纯铜的组织和纯度对其表面氧化影响

利用氧化增重实验对纯铜的表面氧化性进行研究,分析纯铜的组织和纯度对其氧化性能的影响。结果表明:单晶组织铜氧化速率与晶粒取向有关,单晶铜(100)晶面的氧化速率大于(111)晶面的氧化速率;多晶铜的氧化速率处于单晶铜(100)晶面与(111)晶面氧化速率之间。纯铜的氧化速率与杂质原子类型和温度有关,纯度越高纯铜氧化速率越小。     

组织和温度对Cu表面氧化速率的影响

利用扫描电镜、X射线衍射仪和氧化称重实验对铜表面氧化速率进行研究,分析了不同组织、晶粒和温度对铜氧化性能的影响。结果表明：铜的组织结构是影响其氧化性能的主要因素,非密排的（100）晶面上界面能高、晶面原子堆垛相对疏松和原子尺度上粗糙,且氧化膜生长连续,氧化速率高于密排的（111）晶面;温度升高,铜表面的内能增大,铜原子较易成为活化原子与氧气发生反应,同时增大了铜原子在氧化膜中的扩散速率,加速了铜的氧化;铜试样经过等径角挤压（ECAP）后,（111）晶面铜表面的面积增大,氧化速率降低,晶界不是影响铜氧化速率的主要因素,能量较小的晶面原子所占的面积增大,铜的氧化速率减小。     

稀土Y对铜线材抗氧化行为的影响机理研究

目的 针对纯铜线材的抗氧化性能不足问题,通过稀土微合金化制备了含微量Y元素的铜线材,研究稀土Y含量对铜线材抗氧化性能的影响。方法 采用扫描电子显微镜(SEM)、EDS能谱仪和X射线衍射仪等表征手段,分析了氧化膜脱落后基体表面形貌以及稀土Y元素在氧化过程中的存在形式与氧化膜的生长过程,揭示了添加稀土元素Y提高纯铜抗氧化性能的作用机理。结果 稀土Y的引入提高了纯铜线材的抗氧化性能,在600 ℃、10 h条件下,Cu-0.03Y线材相对于Cu线材氧化增重率由0.55%降低至0.2%,降幅达63%。稀土元素Y的添加使铜线材的(100)晶面占比减少,(111)晶面占比增多,基体表面易被活化的(100)原子面占比降低,铜线材的抗氧化性能提高。在Cu-0.1Y线材中稀土元素浓度较高时发生偏聚,稀土元素与氧的亲和力大于铜与氧的亲和力,偏聚处形成不连续的稀土氧化物,使氧离子与铜离子的接触反应面积增大,相比Cu-0.03Y线材抗氧化性能降低。结论 氧化过程中稀土离子的扩散速率慢、半径大,对铜离子的向外扩散起到阻碍作用,降低了铜离子的扩散速度,提高了铜线材的抗氧化性能。     

表面处理状态对Fecralloy合金氧化膜完整性的影响

研究了表面粗糙度对Fecralloy (Fe 2 2Cr 5Al 0 .3Y ,质量分数 ,% )合金在 12 0 0℃空气中循环氧化生成表面氧化膜完整性的影响。采用SEM技术着重研究了合金表面氧化膜的性质和特点。结果表明合金表面粗糙度对Fecralloy合金表面氧化膜的完整性有重要的影响 ,初始合金表面粗糙度越大 ,氧化膜越容易开裂。讨论了合金表面粗糙度对氧化膜开裂行为的影响。     

