工艺参数对脉冲电沉积Ni-TiN纳米镀层微观组织和性能的影响

电沉积技术是一种方便、高效、低成本制备金属基纳米镀层的方法,其工艺参数直接决定金属基纳米镀层的微观组织及性能。为系统研究电沉积工艺参数对金属基纳米镀层表面形貌、显微组织、力学性能及耐磨损性能的影响规律,本实验采用脉冲电沉积制得Ni-TiN纳米镀层,并利用透射电镜(TEM)、原子力显微镜(AFM)、X射线衍射仪(XRD)、摩擦磨损试验机研究了工艺参数对Ni-TiN纳米镀层的显微结构、显微硬度和性能的影响。结果表明,当电流密度为4A/dm~2时,Ni-TiN纳米镀层的显微硬度为984.7HV,TiN微粒复合量为8.69%(质量分数)。采用不同脉冲频率制得的Ni-TiN纳米镀层,其晶面原子呈现不同方向的面心立方晶格结构。当脉冲频率为200Hz时,Ni-TiN纳米镀层中Ni和TiN的平均粒径分别为87.2nm和34.6nm。当脉冲占空比为20%时,Ni-TiN纳米镀层的显微硬度为980HV,其平均磨损量为7.56mg/mm2。     

汽车齿轮钢电沉积Ni-TiN镀层的制备及耐磨性研究

采用直流电沉积、脉冲电沉积和超声波脉冲电沉积方法,在汽车齿轮钢20CrMnTi表面制备Ni-TiN镀层。利用扫描电镜、X射线衍射仪、显微硬度计及摩擦磨损试验机等研究Ni-TiN镀层的微观组织、显微硬度和耐磨性能。结果表明,在超声脉冲电沉积获得的Ni-TiN镀层中,金属晶粒得到显著细化,组织结构最为致密,且TiN纳米微粒均匀分布于镀层中,Ni晶粒和TiN微粒的平均粒径分别为76.5和41.4nm。当电沉积时间为50min时,直流电沉积、脉冲电沉积和超声脉冲电沉积制得的Ni-TiN镀层显微硬度分别为841,882和923 Hv,超声波脉冲电沉积Ni-TiN镀层的耐磨性最优。     

汽车轴承用GCr15钢表面制备Ni-TiN纳米镀层研究

采用超声波辅助电沉积方法在GCr15钢表面制备了Ni-TiN纳米镀层,并利用摩擦磨损试验机、显微电子天平、扫描电镜、X射线衍射仪等仪器对Ni-TiN纳米镀层的磨损量、表面形貌及物相组成情况进行分析。结果表明,当超声波功率为150 W时,镀层磨损量达到最小值1.1 mg。Ni-TiN纳米镀层的平均显微硬度为648.5 Hv,其平均摩擦因数约为0.45。Ni-TiN纳米镀层主要存在Ni、Ti、N等元素,且Ni元素衍射角分别位于44.8,52.2和76.8°处,TiN粒子的衍射角位于36.7,42.6和61.8°。     

超声波对纳米Ni-TiN复合镀层的影响

采用超声-电沉积的方法制备纳米Ni-TiN复合镀层.利用原子吸收分光光度计(AAS)、高分辨率电子显微镜(HRTEM)和X射线衍射仪(XRD)研究超声波对复合镀层含量、显微组织及微观结构的影响.结果表明,超声波的引入,不仅能提高复合镀层中纳米TiN粒子的含量,还能明显改善显微组织结构,细化晶粒.在超声波功率为200W时,镀层中粒子含量达到最大值9.9%.     

