GCr15轴承钢盘条孔洞缺陷分析及改善

对GCr15高碳铬轴承钢热轧盘条的低倍组织孔洞缺陷进行SEM电镜分析,说明孔洞缺陷的产生与钢中碳、铬元素的分布存在直接关系.GCr15轴承钢在凝固组织的二次枝晶间形成碳、铬偏析生成粗大的M3C、M7C3等共晶碳化物.由于扩散时间及温度的限制,该碳化物未能充分均化固熔在轧制后的拉伸带状组织中,所以酸蚀后的轴承钢热轧盘条断面出现低倍组织孔洞缺陷.为了改善该缺陷,共进行了8组高温扩散试验,结果表明：热轧盘条的低倍组织孔洞缺陷在1 100℃高温扩散后得到明显改善.     

热轧圆棒材内部孔洞缺陷原因分析

通过宏观检验、热酸蚀试验、扫描电镜及能谱分析、金相检验的方法对棒材内部孔洞进行了分析,结果表明:热轧圆棒材内部低熔点硫化物的偏聚是导致其内部产生孔洞缺陷的主要原因。     

高性能不锈钢（8）

耐腐蚀性 高性能不锈钢突出的腐蚀特性不仅归功于它们的高合金含量,而且归功于高含量的铬和其他合金元素相互影响的协调作用。例如,在高铬铁素体不锈钢中,甚至小量的镍也会大大扩大其在还原酸中的钝化程度,随着铬含量的增加,钼耐氯化物点蚀的作用更有效.     

不同酸蚀处理方法对氟斑牙托槽脱落率的影响

目的:观察不同酸蚀方法对氟斑牙粘结托槽的脱落率的影响,筛选一种降低氟斑牙托槽脱落率的临床可行的酸蚀方法.方法:选择14例中度氟斑牙患者的226颗牙齿为研究对象,按左右分为28个区,随机分为4组(每组7个区):分别为酸蚀1 min组(n=56)、酸蚀2 min组(n=57)、酸蚀3 min组(n=57)和酸蚀2次组(n=56),记录第4、8和12周托槽脱落率和托槽脱落后牙面上残留的粘接剂残留指数(ARI).结果:酸蚀2次组和酸蚀2 min组的托槽脱落率明显低于酸蚀1 min组和3 min组(P<0.05);ARI高于酸蚀1 min组和3 min组(P<0.05).酸蚀2次组的托槽脱落率低于酸蚀2 min组,但差异无统计学意义(P>0.05);ARI高于酸蚀2 min组,但差异亦无统计学意义(P>0.05).各组前磨牙脱落率均明显高于前牙(P<0.05),酸蚀2次组的前磨牙脱落率低于其他各组(P<0.05).结论:酸蚀2 min能明显降低氟斑牙托槽脱落率,2次酸蚀比1次酸蚀托槽脱落率降低,尤其是前磨牙托槽脱落率明显降低.     

高碳铬铁渣中铬的存在形态研究

通过对高碳铬铁渣中铬存在形态的研究,揭示了铬渣中的铬主要以水溶态、酸溶态、安全态和残余态四种形态存在.其中水溶态铬含量非常低,酸溶态的铬含量为0.314 8 mg铬每克渣,这部分铬可通过各种途径释放到环境中,对环境造成了污染.安全态和残余态中的铬含量为0.794 6 mg铬每克渣和1.554 0 mg铬每克渣,在自然条件下,这两种形态的铬比较稳定,有利于铬渣湿法解毒与铬的回收利用.     

