人工烟水晶蚀象形貌的研究

对不同掺杂量的人工烟水晶 Y 棒和未掺杂水晶 Y 棒 c 面、±x 面作 HF 酸腐蚀,然后进行扫描电镜蚀象形貌观察。观察到 c 面腐蚀后出现的三方锥体和对应的蚀坑与水晶中三方偏方面体单形方位一致。±x 面蚀坑形貌特征进一步表明了该单形在烟水晶生长中的显露。指出了在±x 这两个面族上蚀坑形貌的方位与晶体内部结构中 Si—O_4四面体在 x 轴方向褶叠螺旋环的旋向一致,使晶体表面形貌与晶体内部结构由表及里有机地联系起来。     

CdGeAs_2晶体的蚀坑形貌观察

采用金相显微镜和扫描电镜观察了垂直布里奇曼法生长的新型红外非线性光学晶体砷锗镉(CdGeAs2)单晶片(101)面蚀坑形貌。选择机械研磨、物理抛光及质量分数为3%溴甲醇在室温下对晶片化学抛光1min左右的工艺,获得了表面平整无划痕的CdGeAs2晶片。报道了一种新的CGA晶体择优腐蚀剂,其组成为HCl∶HNO3∶H2O=1∶1∶1(体积比),室温下腐蚀晶片30s左右后在金相显微镜和扫描电镜下观察到CdGeAs2晶体(101)晶面的腐蚀坑,蚀坑形貌呈取向一致的等腰三角形,边界清晰,具有立体感,并从理论上分析讨论了(101)面三角形蚀坑的形成原因。     

TeO2晶体位错腐蚀形貌与晶体对称性

用化学腐蚀的方法研究TeO2晶体(110)面和(001)面位错蚀坑的形貌，结合晶面极图，并运用对称群理论进行分析论证，理论分析与实验结果相一致．实验结果同时显示，TeO2晶体位错腐蚀坑面由{110}面族构成，即{110}面族是晶体的习性面．     

镍基合金825在元素硫环境中的局部腐蚀特征

通过模拟普光气田元素硫沉积环境,调节腐蚀体系的温度,研究了固溶强化镍基合金825的腐蚀特征,并利用扫描电子显微镜(SEM)、能谱仪(EDS)等技术手段研究了镍基合金825发生点蚀后腐蚀产物的形貌和成分。结果表明,一定温度下元素硫(S8)与酸性NaCl溶液共同作用使镍基合金825产生明显的以点蚀为主的局部腐蚀。腐蚀产物层存在开裂现象,其腐蚀产物主要由Cr、Ni、S、O等元素组成。镍基合金825在高于元素硫熔点的温度及Cl-存在条件下易发生局部腐蚀。     

泥浆膜在大气环境下对钻杆的腐蚀机理研究

采用高温高压釜模拟研究塔里木油田现场环境所用聚磺体系钻井液对S135钻杆的腐蚀行为及腐蚀机理.通过对表面黏附有泥饼的挂片进行XRD和SEM观察,分析钻杆表面黏附的泥饼形貌特征及腐蚀行为.结果表明:S135钻杆发生了局部氧腐蚀,特征为溃疡状腐蚀、局部连片腐蚀和深坑蚀.腐蚀产物主要是正交(斜方)晶系的针铁矿.钻杆腐蚀的主要...     

AZ31镁合金在Hank’s模拟体液中的腐蚀行为研究

研究了AZ31镁合金在Hank's模拟体液中的腐蚀行为,包括腐蚀形貌、腐蚀速度和腐蚀电化学特征参数.通过扫描电子显微镜(SEM)比较了不同腐蚀环境中镁合金样品的腐蚀形貌特征.利用失重法测量了镁合金的腐蚀速度,并依此分析了Hank's模拟体液中各成分对镁合金腐蚀速度的影响.测量并分析了不同pH值下的动电位动态极化曲线.结果表明,镁合金在Hank's模拟体液中的腐蚀主要为氯离子引起的点蚀;H_2PO_4~-和HPO_4~(2-)具有缓蚀作用;pH值的升高可以提高镁合金腐蚀反应的自腐蚀电位,降低腐蚀反应的热力学倾向,稳定腐蚀过程中形成的钝化膜,从而降低了腐蚀速度.     

