简化预处理辅助化学镀制备Cu包覆TiC复合粉末

研究了一种简化预处理辅助化学镀工艺制备Cu包覆TiC复合粉末.利用场发射扫描电子显微镜和能谱仪分析了原始TiC粉末,预处理之后的TiC粉末,Cu包覆TiC复合粉末的表面形貌和成分,同时也阐述了Cu镀层的生长机理.结果表明,经过简化预处理之后的TiC出现了很多表面缺陷,Cu能够均匀的包覆在TiC颗粒表面.其生长机理如下:经过预处理之后的TiC出现很多表面缺陷,成为化学镀过程中的活性点;化学镀过程中,Cu在TiC表面的各个缺陷处形核长大;Cu与Cu之间相互接触相互作用形成密集的网状结构最终形成致密的Cu镀层.     

化学镀法制备Cu/Al2O3复合粉体及其烧结行为

为了解决颗粒增强铜基复合材料中颗粒与铜基体相容性的问题,采用化学镀法使得颗粒表面金属化,通过XRD、SEM、EDS等技术研究了Al2O3纳米粉化学镀铜的工艺,并对Cu/Al2O3复合粉体的烧结行为做了初步探讨.结果表明:Al2O3粉前处理工艺、镀液的各种成分都对粉体表面铜的含量有影响,通过改变装载量可有效控制粉体表面Cu含量.实验中确定了最佳的镀覆工艺,并得到了颗粒较为弥散的Cu/Al2O3复合粉体烧结体.     

钼粉表面化学镀铜复合粉末烧结致密化

对化学镀法制备铜包钼的钼铜复合粉体的烧结致密化特点进行了研究,讨论了化学镀法制备钼铜复合粉的成形性,分析了化学镀铜钼粉的预处理、烧结温度、保温时间及复压复烧工艺对致密化的影响.结果表明,化学镀法制备钼铜复合粉成形性好,生坯相对密度可达到87%.在优化各影响因素的情况下,Mo/28Cu采用常规粉末冶金工艺得到了相对密度达97%的钼铜复合材料,钼铜复合材料具有典型的网络状结构,复合材料内部基本无孔洞,铜相分布均匀.     

机械化学还原法快速制备Mo5Si3-Al2O3纳米复合粉体（英文）

以MoO3粉、Mo粉、Si粉及Al粉为原料,采用机械合金化法合成了纳米Mo5Si3-20%Al2O3(质量分数)复合粉体。采用XRD、SEM、TEM和DTA等对复合粉体在球磨过程中结构变化进行了研究。结果表明:球磨10h后合成的Mo5Si3-20%Al2O3复合粉体,反应以爆炸模式进行。球磨30h后,Mo5Si3和Al2O3的晶粒尺寸分别为36.3nm和21.9nm。随着球磨时间的延长,Mo5Si3和Al2O3的晶粒尺寸变小,衍射峰宽化程度降低。DTA和XRD分析结果表明,复合粉体具有好的热稳定性,球磨30h后再在1000℃退火1h后复合粉体没有发生物相转变。     

熔覆Cu/Mo/Cu复合材料界面组织特征和结合特性

采用熔覆法制备Cu/Mo/Cu复合材料,利用金相显微镜对Cu/Mo/Cu复合材料的界面结构、显微组织进行研究,并通过扫描电镜分析了熔覆+轧制材料的断裂特点和界面结合特性。结果表明：熔覆复合界面平直且结合紧密;熔覆后钼层靠近界面的晶粒发生静态回复和再结晶,分布均匀呈等轴状,钼层中间位置的晶粒沿水平方向保持了原有的扁平状,铜层晶粒为粗大晶粒,大小不一且分布不均匀;铜层为韧性断裂,钼层发生分层断裂现象;剥离过程中材料沿着界面附近分层严重的钼层开裂,复合界面结合紧密。     

α-SiCp/Cu复合材料的制备及其性能研究

采用化学镀铜工艺对SiC粉体进行了表面改性处理,然后烧结制备了α-SiCp/Cu复合材料,研究了SiC粉体含量对α-SiCp/Cu复合材料微观组织与硬度的影响。结果表明,通过化学镀铜工艺可实现SiC粉体的均匀包覆。随着SiC颗粒含量的增加,α-SiCp/Cu复合材料硬度和表面结合能力升高。     

