ECAP制备超细晶铜在0.5mol/L NaCl溶液中的腐蚀行为

利用极化法、电位时间曲线、浸泡实验等研究等径角挤压(Equal Channel Angular Pressing,ECAP)制备的块体超细晶铜和退火态粗晶铜在0.5mol/L NaCl溶液中的腐蚀行为,对比研究ECAP挤压前后腐蚀行为的变化。结果表明:通过ECAP制备的超细晶Cu的腐蚀电流低于粗晶Cu,自腐蚀电位Ecorr比粗晶铜高100mV左右,表明超细晶Cu的耐蚀性比粗晶Cu要好。通过电化学分析和微观腐蚀形貌,超细晶材料的腐蚀表面非常光滑,腐蚀较为均匀,粗晶材料的局部腐蚀现象十分严重。     

锆基大块非晶合金及其晶化合金在0.5mol/L H2SO4中的腐蚀行为研究

根据合金的DSC曲线制定了Zr60Al15Ni25、Zr52.5Al10Ni10Cu15Be12.5和Zr65Al10Ni10Cu15等锆基大块非晶合金的等温退火工艺,获得了与非晶态合金具有相同成分的晶化合金。通过研究非晶态合金和晶化合金在0.5mol/L H2SO4中的极化曲线,结合扫描电镜(SEM)和能量散射X射线谱(EDS)分析,发现,在0.5mol/LH2SO4中非晶态合金和晶化合金都具有非常优异的耐腐蚀性能,但非晶合金的耐腐蚀性能要比晶化合金稍好。这主要是因为晶态合金的结构中不存在晶界、位错等缺陷,同时非晶态合金中的组元具有很高的活性,使合金更快地进入钝态。     

含盐体系中有机铜缓蚀剂的研究进展

叙述了含盐体系中各种有机类铜缓蚀剂的国内外研究进展,阐述了有机类铜缓蚀剂的缓蚀机理和协同作用机理,并展望了铜缓蚀剂新的研究和发展方向。认为应利用现代先进的分析测试技术从分子和原子的水平上研究缓蚀剂在铜表面的行为和作用机理,加强现有缓蚀剂品种的复配技术和绿色环保型缓蚀剂研究。     

应变速率对一种无铼单晶高温合金低周疲劳性能的影响

研究了一种无铼镍基单晶高温合金在1223 K、不同应变速率(5×10^-4s^-1、1×10^-3s^-1、5×10^-3s^-1、1×10^-2s^-1)条件下的低周疲劳行为。结果表明:在四种应变速率条件下,合金均表现出循环稳定。随着应变速率的增加,合金的疲劳寿命逐渐增加,且其半寿命稳定滞后回线环内面积逐渐减少,表明低应变速率合金更容易积累蠕变塑性变形。疲劳裂纹源均萌生于试样表面,随着应变速率的增加,疲劳过程中产生的塑性变形越来越少,疲劳裂纹扩展区的面积逐渐增大。低应变速率时,较大的塑性变形导致合金取向发生明显的偏转,诱发多滑移系开动进而形成位错网;反之,高应变速率时,合金没有产生明显的塑性变形,只有单一方向的位错塞积形成位错束。     

Anisotropic Creep Rupture Properties of a Nickel-base Single Crystal Superalloy at High Temperature

The creep rupture properties of a single crystal superalloy were tested at 975℃/255 MPa as a function of the deviation degrees from [001].The misorientation of the specimens away from [001] distributed approximately along a line between [001]-[011] and [001]-[111] boundaries in the triangle of the stereographic projection.Creep rupture lifetimes of the specimens were not sensitive to the misorientation until the deviation degree exceeded ～30 deg.Two steps of lattice rotation were found in all specimens during creep,first towards the [001]-[111] boundary,and then to [001] or [111] along the boundary.Single slip and strong asymmetric deformation were observed during the first stage of lattice rotation in specimens with large misorientation.The rotation mechanism was associated with the activated slip systems according to the calculated Schmid factors.The impact of lattice rotation on the rupture properties was also discussed.     

Zn-Al-Mg-Ce合金耐长江水和3.5%盐水腐蚀性能研究

研究了Zn-Al-Mg-Ce合金在长江水及3.5%NaCl(质量分数)盐水中的浸泡腐蚀性能,分别测试了其电化学性能,并与Zn、Zn-Al合金、Zn-Al-Mg合金做对比试验。采用扫描电镜和能谱分析了微观组织及成分,分析了耐蚀机理。结果表明:Zn-Al-Mg-Ce合金无论在长江水或3.5%盐水中都显示出电极电位最负、腐蚀电流最小、腐蚀速度最小,其腐蚀速度分别只有Zn的19.4%和23.7%,腐蚀速度由小到大依次为:Zn-Al-Mg-Ce相似文献   

