水平震荡机械研磨对酸性镀铜微观结构的影响

在传统酸性镀铜液中加入玻璃球,玻璃球以不同频率在试样表面滚动-滑动形成机械研磨(MA).利用SEM,XRD和AutoLab考察震荡频率对机械研磨增强镀层(MAEE)的微观结构、晶粒尺寸、沉积速率、孔隙率和在3.5%NaCl(质量分数)溶液中耐蚀性的影响.结果表明,与传统镀层(TEP)相比,水平震荡MA可显著减小TEP镀...     

脉冲电沉积CeO2-SiO2／Ni—W-P纳米复合镀层性能研究

为了探讨脉冲参数对CeO2-SiO2/Ni-W-P四元纳米复合镀层性能的影响,采用脉冲沉积的方法,在普通碳钢表面制备了CeO2-SiO2/Ni-W-P纳米复合镀层.在脉冲关断时间1 000μs和脉冲峰值电流密度30 A/dm2下,研究了脉冲导通时间对纳米复合镀层组织及性能的影响,采用能谱分析、硬度测试、扫描电镜(SEM)等技术对镀层化学组成、沉积速率、显微硬度和表面形貌进行了表征.结果表明,纳米复合镀层中CeO2和SiO2颗粒的质量分数随着脉冲导通时间的延长而增加,当脉冲导通时间为400～600μs时,沉积速率为32.33～38.22μm/h,显微硬度为609～674 HV;脉冲导通时间由100μs增加到400μs时,纳米复合镀层晶粒尺寸降低,但当脉冲导通时间再由400μs增加到1000μs时,纳米复合镀层晶粒尺寸又有所增加.     

稀土添加剂在光亮酸性镀铜中的应用

稀土元素由于具有独特的原子结构,其优异性能在金属表面处理领域中已得到越来越广泛的应用。 光亮硫酸盐镀铜,由于具有低成本、全光亮的优点,所以在装饰性电镀中被广泛应用,但是它存在着几个较大的缺点,就是孔隙率较大,在空气中极易变色,影响着产品总体镀层的耐蚀性能,为了克服这些缺点,往往采用增厚镀铜层的办法,这样既费时,又费料,特别是在电镀自动线上,由于工艺程序设计固定,往往在进入下一道工序之前,镀铜层产生变色,影响镀层的质量。添加稀土添加剂进行光亮酸性镀铜,能降低镀铜层的孔隙率,提高镀层的抗变色能力和耐蚀性,特别是对镀件总体复合镀层抗蚀能力的提高有十分明显的效果,具有十分重要的现实意义。1 实验 镀铜基础液取自某滚镀厂生产自动线10 m~3光亮酸性镀铜液,其原料都是工业级,工艺按常规工艺配方配制,自行配制光亮剂,稀土添加剂(自制),由稀土材料与相应的辅助材料混合配制而成。     

镀铜石墨/铜复合材料的组织和摩擦磨损性能

本实验以电解铜粉为基体,镀铜石墨为润滑相,采用放电等离子烧结技术(SPS)制备镀铜石墨/铜复合材料,研究了镀铜石墨含量对复合材料微观组织、硬度、孔隙率和摩擦磨损性能的影响。结果表明:镀铜石墨均匀分散在Cu基体中能细化晶粒、均匀组织,石墨表面镀铜层能够增强石墨与Cu基体的界面结合。当镀铜石墨含量超过4wt%,复合材料的硬度和孔隙率变化幅度明显增大。镀铜石墨具有细晶强化作用,能提升复合材料的硬度,其含量为4wt%时,复合材料的硬度达到最大值57.8HV,但镀铜石墨含量和孔隙率的共同作用使得复合材料的硬度呈先增大后减小的趋势。随着镀铜石墨含量增加,复合材料孔隙率逐渐增大,摩擦系数、磨损量逐渐减少,镀铜石墨含量为8wt%时,复合材料的摩擦系数、磨损量相比纯铜分别降低63.9%、96.3%。镀铜石墨作为润滑相紧密镶嵌在铜基体中,显著提高了复合材料的摩擦磨损性能。复合材料摩擦磨损机理主要为磨粒磨损、粘着磨损和氧化磨损。     

镍钴合金电沉积中硫酸钴影响的探讨

电沉积镍层硬度低,耐磨性差,在瓦特型镀镍液中加入硫酸钴可以提高镀层的抗热性能、耐蚀性能和韧性.采用硫酸盐电解液电沉积镍钴合金,研究了电解液中硫酸钴浓度与镀液分散能力、深镀能力的关系及其对镀层显微硬度、孔隙率和内应力的影响.同时,利用扫描电子显微镜分析了沉积层的表面形貌.结果表明:随着镀液中硫酸钴浓度的增大,镀液的分散能力下降,深镀能力升高;镀层显微硬度显著提高,内应力和孔隙率也有所增加.镍钴合金沉积层比纯镍镀层更细致、结晶均匀.     

