Ni-Cr薄膜换能组件静电响应特性与发火概率预测研究

针对电火工品在静电放电影响下可能发生误发火的问题,以Ni-Cr薄膜换能组件为研究对象,提出了一种分析其在人体静电放电下的响应特性,并预测发火概率的方法。首先,介绍了Ni-Cr薄膜换能组件系统架构,并建立了电火工品静电放电等效电路模型;其次,研究了Ni-Cr薄膜换能组件静电放电响应特性,分析了换能组件尺寸和放电电压对薄膜桥区温度的影响规律;最后,构建了Ni-Cr薄膜换能组件在统计特征下的输入条件,确定了换能组件失效判据,进而结合发火感度试验与数理统计方法,实现了在静电放电条件下电火工品发火概率的预测。研究结果表明:预测发火概率与试验值误差不超过5%,验证了本文方法的有效性。

Gd改性Ni-Cr钎料钎焊金刚石组织和性能研究

本研究旨在减少钎焊金刚石的热损伤,提高钎焊金刚石的力学性能。采用Gd改性的Ni-Cr合金钎料,在1080℃保温5 min对金刚石进行真空感应钎焊试验,并利用SEM、EDS及XRD对钎料的微观组织和金刚石焊后界面微结构进行测试分析。结果表明,Gd的添加提高了Ni-Cr合金钎料的力学性能,钎料中生成了两种新的稀土化合物(Gd_(2)Ni_(17)和GdNi_(5))。添加适量的Gd可提高金刚石的出露度,且钎焊接头中生成的新型Gd_(2)Ni_(17)化合物有利于减少钎焊金刚石的热损伤。此外,当Gd的添加量为0.8%时,金刚石的暴露量达到其自身高度的62.1%,力学性能测试证实使用该钎料钎焊的金刚石的静压强度和磨削性能高于使用纯镍铬合金钎焊的钻石。

贴膜式Ni-Cr换能元设计及性能研究

通过热压工艺将5μm的Ni-Cr薄膜附着在聚酰亚胺薄膜上制备了贴膜式Ni-Cr薄膜,采用激光刻蚀加工工艺制备了贴膜式Ni-Cr换能元电桥,仿真优化设计了蝶形、S形换能元电桥,并开展了2种形状电桥的贴膜式Ni-Cr换能元的伏安特性、最大不熔断电流、50 ms脉冲恒流电爆特性以及发火特性试验研究。研究结果表明:桥区长度为3 mm的换能元电桥在1 A 5 min恒流激励后桥区温度最低;贴膜式Ni-Cr换能元在33μF电容放电时,随着充电电压的升高断桥时间缩短,蝶形和S形未发生断桥的电压分别为16,20 V;蝶形和S形换能元在5 min恒流脉冲输入下的最大不熔断电流分别为1.3,1.2 A;在50 ms脉冲恒流电爆时,随着施加电流幅度的不断增加,其工作电压也不断增高,其断桥时间越来越短,S形换能元和蝶形换能元分别在2.4,2.3 A时电桥未发生爆炸;33μF、28 V电容放电下贴膜式Ni-Cr换能元可以点燃斯蒂芬酸铅,并正常发火。

Effects of iron oxide on crystallization behavior and spatial distribution of spinel in stainless steel slag

Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter.However,the re-lease of chromium from stainless steel slag(SSS)during SSS stockpiling causes detrimental environmental issues.To prevent chromium pollution,the effects of iron oxide on crystallization behavior and spatial distribution of spinel were investigated in this work.The results revealed that FeO was more conducive to the growth of spinels compared with Fe2O3 and Fe3O4.Spinels were found to be mainly distrib-uted at the top and bottom of slag.The amount of spinel phase at the bottom decreased with the increasing FeO content,while that at the top increased.The average particle size of spinel in the slag with 18wt%FeO content was 12.8μm.Meanwhile,no notable structural changes were observed with a further increase in FeO content.In other words,the spatial distribution of spinel changed when the content of iron oxide varied in the range of 8wt%to 18wt%.Finally,less spinel was found at the bottom of slag with a FeO content of 23wt%.

