NiAl微晶涂层对NiAl-TiC复合材料高温氧化性能的影响

研究了磁控溅射ＮｉＡｌ微晶涂层对ＮｉＡｌ－ＴｉＣ（２０％,体积分数）复合材料１０００－１１００℃高温氧化性能的影响。结果表明,ＮｉＡｌ微晶涂层大大提高了ＮｉＡｌ－ＴｉＣ复合材料的恒温及循环氧化性能,降低氧化速率几个数量级,对于ＮｉＡｌ－ＴｉＣ复合材料来说,其表面形成以ＴｉＯ２为主的复合氧化物,而施加ＮｉＡｌ微晶涂层后,其表面氧化物主要是Ａｌ２Ｏ３。     

涂层对Ti60合金高温氧化性能及力学性能的影响

研究了四种涂层对Ｔｉ６０合金高温氧化性能及热暴露后力学性能的影响。在７００－８００℃下,溅射纯Ａｌ,Ｔｉ－３６Ａｌ,Ｎｉ－１６Ｃｒ０２．５Ａｌ（均为质量分数,％）和反应溅射Ａｌ２Ｏ３涂层大大降低了Ｔｉ６０合金的氧化速率。综合考虑涂层的抗氧化性能及涂层基材的相容性,７００℃时,Ａｌ２Ｏ３涂层的效果较好;而８００℃时,ＴｉＡｌ支的效果较好,四种涂层不同程度地提高了Ｔｉ６０合金热暴露后（６００℃,１００     

溅射TiAlCr涂层对Ti-24Al-14Nb-3V抗氧化性能的影响

研究了溅射Ｔｉ５０Ａｌ１０Ｃｒ及Ｔｉ５０Ａｌ２０Ｃｒ涂层对Ｔｉ２４Ａｌ１４Ｎｂ３Ｖ抗高温氧化性能的影响。结果表明,在８００℃下,Ｔｉ５０Ａｌ１０Ｃｒ及Ｔｉ５０Ａｌ２０Ｃｒ涂层表面由于可形成粘附性良好的Ａｌ２Ｏ３膜,大大改善了Ｔｉ２４Ａｌ１４Ｎｂ３Ｖ的抗高温氧化性能。９００℃时在Ｔｉ５０Ａｌ１０Ｃｒ涂层表面长出大量ＴｉＯ２,导致其氧化增重较大;而在Ｔｉ５０Ａｌ２０Ｃｒ涂层表面生成了连续Ａｌ２Ｏ３,其抗氧化性能良好。然而,由于ＴｉＡｌＣｒ涂层与基体热膨胀系数不同,在循环氧化过程中涂层出现一些裂纹,导致其抗循环氧化性能有所下降。     

MCrAlY涂层对TiAl金属间化合物抗高温氧化性能的影响

研究了溅射Ｃｏ－３０Ｃｒ－６Ａｌ－０．５Ｙ及Ｎｉ－３０Ｃｒ－６Ａｌ－０．５Ｙ涂层对ＴｉＡｌ金属间化合物抗高温氧化性能的影响。结果表明，在９００℃－１０００℃范围内，ＣｏＣｒＡｌＹ，ＮｉＣｒＡｌＹ涂层表面由于可形成粘附性良好的Ａｌ２Ｏ３膜。大大改善了ＴｉＡｌ金属间化合物的抗氧化性能。     

TiAlCr涂层对TiAl金属间化合物抗高温氧化性能的影响

研究了溅射Ｔｉ－５０Ａｌ－１０Ｃｒ涂层在８００－１０００℃对ＴｉＡｌ金属间化合物抗高温氧化性能的影响。结果表明,ＴｉＡｌ合金由于形成Ａｌ２Ｏ３和ＴｉＯ２的混合氧化物而表现出较差的抗高温氧化性能,而ＴｉＡｌＣｒ层由于形成粘附性了的Ａｌ２Ｏ３膜而大大提高了ＴｉＡｌ的恒温及循环氧化性能,经９００℃１０００ｈ长时间氧化。ＴｉＡｌＣｒ涂层对ＴｉＡｌ合金仍能提供很好的防护,涂层和基格结合我孔洞及裂纹出现,表现     

退火对亚微结晶钛及BT8钛合金减震性和弹性的影响

对Ｎｉ－９．７Ｃｒ－５．５ｌ－７Ｔｉ溅射纳米晶涂层进行了空气中高温氧化实验,观察并分析了Ｔｉ的作用及影响,研究结果表明：由于涂层中相对较高的Ｔｉ含量,１０００℃氧化２００ｈ后生成了由α－Ａｌ２Ｏ３和ＴｉＯ２组成的复杂氧化膜。ＴｉＯ的存在并没有降低涂层的抗高温氧化性能,而且生成的氧化膜与涂层基体有着很好的粘附性。这主要在于氧化初期生成的ＴｉＯ２在随后氧化过程中没有发生长大,从而保证了保持性氧化膜的完     

