浸镀铜前处理对铝合金表面Ni-P镀层结构与性能的影响

化学镀Ni-P是提高铝合金表面耐蚀耐磨性的主要方法之一,但施镀前通常要进行前处理,以去除表面氧化膜。以氯化胆碱-乙二醇低共熔体系为溶剂,CuCl2·2H2O为铜源,通过浸镀方法在铝合金表面制备铜层,再后续化学镀NiP,并与未经浸镀前处理和浸锌前处理铝合金表面的化学镀Ni-P层进行对比。利用扫描电子显微镜、X射线衍射、动电位极化及ASTM D3359-93胶带测试法研究了不同前处理方法对Ni-P镀层结构和性能的影响。结果表明:与未经浸镀前处理和浸锌前处理相比,通过浸镀铜前处理的铝合金表面得到的Ni-P镀层呈常规的胞状颗粒结构,腐蚀电位与腐蚀电流分别为-0.343V和2.109×10-6 A/cm2,耐蚀性较好;根据ASTM D3359-93标准,镀层与基底的附着性为5B。     

Photocathodic protection properties of NiP/TiO2 bilayer coatings by a combined electroless plating and sol–gel method

A combined electroless plating and sol–gel method was developed for preparing a NiP/TiO₂ bilayer coating to achieve an especial photocathodic protection effect for A3 low carbon steel. Photocathodic protection properties of the coating were investigated by the electrochemical method. Surface morphology and structure of the coating were characterized by scanning electron microscope (SEM) and X‐ray diffraction (XRD). The results show that the open circuit potential (OCP) of the NiP/TiO₂ coating electrode shifts to ?0.42 V under UV irradiation, which is lower than the corrosion potential of A3 low carbon steel. When the light is turned off, the photocathodic protection effect cannot be maintained. In addition, the mechanism of photocathodic protection for the coating was also explored.     

Microstructure evolution and surface characteristics of NiP and CrN composite coatings under phosphate glasses molding process

The NiP, CrN, NiP/CrN multilayer, and NiPCrN multicomponent composite coatings were fabricated by magnetron co-sputtering. Simulation of molding process on various coating systems was conducted against phosphate glass. The 50 mol.% P₂O₅-50 mol.% ZnO glass was chosen for the molding process due to its low glass transition temperature, T_g, around 400 °C and significant reaction at a high temperature. Phase evolution and surface characteristics of the coatings in the as-deposited and hot-pressed states were analyzed. Smooth surface morphology with a low roughness value below 5.0 nm was observed for the coatings under the hot pressing process. Grain growth and precipitation of the coatings were retarded under loading. Glass sticking behavior occurred in the NiP coating, while severe delamination of NiPCrN multicomponent composite coating was found. On the other hand, single layer CrN and NiP/CrN multilayer coatings showed superior surface and anti-sticking properties against phosphate glasses after the simulated molding process. The feasibility of NiP, CrN, and related composite coatings for phosphate glass molding is discussed.     

选区电化学沉积镍镀层的微观形貌及耐磨性

利用选区电化学沉积技术在45钢基体上沉积镍镀层,并对其进行形貌观察、能谱分析探寻选区电化学沉积镍镀层组织生长规律,并将镀层和基体耐磨性进行了试验对比。结果表明,选区电化学沉积生长过程为由小型颗粒逐步生长堆叠成为致密镀层;晶粒生长呈螺旋式上升堆叠形态,球状晶粒内部和表面存在微裂纹;晶粒间隙处存在氧元素,氧化反应对于小型晶粒之间的相互融合起抑制作用;选区电化学沉积镍镀层结构组织更加致密,镀层组织与基体组织间存在明显的分界线,镀层组织相较于基体材料耐磨性更好。     

