Fabrication of Cu/graphite film/Cu sandwich composites with ultrahigh thermal conductivity for thermal management applications

Effective thermal management of electronic integrated devices with high powder density has become a serious issue, which requires materials with high thermal conductivity (TC). In order to solve the problem of weak bonding between graphite and Cu, a novel Cu/graphite film/Cu sandwich composite (Cu/GF/Cu composite) with ultrahigh TC was fabricated by electro-deposition. The micro-riveting structure was introduced to enhance the bonding strength between graphite film and deposited Cu layers by preparing a rectangular array of micro-holes on the graphite film before electro-deposition. TC and mechanical properties of the composites with different graphite volume fractions and current densities were investigated. The results showed that the TC enhancement generated by the micro-riveting structure for Cu/GF/Cu composites at low graphite content was more effective than that at high graphite content, and the strong texture orientation of deposited Cu resulted in high TC. Under the optimizing preparing condition, the highest in-plane TC reached 824.3 W·m⁻¹·K⁻¹, while the ultimate tensile strength of this composite was about four times higher than that of the graphite film.     

脉冲激光热力冲击效应对电沉积的作用

脉冲激光电化学复合沉积利用激光的热力冲击效应可以有效提高沉积效率,改善加工质量。在所构建的纳秒脉冲激光电化学沉积加工系统中,利用激光辐照和电化学沉积的方法对铜进行了复合沉积试验。分析了激光的热力冲击效应对电沉积的作用机理,激光产生的力效应使阴极基片发生弹性变形,改变了电极电势和电流密度,提高了电沉积质量。通过加工试验,研究了激光平均功率密度对沉积质量和沉积效率的影响,并进行了讨论。试验结果表明,激光平均功率密度介于100~400 kW/cm2时可以获得较好的沉积层质量。激光平均功率密度在200 kW/cm2左右,沉积速率取得最大值。     

电沉积法制备泡沫镍的研究

泡沫镍是泡沫金属中重要的一种,它因具有良好的透流体性能、电磁屏蔽性能、吸音性能、抗冲击性能而广泛用于各个领域,尤其是军工领域.本实验通过研究粗化时间对泡沫镍空隙率的影响、硫酸铜含量对化学镀铜镀速的影响、硫酸铜含量对均镀能力的影响以及氯离子和电镀温度对电镀镍的影响等方面工作,制备出孔隙率较高、孔型容易控制和通孔的泡沫镍.     

Structure and photoluminescence properties of Ag-coated ZnO nano-needles

A large number of zinc oxide (ZnO) nano-needles were synthesized by thermal oxidation of pure zinc. The surfaces of ZnO nano-needles were coated with a layer of Ag by pulse electro-deposition technique. The uncoated and coated ZnO nano-needles were characterized by using the X-ray diffraction and the scanning electron microscope (SEM). The results showed that the uncoated samples were close-packed hexagonal structure, which showed needle-like morphology. Their average diameter is about 40 nm, lengths up to 5 μm. At the same time we observed that the prepared ZnO nano-needles have been coated with Ag successfully. The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the uncoated ZnO nano-needles have two fluorescence peaks at 388 nm and 470.8 nm, respectively, the relative intensity of 143.4 and 93.61; and the Ag-coated ZnO nano-needles showed a pair of strong peaks at 387.4 nm and 405.2 nm, the relative intensity of 1366 and 1305, respectively, indicating that the Ag-coated ZnO nano-needles can increase the absorption of UV light.     

通用型阴极电泳色浆的制备分析

彩色阴极电泳涂料是未来发展的必然趋势,那么彩色通用型阴极电泳色浆是将来生产彩色阴极电泳涂料的首选着色剂.介绍了通用型阴极电泳色浆的定义、理化指标、材料选择及色浆的稳定理论,以及生产工艺和色浆的组成成分.分析了粒径对色浆性能的影响,讨论了体系中颜料与液态组分的最优化确定方法.这对生产通用型阴极电泳色浆有一定的指导意义.     

电化学沉积法制备稀土掺杂氧化钇荧光薄膜的发光性能

通过改变氧化钇薄膜中掺杂稀土元素的种类,来控制发光薄膜的荧光发射波长.利用电化学沉积法制备稀土掺杂氧化钇荧光薄膜.电化学沉积法制备的薄膜结晶效果好,掺杂离子分布较均匀,且不需要高温高压或者真空条件,成本很低.所制备的Y2O3:Ln荧光发光薄膜经XRD分析具有立方晶体结构;不同稀土掺杂的氧化钇呈现出不同的表面形貌;掺杂的Ln离子均匀地分布在薄膜中,经测试所有的Y2O3:Ln荧光发光薄膜都显示出较强的发射强度,且发光波长随着掺杂离子的不同而不同:Y2O3:Er3+发绿光,Y2O3:Ce3+发黄绿光,Y2 O3:Sm3+发蓝光,Y2O3:Pr3+发橙光.因此,电化学沉积法可用于制备具有不同发光波长的氧化钇荧光薄膜.     

