疏水/超疏水Ti合金表面液滴的运动特性

采用激光加工技术在Ti6Al4V合金表面构建点阵微结构,利用自组装分子膜技术在微结构表面沉积低表面能物质,制备疏水/超疏水表面。采用自制测试系统测试液滴在试样表面的静态接触角和滚动角,用高速摄像机拍摄液滴滴落到试样表面的运动过程。结果表明,经激光加工和低表面能修饰可构建Ti6Al4V疏水/超疏水表面,其最大接触角为151.4°,表面静态接触角随点阵间隔的增大而减小;液滴静态接触角与液滴滴落高度相关,同一表面上的液滴静态接触角由最后一次滴落高度决定。液滴滴落到水平试样表面的铺展系数由试样表面粗糙度和静态接触角决定,表面粗糙度和静态接触角越大,液滴铺展系数越小。当滴落高度从0 mm增大到20 mm时,铺展系数的增大幅度约为50%。     

Formation of gradient palladium-hydrogen alloy and the change in the form of a palladium plate during one-sided hydrogen saturation

Forming of a palladium plate (60 × 5.5 × 0.27 mm) saturated one-sidedly with hydrogen at 240°C at various hydrogen pressures from 0.03 to 0.43 MPa has been investigated experimentally. It has been established that forming of a palladium plate during its saturation with hydrogen is time-dependent and occurs in two functionally different stages. At the first stage, the plate becomes bent and its bending quickly reaches the maximum value. At the second, much longer stage, the plate straightens back almost completely. An increase in pressure of gaseous hydrogen leads to a sharp rise in the maximum possible bending of the plate. The degree of reversibility of hydrogen-induced bending of the plate also grows with an increase in hydrogen pressure. The experimental research and an analysis within the framework of the elasticity theory has shown that the palladium plate investigated demonstrates during mechanical loading the elastic reversible bending at deflections approximately three times smaller than those observed upon hydrogen loading. It is concluded that the mechanism of bending of the palladium plate upon saturation with hydrogen is fundamentally different from that under mechanical loading. A fundamental feature of the process of hydrogen-induced shape change is in that it is always implemented through the formation and development of the temporary gradient material of a metal-hydrogen type. Under experimental conditions of this work, the hydrogen-induced reversible bending of the palladium plate results from the “work” of the temporal gradient elastically stressed coherent alloy α-PdH _n .     

铜合金表面织构冷压成形实验研究

研究了一种高效低成本的表面织构加工方法——表面织构冷压成形工艺,并验证了其制备功能性表面织构的可行性.将铜合金在不同温度下退火制备不同晶粒尺寸的试样,通过自行开发的表面织构冷压成形系统,对铜合金进行圆形凹坑表面织构冷压成形实验.使用超景深三维显微镜对织构形貌进行分析,并研究了不同载荷、晶粒尺寸对单点表面织构冷压成形结果...     

钛合金超声振动研磨表面粗糙度特性试验研究

根据超声振动研磨加工原理,采用自行研制的超声振动研磨装置对塑性难加工材料钛合金(TC4)表面粗糙度特性进行了试验研究。试验采用单因素法,分别研究了工件转速、超声振动振幅以及磨料粒度对工件表面粗糙度的影响规律。试验结果表明:超声振动的附加在一定程度上降低了工件表面粗糙度。所获得的结论对超声振动研磨中加工参数的选择具有一定的参考价值。     

The model of deformation-induced segregation near a moving grain boundary in the Fe-Cr-Ni alloy

A model is proposed of diffusion-induced segregation at a moving grain boundary in a three-component alloy upon severe plastic deformation with allowance for generation and absorption of point defects and their mutual recombination. Redistribution of atoms of alloying elements and formation of near-boundary segregates during severe plastic deformation in stable austenitic alloys of the Fe-12Cr-30Ni type is studied. It has been shown by numerically solving an appropriate set of equations that the motion of a grain boundary leads to the formation of a deformation-induced segregation with an asymmetrical profile of the component concentrations. The boundary is being enriched with nickel and depleted of the other components.     