硬质合金刀具ZrC涂层的沉积

采用原位卤化反应直接形成的ZrCl4气体作为Zr源,在硬质合金刀具上沉积CVD-ZrC涂层。用SEM,XRD分析检测了合金刀具基底不同表面上沉积生长ZrC涂层的厚度均匀性、沉积速率、形貌组织、织构取向;通过理论计算与工艺实际的涂层沉积转化率对比,定量表征了该沉积体系工艺参数下ZrC涂层的沉积转化率。结果显示,CVD涂层炉内不同位置合金刀片表面沉积的ZrC涂层均匀;由于工艺温度限制,涂层沉积速率较低;ZrCl4转化为ZrC涂层的工艺实际转化率约11%,在理论最大转化率14%范围内;相同温度下随着沉积压力升高,涂层的沉积转化率缓慢降低到10%并趋于稳定;直接在合金基底沉积形成的ZrC涂层为细小的颗粒状形貌,而在合金基底TiN涂层表面上沉积生长的ZrC具有典型的片状组织形貌;对应的涂层生长织构取向从(311)到(111)转变。     

不同工艺参数下超音速等离子喷涂层界面结合行为及其分形特性∗

随着研究不断深入，分形几何可以用来描述涂层的表面形貌和复杂性，分形维数可实现形貌结构的定性描述向定量表征转变。为研究超音速等离子喷涂层界面结合行为与其分形维数之间的关系，采用对比试验研究喷涂距离、喷涂电流等工艺参数对涂层结合界面形貌和结合强度的影响，并引入分形理论对界面结合行为进行定量表征，进而探究结合界面形貌、结合强度、分形维数三者的对应关系。结果表明：相比于喷涂电流，喷涂距离对分形维数的影响更为显著。当喷涂距离为 80 mm 和 100 mm 时，随着喷涂电流从 400 A 增大到 500 A，分形维数呈先减小后增大趋势，最小为 1.115 0；当喷涂距离为 120 mm 时，粒子在等离子焰流中的飞行时间增长，随电流增大，涂层界面分形维数则先增大后减小。界面分形维数与涂层结合强度之间存在着正相关的对应关系。当分形维数在一定范围内呈增大趋势时，涂层 / 基体结合界面处孔隙减少、结合强度增大。 因此，涂层 / 基体结合行为的分形特性研究对评价涂层质量具有重要意义。     

涂层风沙冲蚀损伤表面分形维数预测模型

目的 建立涂层风沙冲蚀损伤表面分形维数预测模型,重构冲蚀损伤表面形貌,为涂层风沙冲蚀损伤表面形貌研究提供基础。方法 进行了聚氨酯防腐面漆涂层风沙冲蚀损伤试验,建立了多粒径粒子冲击模型,利用赫兹接触理论求解冲击损伤面积及其分布概率,分析表面损伤的演化规律得到损伤面积增长迭代关系式,结合分形分布理论求解损伤表面分形维数,分析不同参数对理论模型的影响。利用理论模型重构损伤表面形貌、预测表面分形维数并与试验结果进行对比分析。结果 冲蚀试验中,随冲蚀时间、角度的增加,随机均匀分布的损伤区域逐渐叠加联通,分形维数也随之增大;表面分形维数存在最大值,斜角度下单粒子冲击损伤区域为彗星形。理论模型中,主导粒子粒径越大,分形维数初期增长速度越慢;冲击损伤面积越大,分形维数初期增长速度越快;损伤尺度系数越大,分形维数最大值越大;冲蚀前损伤面积越大,初始分形维数越大。对比理论模型与试验结果,重构损伤表面形貌损伤演化规律与试验结果相似,表面形貌余弦相似性及分形维数相关性系数均大于0.9。结论 通过分析固体粒子冲蚀现象特点和试验结果,发现风沙冲蚀是非线性的反馈的动力学系统,涂层冲蚀表面形貌具有迭代的损伤演化过程。...     

C掺杂TiAlN涂层的硬度演变机理EI北大核心CSCD

C元素掺杂TiAlN涂层的增硬机理尚不明确,为了揭示C元索对涂层硬度的作用规律,采用阴极电弧离子镀膜技术在316不锈钢表面制备C原子比率分别为0%、3.87%、9.24%、14.76%、20.57%、25.90%的TiAlCN涂层,通过试验研究和密度泛函理论系统地从原子量级角度阐述C掺杂对涂层硬度的作用规律及机理。研究结果表明:C原子会置换TiAlN晶胞中的部分N原子形成TiAlCN固溶体相:随着C含量的增加,涂层硬度呈现先上升后下降的趋势,在C含量为14.76%时,涂层中Ti-N键转化成为Ti-C键的数量达到饱和,硬度达到最高值31.60GPa;当C原子含量高于14.76%时,涂层中出现类石墨结构,且随着C含量的增加,sp^(2)层状结构增多,在抵抗外界压力时石墨层发生侧滑,涂层硬度降低;第一-性原理数值模拟结果显示,随着C含量从0%增加到15.625%,涂层硬度逐渐上升是由于共价性较强的Ti-C键逐渐增加。阐明C元素掺杂对涂层硬度的作用变化规律,有利于指导超硬涂层的工艺设计和生产。     

