电子束辐照下铜超微粒子氧化与还原过程的高分辨电子显微镜观察

利用电子显微镜中的电子束对铜超微粒子进行了连续地照射和跟踪观察,结果表明电子束使Cu与镜筒中的低氧压气氛发生了反应,电子束的辐照使纳米量级的Cu粒子发生了氧化并被消耗,首先生成一种类非晶膜,然后生成Cu的晶态氧化物,新生成的Cu的晶态氧化物,在电子束的进一步照射下,又发生了还原反应,不断地还原为铜     

电子束辐照下铜氧化现象的电镜研究

用电子显微镜的电子束对铜超微粒子和铜的薄膜样品进行了连续的照射和跟踪观察，结果表明，电子束不仅使铜超微粒子与镜筒中的气氛发生了氧化反应，而且使铜薄膜样品也发生了氧化反应，反应的途径都是：铜的表面首先生成一层很厚的类非晶膜，接着类非晶膜在电子束的进一步照射下再转变为铜的晶态氧化物。本文的结果进一步证实了类非晶膜在铜的氧化过程中实质上是起着一咱氧化的“先驱态”作用的结论。     

高能球磨Si还原CuO的固态还原反应

通过对Ｓｉ和ＣｕＯ粉末进行高能球磨制备了Ｃｕ和ＳｉＯ２的复合材料。表明了一般条件下难以进行的固态还原反应，在高能球磨时可以发生；还原产物为纳米级的Ｃｕ和非晶的ＳｉＯ２，还原反应的进程有赖于高能球磨的条件；利用高能球磨可以直接制备纳米级氧化物金属复合材料     

高能球磨Si还原Cu的固态还原反应

通过对Ｓｉ和ＣｕＯ粉末进行高能球磨制备了Ｃｕ和ＳｉＯ２的复合材料。表明了一般条件下难以进行的固态还原反应，在高能球磨时可以发生，还原产物为纳米级的Ｃｕ和非晶的ＳｉＯ２，还原反应的进行有整于高能球磨的条件；利用高能球磨可以直接制纳米级氧化物、金属复合材料。     

Cu在熔融（Li,K）2CO3中的热腐蚀行为研究

采用电化学阻抗谱技术研究了Ｃｕ在６５０℃熔融（Ｌｉ,Ｋ）２ＣＯ２中的腐蚀行为,在腐蚀初期,Ｃｕ的腐蚀的电化学阻抗谱呈典型的腐蚀反应受氧化剂粒子扩散控制的特征,随着腐蚀的进行,在Ｃｕ的表在逐渐形成了Ｃｕ２Ｏ膜,但同时,生成的Ｃｕ２Ｏ也发生溶解,使Ｃｕ局部遭受较快腐蚀,其电化学阻抗谱呈双抗弧特征,提出了相应的等效电路,并求取了相关电化学参数。     

Cu－Al爆炸焊结合层的透射电镜研究SCIEI

用透射电镜（ＴＥＭ）研究了Ｃｕ－Ａｌ爆炸焊的结合层，爆炸焊连接是由熔化和扩散共同作用的结果．在熔区内存在非晶态与晶态，晶态主要由ＣｕＡｌ_２．Ｃｕ_３Ａｌ_２和Ｃｕ_４Ａｌ组成．与熔区相邻的Ａｌ侧发生了再结晶，Ｃｕ向Ａｌ中的扩散距离＜１００ｎｍ，析出针状的ＣｕＡｌ_２相与熔区相邻的Ｃｕ侧只发生了回复，Ａｌ向Ｃｕ中的扩散距离＜１００ｎｍ，形成了新相层，可能是Ｃｕ_３Ａｌ_２和Ｃｕ_４Ａｌ．在非熔化区存在Ｃｕ和Ａｌ的互扩散，形成新相层的厚度＜１００ｎｍ．     