电子封装用Cu/Mo/Cu复合材料的工艺研究

研究了浸涂助复剂（铝基合金）和室温轧制工艺对Cu／Mo／Cu复合界面结合强度的影响，简述了Cu／Mo／Cu复合板室温轧制成形工艺过程，详细分析了表面和界面清理、初道次轧制临界变形率及热处理工艺等因素对复合板结合强度的影响。实验结果得出，钼板浸涂Al—Mn—Zn—Sn合金助复剂后的热处理温度为800～850℃；初道次轧制变形率为45％最佳；复合轧制后合适的退火工艺为450℃，保温60min。     

Preparation and Properties of W-15Cu Composite by Electroless Plating and Powder Metallurgy

用化学镀和粉末冶金的方法制备出W-15Cu复合材料。首先用化学方法对W粉表面预处理,然后在其表面化学镀铜。得到的复合粉末用图谱进行表征。发现用化学镀的方法制备出的W-15Cu复合粉末纯度非常高,且W颗粒均匀、被Cu致密的包覆着。呈现出包状结构。这种复合粉末表现出优异的压制性能,压坯分别在300, 400, 500, 600 MPa的压制压力下成形。压坯在1250 ℃温度下保温90 min烧结后,从其断口形貌可以发现W颗粒没有明显的长大,且W颗粒表面特征并没有发生改变,仍然表现出预处理后的表面特征。对烧结体的相对密度、硬度、抗弯强度和电导率同样进行了表征     

CNTs/SiC/Cu复合材料制备及性能

以碳纳米管(CNTs)、碳化硅(SiC)粉体、锌(Zn)粉和CuSO_4·5H_2O为主要原料,用化学镀的方法制备CNTs /Cu复合粉体,再采用非均相沉淀法制备CNTs/SiC/Cu复合粉体.在750 ℃、100 MPa的制度下进行真空热压烧结后制得CNTs/SiC/Cu复合材料,其中Cu的含量(体积分数,下同)为70%,CNTs的含量(体积分数, 下同)分别为0,3%,5%,8%,12%.利用XRD、SEM分析样品的物相组成和显微结构;利用阿基米德排水法、显微硬度计、三点弯曲法测试了复合材料的密度、显微硬度和抗弯强度.结果表明,随着碳纳米管含量的增加,CNTs/SiC/Cu复合材料的密度、显微硬度和抗弯强度等性能发生相应变化,其中,抗弯强度呈现逐渐升高趋势.与未添加碳纳米管的30SiC/70Cu复合材料相比,添加12%CNTs的12CNTs/18SiC/70Cu 样品,抗弯强度提高了21.45 MPa.     

Cu/Mo/Cu轧制复合界面的结合特性

采用轧制方法制备Cu/Mo/Cu复合材料,利用金相显微镜、扫描电镜和电子拉伸机等研究Cu/Mo/Cu复合材料的界面结构、断裂特点和工艺参数对结合强度的影响。结果表明:轧制前经(750℃,8 min)热处理,道次变形量为55%,复合材料的界面结合紧密,最大剪切强度为77 MPa;钼层金属显微组织呈扁平纤维状,组织较为均匀,铜层金属的晶粒呈等轴状,由界面至表面晶粒逐渐增大,且分布很不均匀;复合机制为典型的裂口结合和机械啮合。     

Cu/Mo/Cu复合板界面变形及厚度配比

采用热轧+温轧方法制备Cu/Mo/Cu复合板,研究轧制工艺对复合板结合界面及组元厚度配比的影响。结果表明：经过轧制变形后,铜钼界面实现紧密结合且结合机制为齿状啮合,铜层外表面和靠近界面层的晶粒比中部细小;随着变形量的增加,铜层等轴状晶粒沿轧制方向被拉伸,界面结合效果明显改善,且由齿状变得较为平直。分析组元厚度配比,铜层变形量较钼层的大,随着总压下量的增加,组元压下率的差值减小,变形量逐渐趋于一致;首次提出了Cu/Mo/Cu三层复合板厚度配比的关系,为实际选择原料提供依据     