CdZnTe晶体(111)面、(110)面和(100)面的蚀坑形貌观察

利用CdZnte晶体晶面夹角之间的关系采用激光正反射法对改进布里奇曼法生长的CdZnTe单晶进行定向,研磨出了CdZnTe单晶体的(111)、(100)面.采用自行研制的HHKA腐蚀液对三个面进行择优腐蚀,得到了(111)、(100)和(110)面的腐蚀照片,并计算出了蚀坑密度(EPD)约为104～105/m2数量级.结果表明生长晶体的质量较好.     

LY6铝合金的局部腐蚀行为研究

探讨LY6合金的局部腐蚀行为对扩大其应用范围意义重大,采用加速腐蚀试验和微观腐蚀形貌观察等方法,研究了经自然时效处理的LY6铝合金在含Cl-的典型环境中的点蚀、晶间腐蚀、应力腐蚀断裂和剥蚀等局部腐蚀行为,并讨论了它们的机理和相互关系.在试验环境下,LY6铝合金对点蚀、晶间腐蚀、剥蚀和应力腐蚀断裂都存在敏感性,合金中S相(Al2CuMg)、θ相(CuAl2)及MnAl6等第二相的存在是发生上述局部腐蚀的根本原因.研究表明,合金的剥蚀是一个从点蚀发展到晶间腐蚀,然后在应力协同作用下发生破坏的过程.恒载荷应力腐蚀拉伸法和断口形貌观察发现,LY6铝合金应力腐蚀断裂是由于阳极溶解作用的结果.     

Ti基金属玻璃复合材料的腐蚀行为

采用水冷铜坩埚悬浮熔炼-铜模吸铸法制备了直径为3mm的(Ti0.5Ni0.5)80Cu20金属玻璃复合材料试样,对合金的组织结构进行表征,用电化学工作站三电极体系测试了不同腐蚀介质中的动电位极化曲线,并分析表征电化学腐蚀后的形貌和腐蚀产物。结果表明:合金组织由非晶基体+形状记忆晶体相组成,在铸造过程的温度梯度下呈现梯度组织,边缘为快冷形成的无序密堆非晶结构,心部主要析出相为过冷奥氏体相。在人工海水和模拟人体的PBS溶液中,合金均表现出良好的耐蚀性。与晶态TC4合金相比,自腐蚀电位高,腐蚀的热力学倾向小;自腐蚀电流密度低,极化电阻高,腐蚀的动力学速率低。合金在PBS溶液中由于介质中活性阴离子浓度低,比在人工海水中表现出更优异的抗蚀性。在腐蚀形貌中未发现点蚀坑,边缘区的氧化膜较心部区域更为致密均匀。     

G105钢钻杆在不同浓度NaCl溶液中的高温高压腐蚀及常温电化学行为

目前,对G105钢钻杆在不同Cl-浓度下的腐蚀研究较少,通过高温高压釜模拟石油井动态高温高压环境,研究了G105钢钻杆在不同浓度NaCl溶液中的高温高压腐蚀行为,采用极化曲线研究了其常温电化学腐蚀行为。采用体式显微镜和扫描电镜(SEM)观察腐蚀产物膜形貌;采用X射线能谱分析仪(EDS)分析了腐蚀产物膜成分。结果表明:G105钢钻杆在含Cl-介质中发生孔蚀,严重时会出现明显的蚀坑;随着Cl-浓度的增加,钻杆的腐蚀速率和程度增加。     

择优蚀坑表征立方晶系冷轧电工硅钢取向性

为确定电工硅钢的晶粒取向性,应用蚀坑技术研究了冷轧无取向硅钢、取向硅钢因择优腐蚀所形成的蚀坑与晶粒取向的关系,分析了{100}面系蚀坑形貌的演变过程,从晶体学角度建立了蚀坑形貌与晶面指数的对应关系.结果发现:无取向硅钢形成不同形貌的蚀坑,其晶面指数为(001)、(011)和(111),或是由它们演变形成的其他晶面指数;取向硅钢形成的蚀坑为同一类型,晶面指数为(011)或由其演变形成的其他晶面指数;晶界也会形成蚀坑,其形貌与相邻晶粒间的取向差有关,取向差大,形成{100}、{110}和{111}面系的蚀坑,取向差小,形成{110}面系的蚀坑.取向硅钢的蚀坑分布具有连续性,晶界的存在并不改变蚀坑的基本特征;取向硅钢蚀坑的底棱相互平行,相差不超过5°,底棱延伸方向与硅钢的轧制方向即[001]方向一致,偏离角度不超过5°.     