Cu－Al爆炸焊结合层的透射电镜研究

用透射电镜（ＴＥＭ）研究了Ｃｕ－Ａｌ爆炸焊的结合层，爆炸焊连接是由熔化和扩散共同作用的结果．在熔区内存在非晶态与晶态，晶态主要由ＣｕＡｌ_２．Ｃｕ_３Ａｌ_２和Ｃｕ_４Ａｌ组成．与熔区相邻的Ａｌ侧发生了再结晶，Ｃｕ向Ａｌ中的扩散距离＜１００ｎｍ，析出针状的ＣｕＡｌ_２相与熔区相邻的Ｃｕ侧只发生了回复，Ａｌ向Ｃｕ中的扩散距离＜１００ｎｍ，形成了新相层，可能是Ｃｕ_３Ａｌ_２和Ｃｕ_４Ａｌ．在非熔化区存在Ｃｕ和Ａｌ的互扩散，形成新相层的厚度＜１００ｎｍ．     

盐酸介质中铜置换钯的两种反应机理

用旋转圆盘法考察了盐酸浓度对铜置换Ｐｄ（Ⅱ）反应速度的影响，发现在低盐酸深度（０．０１～０．１ｍｏｌ／Ｌ）时，反应速度极快，在液相中发生ＣｕＣｌ＾－２对Ｐｄ（Ⅱ）的化学还原，反应产物Ｃｕ与Ｐｄ的摩尔比为１：１，铜离子为二价；在较高酸度（３～５ｍｏｌ／Ｌ）时，反庆速度显著变慢，转换反应仅在铜片表面进行，属于电化学反应机理，速率方程为ｌｏｇＣ０／Ｃｔ＝２．７２３×１０＾－３ｔ－０．００２，产物Ｃｕ与Ｐ     

用非晶态合金作中间层对Si_3N_4陶瓷进行扩散焊连接

研制了两种非晶态物质Ｃｕ_（５０）Ｔｉ_（５０），Ｃｕ_（５０）Ｔｉ_（５０）Ｂ作为对Ｓｉ_３Ｎ_４扩散焊连接的中间层材料．研究结果表明：用非晶态作为中间层可改善工艺条件，降低扩散焊温度；非晶态中间层接头比其相应晶态中间层接头的剪切强度有明显提高．其中硼对提高接头剪切强度贡献很大．用非晶态Ｃｕ_（５０）Ｔｉ_（５０）Ｂ作中间层时，接头强度最高可达３４０ＭＰａ用晶态和非晶态Ｃｕ_（５０）Ｔｉ_（５０），Ｃｕ_（５０）Ｔｉ_（５０）Ｂ作中间层对Ｓｉ_３Ｎ_４进行扩散焊连接的机制是：活性元素Ｔｉ向陶瓷界面扩散和富集并与Ｓｉ_３Ｎ_４发生反应生成界面相ＴｉＮ，ＴｉＳｉ_２等．从而实现连接．     

SiC表面氧化层的非晶化转变

用Ｘ射线衍射仪和爱射电子显微镜研究了氧化态ＳｉＣ颗粒表面ＳｉＯ２氧化层与铝基体复合前后的结构；试验结果表明，１１００℃下ＳｉＣ颗粒表面生成的ＳＩＯ２层为晶态，与铝基体复合后在电子束的照射下将转变为非晶态。为ＳｉＯ２层的非晶转变机制作了初步的探讨。     

气液两相稳定的Fe超微粒的氧化特性和磁性

用气液两相稳定法对Fe超微粒表面进行了稳定化处理。试验结果表明,在空气中温度低于150℃时,用气液两相稳定法处理的Fe超微粒比用气相稳定法处理的Fe超微粒更稳定,饱和磁化强度更高。这是因为气液两相稳定法稳定化处理后在Fe超微粒表面形成了氧化层和有机层双层结构。     