晶面及液体环境对氧化镓研磨过程摩擦学特性的影响研究

目的 探讨具有各向异性的氧化镓晶片不同晶面的研磨加工差异.方法 通过化学气相沉积法制备了高质量的自支撑金刚石厚膜,采用扫描电镜及拉曼光谱对其进行表征,将其作为摩擦副材料,在三种不同液体环境下研磨 β-Ga2O3晶片的(100)晶面及(010)晶面,比较摩擦学特性的差别.借助三维扫描系统、扫描电镜及EDS能谱,观察与分析了加工后的氧化镓及自支撑金刚石厚膜的表面形貌、成分及磨损机理.结果 (100)晶面及(010)晶面在去离子水环境中的摩擦系数最大,而当液体环境为乙二醇及三乙醇胺溶液时,研磨过程中形成了很薄的化学反应膜,减少了犁沟效应,摩擦系数较小.且在液体环境为三乙醇胺时,加工后氧化镓晶片的(100)晶面及(010)晶面的粗糙度最小.研磨加工后,(010)晶面比(100)晶面的表面粗糙度(Ra)小.结论 (010)晶面与(100)晶面在不同液体环境下研磨加工存在一定的差异性,(010)晶面比(100)晶面更易获得较好的表面质量.加工过程中,磨损机理为先产生二体磨损,一段时间后再形成三体磨粒磨损.     

纯铜双层辉光离子渗钛高温氧化性能的研究

采用双层辉光离子渗金属技术，在纯铜表面形成均匀的渗钛层．对离子渗钛试样和纯铜试样在400℃和700℃进行了高温氧化对比实验，分别给出了它们的氧化动力学曲线，用扫描电子显微镜观察分析氧化表面形貌，结果表明纯铜表面离子渗钛后提高了高温抗氧化的性能，降低了氧化速率，离子渗钛层的氧化膜致密，对继续氧化有阻碍作用。     

Fecralloy合金1 250 ℃空气中循环氧化表面氧化膜特征

研究了一种添加稀土元素Y的Fecralloy(Fe-22Cr-5Al-0.3Y)合金在1 250 ℃静态空气中的循环氧化行为,采用SEM, XRD及EDX分析技术研究了合金表面氧化膜的性质和特点。结果表明合金表面生成的氧化膜成分以α-Al2O3为主,合金表面粗糙度对Fecralloy合金表面氧化膜的完整性有重要的影响。讨论了合金表面氧化膜开裂和剥落的特点。     

铜砷共存时砷含量对钢的高温氧化行为与热裂性的影响

采用热重分析仪、扫描电镜(SEM)和Gleeble模拟热压缩试验等研究了铜砷共存时砷含量对含0.22mass％Cu钢的高温氧化行为(1000～1150℃)及热裂性的影响.结果表明:当氧化温度低于1100℃时,试验钢的氧化动力学先服从线性规律,后服从抛物线规律;当温度高于1100℃时,氧化后期脱离抛物线规律.随砷含量的增加,试验钢的抛物线阶段的氧化速率常数Kp和氧化增质量增加,氧化激活能降低.砷含量越多,试验钢的氧化层总厚度越厚.钢中砷元素的加入量越多,向基体渗透的富铜液相量越大,钢在热加工过程中的表面热裂倾向性越大,并且富铜液相量和钢表面热裂倾向性在1050℃时达到最大.     

下引法连铸单晶铜试验研究

利用自制下引式真空熔炼、氩气保护连续定向凝固设备制备出φ16mm的单晶纯铜棒材,研究了各工艺参数对连铸单晶铜凝固过程中温度分布的影响,分析了铸锭凝固过程中的表面质量和凝固组织的变化情况.结果表明:拉坯速度、熔体温度、冷却水量等工艺参数对固液界面的形状和位置有显著影响,并通过影响固液界面位置和形状来作用于凝固过程.连铸单晶铜凝固过程中,铜在结晶器内熔点位置即为固液界面位置,理想的固液界面位置在距离结晶器出口30～40mm处;铸锭凝固过程中逐渐淘汰的晶面为(311)、(220)和(111),最后单晶生长的晶面为(200),其晶体生长方向为[100].     