Dislocation Behaviour near the Crack Tip in Bulk Fe-3% Si Single Crystal

An investigation has been made of the disloca-tion distribution and dislocation free zone near thecrack tip in bulk Fe-3% Si single crystal duringdeformation in SEM.It has been found that anumber of dislocations were emitted from the cracktip during deformation.After that,the dislocationsmoved rapidly away from the crack tip,which indi-cated that they were strongly repelled by the stressfield at the crack tip.Between the crack tip and theplastic zone there is a region of dislocation-free,which is referred to as dislocation-free zone (DFZ).The length of DFZs is roughly estimated 100μm which is much longer than that found in thinfoil specimen.The variation of dislocation densityas a function of the distance from the crack tip wasmeasured,which showed that the dislocations areinversely piled up in the plastic zone.The length ofDFZs increased with both the length of pre-crackand the amplitude of applied stress.     

表面粗糙度对GCr15轴承钢在0.05 mol/L NaCl溶液中腐蚀行为的影响

轴承表面粗糙度是影响轴承寿命、可靠性等的重要因素之一,但目前有关轴承表面粗糙度与其耐蚀性的关系研究较少.为此,采用浸泡试验、开路电位-时间(OCP-t)法、电化学阻抗谱(EIS)等方法,研究了表面粗糙度Ra分别为1.35,1.05,0.15 μm的GCr15轴承钢在0.05 mol/L NaCl溶液中的腐蚀行为.结果 ...     

温度对X80管线钢在0.5mol/L Na_2CO_3+1.0mol/L NaHCO_3溶液中电化学腐蚀性能的影响

目前,有关温度对CO_3~(2-)-HCO_3~-环境下X80管线钢腐蚀行为的影响规律尚无统一的认识。为了探究高强度钢在不同温度的0.5 mol/L Na_2CO_3+1.0 mol/L NaHCO_3溶液中的腐蚀行为,采用动电位极化、电化学阻抗技术,并结合金相显微镜观察研究了温度对X80管线钢在0.5 mol/L Na_2CO_3+1.0 mol/L NaHCO_3溶液中电化学腐蚀行为的影响规律,并通过Mott-Schottky曲线对不同温度下钝化膜的半导体性质进行探讨。结果表明:温度从30℃上升至75℃时,X80钢的点蚀电位和电荷转移电阻均逐渐减小,腐蚀现象越明显;当温度达到90℃时,点蚀电位和电荷转移电阻反而增大,腐蚀程度有所减缓;在0.3~0.7 V内,钝化膜呈现出典型的n型半导体特征;随着温度的升高,钝化膜内的施主电流密度和平带电位呈现先降低后增加的趋势,钝化膜稳定性先减弱后增强;在75~90℃之间存在一个临界温度,此温度下钝化膜的缺陷密度最大,保护性最差。     

The Inhibitive Effect of para-Amino Benzoic Acid and Its Polymer on Corrosion of Iron in 1 mol/L HCl Solution

Poly p-aminobenzoic acid has been synthesized by chemical oxidation method. The inhibitive effect of poly p-aminobenzoic acid on iron in 1 mol/L HCI solution was investigated by polarization and electrochemical impedance spectroscopy and compared with that of monomer p-aminobenzoic acid. The effectiveness of poly p-aminobenzoic acid is very high in comparison with that of monomer. The results show that both cathodic and anodic processes were suppressed by p-aminobenzoic acid and poly p-aminobenzoic acid of iron dissolution in 1 mol/L HCI by their adsorption on the iron surface. The inhibition efficiency of both p-aminobenzoic acid and poly p-aminobenzoic acid were found to increase with the inhibitor concentrations. Ultraviolet （UV） reflectance studies of the iron surface after exposure to inhibitor acid show that poly p-aminobenzoic acid is strongly adsorbed on iron surface.     

气膜孔分布对DD6单晶高温合金高周疲劳断裂行为的影响

利用带不同电液束加工气膜孔分布的DD6单晶气冷叶片模拟试样,研究其在常温下的高周疲劳性能,并对试样断口及断口侧面形貌进行宏观与微观观察。结果表明:在相同的实验条件下,气膜孔的存在对试样高周疲劳寿命的影响较大,无孔试样的平均寿命约为带3排孔试样的4倍,但是气膜孔布局对疲劳寿命的影响相对较小。通过断口宏观与微观观察发现,无孔试样呈线源特征,而1~3排孔试样裂纹均从气膜孔附近起源,呈多源特征。根据断口和晶体学理论推测,对于无孔、1排孔和多排孔试样的中间部位,裂纹沿{001}滑移面扩展;而对于多排孔试样的上下2排孔孔周的裂纹沿{111}滑移面扩展。采用有限元方法分析4种不同试样孔边应力场的分布规律,数值模拟分析结果与试样的断裂位置及形貌吻合。     

The Inhibitive Effect of para-Amino Benzoic Acid and Its Polymer on Corrosion of Iron in 1 mol/L HC1 Solution