超细硬质合金中晶粒非均匀长大机理

采用市售的粒度为0.8μm的WC粉末和粒度为1.6μm的Co粉制备了WC-10%Co超细硬质合金,通过金相显微镜﹑扫描电子显微镜观察了不同烧结温度下制备的试样WC晶粒形貌,对超细晶粒硬质合金非均匀长大现象及机理进行了研究。结果表明:粉末湿磨后的粗大颗粒在烧结过程中起晶核作用,是引起晶粒非均匀长大的关键因素。固相烧结时,烧结体中细小颗粒受到张力的作用发生旋转,当其取向与邻近的大颗粒取向一致时,形成共格界面,以粗大晶粒为核心以并合的方式非均匀长大;液相烧结时,细小晶粒溶解并优先地在大晶粒的某些低能量晶面如(0001)和(1010)面析出,引起晶粒异常长大。本研究中,当烧结温度达到1 410℃时,WC晶粒可异常长大为接近20μm的粗大晶粒。     

Co-electrodeposition and characterization of Cu-Si3N4 composite coatings

Smooth copper coatings containing well-distributed silicon nitride particles were obtained by co-electrodeposition in acidic sulfate bath. The cathodic current density did not show significant influence on incorporated particle volume fraction, whereas the increase of particle concentration in the bath led to its decrease. The increase of stirring rate increased the amount of embedded particles. The microhardness of the composite layers was higher than that of pure copper deposits obtained under the same conditions due to dispersion-strengthening and copper matrix grain refinement and increased with the increase of incorporated particle volume fraction. The microhardness of composites also increased with the increase of current density due to copper matrix grain refining. The composite coatings presented higher strength but lower ductility than pure copper layers. Pure copper and composite coatings showed the same corrosion resistance in 0.5 wt.% H₂SO₄ solution at room temperature.     

Influence of the electrolytic solution composition on the process of electrochemical synthesis of nanodimensional cupriferous powders

The cathode reduction ability of nanodimensional cupriferous powders consisting of nanodimensional particles was shown. The smallest crystalline spongeous formations are deposits obtained at limiting current density. The organic cosolvent role in the process of electrochemical deposition of ultrafine metal-containing powders from water-isopropanol alcohol copper dichloride solutions was shown. Geometrical parameters of the obtained particles were determined by transmission electron microscopy.     

The Effect of Sintering on the Properties of Ultrafine

研究了一种化学气相沉积(CVD)制备超细铼粉的新方法,即以NH4ReO7为原料,通过将其分解为Re2O7后气相输运至还原区,经氢气还原生成超细铼粉。对不同还原温度下制备的超细铼粉样品,采用XRD、SEM、激光粒度分析进行表征,实验揭示了烧结作用对晶粒尺寸、形貌、表面状态及粒度等粉末性能的影响规律。结果表明,随还原温度升高,烧结作用增强,制备的超细铼粉晶粒尺寸增大,具有更好的球形度,表面趋于光洁,平均粒径增大。     

烧结作用对CVD法超细铼粉性能的影响

研究了一种化学气相沉积(CVD)制备超细铼粉的新方法,即以NH4ReO7为原料,通过将其分解为Re2O7后气相输运至还原区,经氢气还原生成超细铼粉.对不同还原温度下制备的超细铼粉样品,采用XRD、SEM、激光粒度分析进行表征,实验揭示了烧结作用对晶粒尺寸、形貌、表面状态及粒度等粉末性能的影响规律.结果表明,随还原温度升高,烧结作用增强,制备的超细铼粉晶粒尺寸增大,具有更好的球形度,表面趋于光洁,平均粒径增大.     

Electrodeposition and characterization of Cu-Nb composite coatings

Copper coatings containing well-distributed Nb particles were obtained by co-electrodeposition in an acidic sulfate bath. Nb particle concentration in the bath was the most significant factor for the incorporation of Nb particles in copper, followed by stirring rate, whereas current density presented low significance. High Nb particle concentration and low stirring rate led to a higher incorporated Nb particle content. The microhardness of the composite layers was higher than that of pure copper deposits obtained under the same conditions due to copper matrix grain refinement and increased with the increase of both current density and incorporated Nb particle volume fraction. The corrosion resistance of Cu-Nb composites in 0.5 wt.% H₂SO₄ solution at room temperature was higher than that of pure copper and increased with the increase of the Nb content.     

Fabrication of cast carbon steel with ultrafine TiC particles

The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.     

Fabrication of cast carbon steel with ultrafine TiC particles

The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.