多弧离子镀Ti-N镀膜的扩散屏障作用

设计了３种复合镀层系，研究了多弧离子镀Ｔｉ－Ｎ镀膜对Ａｌ，Ｎｉ，Ｃｏ的扩散屏障作用及Ｔｉ－Ｎ镀膜在１０００和１１００℃长期时效时的热稳定化结果表明，在１０００℃以下时效时，Ｔｉ－Ｎ镀膜稳定性良好，并可有效地阻止Ａｌ向基材扩散，可减缓、阻止Ｎｉ，Ｃｏ在ＣｏＣｒＡｌＴａＹ涂层与基体间的互扩散行为；在１１００℃时效时，Ｔｉ－Ｎ镀膜未分解，也不与基材及ＣｏＣｒＡｌＴａＹ涂层间发生互扩散，但组织形态由薄膜变为颗粒状，颗粒状Ｔｉ－Ｎ无法阻止Ｎｉ，Ｃｏ在ＣｏＣｒＡｌＴａＹ涂层与基材间的互扩散．     

等离子喷涂ZrO2-NiCoCrAlY梯度涂层的界面强化热处理工艺

在大气条件下经高温长时间保温后,ＺｒＯ２ＮｉＣｏＣｒＡｌＹ 梯度涂层中的ＮｉＣｏＣｒＡｌＹ 组元发生严重氧化, 形成大量的ＮｉＯ, Ａｌ２Ｏ３ 和Ｃｒ２Ｏ３ 等氧化物, 导致ＺｒＯ２ 表面层中产生粗大网状裂纹, 并最终导致ＺｒＯ２ 表面层碎裂而失效。对梯度涂层进行（９００ ℃） 保温（８ ｈ） 的真空热处理后, 涂层完好无损, ＮｉＣｏＣｒＡｌＹ 底层与ＴＣ４ 基体发生了冶金化学反应, 在涂层与基体界面形成了含ＮｉＴｉ, ＮｉＴｉ２ 和ＴｉＡｌ３ 等化合物的反应层, 涂层的抗热震性能得以显著地提高     

Ni-Cr-Al-Y涂层真空热处理过程中元素的行为

采用电弧离子镀技术在铸造镍基合金Ｋ１７和Ｎｉ３Ａｌ基合金ＩＣ－６沉积Ｎｉ－Ｃｒ－Ａｌ－Ｙ涂层。结果表明,在沉积过程中由于电弧离子镀的“溅射”和“反溅射”效应以及基体和涂层发生互扩散的共同作用下,沉积的Ｎｉ－Ｃｒ－Ａｌ－Ｙ涂层在靠近基体区含有少量基体元素,如Ｃｏ,Ｔｉ和Ｍｏ等,Ｋ１７合金中的Ａｌ元素可抑制Ｃｒ由涂层向基体扩散,ＩＣ－６合金中由于还含有Ｍｏ元素,使这种抑制作用进一步增强,在１０５０℃真     

多弧离子镀Ti—N镀膜的扩散屏障作用

设计了３种复合镀层系，研究了多弧离子镀Ｔｉ－Ｎ镀膜对Ａｌ，Ｎｉ，Ｃｏ的扩散屏障作用及Ｔｉ－Ｎ镀膜在１０００和１１００℃长期时效时的热稳定性。结果表明，在１０００℃以下时效时，Ｔｉ－Ｎ镀膜稳定性良好，并可有效地阻止Ａｌ向基材扩散，可减缓、阻止Ｎｉ，Ｃｏ在ＣｏＣｒＡｌＴａＹ涂层与基体间的互扩散行为；在１１００℃时效时，Ｔｉ－Ｎ镀膜未分解，也不与基材及ＣｏＣｒＡｌＴａＹ涂层间发生互扩散，但组织形态由薄膜     

Dynamics of a lattice of magnetic nanoparticles under action of a pulse of a magnetic field

Processes of quasistatic and dynamic magnetization reversal have been studied for the case of planar 6 × 6 lattices of magnetic nanodipoles that possess a cubic crystallographic anisotropy. The response of the total magnetic moment to a magnetic-field pulse of various duration and polarization have been determined for different equilibrium configurations of the lattices. Along with the in-plane configurations of magnetic moments, configurations with one and two dipoles oriented perpendicular to the plane of the lattices have been considered.     

Dynamics of a heterogeneous polymer system obtained as a result of a conductor explosion

The performed studies allowed us to obtain a composite with regulated structure formation at ?? ?? 0.06 vol % of copper and directed changes of the electrophysical properties in a dielectric using the explosion of a conductor.     

Study of a Neural Network with a Meta-layer

We consider the network studied by Amit et al. (i.e. a network that is quite closely related to the Hopfield model). We show that it is possible to save a significant amount of connections if it is reinterpreted as a two-layer system. One of the layers can be interpreted as the basis layer and the other one as a meta-layer. This system is suited for the storage of orthogonal groundstates. However, an extension of the meta-layer allows one to store mixture-states (multicomponent states) as well. This bears a system in which taxonomies as well as looser associative links can be stored. Due to the topological properties of the mixture-states, the system can be provided with a learning rule according to which the memories reorganize in a way that is suited for some aspects of genetic psychology     