用BP神经网络模型预测Ni-TiN镀层的耐腐蚀性能

采用脉冲电沉积方法,在45钢表面制备NiTiN镀层。采用X射线衍射仪和扫描电镜对Ni-TiN镀层进行组织结构和表面形貌分析,利用BP神经网络模型对Ni-TiN镀层的耐腐蚀性能进行预测。结果表明,在Ni-TiN镀层中存在Ni和TiN相。衍射角2θ=44.80,52.23和76.75°分别对应于镍晶面的(111)、(200)和(220);而衍射角2θ=36.63,42.62和61.79°则分别对应于TiN晶面的(111)、(200)和(220)。在TiN粒子浓度一定时,大电流密度和小占空比脉冲电沉积可获得表面致密、光滑,腐蚀坑较小的镀层。3×8×1型神经网络模型的预测结果与实测结果相差不大,最大误差为4.1%。     

热处理温度对纳米Ni-TiN复合镀层的影响

恰当的热处理工艺参数是提高纳米Ni-TiN复合镀层性能的关键因素。采用超声-脉冲电沉积的方法制备了纳米Ni-TiN复合镀层,分析了热处理温度对Ni-TiN复合镀层的表面形貌、显微硬度、耐磨性能以及结合强度的影响规律。研究表明:热处理温度对镀层的耐腐蚀性和镀层与基体的结合力都有重要的影响,当热处理温度为400℃时,纳米Ni-TiN复合镀层不仅具有平整的表面,而且具有优良的耐腐蚀性;而镀层的结合强度在300℃时最佳。     

热处理对纳米Ni-TiN复合镀层摩擦磨损性能的影响

采用超声-电沉积的方法制备了纳米Ni-TiN复合镀层。测试了不同热处理温度下纳米Ni-TiN复合镀层的硬度和磨损量,对镀层的摩擦磨损性能进行了分析。结果表明,热处理温度在300℃时纳米Ni-TiN复合镀层的硬度和耐磨性能最佳,硬度为932.28HV,磨损量为13.5mg;复合镀层的摩擦系数随着热处理温度的升高而略有增大。     

脉冲电沉积纳米Ni-TiN复合镀层

为了改善基体的耐磨性能,采用脉冲电沉积法,在不锈钢基体上制备纳米Ni-TiN复合镀层.研究了TiN粒子浓度、电流密度及搅拌速度等对复合镀层磨损量的影响.利用高分辨电子显微镜对复合镀层进行观察,并进行腐蚀试验测试.结果表明:纳米Ni-TiN复合镀层的最佳工艺参数为TiN粒子的浓度4 g/L,电流密度4 A/dm2,搅拌速度2000 r/min.在纳米Ni-TiN镀层中,纳米TiN粒子的直径均不超过50 nm,镍晶粒得到细化;且该复合镀层具有优良的耐腐蚀性.     

基于RBF神经网络的镍基TiN纳米复合镀层显微硬度预测

针对神经网络在预测复合镀层性能方面的应用情况,以及传统的BP神经网络存在缺陷;通过对RBF神经网络的基本原理和特点的研究,建立了利用RBF神经网络对Ni-TiN纳米复合镀层显微硬度进行预测的模型。通过实验数据验证了所建立的RBF神经网络模型具有很高的精确度,其最小相对误差可达0.62%,而且所建立的预测模型具有优化工艺参数的功能,对复合镀层的其它性能进行预测具有指导意义。     

多场耦合参数对电沉积Ni-TiN纳米镀层性能的影响

利用多场耦合电沉积技术制备Ni-TiN纳米镀层,获得良好的高硬度、耐磨性好的复合镀层材料。研究多场耦合沉积的主要参数阴极电流密度、超声波功率和磁场强度对显微硬度、耐磨性的影响。结果表明,随镀液中磁场强度、阴极电流密度和超声波功率的增加,Ni-TiN纳米镀层中的显微硬度呈先增加后减小的变化趋势,而镀层的磨损量与之相反。多场耦合电沉积的最优工艺参数组合为阴极电流密度1.5 A/dm~2、超声波功率200 W、磁场强度0.6 T。在最佳工艺参数下制备的Ni-TiN纳米镀层表面粗糙程度较小,晶粒较细致,组织均匀度较好。     