Microwave-assisted exploration of the electron configuration-dependent electrocatalytic urea oxidation activity of 2D porous NiCo_(2)O_(4) spinel

Urea holds promise as an alternative water-oxidation substrate in electrolytic cells.High-valence nickelbased spinel,especially after heteroatom doping,excels in urea oxidation reactions(UOR).However,traditional spinel synthesis methods with prolonged high-temperature reactions lack kinetic precision,hindering the balance between controlled doping and highly active two-dimensional(2D)porous structures design.This significantly impedes the identification of electron configuration-dependent active sites in doped 2D nickel-based spinels.Herein,we present a microwave shock method for the preparation of 2D porous NiCo_(2)O_(4)spinel.Utilizing the transient on-off property of microwave pulses for precise heteroatom doping and 2D porous structural design,non-metal doping(boron,phosphorus,and sulfur)with distinct extranuclear electron disparities serves as straightforward examples for investigation.Precise tuning of lattice parameter reveals the impact of covalent bond strength on NiCo_(2)O_(4)structural stability.The introduced defect levels induce unpaired d-electrons in transition metals,enhancing the adsorption of electron-donating amino groups in urea molecules.Simultaneously,Bode plots confirm the impact mechanism of rapid electron migration caused by reduced band gaps on UOR activity.The prepared phosphorus-doped 2D porous NiCo_(2)O_(4),with optimal electron configuration control,outperforms most reported spinels.This controlled modification strategy advances understanding theoretical structure-activity mechanisms of high-performance 2D spinels in UOR.

Y元素对Ni-Cr非晶钎料钎焊金刚石组织和性能的影响

钎焊金刚石工具因化学冶金结合方式而具备较高的结合强度,在陶瓷、半导体和玻璃等硬脆性材料的加工行业及轨道交通、航空航天等领域中拥有广泛的应用前景。虽然Ni基钎料钎焊金刚石工具在结合强度、耐磨性及服役环境方面具有一定的优势,但是较高的钎焊温度和化学侵蚀会对金刚石磨粒造成较为严重的热损伤,从而影响金刚石工具的工作效率和服役寿命。为了降低钎焊过程中金刚石的热损伤,采用掺杂Y元素的Ni-Cr非晶钎料钎焊金刚石,通过SEM研究了钎焊金刚石试样的界面微观形貌,使用拉曼光谱仪分析了钎焊金刚石试样的石墨化程度,同时还探究了钎焊金刚石试样的力学性能。结果表明,当Y元素的质量分数为0.8%时,钎焊试样的金刚石形貌最为完整,钎焊层硬度最高为533 HV_(0.1),金刚石出露度较高为76.2%且石墨化程度较低。另外,Y元素的添加细化了碳化物的尺寸,降低了碳化物微裂纹的产生。相较于未添加Y元素的钎焊试样,添加Y元素的金刚石钎焊试样的抗压强度提升了约50.4%,磨削性能提高了43.5%,金刚石的脱落数量最少。表明,用Y元素掺杂的Ni-Cr非晶钎料可成功制备出钎焊金刚石试样,同时还降低了钎料中的触媒元素对金刚石的侵蚀作用,改善了热损伤和磨削性能。本研究为非晶钎料在钎焊金刚石工具领域中的应用提供了可靠的理论支持,并为相关工业生产提供了新的技术路径,在降低生产成本和推动绿色生产方面具有一定的实际意义。

Cu-Sn、Ni-Cr、Co烧结助剂对Ni_(3)Al基金刚石复合材料性能的影响

采用真空热压法制备了Ni_(3)Al基金刚石复合材料,研究了不同烧结助剂对复合材料力学性能和微观结构的影响,并对Ni_(3)Al基金刚石钻头的钻孔性能进行了测试。结果表明,在添加0~30vol%的Cu-Sn、Ni-Cr、Co烧结助剂后,Ni_(3)Al基金刚石刀头的致密度、抗弯强度、硬度得到提高。Ni3Al基金刚石复合材料的抗弯强度随着Ni-Cr、Co烧结助剂含量的增加而提高。Cu-Sn、Ni-Cr烧结助剂中的Cr元素在金刚石的表面出现了富集现象。将添加Cu-Sn、Ni-Cr烧结助剂的Ni_(3)Al基金刚石复合材料制备成工具进行钻削测试,发现Ni_(3)Al基金刚石复合材料的失效形式可以分为微破碎、磨耗、宏观破碎3种形式,钻削试验中并没有发现整颗金刚石脱落的现象,表明Ni_(3)Al基对金刚石的把持力较大,强度较高。

Healing the structural defects of spinel MnFe_(2)O_(4) to enhance the electrocatalytic activity for oxygen reduction reaction