一种可焊性半光亮镀镍工艺

目的解决镀镍层可焊性不良的问题,使得光电子器件外壳镀镍层可焊性满足回流焊要求,并且保存半年后可焊性不降低。方法以氨基磺酸镍为体系,考察温度、p H值、电流密度与沉积速率的关系,采用回流焊和浸润法对镀层可焊性进行表征,并考察镀层的质量、结合力及盐雾性能指标。结果镀液体系在比较宽泛的电流密度和温度范围内,都能得到可焊性优良的镀层,其沉积速率随电流密度的增大呈线性增加。浸润法和回流焊接试验表明,镀层可焊性满足要求。在稳态湿热(45℃,RH=95%)环境中48 h或恒温烘烤(150℃,1 h)后,镀层可焊性仍均满足要求。结论在电流密度1~5 A/dm2,p H值3.2~4.4,温度40~55℃的条件下能得到优良的可焊性镀层,满足回流焊对镀层可焊性的要求,并且放置半年后可焊性不降低。     

Cracking of a Cobalt-Based Hardfacing of a Gate Valve Disk in a Desalination Power Plant

Cobalt-based alloys of the Stellite family are used as hardfacing for sealing surfaces of valves operating in desalination and power plants because of their excellent low friction and anti-galling properties in high-load sliding contact under the prevailing conditions. However, insufficient control of pressure and temperature during operation can degrade the integrity of the hardfaced material thus leading to its premature failure. This article presents a failure investigation carried out on the disk of a main stop gate valve that was used in a desalination plant. The disk was manufactured from X20 as a substrate material and a cobalt-based alloy for hardfacing. The cobalt-based hardfacing suffered from many surface and subsurface cracks that degraded its integrity. It was concluded that high-pressure steam flowing against the disk had tilted it and, thus, disturbed the alignment between the surfaces of the disk and the seat, leading to wear and large frictional heat that resulted in the degradation of the microstructure of the hardfacing layer and formation of the observed cracks.     

Dynamics of a magnetization-reversal nucleus in a ferromagnet

This paper is devoted to a theoretical investigation of the effect of an applied magnetic field and damping on the dynamics of magnetization-reversal nucleus represented by interacting domain walls (DWs) with opposite topological charges. It is shown that at initial amplitudes that are less than the amplitude of the critical nucleus of magnetization reversal, nonlinear vibrations of strongly interacting DWs are observed. In the presence of dissipation, the nonlinear vibrations are damped vibrations with a frequency that changes with time. At the initial amplitudes that are greater than the amplitude of the critical nucleus, the magnetization-reversal nucleus decays with the formation of a solitary domain. The motion of two interacting 180° DWs relative to their common immobile center in fields that are less than the Walker field is translational; in higher fields, it is oscillatory. It is shown that DW vibrations are accompanied by a periodic transformation of their structure from Bloch into Néel and vice versa with a frequency that depends on the field, damping, quality factor, and the initial amplitude of the magnetization-reversal nucleus.     

Formation of a Rhenium-Base Coating on a Nb-Base Alloy

To protect Nb–5Mo–15W alloy against high-temperature oxidation a novel coating was developed involving electroplating of a Re–Ni film, followed by pack cementation with Cr and Al. The coating consisted of a duplex-layer structure, an inner (Re–Cr) or Re(Cr) layer and an outer Cr(Al) or NiAl layer. The Re–Ni film containing more than 70at.%Re, developed in the present investigation, is more useful than the conventional low Re–Ni film. The inner (Re–Cr) and Re(Cr) layer acts as a diffusion barrier between the Nb–5Mo–15W alloy substrate and the outer -Cr(Al) or -NiAl layer, which forms a protective -Al₂O₃ scale. The coated Nb–5Mo–15W alloy was oxidized in air at 1373K for up to 360ks, showing very good oxidation resistance.     

列车车钩尾销孔裂纹分析

某型列车运载量增大后,列车车钩尾销孔牵引弧面位置大量出现裂纹。本文车钩尾销孔的化学成分和机械性能进行了检测,观察了车钩钩尾销孔裂纹的宏微观形貌,并对裂纹位置的金相组织进行了检测。结果表明,车钩钩尾销孔裂纹在径向上为脆性断裂特征,而周向上为疲劳断裂特征。分析认为,由于列车运载量增大,车钩尾销孔位置的工作应力增大,同时由于车钩尾销孔处淬硬层与基体的性能差异较大且无明显的过渡层,在工作应力作用下淬硬层首先发生脆性断裂并沿径向扩展,至淬硬层与基体界面处则沿着性能较弱的界面疲劳扩展。     

高炉大钟拉杆断裂原因分析

高炉大钟拉杆在工作过程中突然发生断裂,为了查明断裂原因,对拉杆头部的断口进行了宏微观分析和拉杆头部的材质解剖分析。分析结果表明,拉杆断裂的裂纹源位于表面R5过渡圆弧处,裂纹由表面向内疲劳扩展至断裂。表面裂纹萌生原因是拉杆在腐蚀性高炉煤气粉尘和轴向拉伸等工作应力的综合作用下,形成的应力腐蚀裂纹。建议加大R5过渡圆弧的尺寸,拉杆材质最好选用抗氧化性和耐腐蚀性较好的低碳低合金钢。