真空感应熔炼气雾化法制备高强度PH13-8Mo钢粉末的特性表征

采用真空感应熔炼气雾化(VIGA)法制备出球形高强度PH13-8Mo钢粉末,通过不同目数的筛网对粉末进行筛分,得到120~212μm,53~120μm,15~53μm和<15μm不同粒度区间的高强度PH13-8Mo钢粉末。利用氧氮分析仪、扫描电镜(SEM)、激光粒度分布仪和智能粉体特性测试仪等分析手段研究了不同粒径区间的PH13-8Mo钢粉末的氧含量、表面形貌、表面及内部微观组织、流动性和松装密度。结果表明:随着粉末粒度区间减小,PH13-8Mo钢粉末的比表面积从0.017 m^2/g显著增大到0.243 m^2/g,粉末中的O含量从0.017%增大到0.033%;当PH13-8Mo钢粉末粒径的范围为15~53μm区间时,粉末中的O含量相对较低,冷却速率较大,卫星球颗粒少,表面和内部组织主要由胞状晶和微晶组成,且该粒度范围的PH13-8Mo钢粉末的松装密度和流动性指数高。     

Al2O3/Mo composite and its tribological behavior against AISI201 stainless steel at elevated temperatures

Al₂O₃-reinforced molybdenum (Mo) composites were successfully prepared by powder metallurgy to improve the wear resistance of Mo components at high temperature. The reinforced Al₂O₃ particles are uniformly distributed in the Mo matrix; thus, the Al₂O₃/Mo composite is harder than monolithic Mo. The friction coefficients of both monolithic Mo and the Al₂O₃/Mo composite decrease by 37% and 42%, respectively, at 700 °C compared with those at room temperature (self-lubricating phenomenon). This phenomenon is attributed to the formation of very soft MoO₃ and FeMoO₄ metal oxides on the friction surface at high temperature. The Al₂O₃/Mo composite has better wear resistance than monolithic Mo at both room temperature and at 700 °C. The notable resistance of the composite particularly at 700 °C can be attributed to its increased hardness and the soft tribofilm forming on the worn surface.     

The corrosion resistance of a Fe/Cu composite

A composite made from a mixture of iron and copper powders was produced and characterised. The Cu addition favours the production of sintered Fe in the powder metallurgy industry processes. The corrosion behaviour in different electrolytic solution (sodium chloride or hydrochloric, acetic or sulphuric acids) and the corrosion rates were obtained from the weight loss and potentiodynamic methods – intersection and linear polarisation resistance. The values in hydrochloric and sulphuric acid vary slightly with respect to the average value of 78 mV/decade. The values obtained in acetic acid and sodium chloride are higher probably due to the formation of a thin film layer over the metallic surface. The morphology was analyzed through the observation by optical and scanning electron microscopy. It has been determined the nature of the oxide layer, Fe₃O₄, by X‐ray photoelectron spectroscopy (XPS), isolating the composite from the atmosphere. Thus, this oxide layer acts as a corrosion protective surface.     

Suppressing effect of 0.5 wt.% nano-TiO2 addition into Sn-3.5Ag-0.5Cu solder alloy on the intermetallic growth with Cu substrate during isothermal aging

This study investigated the effects of adding 0.5 wt.% nano-TiO₂ particles into Sn3.5Ag0.5Cu (SAC) lead-free solder alloys on the growth of intermetallic compounds (IMC) with Cu substrates during solid-state isothermal aging at temperatures of 100, 125, 150, and 175 °C for up to 7 days. The results indicate that the morphology of the Cu₆Sn₅ phase transformed from scallop-type to layer-type in both SAC solder/Cu joints and Sn3.5Ag0.5Cu-0.5 wt.% TiO₂ (SAC) composite solder/Cu joints. In the SAC solder/Cu joints, a few coarse Ag₃Sn particles were embedded in the Cu₆Sn₅ surface and grew with prolonged aging time. However, in the SAC composite solder/Cu aging, a great number of nano-Ag₃Sn particles were absorbed in the Cu₆Sn₅ surface. The morphology of adsorption of nano-Ag₃Sn particles changed dramatically from adsorption-type to moss-type, and the size of the particles increased.The apparent activation energies for the growth of overall IMC layers were calculated as 42.48 kJ/mol for SAC solder and 60.31 kJ/mol for SAC composite solder. The reduced diffusion coefficient was confirmed for the SAC composite solder/Cu joints.     

Behavior of porosity and copper oxidation in W/Cu composite produced by plasma spray

A spherical tungsten (W)/copper (Cu) composite powder was plasma-sprayed onto a boron-nitride-coated graphite substrate to produce heat sink material for the electronic packaging by atmospheric plasma spray using different input powers. At the surface of the deposited layer, Cu became oxidized to cuprite (Cu₂O). The degree of oxidation at the surface layer did not vary significantly with input power. Very little Cu₂O was detected at the inner layers after grinding off the 70 μm from the surface. The input powers had a strong effect on the porosity in the deposit layers. The porosity in the deposit layers at 25 kW was very small, about 3 vol%. The microstructures of W/Cu composite were discussed.     