Spinel metal oxides containing Mn,Co,or Fe(AB_(2)O_(4),A/B=Mn/Fe/Co)are one of the most promising nonPt electrocatalysts for oxygen reduction reaction(ORR)in alkaline conditions.However,the low conductivity of metal oxides and the poor intrinsic activities of transition metal sites lead to unsatisfactory ORR performance.In this study,eutectic molten salt(EMS)treatment is employed to reconstruct the atomic arrangement of MnFe_(2)O_(4)electrocatalyst as a prototype for enhancing ORR performance.Comprehensive analyses by using XAFS,soft XAS,XPS,and electrochemical methods reveal that the EMS treatment reduces the oxygen vacancies and spinel inverse in MnFe_(2)O_(4)effectively,which improves the electric conductivity and increases the population of more catalytically active Mn^(2+)sites with tetrahedral coordination.Moreover,the enhanced Mn-O interaction after EMS treatment is conducive to the adsorption and activation of O_(2),which promotes the first electron transfer step(generally considered as the ratedetermining step)of the ORR process.As a result,the EMS treated MnFe_(2)O_(4)catalyst delivers a positive shift of 40 mV in the ORR half-wave potential and a two-fold enhanced mass/specific activity.This work provides a convenient approach to manipulate the atomic architecture and local electronic structure of spinel oxides as ORR electrocatalysts and a comprehensive understanding of the structureperformance relationship from the molecular/atomic scale.

Striking Stabilization Effect of Spinel Cobalt Oxide Oxygen Evolution Electrocatalysts in Neutral pH by Dual-Sites Iron Incorporation

Developing stable and efficient nonprecious-metal-based oxygen evolution catalysts in the neutral electrolyte is a challenging but essential goal for various electrochemical systems.Particularly,cobalt-based spinels have drawn a considerable amount of attention but most of them operate in alkali solutions.However,the frequently studied Co-Fe spinel system never exhibits appreciable stability in nonbasic conditions,not to mention attract further investigation on its key structural motif and transition states for activity loss.Herein,we report exceptional stable Co-Fe spinel oxygen evolution catalysts(~30%Fe is optimal)in a neutral electrolyte,owing to its unique metal ion arrangements in the crystal lattice.The introduced iron content enters both the octahedral and tetrahedral sites of the spinel as Fe^(2+)and Fe^(3+)(with Co ions having mixed distribution as well).Combining density functional theory calculations,we find that the introduction of Fe to Co_(3)O_(4)lowers the covalency of metal-oxygen bonds and can help suppress the oxidation of Co^(2+/3+)and 0^(2-).It implies that the Co-Fe spinel will have minor surface reconstruction and less lattice oxygen loss during the oxygen evolution reaction process in comparison with Co_(3)O_(4)and hence show much better stability.These findings suggest that there is still much chance for the spinel structures,especially using reasonable sublattices engineering via multimetal doping to develop advanced oxygen evolution catalysts.

Unveiling the geometric site dependent activity of spinel Co_(3)O_(4)for electrocatalytic chlorine evolution reaction

Spinel cobalt oxide(Co_(3)O_(4)),consisting of tetrahedral Co^(2+)(CoTd)and octahedral Co^(3+)(CoOh),is considered as promising earth-abundant electrocatalyst for chlorine evolution reaction(CER).Identifying the catalytic contribution of geometric Co site in the electrocatalytic CER plays a pivotal role to precisely modulate electronic configuration of active Co sites to boost CER.Herein,combining density functional theory calculations and experiment results assisted with operando analysis,we found that the Co_(Oh) site acts as the main active site for CER in spinel Co_(3)O_(4),which shows better Cl^(-)adsorption and more moderate intermediate adsorption toward CER than CoTd site,and does not undergo redox transition under CER condition at applied potentials.Guided by above findings,the oxygen vacancies were further introduced into the Co_(3)O_(4) to precisely manipulate the electronic configuration of Co_(Oh) to boost Cl^(-)adsorption and optimize the reaction path of CER and thus to enhance the intrinsic CER activity significantly.Our work figures out the importance of geometric configuration dependent CER activity,shedding light on the rational design of advanced electrocatalysts from geometric configuration optimization at the atomic level.