腐蚀类型——电化学腐蚀（点蚀）

点蚀是局部腐蚀的一种形式,导致金属中产生小洞。这些洞的直径大多相对较小。点蚀是一种相当隐蔽的腐蚀形式,只占整个结构重量损失很小百分比的孔洞就可引起设备损坏。点蚀由凹点开始,其形成过程可从几个月到数年。在腐蚀性非常强的环境下,如含有氯化铁的酸介质,X2CrNi9-11（304L）不锈钢甚至在两三天内就会发生严重的腐蚀。     

电位滴定法测定齿轮酸蚀检测用酸蚀液、漂白液总酸度

准确测定使用过程中的齿轮酸蚀检测用酸蚀液、漂白液的总酸度,对于判定齿轮酸蚀检测用酸蚀液、漂白液能否继续使用具有重要意义。实验通过加入10mL草酸钠饱和溶液以有效掩蔽溶液中的Fe²⁺和Fe³⁺,采用0.5mol/L氢氧化钠标准滴定溶液进行滴定,选取滴定过程中第1个等当点EP1为滴定终点,实现了电位滴定法对齿轮酸蚀检测用酸蚀液、漂白液总酸度的测定。采用实验方法对未使用的、使用7d的、使用14d的齿轮酸蚀检测用酸蚀液、漂白液总酸度进行测定,并进行加标回收试验,结果表明,这3种样品测定结果的相对标准偏差(RSD,n=6)均小于1.0%,加标回收率分别在99%~102%、98%~102%之间。分别采用实验方法和手动酸碱滴定法对使用14d的齿轮酸蚀检测用酸蚀液和漂白液总酸度进行测定,测定结果基本一致。     

连铸坯热酸蚀检验反应机理及过程优化

 热酸蚀法是连铸坯质量检验的一种常用方法,但目前使用效果不稳定,检验过程中容易出现过腐蚀或腐蚀不够的现象,其反应机理也存在争议。以高碳钢为例,探索一种热酸蚀检验反应机理的研究方法,旨在确定热酸蚀检验的具体反应机理,并对热酸蚀检验的过程优化提供理论指导。首先原位分析组织形貌在酸蚀过程中的变化规律,然后对酸蚀前后物相变化和酸蚀过程中不同物相对应的腐蚀行为观察分析,结合对酸蚀过程进行的数值模拟、极化曲线测量及电化学理论,共同分析热酸蚀过程的反应机理,并由此展开过程优化。结果表明,热酸蚀检验机理可以用不同物相间的微电池反应解释,即铸坯中的Fe₃C相可以与周围基体发生微电池反应,碳浓度高的偏析区域Fe₃C较多,微电池分布密度大,在热酸蚀过程中腐蚀速率较快,铸坯中腐蚀速率的差异导致不同区域腐蚀形貌的不同,最终显示出铸坯的低倍组织及缺陷情况。并根据反应机理得出酸蚀效果随酸蚀时间的增长存在拐点,且所研究钢种最佳反应时间为300 s,同时发现适当提高温度可以增大铸坯中不同区域在酸蚀过程中腐蚀速率的差异,有利于改善酸蚀效果。这对连铸坯质量优化及高品质钢质量稳定性的提升具有重要意义,同时所提出的研究方法对类似检验的过程优化也具有参考价值。     

酸蚀法观察钢中夹杂物的三维形貌

 使用酸蚀法成功揭示了铝镇静钢中夹杂物的三维形貌和成分。酸蚀钢样品过程中,Al2O3夹杂物基本不与酸发生反应,只是样品基体与酸反应。短时间的酸蚀不会破坏夹杂物的成分。观察得到所研究的铝镇静钢中主要为粒径5~200 μm的各种形貌的Al2O3夹杂物。本研究表明,酸蚀法是得到夹杂物三维形貌和成分的有效方法。     

某些变色酸单偶氮化合物与铝的荧光反应及其分析应用

本文研究了酸性铬深蓝、铬蓝SE、酸性铬蓝K、铬偶氮酚KS等四种变色酸单偶氮化合物与铝的荧光反应的适宜条件、反应产物的荧光特性、反应的灵敏度和选择性以及螯合物的组成.方法可用于钢铁和水中痕量铝的测定,取得了满意的结果.     