铝合金Ti(C,N)/TiN多元多层膜与阳极氧化膜性能比较

分别采用多弧离子镀技术及阳极氧化技术在LF6防锈铝基体表面制备了Ti(C,N)/TiN/Ti(C,N)/TiN/ Ti(C,N)/TiN六层多元多层膜及阳极氧化膜,并对比考察研究了该两种膜的力学性能和摩擦学性能,结果表明:多元多层膜与阳极氧化膜划痕临界荷载分别为76N,60N;显微硬度分别为HV0.251404,HV0.25520;二者摩擦系数都较高,分别为0.66,0.76;都使对偶件磨损;但与传统的阳极氧化膜相比,多元多层膜硬度与耐磨性都提高了近2倍,且其摩擦曲线平滑,呈稳定磨损状态,而阳极氧化膜摩擦曲线呈跳跃状,呈非稳定磨损状态.     

Hydrogen sorption-desorption characteristics of mixed and composite NiTiN nanoparticles

Mixed and composite NiTiN nanoparticles were prepared by an active plasma-metal reaction method. Homogeneous distribution of spherical Ni and cubical TiN nanoparticles is observed for the mixed NiTiN nanoparticles. Dumbbell-like morphology is seen for the composite NiTiN nanoparticles. Good thermal stability of both nanoparticles is confirmed. Hydrogen sorption-desorption characteristics of the nanoparticles were examined by temperature-programmed desorption measurements. Hydrogen desorption at 620–680 K is observed for the composite NiTiN nanoparticles, that is considered to be due to the spillover hydrogen. Effect of CO coadsorption on the hydrogen desorption is also examined and new adsorption states are suggested.     

Effects of Ni and TiN Coatings on the Alumina/Heat-Resistant Steel Interface Properties

Ni and TiN coatings on alumina particles were achieved using a chemical vapor deposition (CVD) method. The coated alumina was then used as raw materials to prepare alumina/heat-resistant steel (HRS) composites. The effects of Ni/TiN coatings on the alumina/HRS interface strength and oxidation resistance at elevated temperature were investigated. It is found that the both coatings can improve the alumina/HRS interface bonding strength and Ni coating has a more significant effect. For the composite made from Ni-coated alumina and HRS, the interface exhibited a better oxidation resistance due to the dissolution of Ni coating into the HRS matrix. However, the composite of TiN-coated alumina/HRS has a poor oxidation resistance behavior because TiN still existed on the alumina/HRS interface.     

Improvement of heavy dopant doped Ni-silicide using ytterbium interlayer for nano-scale MOSFETS with an ultra shallow junction

In this paper, a novel Ni silicide with Yb interlayer (Yb/Ni/TiN) on a boron cluster (B18H22) implanted source/drain junction is proposed for the first time, and its thermal stability characteristics are analyzed in depth. The proposed Ni-silicide exhibits a wider RTP temperature window for uniform sheet resistance, surface roughness and better thermal stability than the conventional structure (Ni/TiN). In addition, the cross-sectional profile of the proposed Ni-silicide showed less agglomeration despite the high temperature post-silicidation annealing, and it can be said that the proposed structure was little dependence on the temperature post-silicidation annealing. The improvement of Ni silicide properties is analyzed and found to be due to the formation of the rare earth metal--NiSi (YbNi2Si2), whose peaks were confirmed by XRD. The junction leakage current of the p + -n junction with Yb/Ni/TiN and B18H22 implantation is smaller than that with Ni/TiN by almost one order of magnitude as well as improving the thermal stability of ultra shallow junction.     