单晶铜线材在潮湿环境中的表面氧化规律研究

采用氧化增重实验,通过改变温度、水蒸汽流量两个参数,对单晶铜线材的表面氧化行为进行了研究.结果表明:单晶铜线材在潮湿环境中的氧化由三个阶段构成;温度与水蒸汽流量两个因素对单晶铜线材的表面氧化均有显著影响,温度越高、水蒸汽流量越大,氧化速率越快;单晶铜线材在潮湿环境下的氧化产物是Cu2O,其氧化速度由Cu2O的生长速度控制,氧化膜对线材的后期氧化起阻碍作用.     

离子注入Cu薄膜的氧化行为研究

研究了用强流金属蒸汽弧离子源（ＭＥＶＶＡ源）注入Ｃｒ对Ｃｕ薄膜的抗氧化性能、导电性能和氧化特征的影响。利用Ｘ射线衍射、Ｒｕｔｈｅｒｆｏｒｄ背散射和扫描电镜 离子注入前后氧化物结构和氧化物形态演变。结果表明,在薄膜的表面层注入一定剂量的Ｃｒ能有效地改善Ｃｕ薄膜的抗氧化性能,而对薄膜的电导性能无显著影响;离子注入显著影响薄膜表面氧化铜的结构和形态。探讨了离子注入对氧化铜结构和形态的影响机理。     

高能高速等离子喷涂MCrAlY涂层的抗高温氧化性能

为提高Ni3Al基高温合金IC6的抗高温氧化性能,采用高能高速等离子喷涂设备在其表面制备了MCrAlY涂层,测试了1 000℃高温条件下经300h氧化后涂层的抗氧化性能。结果表明:300h试验后,涂层的单位面积氧化增重为5.584g/m2,氧化速率为0.019g/m2·h,达到了完全抗氧化级。分析认为:高能高速等离子喷涂工艺制备的MCrAlY涂层与基体结合紧密,孔隙、裂纹及氧化物夹杂含量少,有效的阻隔了氧气的扩散通道,使得氧化物的生长缓慢。同时在高温氧化过程中,涂层表面生成了大量的Al2O3膜,阻碍了金属原子与氧原子的扩散,降低了涂层的氧化速率。另外涂层中含有的Y及Y2O3增加了氧化膜的粘附性,对氧元素的扩散具有抑制作用。     

High orientation Al films growth on LiNbO3 single crystal and its adhesion

High orientation Al films were deposited on 64°Y-XLiNbO3 substrate by DC magnetron sputtering and the influence of deposition temperature on microstructure and adhesion properties of Al films were investigated. The results show that crystallographic orientation of films varies with substrate temperature and the adhesion strength between LiNbO3 and Al films strongly depends on crystallographic orientation of Al films. The (111) orientated Al films shows stronger adhesion strength to LiNbO3 substrate than (100) orientated films. There is an optimum substrate temperature of 60 ℃ and hardening temperature of 200 ℃ for obtaining high (111) orientated Al films with good surface structure and adhesion property. Using this Al film, we have successfully fabricated the SAW filters with high frequency of about 1.89 GHz.     

紫铜表面渗铝层的高温抗氧化性能

采用粉末包装法在紫铜表面渗铝.研究了紫铜和渗铝后的紫铜在空气中的高温氧化行为.用扫描电子显微镜(SEM)和X射线衍射仪(XRD)观察、分析了氧化膜的微观形貌和相组成,并讨论其氧化机理.结果表明:紫铜渗铝后不仅提高了高温抗氧化性能,而且氧化行为及其氧化层的结构也发生了变化.未渗铝的紫铜试样700℃氧化100 h后相组成为Cu2O和CuO,而渗铝后试样表面优先形成Al2O3氧化膜.氧化动力学曲线为抛物线型.     