Effect of WC and CeO2 on microstructure and properties of W–Cu electrical contact material

W–Cu alloys with an individual addition of WC and CeO₂ particles were prepared by means of powder metallurgy and infiltration, and the effect of WC and CeO₂ individual addition on microstructure and properties of W–Cu alloys was investigated. The results show that W–Cu alloys with a separate addition of 1.5 wt% WC and 0.5 wt% CeO₂ have desired properties, but an excessive addition decreases hardness and electric conductivity. The vacuum electrical breakdown tests show that the individual addition of WC and CeO₂ results in the enhancement of the breakdown strength and decrease of the chopping current. The microstructual analysis of W–Cu alloys with WC or CeO₂ addition after vacuum electrical breakdown 50 times shows that the vacuum electrical arcs spread on the cathode surface. Meanwhile, W–Cu alloys with WC or CeO₂ addition has a slight splash of molten copper, a less amount of cathode craters, and fine dispersed cathode craters on the entire surface of W–Cu alloys.     

Microstructure evolution,mechanical properties and tailoring of coefficient of thermal expansion for Cu/Mo/Cu clad sheets fabricated by hot rolling

The law of microstructure evolution and mechanical properties of hot roll bonded Cu/Mo/Cu clad sheets were systematically investigated and the theoretical prediction model of the coefficient of thermal expansion (CTE) of Cu/Mo/Cu clad sheets was established successfully. The results show that the deformation of Cu and Mo layers was gradually coherent with an increase in rolling reduction and temperature and excellent interface bonding was achieved under the condition of a large rolling reduction. The development of the microstructure and texture through the thickness of Cu and Mo layers was inhomogeneous. This phenomenon can be attributed to the friction between the roller and sheet surface and the uncoordinated deformation between Cu and Mo. The tensile strength of the clad sheets increased with increasing rolling reduction and the elongation was gradually decreased. The CTE of Cu/Mo/Cu clad sheets was related to the volume fraction of Mo. The finite element method can simulate the deformation and stress distribution during the thermal expansion process. The simulation result indicates that the terminal face of the clad sheets was sunken inward.     

气雾化Al-Zn-Mg-Cu-Zr粉在半固态轧制过程中显微组织的演变(英文)

在H2气氛下,采用半固态轧制工艺将Al-5.8Zn-1.63Mg-2.22Cu-0.12Zr(质量分数)粉末成功轧制成相对密度为76.1%~88.0%的生带材。分析了温度对生带材显微组织和力学性能的影响规律。当轧制温度由580°C上升到610°C时,加速了原始颗粒边界和内部孔洞的消失、粒子的扩散、晶界的变化;显微组织演变的机制由致密为主的阶段转变为以晶粒粗化为主的阶段;η(MgZn2)相的数量在减少,更多的Al2Cu粒子在晶界处析出。获得了Al-5.8Zn-1.63Mg-2.22Cu-0.12Zr(质量分数)粉末的最佳半固态轧制温度。当液相分数为53%~67%时可以制备出具有较高密度的生带材。该研究有助于采用半固态轧制将金属粉末制备出性能较好的带材。     

High Pressure Cold Sprayed (HPCS) and Low Pressure Cold Sprayed (LPCS) Coatings Prepared from OFHC Cu Feedstock: Overview from Powder Characteristics to Coating Properties

Cold spraying enables high quality Cu coatings to be deposited for applications where high electrical and/or thermal conductivity is needed. Fully dense Cu coatings can provide an effective corrosion barrier in specific environments. The structure of cold-sprayed Cu coatings is characterized by high deformation which imparts excellent properties. Coating properties depend on powder, the cold spray process and post treatments. First of all, powder characteristics have a strong influence on the formation of pure coatings. Secondly, cold spraying provides dense, adherent, and conductive coatings by using HPCS and LPCS. Furthermore, an addition of Al₂O₃ particles to the Cu powder in LPCS process significantly improves coating properties. Also, heat treatments improve electrical conductivity. This study summarizes optimal characteristics of Cu powder optimized for cold spraying, achieving high coating quality and compares properties of HPCS Cu, LPCS Cu and Cu+Al₂O₃ coatings prepared from the same batch of OFHC Cu powder.