Effect of alloy microstructure on electroless NiP deposition behavior on Alloy AZ91

Various magnesium alloys, which were assumed as reference to the individual behavior of each microstructural constituents of Alloy AZ91 in the coating bath, were designed to analyze the hypophosphite-reduced electroless nickel coating characteristics on them in both uncoupled and coupled conditions. Galvanic coupling of β phase to the matrix phase in the coating bath was observed to decelerate the deposition rate on the matrix phase. This behavior was attributed to the effective cathodic action of β phase in the coating bath as a result of the catalytic cathodic reactions on it. The variation in the Al content of the matrix phase was also estimated to affect the NiP deposition behavior due to the small scale galvanic interactions. The previously Ni nucleated sites on the alloy surface behaved as the most preferential sites for further Ni nucleation and growth. Low temperature heat treatment (230 °C for 2 h) caused a considerable increase in the surface hardness with negligible decrease in the corrosion resistance. High temperature heat treatment (400 °C for 1 h) improved the surface hardness further with significant deterioration in the corrosion resistance.     

氢、氧原子刻蚀CVD金刚石涂层石墨相的机理研究

采用第一性原理分子模拟计算方法对氢、氧原子刻蚀石墨相的过程进行分子动力学仿真，分析了2种原子在石墨相上的吸附过程及刻蚀反应的反应热和反应能垒。结果表明:氧原子在石墨相表面的吸附能强于氢原子吸附能，同时氧原子的化学反应活性大于氢原子的，更容易在石墨结构表面发生电子转移反应；氢原子促使石墨相表面的C—C键断裂需要两步反应，而氧原子则只需要一步反应，氢原子刻蚀石墨相的反应能垒比氧原子的高，所需能量更多。同时，通入含氧气源可以有效降低CVD金刚石涂层的沉积温度，提高金刚石涂层的质量。      

ZM5镁合金无铬前处理化学镀镍层的性能

采用优化的Na4P2O7+Na2SO4+NaNO3体系的化学蚀刻无铬前处理化学镀镍工艺,在ZM5镁合金上制备Ni-P镀层。利用扫描电镜、能谱仪、X射线衍射仪分析镀层的微观形貌、成分和相结构。通过电化学方法和摩擦磨损试验评价了镀层的耐蚀性和耐磨性。结果表明:无铬前处理工艺制备的镀层中P的质量分数为12.90%。与ASTM标准的含铬前处理工艺得到的镀层的耐蚀性和耐磨性相比,无铬前处理得到的镀层的自腐蚀电位为-0.506V,腐蚀电流密度为2.132×10-6 A/cm2,接近ASTM工艺含铬前处理得到的镀层的耐蚀性能;同时其磨损率为3.056×10-4 mg/s,与ASTM工艺的1.778×10-3 mg/s相比,其抗摩擦磨损性能明显优于含铬前处理的镀层。无铬前处理化学镀镍显著提高了ZM5镁合金的耐蚀性和耐磨性。     

Corrosion under mixed flowing gas conditions of various connector coatings

This paper presents an investigation on the corrosion performance of Ni/Au, NiP/Au, Ni/NiP/Au and Ni/NiPd/Au electrical connector coating systems. The coating systems were exposed to 10 days Class III mixed flowing gas and were subsequently examined by X‐ray diffraction, focused ion beam microscopy, scanning electron microscopy and energy dispersive spectroscopy to evaluate the performance of each coating system. The Ni/Au coating system showed the worst performance followed by NiP/Au and Ni/NiP/Au. The Ni/NiPd/Au coated connector materials exhibited the least surface corrosion and this was attributed to a number of factors including a thicker coating system, more compact gold layer with fewer defects and a reduction in the electrochemical potential difference between layers reducing the local cell effect.     