Topography of etched rhombohedral faces of quartz crystals: evidence for orientation effects

A study has been made of the rate at which the rhombohedral faces of a natural quartz crystal are etched in a concentrated ammonium bifluoride solution. The thickness of the disturbed surface layer created by an initial mechanical lapping is estimated from rate data. The etching rate as well as this thickness are found to be sensitive to natural face orientation. The changes in the surface texture of the rhombohedral faces with repeated chemical etchings are investigated. The variation in the roughness parameters with the average depth of etch shows both directional and orientation effects. The chemical attack results in the formation of stable etch figures characteristic to the orientation of the surface on which they lie and which enlarge with repeated etchings. finally, schematic etch figures are proposed for the differently oriented rhombohedral faces.     

Dislocation etch pits in zinc selenide

It is shown that triangular etch pits are produced at the points of emergence of dislocation lines on the (111) zinc faces of single crystals of zinc selenide. Conical etch pits can be produced on the (¯1¯1¯1) selenium faces with a solution of one part HCl to three parts HNO₃. Etch patterns produced following indentation confirm the identity of the etch pits. Triangular etch figures which are associated with stacking fault tetrahedra have also been observed.     

Selective etching of habit faces of ferroelectric Ca2Sr(C2H5CO2)6 crystals

Crystallographically oriented etch traces produced by selective etchant on (111) and (110) habit faces of dicalcium strontium propionate [Ca₂Sr(C₂H₅CO₂)₆] crystals are attributed to the growth traces nucleated during the superficial growth of crystal. This view is supported by the absence of such etch traces on seized habit faces and from the observations of layer structure on the bottom faces. Mother liquid acting as an etchant produces circular terraced depressions on habit faces. These depressions originate at the sites of isolated impurity centres. Identical features such as circular etch structures bounded by cylindrical outer periphery produced on cooled faces are attributed to isolated domains.     

Type and formation mechanism of thermal etch pit on annealed (111) CdZnTe surface

Type and formation mechanism of thermal etch pits on annealed (111) CdZnTe surface were studied with scanning electron microscopy and atomic force microscopy. Four kinds of thermal etch pits on CdZnTe (111) Te face and two kinds of thermal etch pits on (111) Cd face were identified. The density of thermal etch pits on (111) Te face was estimated; it was two orders of magnitude higher than that of (111) Cd face. A formation mechanism of the thermal etch pits on (111) CdZnTe during the annealing process is proposed. The different behaviors of the thermal etch pits on the two faces of (111) CdZnTe are discussed.     

Etching studies on (1 0 0) faces of gel-grown ammonium dihydrogen orthophosphate crystals

Chemical etching employing specific etchants with varying etch times (20–60 s) has been successfully applied for the first time to reveal dislocation sites on the polished (1 0 0) faces of ammonium dihydrogen orthophosphate single crystals grown at ambient temperature, using a modified gel technique of double diffusion in a U-shaped beaker assembly. The selective behaviour of the etchant for straight and inclined dislocations has been demonstrated. Growth striations due to temperature fluctuations, low-angle tilt boundary and etch channels corresponding to stacking faults were clearly observed. Surface structures of the etched faces were photographed by optical and scanning electron microscopes and are discussed.     

Dislocation etch pits and growth of arsenic-antimony single crystals

Single crystals of an arsenic-antimony solid solution have been grown at the minimum melting point (612‡C) composition (25.5 at.% arsenic) where the solidus and liquidus touch. Pyramidal etch pits produced on (111) cleavage faces mark the sites of emergence of dislocations; dislocation densities are low, ranging between 10³ and 10⁵ per cm². The relationship between an unambiguous, right handed axial set and etch pit orientation on the (111) surface is established. The permissible Burgers vectors and dislocation reactions are detailed and are related to the observed etch pit types. In general, the results obtained also apply to the A7 structure elements themselves and amend previous findings of the crystallographic relationships between dislocation directions and etch pits.     

Orientation effects in chemical etching of quartz plates

The development of etch patterns of z-, y- and x-cut quartz plate is studied as a function of the specimen orientation. Plates of different cuts exhibit typical etch patterns satisfying either digonal or trigonal symmetry of -quartz crystal. The changes of surface profilometry traces with depth of etch are also found to depend mainly on orientation dependence. The experimental data can be interpreted satisfactorily and consistently in terms of the structural reaction mechanism proposed by Ernsberger and in terms of the stability criterion. Some progress in the prediction of changes of etch figures with prolonged dissolution can thus be made by using some of the information reported in this paper.