γ预辐照对管流冲刷条件下铍在EDM--1中腐蚀性能的影响

构建管流式冲刷腐蚀实验装置研究γ预辐照对铍在一号电火花加工油（EDM-1）中腐蚀性能的影响,研究铍试样质量变化,进行表面形貌及成分分析.结果表明,铍在EDM-1管流冲刷条件下受冲刷腐蚀和化学腐蚀的共同作用,前者主要受试样表面形态影响,后者主要受γ预辐照剂量、杂质元素、EDM-1中含硫有机物等的影响.辐照前后,试样质量均呈现先减小、后增大、再减小趋势,腐蚀速率基本随辐照剂量的升高而增大.γ预辐照促进了铍试样在EDM-1中点蚀核和蚀孔的产生,腐蚀2880 h后,未接受预辐照试样仅产生较为明显点蚀核,而接受200和100 kGy预辐照试样中的部分点蚀核发展成为蚀孔,前者直径约为后者2倍.点蚀核和蚀孔区域出现Al、Si、Fe、Cr、Ti等杂质元素及S元素,杂质元素为诱导产生点蚀的重要因素,含S有机物发生化学反应分别生成物理吸附和化学吸附于蚀孔内部的SO₂和SO_x,促进蚀孔的形成及扩展.      

铜管在羧酸环境下的腐蚀行为和腐蚀机理研究

铜管是空调及制冷行业用热交换器的核心部件,在服役过程中常由于蚁穴腐蚀导致设备提前失效。本文采用蒸气腐蚀、电化学腐蚀方法研究了铜管在羧酸环境下的腐蚀行为,通过金相显微镜（OM）、扫描电镜（SEM）、 X射线粉末衍射仪（XRD）观察和分析了表面腐蚀形貌和腐蚀产物的结构,通过接触角测量仪研究了羧酸与铜管的界面行为。结果表明,与CH3COOH蒸气腐蚀相比,铜管在HCOOH蒸气环境下的腐蚀速度慢,腐蚀产物更致密。在HCOOH蒸气环境下,铜管容易出现蚁穴腐蚀。铜管表面的腐蚀产物主要由羧酸铜和氧化亚铜组成。蚁穴腐蚀属于电化学腐蚀,腐蚀机理复杂。腐蚀初期,表面氧化膜被聚集在铜管表面的羧酸溶解,暴露的铜基体作为微观阳极,之后,腐蚀坑内产生的微裂纹的尖端作为微观阳极,使腐蚀加速,直至贯穿管壁。     

Pitting corrosion behavior of cerium treated HSLA steel induced by sulfide inclusions in 3.5 wt% NaCl solution

Pitting corrosion behavior of Ce treated HSLA steels induced by sulfide inclusions in 3.5 wt% NaCl solution was investigated with potentiodynamic polarization and immersion corrosion test.The results show that Ce added steels exhibit better pitting corrosion resistance with lower corrosion current density and bigger pitting potential compared with steel without Ce,which is mainly attributed to optimized characteristics of spherical Ce-oxysulfide inclusions with less number density,smaller average size and lower pitting corrosion susceptibility.The spherical Ce₂O₂ S inclusions precipitated on the surface of CeAlO₃ inclusions in the Ce added steels induce pits with bigger opening mouth and shallow depth,reducing their tendency of extension to go deeper due to occlusion corrosion battery in the pitting holes.Furthermore,corrosion inhibitor Ce(OH)₃ generated by Ce₂O₂ S hydration can weaken electrochemical corrosion of the matrix micro-region around the pits.To avoid harmful bigger inclusions,Ce content in steels should be regulated within reasonable range,0.015 wt% Ce in present steels effectively modified inclusions to acquire the best pitting corrosion resistance of the steels.     