The Spectral Characterization of Blue Spinel and Other Blue Gemstones with the Alexandrite Effect

In gemmology,the term“Alexandrite effect”is used to describe colour change phenomenon when a gemstone is observed under different light sources,usually between daylight and incandescent light.The definition of the Alexandrite effect is constantly being broadened with new discovery of gem resource.The traditional definition of the Alexandrite effect attributing the colour change phenomenon to the presence of two maximum transmission regions and a maximum absorption region in the absorption spectra.In this study,7 blue spinels and 5 blue gemstones(including tanzanite,kyanite,fluorite,and 2 sapphires)showing the Alexandrite effect were investigated.The goal is to explain the cause of blue-to-violet Alexandrite effect and the spectral features causing such colour change.In the UV-Vis spectra,all samples showed a maximum absorption peak in the range of 534-610 nm,within the green region to orange region.The traditional explanation of green to red Alexandrite effect required a transmission window in the red region;however,some of our samples did not show this transmission window and the blue-to-violet Alexandrite effect was still visible.Therefore,it is incomplete to explain the mechanism of the Alexandrite effect according to their characteristic absorption spectra,a systematic study based on modern colour science and colour perception in human vision is required to elucidate the blue-to-violet Alexandrite effect.

Ni-Cr合金烤瓷界面反应微观机理

对临床失败Ni-Cr合金烤瓷修复体分析,Ni-Cr合金与陶瓷界面平滑,无明显的反应层生成,修复体内存在裂纹和气孔。通过扫描电镜、能谱与X射线衍射仪,对Ni-Cr合金与陶瓷界面反应研究结果表明,Al2O3陶瓷表面富集的氧离子,与合金中的Ni,Cr反应,还原生成Al,并与Ni化合生成AlNi3,而Cr则被氧化后与Sn生成SnCrO的复合氧化物。在Ni-Cr合金烤瓷界面处形成一连续的反应薄层,可显著改善Ni-Cr合金与陶瓷间的界面冶金结合,减少界面缺陷,实现Ni-Cr合金与陶瓷的可靠结合。

三价铬脉冲电沉积纳米晶Ni-Cr合金工艺

采用脉冲电沉积方法对三价铬电沉积Ni-Cr合金镀层工艺进行研究,确定并优化三价铬脉冲电沉积Ni-Cr合金的最佳镀液配方及工艺参数。研究镀液中各成分及工艺参数对三价铬脉冲电沉积Ni-Cr合金厚度及合金镀层中铬的影响,利用扫描电镜和电子能谱分析Ni-Cr合金镀层的形貌、微观结构和化学组成。结果表明,镀层厚度和Ni-Cr合金中铬含量在不同浓度的络合剂、稳定剂、乙酸钠及不同的电流密度、温度、pH值、占空比和脉冲频率下都存在极大值,且Ni-Cr合金厚度随合金中铬含量的增加而减少。当铬含量为24%时,镀层的厚度大于10μm,无裂纹,其晶粒为纳米球状晶粒。

添加石墨对Ni-Cr合金保护气氛钎焊金刚石磨粒界面组织的影响

钎焊单层金刚石工具磨粒具有高的出刃和把持力,但在高温钎焊过程中易造成金刚石较大的热损伤,利用在Ni-Cr合金中添加适量的石墨,期望能够阻止金刚石石墨化,降低金刚石焊后热应力和过度反应。采用添加质量分数为0%、1%、2%石墨的Ni-Cr合金作为钎料对金刚石进行保护气氛钎焊试验,钎焊温度1 050℃保温5 min,利用扫描电镜对焊后金刚石的形貌和焊缝组织进行分析,测试钎缝的显微硬度。结果表明,添加1%石墨的钎料对金刚石润湿性较好,添加的C元素能够与Cr元素反应后形成碳化物,其中部分Cr3C2在金刚石表面形核长大,并与金刚石有一定位向关系,Cr7C3的形貌由实心转变为空心,钎缝中形成簇状共晶石墨,显微硬度由630 HV0.2下降到580 HV0.2,有利于金刚石磨粒的后期出露和降低热应力。

Ni-Cr合金真空钎焊金刚石界面反应的热力学与动力学分析

采用Ni-Cr合金钎料 ,适当控制钎焊工艺 ,实现了金刚石与钢基体的高强度连接。采用扫描电子显微镜 (SEM)和能谱仪 (EDS)及X射线衍射结构分析了真空加热条件下 ,Ni-Cr合金钎料与金刚石之间的界面反应 ,探讨了钎料与金刚石界面处碳化物的形成机理。结果表明 ,Ni-Cr合金钎料中的Cr和少量Si在金刚石表面富集并与金刚石中的C发生反应生成Cr7C3 、Cr3 C2 碳化物 ,其中Cr7C3 呈笋状生长 ,Cr3 C2 呈片状 ,可能有少量SiC生成。金刚石与钎料的界面形成了金刚石 \SiC \Cr3 C2 \Cr7C3 钎料的梯度材料 ,实现了Ni-Cr合金与金刚石的冶金结合。