基体表面粗糙度对H13钢板表面镀铬层的影响

分析测试H13钢表面镀铬层的表面形貌与结构、粗糙度、显微硬度、厚度、电化学阻抗及极化曲线,研究了H13钢基体表面粗糙度R_a对其表面镀铬层结构与性能的影响。结果表明:电镀时间小于30min时,随着R_a的增加,镀铬层晶粒尺寸减小,堆积趋于稀疏;电镀30 min后,不同R_a的镀铬层晶粒尺寸及分布基本相同;电镀60 min后,随着R_a的增加,镀铬层晶粒的尺寸明显增大;当R_a值小于0.504μm时,(200)面为铬晶粒的优势生长面,当R_a值为0.504μm时,(211)面为铬晶粒的优势生长面;随电镀时间的增加,镀铬层的厚度和显微硬度逐渐增大;当电镀时间相同时,随着R_a的减少,镀铬层的厚度减少,显微硬度增加,镀铬层的耐蚀性逐渐提高。     

硫代硫酸盐无氰镀银工艺

无氰镀银是电镀银的发展方向,目前仍存在许多问题.采用硫代硫酸盐无氰镀银工艺,分别以AgNO3和AgBr为主盐进行镀银,研究了主盐含量、电流密度对镀层表观质量、沉积速率、显微硬度的影响,测量了镀层结合强度、晶粒尺寸,确定了2种体系制备镀层的最佳工艺.结果表明:AgNO3体系AgNO3最佳用量为40 g/L,最佳电流密度为0.25 A/dm2,制备的镀层光亮平整,晶粒尺寸为35 nm;AgBr体系AgBr最佳用量为30 g/L,最佳电流密度为0.20 A/dm2,制备的镀层光亮平整,晶粒尺寸为55 nm;与AgBr体系相比,AgNO3体系适宜电镀的电流密度范围较宽,制备的镀层显微硬度较大,晶粒尺寸小;2种体系制备的镀层均为纳米晶.     

表面机械研磨处理对Cu-10wt％Ni合金组织及性能的影响

对Cu-10％(质量分数)Ni合金进行表面机械研磨处理,采用X射线衍射仪、光学显微镜、显微硬度测试仪等对处理不同时间样品的组织及性能进行了分析.结果表明表面机械研磨处理后,Cu-10％(质量分数)Ni合金实现了表面纳米化.处理时间30min时,表面晶粒尺寸为42.92nm,随着处理时间的延长,晶粒逐渐细化,强烈变形层逐...     

钢线材硫酸盐体系电镀纳米晶锌镀层工艺研究

为了克服传统线材高速电镀锌工艺存在的镀层耐蚀性能差问题,研究了硫酸盐电镀纳米晶锌镀层的工艺.采用场发射扫描电子显微镜、透射电镜和X-射线衍射技术对镀锌层的表面形貌及晶粒尺寸进行了表征,利用极化曲线和线材缠绕试验对纳米晶锌镀层的耐蚀性能和延展性能进行了研究.结果表明:在基础硫酸盐镀液体系中,仅通过改变脉冲电镀参数并不能得到纳米晶锌镀层;而在含有唯一添加剂(晶粒细化剂1 g/L)的基础硫酸盐镀液体系中,通过对双脉冲电镀参数的优化,得到了平均晶粒尺寸为31 nm,结晶细密、平整、光亮的纳米晶锌镀层;该纳米晶锌镀层在低碳钢板材和线材表面重现性良好;纳米晶锌镀层的耐蚀性能优于传统粗晶锌镀层,且具有良好的延展性.     

Ni-Co-P合金镀层显微硬度及其耐海水腐蚀性

采用电沉积技术制备了Ni-Co-P合金镀层,并对镀层的表面形貌、晶相结构、显微硬度及耐腐蚀性进行了表征和分析.研究结果表明:Ni-Co-P合金镀层表面均匀平整,晶粒尺寸细小,显微硬度均优于Ni-P合金镀层;当镀液中CoSO4·7H2 O含量为50 g/L时,Ni-Co-P合金镀层的显微硬度达到766.3 HV0.2.在人工海水环境中,Ni-Co-P合金镀层的开路电位稳定值更正,腐蚀电流密度与腐蚀速度最小分别为0.68μA·cm-2和8.25μm·year-1;且Ni-Co-P合金镀层的容抗弧半径均大于Ni-P合金镀层,电荷转移电阻(Rct)高达9.902×104Ω·cm-2,约为Ni-P合金镀层的6倍,表现出优异的耐海水腐蚀性能.     