镁合金化学镀镍磷合金研究进展

镁合金因性能优异而用途广泛,但其耐蚀性很差,而化学镀镍磷合金能有效改善其耐蚀性。对镁合金化学镀镍磷合金的基本原理以及新工艺研究进行了概述,并展望了今后镁合金化学镀镍磷合金的发展趋势。     

ZL104合金表面化学镀镍磷合金层的研究

在ＺＬ１０４合金表面上进行Ｎｉ－Ｐ与Ｎｉ－Ｃｕ－Ｐ化学镀,以提高ＺＬ１０４合金材料的耐蚀性与耐磨性。结果表明：化学镀可以显著提高ＺＬ１０４合金表面的硬度,并改善其在５％ＮａＣｌ溶液中的耐蚀性;在２００～５２０℃温度下热处理后,镀层的硬度显著提高,但耐蚀性略有降低,这可能与镀层中的析出物Ｎｉ３Ｐ析出有关。     

Regimes of droplet train impact on a moving surface in an additive manufacturing process

In jetting-based additive manufacturing, one or more droplet trains are deposited on a moving surface to fabricate layers in an additive approach. The impact behaviour of the droplets onto the surface defines the final fabricated layer properties in terms of geometry and surface finish. This paper reports on such behaviour when depositing a solution of a bio-degradable resin towards an ultimate goal of fabricating bone implants in an additive manufacturing process. The solution was jetted via a fixed single nozzle continuous piezoelectric printhead on a moving surface. The effect of two main process parameters, jetting frequency and substrate linear velocity, on the impact behaviour was investigated. Quantitative analysis was undertaken to investigate the droplet formation characteristics and droplet/surface interactions. The phenomena associated with the interaction at the front of the advancing liquid layer were correlated with the process conditions. The result was a classification of the droplet train/moving surface interactions into three main regimes depending on the droplet impingement characteristics and the surface motion.     

镀液pH值对铝合金表面化学镀Ni-P合金镀层性能的影响

通过研究酸性镀液中pH值对铝合金表面化学镀Ni-P合金性能的影响,寻求最佳pH值。铝合金表面化学镀Ni-P后,能使铝合金的抗腐蚀性能、耐磨性能、可焊性能和电接触性能得到提高,镀层与铝基体间结合力好,外观漂亮,而且通过镀覆不同的镍基合金,可赋予铝及其合金各种新的性能,如磁性能、润滑性等。     

Research on depositing Ni45 alloy on titanium alloy surface by electrospark deposition

Taking Ni45 bar as electrode, a strengthened layer of thickness up to 50 μm was built up on BT20 titanium alloy matrix by means of electrospark deposition. Results of phase analysis by using of X-ray diffraction confirmed that the deposition layer was composed mostly of three phases, NiTi, NiTi2 and Ti. The surface microhardness of the deposition layer was up to 910 HV0.05, about 2.7 times as high as that of the matrix. The hardness at the cross-section of the entire deposition layer showed a gradient distribution. The effects of capacitance and deposition time on thickness of deposition layer were also studied, and results showed that with relatively low capacity and short deposition time the deposition layer without cracks can be obtained.     

AlTiB晶粒细化剂微观组织的电镜观察

简要概括了AlTiB合金细化剂生产中影响其质量的几个环节.采用非腐蚀方法制备试样,保持样品真实的状态.在扫描电镜下观察了铸态、加工变形后中间合金微观组织的变化,得到一些更详细的信息.概括了以前一些细化机制.讨论了TiAl3、TiB2粒子在晶粒细化过程中可能起的作用;并把"表面重构"和"过渡层"的概念引入到AlTiB中间合金细化剂细化机制的讨论中.     

The influence of surface roughness and deformation on dechromization of a Cu-Cr alloy

In order to realize the dechromization of a Cu-Cr alloy in HCl solution, the influence of surface roughness and deformation on dechromization of the Cu-Cr alloy was studied by means of metallographic observation, TEM, SEM/EDX, and CH1660A electrochemical instrument. The results showed that the bigger the sample＇s deformation and surface roughness, the shorter the incubation time of dechromization of the Cu-Cr alloy, and the trend of dechromization increases. Simultaneously, the deformation can increase the dechromization rate, invite stress corrosion, and decrease the compactibifity of the microstructure of the dechromization layer. And yet the surface roughness does not obviously affect the dechromization rate and the compactibility of the dechromization layer.     