制取带中间层的Al2O3+ N i 复合材料的工艺研究

为了制取Al₂O₃+ Ni 复合材料, 首先用化学汽相沉积(CVD) 法在Al₂O₃颗粒表面镀TiN。用SEM (扫描电镜) 和EDX (能谱) 分析镀层的均匀性。用X 射线荧光光谱法分析粉末的Ti 含量。然后用热压法制取这种金属陶瓷复合材料。由于TiN 中间层的存在, 复合材料的致密化和力学性能获得明显改善      

Co-Induced Low-Temperature Silicidation of Ni Germanosilicide Using NiPt Alloy and the Effect of Ge Ratio on Thermal Stability

In this paper, novel Ni germanosilicide technology using NiPt alloy and Co overlayer has been proposed. Using the Co overlayer after NiPt deposition on Si_1-xGe_x, the formation temperature of low resistive Ni germanosilicide is lowered with high thermal stability. The thermal stability of Ni germanosilicide with different Ge fraction in is also characterized. The sheet resistance degrades as increasing the Ge fraction (x) in Si_1-xGe_x when NiPt/TiN is used. However, using the Co overlayer, the sheet resistance property among Ni germanosilicide formed with different Ge fraction is improved greatly compared with those of NiPt/TiN case (without Co overlayer). Therefore, low-temperature formation of highly thermal robust Ni germanosilicide can be achieved through the NiPt/Co/TiN tri-layer.     

Some applications of the Hall-Petch Relationship for single-phase imperfect polycrystals

In this article, the modified Hall-Petch Relationship (HPR) theory is considered further to explain an anomaly that arises in the case of nanocrystals. Strength of the material decreases as grain size decreases if the grain size is below a critical dimension. This is referred to as the “negative slope effect” in the HPR (i.e., K < 0). This effect is rationalized with the proposed revision to the HPR. A new modified HPR equation to characterize microhardness has also been derived. The new approach has been applied to films of TiN, TiC, TaC, and WxC on glass substrates and to -brass. The calculated microhardnesses of the films are compared with experimentally measured data.     

Interdiffusion at the TiN/Ni interface in the cermet composed of TiN and Ni

In order to investigate the interdiffusion at the TiN/Ni interface in the cermets based on Al2O3 and nickel with a TiN interlayer, an independent experiment was designed and carried out. Pure TiN powder and pure nickel powder were selected as the starting materials. The cermet composed of TiN and nickel was manufactured by the powder metallurgy process including cold compacting and pressureless sintering at various temperatures in vacuum. During sintering, titanium atoms diffuse into nickel lattices forming homogeneous solid solution. This leads to the expansion of the lattice constant. The higher the sintering temperature, the more titanium atoms dissolve, and the more obvious is the expansion which occurs. Only a small amount of nickel diffuses into TiN and dissolves in it. The amount of the nickel is so small that the X-ray diffraction patterns show a stable crystal structure of TiN. © 1998 Kluwer Academic Publishers     

多元氮化物薄膜及其沉积工艺对NiTi记忆合金性能和组织的影响

采用真空阴极电弧沉积技术,在NiTi记忆合金表面沉积了TiAlBN和TiAlCrFeSiBN多元膜和TiN薄膜,研究了薄膜成份及沉积工艺对NiTi合金性能和组织的影响.结果表明,在NiTi合金表面沉积TiAlBN和TiAlCrFeSiBN多元膜和TiN薄膜均可降低合金在Hank溶液中的Ni溶出速率,其中多元膜的Ni溶出速率最小;提高偏压对沉积了TiAlBN多元膜的NiTi合金的Ni溶出速率无明显影响,但使沉积了TiAlCrFeSiBN膜的NiTi合金的Ni溶出速率降低.在TiAlBN和TiAlCrFeSiBN多元膜表面存在较多细小的钛滴和孔隙,钛滴与薄膜基体之间的融合良好;在TiN薄膜表面存在一些大钛滴和孔隙,钛滴与薄膜基体之间的融合不好.镀膜后,NiTi基体的加热相变点移向低温区,其幅度与薄膜成份及沉积工艺有关,提高偏压使沉积了两种多元膜的NiTi基体的相变点移动幅度增大,但却使沉积了TiN膜的NiTi基体的相变点的移动幅度减小.镀膜过程均使NiTi中的M体尺寸增大.