Gradient Microstructure and Properties of Surface Mechanical Attrition–Treated AZ91D Alloy: An Effect of Colliding Balls Velocity

The surface properties of the AZ91D alloy are altered using surface mechanical attrition treatment (SMAT), a promising method of severe surface deformation, where the role of process parameters is crucial. In this study, specimens are SMATed using ≈3 and ≈10 m s⁻¹ ball velocities (maintaining a constant percentage coverage). The SMATed specimens show higher twin density near the surface, which is reduced gradually, and twin thickness is increased with increasing depth. Further, high-velocity balls cause more twin density and better grain refinement (≈32 nm grain size at the surface). The higher ball velocity helps form a considerably thicker gradient layer (≈3500 μm) with higher hardness (≈1.98 GPa) and compressive residual stress (≈281 MPa) within a shorter SMAT duration (≈10 min). Ball velocity also influences nanomechanical properties such as nanohardness, creep resistance, strain rate sensitivity (SRS), etc. The non-SMATed alloy's SRS is about 0.037–0.040. The gradient microstructure affects SRS. The SRS value near the SMATed surface (where the reduced grain size plays a dominating role) is about 0.018–0.027; however, it drops suddenly to ≈0.01 (with a slight increase in depth), and subsequently, it rises with an increased distance in the SMATed layer (where twins play a dominating role).     

表面机械研磨对H13钢表面性能的影响

使用表面机械研磨（SMA）方法处理H13钢表面使其表面获得一层变形层。采用SEM,TEM及硬度试验等检测方法对变形层的厚度、晶粒大小、截面硬度梯度和热稳定性等进行了分析;同时对H13钢在SMA处理前后的渗氮行为进行了比较。结果表明,经SMA处理后,H13钢表面形成了约10μm厚的变形层,变形层内的晶粒明显细化,并且这些晶粒具有较好的热稳定性;此外,可以大大提高H13钢渗氮的效率。     

球形纳米氧化铝颗粒制备微晶陶瓷及传质动力学研究

采用球形纳米氧化铝颗粒制备氧化铝微晶陶瓷,研究造粒、烧结等工艺过程对陶瓷微观结构和力学性能的影响,并结合动力学计算分析球形颗粒在烧结过程中的传质特性。结果表明:通过液相造粒掺入0.8%(质量分数)的PVA能够优化球形颗粒的压制成型并提高坯体密度。烧结温度从1400℃提高至1550℃,陶瓷相对致密度由74.1%增大至97.5%,而晶粒尺寸由0.6μm仅增至1.4μm,这与球形颗粒自身稳定的形态及其堆积形成的均匀孔隙有关。在1550℃下烧结时间由30 min延长至120 min时,气孔率由4.8%降低至0.4%,晶粒尺寸则由1.2μm增至2.7μm。另外,通过动力学计算得出球形颗粒的烧结活化能为788 kJ/mol,证实球形颗粒在烧结前期和中期具有生长惰性,利于获得微晶结构。经1550℃保温90 min的陶瓷,其密度达到98.9%,平均晶粒尺寸仅为1.6μm,硬度达到26.4 GPa,弯曲强度为574 MPa。     

Characterization of r.f.-sputtered ZnO thin films by X-ray diffraction and scanning electron microscopy

Thin films of ZnO, ranging in thickness from 0.08 to 6 μm, have been prepared by r.f. sputtering on substrates of either quartz or glass under various deposition conditions and subsequently characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results from XRD indicate that the grain size increases from 0.01 to 0.5 μm as the film thickness is increased from 0.08 to 6 μm for deposition at 65 °C and increases from 0.1 to 0.3 μm as the deposition temperature is increased from 65 to 480 °C for a constant film thickness of 2 μm, whereas the lattice strain and dislocation density decrease slightly under similar conditions. Results from SEM indicate that the particle size parallel to the plane of the film is approximately equal to the mean grain size perpendicular to the plane of the film, suggesting that growth proceeds by the nucleation of new grains rather than by the elongation of columnar grains in the growth direction. General observations indicate that microstructural parameters, such as grain size, grain shape and lattice strain, depend sensitively on the exact nature of the deposition conditions.     