杂质铜离子对电镀镍层组织形貌及耐蚀性的影响

目的 研究电镀镍液中存在的铜离子杂质对电镀镍层微观组织和耐蚀性能的影响。方法 以五水合硫酸铜的形式向电镀镍液中加入不同质量浓度(5、10、30 mg/L)的铜离子杂质,并以初始配制的电镀镍液(0 mg/L Cu²⁺)为空白组对照。选用低电流密度(0.5 A/dm²)在Q235钢上电镀镍层,并通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线光电子能谱(XPS)和电化学分析技术对电镀镍层的表面微观形貌、晶体织构、表面各元素化学态信息及耐蚀性能进行表征和分析。结果 随着电镀镍液中铜离子浓度的增加,镍层的颜色逐渐变灰,外观质量降低。当电镀镍液中铜离子的含量在工业容忍度范围内时(≤10 mg/L),镍层的颜色较为光亮,晶粒尺寸较小且均匀。当铜离子的浓度大于工业容忍度时(>10 mg/L),晶粒开始变得粗大,且尺寸不均匀。镍晶的生长方式并未改变,仍以螺旋位错的方式进行生长。镀液中存在的铜离子改变了镍晶体的结构,主峰的衍射角度向大角度发生偏移,半峰宽逐渐变大,晶面间距减小,同时影响了镍晶体的择优生长取向,晶粒逐渐由(111)和(200)面转为(111)和(220)面生长。XPS测试结果显示,铜离子浓度的增加导致镍的析出效率降低,铜离子在镍层中析出,并以单质铜和氧化铜的形式存在于镍层中。电化学测试结果表明,电镀镍液中存在的铜离子降低了镍层的耐蚀性能。当铜离子的质量浓度从0 mg/L增加至30 mg/L时,镍层在质量分数为3.5%的NaC1溶液中的开路电位(OCP)逐渐降低,自腐蚀电位由?0.487 mV降至?0.547 mV,自腐蚀电流密度由7.898 9 μA/cm²增加至17.316 μA/cm²。电化学阻抗模值和相位角变小,电荷转移电阻(Rct)由1 798 Ω.cm²减小至851 Ω.cm²。结论 在瓦特液中,微量铜离子杂质会导致镍结晶粗大,镀层外观灰暗。镍层中的杂质铜原子会引起一定程度的晶格畸变,使晶格常数变小,晶粒生长择优取向发生改变。随着铜离子杂质浓度的增加,电镀镍层在质量分数3.5%的NaCl溶液中的自腐蚀电流密度增大,阻抗值相应地降低,抗腐蚀性能下降。     

光电薄膜SnS的制备及其性能

在溶液的pH=2.7,离子浓度比Sn2+/S2O2－3=1/5和电流密度J=3.0mA／cm2的条件下,用阴极恒电流沉积法在ITO导电玻璃基片上制备出了Sn0.995S1.005膜层,并用扫描电镜观察了该薄膜的表面形貌，发现其颗粒较均匀，粒径大小在200～800nm之间．用X射线衍射分析了其物相结构，表明它是具有正交结构的SnS多晶薄膜．通过测量薄膜样品的透射光谱和反射光谱，计算得到其直接禁带宽度Eg=1.23eV．用四探针法测得其导电类型为p型，电阻率为7.5Ω·cm.     

电沉积Co-Mo合金薄膜的结构和热稳定性

通过电沉积,在铜基体上制备了Co-Mo合金薄膜.讨论了薄膜组成与结构以及非晶合金的晶体结构与热处理温度的关系.测定了薄膜磁性能(饱和磁化强度和矫顽力)随热处理温度变化的关系曲线.结果表明,薄膜中钼含量(质量分数)为6.05%～30.03%时,镀态Co-Mo合金薄膜具有非晶态结构;经连续升温到400℃并热处理1.5 h后,Co-Mo非晶态合金发生晶化,且随着薄膜中钼含量的增加,薄膜的晶化温度提高,热稳定性增强;在较高温度(高于500 ℃)下热处理后,Co-Mo非晶态合金晶化,并析出单一的hcp-Co相;热处理后,Co-Mo合金薄膜的软磁性变差.     

Sodium molybdate—a possible alternate additive for sodium dichromate in the electrolytic production of sodium chlorate

Sodium dichromate is commonly used in sodium chlorate production to maintain high current efficiency; however, it is also a well documented carcinogen. To reduce the environmental impact, identification of a suitable alternative with similar buffering characteristics to dichromate and without adverse effect on the electrolytic performance of sodium chlorate production is important; sodium molybdate is a good candidate. Molybdate ion and its conjugated acid work as a buffer pair at pH 5–6, a lower and slightly narrower pH window than the typical buffer region of dichromate. Nonetheless, the molybdate buffer works effectively during the electrolytic process by maintaining pH at 5.9. Although the use of molybdate buffer will lower the overpotential of hydrogen evolution reaction (HER) by 100 mV, the average off-gas oxygen content is noticeably compromised at 3.6–4.6%, measured using a pilot cell operated at 3 kA m⁻²and 80 °C during a 3-day trial. The resulting current efficiency of 91 92% is significantly lower than when dichromate is employed as the process additive (> 96%). Mixtures of different dichromate and molybdate ratio were also investigated in terms of the resulting cathode surface potential.