氮化钛沉积膜的摩擦性能研究

采用等离子电弧沉积法在9Crl8钢表面制备了厚约0．5μm的TiN薄膜，通过显微硬度测试以及纳米压痕和纳米划痕试验，对比考察了9Crl8钢及其表面T|N薄膜的机械和摩擦性能．结果表明，9Crl8钢及其表面T．N沉积膜的纳米硬度分别为8GPa和38GPa，弹性模量分别为250GPa和580GPa，9Crl8、TiN和有机薄膜的摩擦系数分别为0．40、0．12和0．10；TiN沉积膜可显著提高基体钢的承载和耐磨能力．     

真空磁过滤电弧离子镀法制备DLC膜的机械性能

采用真空磁过滤电弧离子镀法分别在9Cr18和40CrNiMo钢上沉积厚约为0.2μm的类金刚石（DLC）膜。为了检测成膜质量，分别使用纳米压痕和纳米划痕技术表征钢基材和DLC/基材的机械性能，对这种亚微米厚的膜，纳米压痕技术和纳米划痕技术能提供丰富的近表面的弹塑性变形，断裂和摩擦等的信息。同DLC/40CrNiMo相比。DLC/9Cr18的硬度高和固体润滑效果显著，9Cr18是较为理想的基体材料。     

碳化硅薄膜的力学性能测试分析

对利用射频磁控溅射及真空退火方法在(100)硅晶片衬底上制备的纳米晶碳化硅(SiC)薄膜,用纳米压痕仪进行了力学性能测试分析。纳米压痕技术测试给出两块SiC薄膜样品I和II的弹性模量/硬度分别约为106GPa/9.5GPa和175GPa/15.6GPa。纳米划痕技术测试两块SiC薄膜的摩擦系数分别约为0.02~0.15和0.05~0.18,显示出良好的润滑性能;对薄膜的临界附着力等进行测量以评价膜基结合强度,分析了划痕过程中薄膜近表面弹塑性变形和断裂信息。在原子力显微镜下对SiC薄膜样品的初始表面及残余压痕和划痕形貌进行了观察分析,与测试结果相符。综合比较,样品II的整体性能优于样品I。本文中薄膜的弹性模量和硬度值较低可归因于制膜技术的不同和表层碳含量偏高。     

磁过滤多弧离子镀C/C多层膜在模拟体液中的微磨粒磨损行为

采用磁过滤直流阴极真空弧源沉积技术在Ti6Al4V表面制备C/C多层DLC膜,利用纳米压痕划痕仪测试薄膜的纳米硬度和膜-基结合强度,采用微磨粒磨损试验机对C/C多层DLC膜在模拟体液环境中的磨损性能进行评价,并与Ti6Al4V的耐磨性能进行对比.结果表明:C/C多层DLC膜硬度达54.82 GPa,弹性模量和划痕临界载荷分别为342.27 GPa和0.52 N;在模拟体液环境中DLC膜的耐磨性能显著优于Ti6Al4V合金,DLC膜的磨损机制主要包括二体磨损及混合磨损;随着料浆浓度的增加,DLC膜的磨损机制从二体磨损向混合磨损过渡.     

脉冲直流等离子体增强化学气相沉积Ti—Si—N纳米薄膜的摩擦磨损特性

采用工业型脉冲等离子体增强化学气相沉积设备，通过调节氯化物混合比例控制薄膜成分，在高速钢基材表面于550℃下沉积由纳米晶TiN和纳米非晶Si3N4组成的Ti—Si—N复合薄膜；采用扫描电子显微镜、透射电子显微镜、X射线衍射仪及X射线光电子能谱仪分析了薄膜的结构、组成和化学状态；采用球-盘高温摩擦磨损试验机考察了薄膜同GCrl5钢对摩时的摩擦磨损性能．结果表明：薄膜的Si含量在0％～35％范围内变化，随着Si含量增大，薄膜沉积速率增大，但薄膜由致密形态向大颗粒疏松态过渡；薄膜的晶粒尺寸为7～50nm；Ti—Si—N薄膜的显微硬度高于TiN的硬度，最高可达60GPa；引入少量Si可以显著改善TiN薄膜的抗磨性能，但薄膜的摩擦系数较高(室温下约0．8、400℃下约0．7)；随着Si含量的增加，Ti—Si—N薄膜的耐磨性能有所降低，其原因在于引入导电性较差的Si元素使得薄膜的组织变得疏松．     