A Study on the Corrosion and Wear Behavior of Electrodeposited Ni-W-P Coating

In this study, the tribocorrosion of electroplated Ni-W-P alloy coating (3.9 to 4.3 at. pct W and 13.1 to 14.7 at. pct P) on a cylindrical copper substrate was investigated using a block-on-ring tester. The wear and corrosion performance of the coating and their synergic effect were measured at different overpotentials. Under simple immersion corrosion conditions with an increasing overpotential from open-circuit potential to +400 mV_SCE, the surface of the coating initially showed no obvious corrosion, eventually developing pitting holes that subsequently enlarged and showing the spreading of cracks. The corrosion products were a mixture of NiO, WO₃, and phosphate, and the corroded surface was P-rich, porous, and less crystalline than the pristine coating. Corrosion and mechanical wear had little influence on tribocorrosion at low overpotential values. However, the synergic effect drastically became stronger at high overpotentials. The surface was full of large pitting holes and grooves. The weight loss due to the corrosion component increased linearly with the overpotential but was limited in comparison with the wear component, which was the main cause of weight loss. On the other hand, the friction coefficient first increased and then decreased with an increase in overpotential. Both the surface morphology of the corroded coating and the thickness of the corrosion oxide play important roles in this friction characteristic.

     

Pulmonary parenchymal manifestations surrounding small peripheral masses: pathologic correlation with chest radiographs and diagnostic value

The corrosion of aluminium (Al) in several brands of soft drinks (cola- and citrate-based drinks) has been studied, using an electrochemical method, namely potentiodynamic polarization. The results show that the corrosion of Al in soft drinks is a very slow, time-dependent and complex process, strongly influenced by the passivation, complexation and adsorption processes. The corrosion of Al in these drinks occurs principally due to the presence of acids: citric acid in citrate-based drinks and orthophosphoric acid in cola-based drinks. The corrosion rate of Al rose with an increase in the acidity of soft drinks, i.e. with increase of the content of total acids. The corrosion rates are much higher in the cola-based drinks than those in citrate-based drinks, due to the facts that: (1) orthophosphoric acid is more corrosive to Al than is citric acid, (2) a quite different passive oxide layer (with different properties) is formed on Al, depending on whether the drink is cola or citrate based. The method of potentiodynamic polarization was shown as being very suitable for the study of corrosion of Al in soft drinks, especially if it is combined with some non-electrochemical method, e.g. graphite furnace atomic absorption spectrometry (GFAAS).     

Corrosion Performance of High Strength 15Cr Martensitic Stainless Steel in Severe Environments

High pressure and high temperature corrosion performance of high strength 15 Cr martensitic stainless steel was studied in different severe environments—live acid(10%HCl+1.5%HF+3%HAc+5.1% corrosion inhibitor),spent acid and formation water containing CO2.The results show that the corrosion of high strength 15 Cr martensitic stainless steel in live acid is most serious,and the uniform corrosion rate is far greater than those in spent acid and formation water containing CO2 corrosion environments,but all of them can be acceptable for oilfield.Acidizing corrosion inhibitor displays a good matching ability with the high strength 15 Cr martensitic stainless steel in terms of decreasing the uniform corrosion rate,which changes mainly the anodic process of high strength 15 Cr martensitic stainless steel.The corrosion potential moves to the positive direction,thus the corrosion current density decreases significantly.There are some different degrees of pitting of high strength 15 Cr martensitic stainless steel after corrosion tests in live acid,spent acid and formation water containing CO2,and the pitting density aggravates significantly and the maximum pit depth decreases in the corrosion sequence.     

多相流动状态下Cl~-对X70钢CO_2腐蚀的影响

用自制实验装置模拟起伏管路段塞流动条件下X70钢CO2腐蚀环境,通过电子显微镜、腐蚀挂片以及电化学在线监测等,对挂片表面形貌、腐蚀速率以及挂片在线腐蚀情况进行分析,采用实验与数值仿真研究了多相流动状态下Cl-对X70钢CO2腐蚀速率的影响,结果表明:在较低的Cl-浓度下,Cl-浓度对碳钢均匀腐蚀速率的影响存在一个临界浓度,超过临界浓度,碳钢均匀腐蚀速率大幅升高,继续增加Cl-浓度,对均匀腐蚀速率影响不大;在较高的Cl-浓度下,Cl-浓度对碳钢点蚀的影响也存在一个临界值,低于临界值,碳钢点蚀处在点蚀孔形成与钝化的动态平衡过程,高于临界值,这种平衡被打破。     