Oxide removal and desorption of oxygen from partly oxidized thin films of copper at low pressures

Partly oxidized copper films were annealed in a controlled vacuum of 10^–7 Pa at a temperature of 450° C. The changes discussed below were observed in situ with a specially designed high-resolution transmission electron microscope. The thin, (100)-oriented, single-crystal films of copper had been oxidized immediately prior to the annealing studies at the same temperature and at an oxygen partial pressure of 7×10 ^–1 Pa, until the desired fraction of the copper film was converted to oxide. It was observed that the oxide disappeared during annealing as long as some copper was left unoxidized. The disappearance of the oxide is explained as being due to dissociation of the oxide at the oxide-metal interface followed by diffusion of oxygen into the metal and desorption of oxygen from the surface of the unoxidized copper. The rate of disappearance of the oxide was found to be proportional to the surface area of unoxidized copper, i.e., the desorption was found to be the rate — limiting step. In the case of heavily oxidized films (>50%), holes were observed to develop in the oxide near the oxide-metal interface after an annealing period of 2–3 hr. Upon resumption of the oxidation, these holes first disappeared, and the normal oxidation behavior was then resumed. The formation of holes may be explained by vacancy clustering. When completely oxidized films were annealed, recrystallization of the oxide was observed.This work was performed at the Ames Research Center and funded by NASA Grants Nos. NCA2-OP390-403 and NSG-2025.     

The kinetics of the oxidation of aluminum—copper alloys in oxygen at high temperature

The oxidation behavior of high purity aluminum—copper alloys has been studied at temperatures from 475 to 575°C in dry oxygen at a pressure of 76 torr. The oxidation product was found to be duplex in nature consisting of both amorphous and crystalline γ-Al₂O₃. Roughly cylindrical crystals of γ-Al₂O₃ of constant thickness, at any given temperature and alloy content, grow into the metal from the amorphous oxide—metal interface by inward diffusion of oxygen through the overlying amorphous film. The amorphous oxide film, growing by outward diffusion of metal ions, forms between the crystals of γ-Al₂O₃ with accurately parabolic kinetics throughout the temperature and alloy composition ranges. Above the crystalline phase the amorphous oxide forms at a lower rate because of the additional resistance conferred to cation egress afforded by the crystalline oxide. In general, it was found that increasing copper content of the alloy in the range 0·1–4 per cent Cu caused a reduction in the crystal nucleation density and in the depth of intrusion of the crystals into the underlying alloy. Conversely, increasing copper content was also found to increase the rate of formation of amorphous γ-Al₂O₃ between the crystals of γ-Al₂O₃ and to increase the rate of radial growth of the crystals. These results are explained in terms of the defect nature of the oxidation products.     

The oxidation of cupro-nickel alloys—II. The kinetics of diffusion in porous inner layers

The oxidation of cupro-nickel alloys at temperatures > 160°C produces a duplex oxide structure. In Part I, diffusion of copper across the inner nickel oxide layer was shown to be rate controlling. This conclusion is tested in this paper by examining the oxidation rate curves of a series of nine metals and alloys extending from pure copper to pure nickel. The isochronal curves are found to pass through a maximum at 75%Cu which is explained by surface diffusion of the copper through a porous nickel oxide structure extending through the metal consumption zone. The surface diffusion coefficient derived from this model is in the range 0.8–2.0 × 10^?14 m² s^?1 in accord with results of other workers.     

Tensile cracking during thermal cycling of alumina films formed by high-temperature oxidation

Plastic relaxation of the stresses, produced by high-temperature oxidation and thermal contraction mismatch on cooling, decreases residual compression in the oxide. For this reason, slow cooling from the oxidation temperature is expected to have a beneficial effect on spalling resistance of protective alumina films. However, there exists a possibility of creating tensile stress in the oxide upon subsequent heating. With increasing stress relaxation on cooling, the magnitude of the tensile stress also increases which may lead to cracking of the oxide at high temperature. Experimental evidence shows an adverse effect of stress relaxation on the mechanical integrity of alumina films formed on Fe–Cr–Al heat-resistant alloys. High cooling and heating rates between oxidation cycles are required to prevent tensile failure of the oxide.