磁控溅射制备BCN薄膜纳米力学和摩擦磨损行为的研究

利用直流磁控溅射技术制备三元BCN薄膜，通过改变N2／Ar流量比（0．0～0．3）得到不同含氮量的薄膜．采用X射线光电子能谱仪和傅立叶红外光谱仪分析薄膜的成分和结构，采用纳米压入仪分析薄膜的纳米力学性能和纳米摩擦磨损特性，分别采用连续刚度测量法和横向力测量法测试薄膜的硬度和划痕行为．结果表明：薄膜中氮含量随N2／Ar流量比增加而增大并趋于稳定；反应气体中的氮优先与硼结合生成B—N键，当N2／Ar流量比超过一定值后，部分氮与碳结合生成C=N键；薄膜的纳米硬度和弹性模量随薄膜中氮含量的增加而下降；BCN薄膜的划痕深度与薄膜的结构密切相关，而摩擦系数受薄膜结构的影响不明显；在相同载荷下薄膜的划痕深度随薄膜中氮含量增加而增大；对于同一试样，薄膜在未破裂之前摩擦系数基本保持在0．10左右，薄膜破裂后摩擦系数迅速增至0．46．     

微纳米尺度膜/基结构界面性能的实验研究

为了研究铜膜/有机玻璃结构的界面性能,首先对沉积在有机玻璃基底上300nm厚的铜膜进行了单轴压缩实验,部分区域的薄膜因屈曲而脱离基底。选择在膜/基粘接良好区域、膜/基脱粘区域分别进行等位移纳米压痕实验。利用膜/基粘接良好区域处硬度/弹性模量与压痕位移的关系来确定膜/基结构的临界脱粘位移。基于宏观力学中表征界面性能的能量法,利用两个区域等位移的塑性功差值来确定界面能量释放率。研究结果表明:当压痕位移约450nm时,膜/基结构开始出现界面脱粘,实验测得铜膜/有机玻璃结构的界面能量释放率值在6.81~10.32J/m2之间。     

分子沉积膜纳米压痕过程的分子动力学模拟

在利用联合原子模型并考虑静电力作用的基础上，采用分子动力学模拟方法研究了金探针作用下分子沉积膜的纳米压痕过程，并对其纳米力学行为进行了理论分析．结果表明，分子沉积膜在探针压下过程中出现了明显的接触跳跃现象，探针下面的膜的分子倾角和法向载荷呈现出相同的滞后趋势，这可能是探针和分子沉积膜之间粘着力作用的结果．     

Ag—Cu／Ti纳米双层膜结合强度测试方法研究

用粘结法（拉伸法，扭转法，断裂力学方法等）和划痕法分别测试了Ag-Cu/Ti纳米双层膜的结合强度，并对其实验结果进行了分析，对比和讨论。结果表明，粘结法由于受胶粘剂粘结强度的限制，只能适用于中低结合强度测试；划痕法适用于软金属薄膜结合强度测试，尤其对高结合强度的薄膜特别有效，而且能测出双层膜及多层膜中膜－膜界面的结合强度和膜基界面的结合强度。     

纳米SiO2颗粒增强镍基复合镀层的组织与微动磨损性能研究

采用电刷镀技术在45#钢表面制备了纳米SiO2颗粒增强镍基复合镀层,用扫描电子显微镜和透射电子显微镜观察分析了复合镀层的表面形貌和微观组织形貌,用纳米压痕仪测试了复合镀层的微观力学性能,并采用PLINT型高温微动疲劳试验机考察了复合镀层在室温至500 ℃下的微动磨损行为.结果表明:纳米SiO2颗粒促进了镀层的晶粒细化,提高了镀层的力学性能,复合镀层的硬度和弹性模量分别比镍镀层提高了2.01GPa和5 GPa,从而改善了镀层的微动磨损性能;复合镀层的耐磨性能约为镍镀层的2倍,这是由于纳米SiO2颗粒对复合镀层具有超细晶强化、硬质点弥散强化以及高密度位错强化机制所致.     