Features of fracture surface in a fully lamellar TiAl-base alloy

The deformation mechanisms associated with different fracture surface appearances of a fatigue tested lamellar TiAl-based alloy have been studied in detail by focussed ion beam and transmission electron microscopy. The results show that linear markings within translamellar plates correspond to twins and/or slip bands. The markings in interlamellar region are associated with the crack propagation from a lamellar boundary to another. The fan-like region with linear markings belongs to a γ grain and the markings are related to twins. Intralamellar crack propagation is associated with twin–twin interaction within a γ lamella.     

300M高强度合金钢表面刷镀镉-钛合金工艺

用正交实验优化了电刷镀镉－钛合金镀液配方,确立了相关的工艺参数,实验结果表明,该工艺可用于飞机起落架的现场维修。     

Stress due to a moving band source of heat and mechanical load on the work surface during grinding

The grinding operation is considered to be equivalent to a moving band source of heat and mechanical load on the surface of a semi-infinite solid, producing very high temperature on the surface of the workpiece. The resulting temperature may result in high stress in the workpiece. It is thus desirable to be able to predict the stress levels expected during the grinding process.     

螺旋燃烧的实验研究与观察

对在Ni-Si、Ti-Ni和铝热反应体系中的螺旋燃烧进行了实验研究与观察.主要研究了Ni-Si系统中原始化学配比、坯体的原始密度、硅颗粒尺寸及起始温度对螺旋燃烧工艺的影响以及Ti-Ni系统中预热温度及原始化学配比对燃烧工艺及模式的影响.结果表明:螺旋燃烧是一种非稳态燃烧,弱的放热反应或反应中的热量损失可能导致燃烧源的不稳定,强化反应过程(如预热)能够改变燃烧模式,使非稳态螺旋燃烧向稳态燃烧转变.     

铝合金表面陶瓷膜层形成机理

用等离子体增强电化学表面处理技术对铝合金表面进行陶瓷化处理,在铝合金表面获得陶瓷膜层,采用Ｘ射线衍射、Ｘ光电子能谱、扫描电镜、透射电镜等测试手段对陶瓷层进行了研究,结果表明：该陶瓷膜层由γ－Ａｌ２Ｏ３,ＡｌＰＯ４和ＣｏＯ等组成;通过对陶瓷膜层的表面形貌和显微结构观察及分析,发现陶瓷膜层形成过程是一个离子运动,表面层不断被击穿形成熔融区,处理体系中的电解质不断向熔融区运动、成核并迅速烧结的过程;陶瓷     

Ca-P涂层在镁合金表面的形成特征

用化学方法在AZ91镁合金表面沉积二水磷酸氢钙涂层以提高镁合金在模拟体液中的生物降解能力。运用扫描电镜、X射线衍射对该涂层在模拟体液中浸泡前、后的显微组织进行分析。结果表明,在预钙化过程中形成的二水磷酸氢钙涂层呈现出两种不同的形貌。预钙化过程中钙化溶液的滴定速度强烈地影响预钙化涂层的形貌。随着钙化涂层在模拟体液中浸泡时间的延长,二水磷酸氢钙的衍射峰逐渐消失,羟基磷灰石在基底表面析出,表明二水磷酸氢钙在浸泡过程中发生溶解。详细讨论了二水磷酸氢钙涂层的结构以及羟基磷灰石涂层的形成机制。     

1420铝锂合金表面氧化膜特征分析

采用多种分析方法对1420铝锂合金表面氧化膜进行了分析。结果表明合金表面富集了元素Li和Mg，且表面主要为由Li和Mg的氧化物组成的疏松氧化膜，其厚度约为0.05mm。合金表面氧化膜的形成与温度密切相关，氧化膜从300℃开始形成速度较快，400℃以上迅速扩展并形成连续的氧化膜，且氧化膜的形貌发生明显变化。