Effect of surface mechanical attrition treatment of titanium using alumina balls: surface roughness,contact angle and apatite forming ability

The effect of surface mechanical attrition treatment (SMAT) of commercially pure titanium (CP-Ti) using 8 mm ? alumina balls was studied. SMAT induced plastic deformation, increased the surface roughness, reduced the grain size and decreased the contact angle (from 64° to 43°) with a corresponding increase in surface energy (from 32 to 53 mJ/m²). Untreated CP-Ti and those treated using alumina balls for 900 s reveals no apatite growth until the 28th day of immersion whereas those treated for 1800 and 2700 s exhibit apatite growth in selective areas and the extent of growth is increased with increase in immersion time in SBF. The study reveals that SMAT using alumina balls is beneficial in imparting the desired surface characteristics, provided the surface contamination is limited, which would otherwise decrease the apatite forming ability.     

热处理温度对LaMgAl11O19涂层热/力学性能的影响

大气等离子喷涂制备的LaMgAl₁₁O₁₉ (LMA)热障涂层无定型相含量较高, 会严重影响涂层服役寿命。通过900~1600 ℃不同温度热处理12 h, 研究晶粒尺寸和孔隙率等微观结构和无定形相含量对LMA涂层力学、热物理以及抗热震性能的影响。结果表明: 喷涂态LMA涂层具有900和1163 ℃两个结晶温度点。900 ℃热处理后, LMA涂层中含有较多的无定形相以及最高的孔隙率((18.88±2.15)%), 1000 ℃测试时,具有最低的热扩散系数(0.53 mm²/s); 由于重结晶和烧结作用使得无定型相含量和孔隙率降低, 1100~1400 ℃之间热处理的涂层具有较高的硬度(1100℃时达到最高值(12.08±0.58) GPa); 1300 ℃热处理的涂层中含有大量微米级片状晶, 具有较高的应变容限以及平均热循环寿命(588次); 热处理温度达到1500 ℃时, 由于片状晶平行堆叠, 晶粒厚度迅速增加, 孔隙率增加、力学性能显著降低。热震过程中由于热应力的反复作用, 涂层内出现晶粒破碎和裂纹扩展等现象, 导致涂层最终失效。     

Studies on Properties and Structure of Electroless Plating Tin Coating

The composition and structure of electroless tin coating were analyzed by SEM and X-ray diffraction. In the meantime, porosity, solderability and extensibility were determined by physical and chemical methods. The results showed that the porosity of the tin coating increases with the rise of bath temperature and decreases as the plating time rises. Solderability is improved with the rise of thickness of tin coating, and decreases when the tin deposit is heated at 180 ～ 200 ℃. The crystalline grain size becomes bigger and bigger with increasing plating time or bath temperature or coating thickness. X-ray diffraction indicates that only Cu and β-Sn phases show up in the diffraction patterns. Tin coating has a strong joint force with copper substrate and excellent function of electrochemical protection as anode coating.     

Influence of Surface Nano-structured Treatment on Pack Boriding of H13 Steel

In order to lower the boriding temperature of hot work steel H13, method of surface mechanical attrition treatment （SMAT）, which can make the grain size of the surface reach nano-scale, was used before pack boriding. The growth of the boride layer was studied in a function of boriding temperature and time. By TEM （transmission electron microscopy）, SEM （scanning electron microscopy）, XRD （x-ray diffraction） and microhardness tests, the grain size, thermal stability of the nano-structured （NS） surface and the thickness,appearance, phases of the surface boride layer were studied. Kinetic of boriding was compared between untreated samples and treated samples. Results showed that after SMAT, the boride layer was thicker and the hardness gradient was smoother. Furthermore, after boriding at a low temperature of 700℃ for 8 h, a boride layer of about 5 μm formed on the NS surface. This layer was toothlike and wedged into the substrate, which made the surface layer combine well with the substrate. The phase of the boride layer was Fe2B. Research on boriding kinetics indicated that the activation energy was decreased for the treated samples.     

Effect of annealing on grain size and flaring limit of seamless SUS 304 stainless microtubes

Size effects make traditional macroforming generally ineffective for microforming. Although the microtube is one of the most important microparts, the effect of grain size on material behavior has seldom been studied. In this study, seamless SUS 304 stainless microtubes were annealed to investigate their grain growth and to analyze their mechanical properties, including yielding stress and strain-hardening coefficient, by conducting a tensile test. A nano-indentation system, Triboindenter, was employed to measure the reduced modulus and hardness of grain. A flaring system was developed to investigate the relationship between flaring limit and T/D (thickness/average grain size) ratio. The method of fabricating a conical micropunch is also described. The optimal T/D ratio, which enhances the flaring limit, is 9.9.