山东龙口北皂煤矿软岩力学特性实验研究

根据室内实验结果, 本文讨论了北皂煤矿的岩石力学性质, 物化特性。泥质岩类的力学性质和水理性质、物化特性有关。泥质岩类具有显著的流动变形和各向异性。     

在役设备材料弹塑性力学参数测定方法综述--小冲杆实验力学研究进展之一

20多年以来,采用小型试件的小冲杆试验技术来测量在役设备材料的各种力学参数已经取得了很大进展,这个方法已经用来确定材料的弹性模量、屈服强度、塑性性能、抗拉强度、韧一脆转变温度、断裂韧度、蠕变性能和黏塑性性能等各种力学性能。由于从小冲杆试验的测量结果来确定材料的力学性能是一个反问题,因此,与此有关的反问题分析方法也得到了相应的发展。本文系统综述小冲杆试验的测量技术及从测量数据来确定材料弹塑性参数的各种经验方法和计算方法,例如有限元分析和参数法、反向有限元法、有限元和反方法、反向识别和人工神经网络、有限元优化和试验变形形状以及杂交反方法等。     

PU/PMMA IPNs复合材料的摩擦学性能和阻尼性能研究

聚合物互穿网络(IPNs),结构可调且设计性强,是制备具有阻尼减振效果兼具海水润滑特性复合材料的一种有效选择.本研究中设计合成了一系列组成成分不同的基于聚四氢呋喃二元醇(PTMG)-聚氨酯(PU)/聚甲基丙烯酸甲酯(PMMA)的互穿网络结构(IPNs),并系统研究了PU/PMMA IPNs在海水润滑条件下的摩擦学性能及其阻尼性能.结果表明:随着PU含量的增加,其摩擦系数和磨损率均显著降低,当PU与PMMA的组成比例为60/40时,复合材料的摩擦系数降低至0.15,质量磨损率0.10%;同时材料的阻尼因子从0.77降至0.24,有效阻尼温域从40℃降至25℃,阻尼性能呈下降趋势.     

On thermodynamic potentials in thermoelasticity under small strain and finite thermal perturbation assumptions

Expressions for thermodynamic potentials (internal energy, Helmholtz energy, Gibbs energy and enthalpy) of a thermoelastic material are developed under the assumption of small strains and finite changes in the thermal variable (temperature or entropy). The literature provides expressions for the Helmholtz energy in terms of strain and temperature, most often as expansions to the second order in strain and to a higher order in temperature changes, which ensures an affine stress–strain relation and a certain temperature dependence of the moduli of the material. Expressions are here developed for the four potentials in terms of all four possible pairs of independent variables. First, an expression is obtained for each potential as a quadratic function of its natural mechanical variable with coefficients depending on its natural thermal variable that are identified in terms of the moduli of the material. The form of the coefficients’ dependence on the thermal variable is not specified beforehand so as to obtain the most general expressions compatible with an affine stress–strain relation. Then, from each potential expressed in terms of its natural variables, expressions are derived for the other three potentials in terms of these same variables using the Gibbs–Helmholtz equations. The paper provides a thermodynamic framework for the constitutive modeling of thermoelastic materials undergoing small strains but finite changes in the thermal variables, the properties of which are liable to depend on the thermal variables.     

Rheological properties of pressure-sensitive adhesives: polyisobutylene/sodium carboxymethylcellulose

The viscoelastic properties of polyisobutylene filled with sodium carboxymethylcellulose were studied. Using shear viscosity data, the relaxation time,, defined as the ratio ₀/G ₀ of the initial viscous and elastic constants was evaluated. The flow activation energy, melt flow index and superposition shift factor were also determined and master curves were generated. A relatively small effect of filler concentration on viscosity was observed, whereas its effect on and the initial first normal-stress coefficient, ₀, was found to be significant.     