铝合金表面电火花沉积层组织与性能

采用电火花沉积技术,以硅青铜作为电极,在空气中对2A12铝合金表面进行了强化.采用扫描电镜、电子能谱分析仪与X射线衍射仪等仪器对沉积层的形貌、组织、元素分布和结构进行了分析与研究;利用显微硬度计和磨损试验机对沉积层的显微硬度与耐磨性进行了测试.结果表明,沉积层连续、致密,与基体呈冶金结合,无明显界面;主要由铜铝金属间化合物组成,显微硬度可达578 HV;沉积层耐磨性较基体显著提高,表面强化效果明显.     

Influence of Deposition Temperature on the Microstructures and Properties of Plasma-Sprayed Al2O3 Coatings

Al₂O₃ coatings were deposited on 1Cr13 substrates by atmospheric plasma spraying at different deposition temperatures of 140, 275, 375, 480, 530, and 660 °C to investigate the effect of coating surface temperature on the lamellar bonding formation. The fractured cross section morphology was characterized by scanning electron microscopy to reveal the lamellar interface bonding. X-ray diffraction was used to characterize the phase contents in the coating. Micro-hardness, Young??s modulus, and thermal conductivity of the deposits were measured for examining the dependency of coating properties on its microstructure. The results show that the interface area bonded through columnar grain growth across splat-splat interfaces was increased with increasing deposition temperature. Moreover, micro-hardness, Young??s modulus and thermal conductivity were increased with the increase of deposition temperature. However, the phase structure of the coating changed little with deposition temperature. The results evidently indicate that the apparent bonding ratio and properties of deposits can be significantly changed in a wider range through controlling the deposition temperature.     

沉积温度对高功率脉冲磁控溅射AlCrSiN涂层结构和性能的影响*

采用高功率脉冲磁控溅射(HiPIMS)技术在不同沉积温度下制备了Al-Cr-Si-N涂层。系统研究了沉积温度对涂层结构、成分、显微形貌、力学和摩擦学性能的影响。结果表明:随着沉积温度由100℃升至350℃,涂层内部开始由非晶向纳米晶转化,300℃时出现fcc-AlN相;涂层平整性和致密性逐步改善,膜/基结合强度逐渐提高,在300℃达到最大值77 N,但温度继续升高至350℃时,严重的轰击刻蚀作用使临界载荷骤降至25 N;涂层硬度逐渐增加,在350℃达到最大值19.4GPa;涂层内应力整体呈下降趋势,由–0.8 GPa逐渐降低至–0.4 GPa左右。     

Effects of processing conditions on the mechanical properties and deformation behaviors of plasma-sprayed thermal barrier coatings: Evaluation of residual stresses and mechanical properties of thermal barrier coatings on the basis of in situ curvature measurement under a wide range of spray parameters

A modified analytical model has been developed to describe the nonlinear elastic response and residual stress in plasma sprayed thermal barrier coatings (TBCs) on the basis of the measured curvature–temperature plot during the spraying process. Evolution of residual stresses and the nonlinear stress–strain relation of the coating during the cooling stage after deposition were identified and the strain-dependent coating modulus was obtained. Wide ranges of deposition temperature from 200 to 850 °C as well as that of passage thickness from 6 to 58 μm were explored in the experiments because significant changes in the TBC microstructure could be expected. The analyzed results were related to the processing parameters in spraying, such as the substrate temperature and passage thickness. A complicated interplay among the coating microstructure, residual stresses and mechanical properties was identified. Generally with increasing deposition temperature or passage thickness, denser microstructures were observed with an increase in elastic modulus. The nonlinear strain–stress curves of TBCs indicated that the coating modulus increased with compressive residual stress due to closing of microcracks and inter-splat sliding. Moreover, the coating modulus depended not only on the magnitude of residual stress but also on the coating thickness and it was found that the axial force, which is the product of the residual stress and coating thickness, could be used to express their synergistic effect.     