硫酸介质中氯化镧与阴离子表面活性剂十二烷基苯磺酸钠(SBDS)对锌的缓蚀协同效应

用失重法研究了硫酸介质中稀土镧(Ⅲ)离子和阴离子表面活性剂十二烷基苯磺酸钠(SBDS)在硫酸介质中对锌的缓蚀协同效应.发现La3+在低浓度下有增蚀作用;SBDS对锌则有一定的缓蚀作用,但最大缓蚀率仅有35%.实验结果亦表明SBDS与La3+对锌表现出强烈的缓蚀协同效应.     

钛合金与NiAl封严涂层的电偶腐蚀行为研究

钛合金材料与不同材料相互连接,并处于富含氯离子的电解质溶液中,有可能使得材料发生电偶腐蚀而遭到破坏。采用极化曲线的方法分别研究了NiAl涂层、TA15的电化学行为。结果表明NiAl涂层的腐蚀电位较TA15的低,二者相差约30 mV,NiAl涂层腐蚀电流为1.718×10-4A,TA15腐蚀电流为1.170×10-5A。研究了NiAl封严涂层和TA15钛合金之间在5%NaCl水溶液中的电偶腐蚀行为。测试了NiAl-TA15电偶对的电偶电流-时间曲线,并通过计算出的平均电偶电流密度,评价了钛合金和NiAl封严涂层的电偶腐蚀敏感性。结果表明,TA15钛合金和NiAl封严涂层之间的电位差很小,电偶腐蚀倾向很小,电偶电流密度为0.0253μA.cm-2。电偶腐蚀过程中,腐蚀电位较低的NiAl涂层作为电偶对的阳极发生腐蚀,钛合金作为阴极得到保护。电偶腐蚀后电偶对的阳极、阴极的自腐蚀电位均升高,阳极电位从-347 mV正移到-242 mV,阴极电位从-323 mV正移到-210 mV;电偶电位为-300 mV。NiAl涂层含有较多孔洞,可以作为腐蚀介质的渗透通道,在含有Cl-并且有溶解氧存在的腐蚀性介质中,容易导致腐蚀的发生与发展。     

Angiogenesis in the gonadal capillary network of the chick embryo

Seventy-one chick embryos of both sexes at the 35 Hamburger and Hamilton (H-H) developmental stage were processed for scanning electron microscopy of vascular corrosion casts and of critical point dried specimens, as well as transmission electron- and light microscopy, in order to study the angiogenic structures. The gonadal subepithelial capillary network was located at the level of the tunica albuginea under the covering epithelium. The casts showed a densely-meshed capillary network and numerous sprouting (nodular protrusions or capillary sprouts) and non-sprouting (enlarged vessels and angiogenic holes) angiogenic structures that were randomly distributed and mixed. Four types of angiogenic holes were encountered in the casts: primary (diameter < 2.5 microns), secondary (diameter > 2.5 microns), tertiary (variable diameter and circular narrowings on one side), and open angiogenic holes. We suggest that the different morphologies reflect evolution of these holes. Furthermore, the open angiogenic hole would probably either form nodular protrusions at its open ends, which tend to join with other nodular protrusions and neighboring capillaries and form new vessels; or there would be fusion with two or more neighboring open holes. Correlative critical point dried sections showed fenestrations in the capillary walls and transcapillary pillars that corresponded to the angiogenic holes found in the casts. Ultrathin sections of the vessels presented typical characteristics of growing endothelium: large nuclei with loosely textured chromatin, abundant cytoplasm rich in cell organelles and intraluminal endothelial processes.