Characterization of powder flow properties from micron to nanoscale using FT4 powder rheometer and PT-X powder tester

The rapid development of nanotechnology has led to a need to further understand the physical characteristics of nanoparticles. In this paper, the flow characteristics of micro-nano alumina particles with different particle sizes were characterized. The FT4 powder rheometer and the PT-X powder tester were used to measure the compression, friction, and dynamic properties of powders. Powder compressibility increased significantly as the particle size decreased from 27 μm to 30 nm. Pressure distribution in the silo was measured and predicted by Janssen's theory, with errors mostly less than 10%. The basic flow energy and the specific energy of the three powders were 4983, 1734, and 244 mJ, and 6.80, 11.70, and 6.70 mJ/g, respectively, indicating that there was no linear relationship between the change in flowability and particle size. The dynamic properties of the powders change from particle-dominated to agglomeration-dominated as the particle size decreases. The conclusion is supported by the results of field emission scanning electron microscopy.     

MAIN FACTORS IN PREPARATION OF ANTIBACTERIAL PARTICLES／PVC COMPOSITE

Zirconium phosphate containing silver was chosen as antibacterial particles in preparing antibacterial particles/PVC composite. The effect of surface property of the antibacterial particles and of their filler content on the properties of antibacterial particles/PVC composite was studied. The effect of the interracial compatibility on mechanical properties of the composite was also discussed. Experimental results showed that the antibacterial PVC composite had good antibacterial property, reaching almost 100% bacteriostatic level at an antibacterial powder filler content of 1.5phr.     

Structure-property relationships in polymer composites with micrometer and submicrometer graphite platelets

The objectives of this work were (a) to investigate the influence of micrometer and submicrometer scale graphite platelets of different aspect ratios and volume fractions on the effective and local quasi-static and dynamic properties of composites with micrometer and submicrometer scale reinforcement, and (b) to compare and evaluate mechanical property measurements of inhomogeneous materials via local (microscale) and bulk (macroscale) experimental methods. Small platelet volume fractions (0.5%) provided proportionally larger increase of the elastic and storage moduli compared to large volume fractions (3.0%). Randomly distributed 15 μm platelets provided marginally higher composite stiffness compared to 1 μm platelets while small volume fractions (0.5%) of 15 μm platelets had a pronounced effect on the effective Poisson's ratio. It was found that local property measurements of inhomogeneous materials conducted by nanoindentation are not representative of the bulk behavior even when the characteristic length of the inhomogeneity is an order of magnitude smaller than the indentation contact area. In this case, statistical averaging of data from a large number of indentations does not result in agreement with bulk measurements. On the other hand, for small aspect ratio platelets with dimensions two orders of magnitude smaller than the nanoindentation contact area, the nanoindenter-obtained properties agreed well with the effective material behavior. It was found that platelets residing at the specimen surface contribute the most to nanoindentation data, which implies that this technique is only valid for well-distributed nanoparticulate and microparticulate systems, and that nanoindentation cannot be used for depth profiling of microstructured composites.     

Dynamic and transient rheological properties of glass filled polymer melts

The dynamic and transient rheological properties of a low density polyethylene melt and a plasticized polyvinylchloride melt filled with glass beads were measured at 200 °C and 180 °C respectively in a modified Weissenberg Rheogoniometer R-17. Its main modification consisted of the use of a piezoelectric transducer instead of the conventional torsion bar, and of the interfacing of a microcomputer Apple II plus to the Rheogoniometer for data acquisition and analysis. The glass beads were pretreated with silane and titanate coupling agents to observe the effect of the chemical modification of the polymer filler interface on these properties. It was observed that both the dynamic viscosity and the storage modulus increased with the weight fraction, but this last parameter did appreciably affect the stress growth and stress relaxation curves of the polymeric matrices at low shear rates. The effect of coupling agents on these properties was varied.