Poly p-aminobenzoic acid has been synthesized by chemical oxidation method. The inhibitive effect of poly p-aminobenzoic acid on iron in 1 mol/L HCl solution was investigated by polarization and electrochemical impedance spectroscopy and compared with that of monomer p-aminobenzoic acid. The effectiveness of poly p-aminobenzoic acid is very high in comparison with that of monomer. The results show that both cathodic and anodic processes were suppressed by p-aminobenzoic acid and poly p-aminobenzoic acid of iron dissolution in 1 mol/L HCI by their adsorption on the iron surface. The inhibition efficiency of both p-aminobenzoic acid and poly p-aminobenzoic acid were found to increase with the inhibitor concentrations. Ultraviolet (UV) reflectance studies of the iron surface after exposure to inhibitor acid show that poly p-aminobenzoic acid is strongly adsorbed on iron surface.     

微纳米尺度单晶铜各向异性表面切削特性实验研究

利用纳米压痕仪和原子力显微镜对微纳米尺度下单晶铜各向异性表面在不同载荷和刻划速度下的切削特性进行实验研究。结果表明:单晶铜各晶面表面在较低载荷下,划痕细小且不明显。随着载荷的逐渐增大,划痕深度和宽度逐渐变大,并形成明显的沟槽,在沟槽的两侧出现明显的侧流现象,探针前方出现切屑堆积,尤其单晶铜Cu(100)切屑堆积较明显;单晶铜Cu(100)在刻划速度为10μm/s、50μm/s时,切削力无明显变化规律,其余两晶向都是在同等载荷下,刻划速度越大,切削力越大。随着刻划速度的增大,切削力趋于稳定;载荷越大,切削力越大,其相应摩擦系数也增大。     

新型折叠夹芯结构材料研究进展

折叠夹芯结构是一种具有轻质、高比强、高比刚度以及多功能潜力的新型三维结构材料,近几年受到国内外学者的极大关注.它将成为新一代结构功能一体化的理想结构材料.主要概述了折叠夹芯结构的发展历程,包括折叠芯材的拓扑构型设计、制备工艺研究以及折叠夹芯结构力学性能、失效方式、数值模拟和隔音、热力学等方面的工作.同时结合折叠夹芯结构的性能和优势,对其可能应用的领域进行预测,并对其未来研究方向进行了展望.     

热处理工艺对SRR99镍基单晶高温合金组织和性能的影响

研究不同固溶处理温度和时效处理温度对SRR99镍基单晶高温合金的微观组织和持久性能的影响。利用扫描电镜和光学金相显微镜对显微组织进行表征和分析,利用GWT304常载拉伸蠕变试验机测试其持久性能。结果表明:随着一次时效温度的提高,二次γ′相尺寸逐渐增大,γ′相体积分数先增加后降低;随着固溶温度的提高,合金中残余共晶含量减少,偏析逐渐降低,在1050℃/150MPa条件下,合金的持久寿命呈现先增加后降低的趋势。     

DD8单晶镍基高温合金热处理制度研究

研究了热处理工艺对ＤＤ８单晶高温合金组织及性能的影响，结果表明，经过１１００℃／８ｈＡ．Ｃ．＋１２４０℃／４ｈＡ．Ｃ．＋１０９０℃／２ｈＡ．Ｃ．＋８５０℃／２４ｈＡ．Ｃ的４级处理明显改善了ＤＤ８单晶合金元素的枝晶偏析，合金中γ相获最佳含量并形成适当尺寸配合，合金获得理想的综合性能。     

人工神经网络在单晶合金设计中的应用

把一种新发展的功能极强的信息处理技术－计算机人工神经网络技术用于单晶合金的高温持久性能预测并和其它方法进行比较，结果表明：这种方法精度最高。     

凝固方向对单晶高温合金枝晶组织的影响

用籽晶法制备了沿不同晶体取向凝同的镍基单晶高温合金试样,研究了单晶中枝晶形貌和一次枝晶臂距随凝固取向的变化规律.结果表明:凝同方向偏离[001]取向小于15°时,枝晶排列比较规则,一次枝晶臂距随偏离角度增大而减小;偏离角度为25°时,部分二次枝晶臂阻断了相邻一次枝晶干的生长,导致一次枝晶臂距增大.沿[011]和[111...     

Influence of Co, W and Ti on the Stress-rupture Lives of a Single Crystal Nickel-base Superalloy

The influence of Co, W and Ti on stress-rupture lives of a Ni-Cr-AI-Mo-Ta-Co-W-Ti single crystal nickel-base superalloy has been investigated using a L9 （34） orthogonal array design （OAD） by statistical analysis. At a selected composition range, Ti content was the most important factor to the effect of the stress-rupture lives and then followed by Co content. W content had the minimum effect on stress-rupture lives. The optimal alloy should contain 10 wt pct Co, 8 wt pct W and zero Ti. The optimized alloy also had good microstructural stability during thermal exposure at 870℃ for 500 h.