Cr颗粒尺寸对Ni-Cr复合镀层氧化行为的影响

利用Ni与不同粒度的Cr颗粒通过复合电镀的方法分别制备了Nip7．5Cr（平均粒度为21nm）、Ni-10．9Cr（平均粒度为39nm）和Ni-12．4Cr（平均粒度为2．4μm）的Ni-Cr复合镀层．Ni-Cr纳米复合镀层与Ni—Cr复合微米颗粒镀层相比，其颗粒分布更为均匀，颗粒间距减少2～3个数量级．900℃恒温氧化实验结果表明：复合微米颗粒的Ni—Cr镀层只形成NiO膜，不能形成连续的Cr2O3膜，氧化速率很快；而Ni—Cr纳米复合镀层。由于能形成连续的Cr2O3膜，氧化速率显著降低，并且这种颗粒尺寸效应随粒度越细越明显．文中对颗粒尺寸效应进行了探讨．

Te对Ni-Cr合金高温抗氧化性能的影响

采用粉末冶金方法制备含Te的Ni-Cr合金试样.在800±5℃高温进行抗氧化实验.通过氧化动力学曲线分析、氧化皮金相组织和断面形貌观察、X-ray分析表明:Te的加入在合金内部形成新相Cr2TeO4和Fe3TeO,提高合金材料氧化皮的粘附性.并且有效抑制Cr2O3的挥发反应,从而改善Cr2O3氧化层的致密性.

显微组织对Ni-Cr合金热腐蚀行为的影响

采用机械合金化法和真空熔炼法制备了不同显微组织的Ni-20Cr(质量分数,%,下同)合金,并研究其在950℃,75%Na2SO4+25%K2SO4(质量分数,下同)盐膜下的热腐蚀行为。结果表明:细晶的机械合金化Ni-20Cr合金热腐蚀后表面形成了单一连续的Cr2O3外氧化膜,有效地阻止了硫的向内扩散,延长了热腐蚀过程的孕育期,呈现出较普通晶粒尺寸的熔炼Ni-20Cr合金更好的抗热腐蚀性能。

Ni-Cr-Mo-Al-Ti-B-MoS_2系合金高温摩擦学特性的研究

用粉末冶金法制备了Ｎｉ－Ｃｒ－Ｍｏ－Ａｌ－Ｔｉ－Ｂ－ＭｏＳ２系宽温度范围自润滑合金材料，测试了合金机械性能及其在室温至６００ ℃范围内的摩擦磨损性能，同时还探讨了其耐磨机理．研究结果表明，ＭｏＳ２ 质量分数为１０％ 的合金具有较好的机械和摩擦磨损综合性能．该合金主要由Ｎｉ基固溶体、Ｎｉ３Ａｌ、Ｎｉ３（Ａｌ，Ｔｉ）、不定比化合物ＣｒｘＳｙ、ＭｏＳ２ 和Ｍｏ２Ｓ３ 等相组成，在室温至３００ ℃范围内摩擦表面形成含硫化合物复合膜而起润滑作用，高温摩擦时承载表面形成釉质层，次表层形成氧化层，其硬度比合金基体高，这是合金具有良好高温耐磨性的基础．高温下摩擦表面及磨屑中的氧化物及残余硫化物的协同作用使摩擦系数进一步降低．

添加Ni包覆MoS_2的Ni-Cr高温固体自润滑材料的研究

通过硝酸镍分解-氢还原法制取镍涂覆二硫化钠粉末,加入到Ni-Cr基体合金中,以防止二硫化钼在高温制备过程及高温使用过程中的氧化分解。添加Ni包覆MoS_2粉末,Ni-Cr25(w％)高温固体自润滑材料的机械性能优于未包覆材料,对(MoS_2/Ni)20w％的高温固体自润滑材料的摩擦磨损性能分析表明:在室温和600℃下,材料有较低的摩擦系数,室温磨损率也很低,在高温下与未添加包覆材料相比前者具有很好的宽温带摩擦学性能。