2 A、保温4 h的渗铝,在500℃即可形成约40μm的渗铝层,在800℃时形成厚约180μm的渗铝层;交流电场能够降低渗铝层表层的含铝量,避免表层形成硬脆富铝相;交流电场粉末法渗铝层在900℃时具有优良的抗氧化性能。分析认为,交流电场的促渗作用与电场对渗铝过程中试样内的扩散、渗剂中的反应与扩散及渗罐内的实际温度等的影响有关。     

碳钢渗铝的组织与腐蚀行为研究

对Q235钢进行了粉末包埋渗铝实验,采用X射线衍射仪分析了渗铝层的相成分,并对渗铝层的微观组织和渗铝钢的耐蚀性能进行了测试。结果表明:配方为20%铝粉+40%Al2O3+20%石墨粉+18%Fe2O3+2%NH4Cl是比较合理的,经980℃×6 h扩散渗铝处理后,渗层致密、均匀、连续,表面质量较好;钢表面渗铝层主要由Fe Al和Fe Al3金属化合物组成,渗层组织主要是针状组织;电化学测试表明,碳钢渗铝后在Na Cl水溶液中的耐蚀性明显好于未渗铝的碳钢。     

Co-Gd合金在尿素-乙酰胺-NaBr熔体中的电沉积及合金性能

在尿素-乙酰胺-NaBr熔盐中采用电沉积方法制备了Co-Gd合金薄膜.运用循环伏安技术研究了Gd、Co的共沉积行为.通过扫描电子显微镜、X射线能谱仪和X射线衍射仪研究了电流密度对镀层表面形貌、元素组成及镀层结构的影响.研究发现,Gd含量随着电流密度的增加呈先增加后减少的趋势,在电流密度为12.5 mA/cm2时达到最大含量54.97%(质量分数).镀层的表面形貌随着Gd含量的增加而变得粗糙.镀态时镀层结构为非晶态,300 ℃热处理后转化为Co(Fm3m)相,在600 ℃热处理后又出现GdCo5 (P6/mmm)相.采用振动样品磁强计测试了镀层的磁性能.结果表明,镀层中Gd的含量对镀层的磁性能有重要影响.在热处理过程中,镀层的饱和强度在600 ℃热处理时达到最大值550.43 kA/m,而矫顽力则在400 ℃热处理时达到最大值34.97 kA/m.     

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.     

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。     

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.     

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.