空心玻璃微珠表面化学镀镍磷合金

以胶态钯为活化液对空心玻璃微珠表面化学镀镍工艺进行了研究.通过环境扫描电镜(ESEM)和能谱分析(EDS)分别对微珠镀镍前后的形貌进行了观察、对镀层成分进行了测试,并对微珠施镀装置进行了设计.结果表明:利用该工艺可在微珠表面形成光滑、均匀的Ni-P镀层,且在微珠间无散落的镀层金属颗粒存在;采用液体搅拌促进镀液循环,有利于微珠的悬浮和分散,并提高镀液的稳定性,为空心玻璃微珠表面的金属化提供了一个简单易行的工艺.     

化学镀 Ni-Mo-P 合金镀层的组织结构与防垢性能研究

目的采用材料测试方法和防垢实验,研究不同工艺条件下的化学镀Ni-Mo-P合金镀层的组织结构与防垢性能。方法在化学镀Ni-P镀层基底上,添加含有钼酸根离子杂多酸盐,在不同工艺条件下化学沉积Ni-Mo-P合金镀层,研究化学镀Ni-Mo-P合金镀层的表面形貌和组织结构,分析镀液中硼酸含量和钼酸铵含量对镀层沉积速率的影响,观测镀层在结垢实验后的表面形貌并分析结垢速率。通过SEM,XRD和EDS对化学镀Ni-Mo-P合金镀层的表面形貌和组织结构进行检测,研究在酸性镀液中硼酸含量对化学镀Ni-Mo-P工艺条件的影响。采用防垢实验测试化学镀Ni-Mo-P合金镀层的防垢性能。结果在化学镀Ni-Mo-P过程中,钼酸根离子杂多酸盐具有稳定作用。化学镀Ni-Mo-P合金镀层的化学沉积镀液的最佳工艺条件为:Ni SO4·6H_2O 16.5 g/L,Na H_2PO_2·H_2O 20 g/L,钼酸钠0.5~0.8 g/L,硼酸2 g/L,乙酸钠7.5 g/L。化学镀Ni-Mo-P合金镀层的结垢速率明显低于化学镀Ni-P镀层,具有良好的防垢能力,形成了非晶态的镀层。结论采用化学镀Ni-P镀层基底上沉积得到非晶态的Ni-Mo-P合金镀层,硼酸具有调节镀液p H值和络合作用,非晶态的Ni-Mo-P合金镀层平均结垢速率最小值为0.58μm/h,具有良好的阻垢能力。     

医用镁合金表面激光重熔羟基磷灰石涂层

为提高医用镁合金的表面耐蚀性和生物相容性,采用等离子喷涂和激光重熔复合技术在镁合金表面制备羟基磷灰石(HA)生物涂层。研究结果表明,所制备的羟基磷灰石涂层为短杆状堆积结构,主要由HA和β-TCP相组成;涂层的弹性模量约为50 GPa,较已临床应用的医用金属材料显著降低,显微硬度约为455 HV,具有较好的耐磨性。涂层在模拟体液中具有很好的耐蚀性,在腐蚀12 d后涂层表面形貌仍然较完整,无腐蚀孔洞出现。钙磷沉积实验结果表明,涂层表面形成一层新的生物磷灰石层,表明涂层具有较好的骨诱导性。     

The Influence of the Coating Deposition Process on the Interdiffusion Behavior Between Nickel-Based Superalloys and MCrAlY Bond Coats

In this work, interdiffusion between two nickel-based superalloys and two MCrAlY bond coats is investigated. The MCrAlY bond coats were applied using two different spraying processes, high velocity oxygen fuel spraying (HVOF) and low-pressure plasma spraying. Of primary interest is the evolution of Kirkendall porosity, which can form at the interface between substrate and bond coat and depends largely on the chemical compositions of the coating and substrate. Experimental evidence further suggested that the formation of Kirkendall porosity depends on the coating deposition process. Formation of porosity at the interface causes a degradation of the bonding strength between substrate and coating. After coating deposition, the samples were annealed at 1050 °C for up to 2000 h. Microstructural and compositional analyses were performed to determine and evaluate the Kirkendall porosity. The results reveal a strong influence of both the coating deposition process and the chemical compositions. The amount of Kirkendall porosity formed, as well as the location of appearance, is largely influenced by the coating deposition process. In general, samples with bond coats applied by means of HVOF show accelerated element diffusion. It is hypothesized that recrystallization of the substrate material is a main root cause for these observations.