Poly-12-hydroxystearic acid (PHSA) is widely used as a coating on colloidal spheres to provide a "hardsphere-type" interaction. These hard spheres have been widely used in fundamental studies of nucleation, crystallization, and glass formation. Most authors escribe the interaction as "nearly" hard sphere. In this paper we directly measure this interaction, using layers of PHSA adsorbed onto mica sheets in a surfaces force apparatus. We find that the layers, in appropriate solvents, have no long-range interaction. When the solvent is decahydronaphthalene (decalin), the repulsion rises from zero to the maximum measurable over a distance range of 15-20nm. The data is converted to equivalent forces between spheres of different diameters, and modeled using a hard core potential. Using zeroth-order perturbation theory and computer simulation, we demonstrate that the equation of state does not deviate from that of a perfect hard-sphere system under any relevant experimental conditions.

A device to study the friction of two molecularly smooth surfaces separated by an ultrathin liquid film is presented along with its design, calibration, and performance. The apparatus can move one of the surfaces and measure the friction force on the other one bidimensionally for both processes. A high mechanical impedance system (104N/m) measures continuous friction forces where only stick-slip was previously observed. The frequency and travel distance of the movement can be varied over a wide range (frequency from 10-4 to 7Hz and distance from1 to 800μm) to provide variations of the shear rate over seven orders of magnitude. The actual movement provided by piezoelectric bimorph drive can be affected by the friction forces and is measured by strain gauges. The friction forces are measured with an accuracy of ±2μN with a capacitance sensor. The mechanical design prevents the surfaces from rolling under force. The apparatus is tested with hexadecane. The potential applications of this apparatus and its limitations are discussed.

With a nano-indenter and a microhardness testing machine, nano-indentation hardness and microhardness are measured in a wide load range (0.1-19600mN) for five materials. Even fused silica and silicon almost have constant hardness during the load range, the nanoindentation hardness of copper, stainless steel and nickel titanium alloy shows obvious indentation size effect, namely that the hardness decreases with the increase of depth. For the measured materials, the nano-indentation hardness is about 10-30% in magnitude larger than the microhardness. The main reasons can be explained as the analysis of the nano-indentation hardness using the projected contact area at peak load Ac instead of the residual projected area Ar, as well as the purely elastic contact assumption describing the elastic/plastic indentation process. The analysis based on a simple model indicates that Ac is always smaller than Ar, and the more heavily the indent piles up (or sinksin), the larger the difference between the nano-indentation hardness and microhardness.

在原子力/摩擦力显微镜（AFM/FFM）实验中，通常只能得到摩擦力信号的相对值，为了比较各种样品表面的微观摩擦性能，常选用新鲜解理的云母作为摩擦力测量的参考样品。由于新鲜解理云母表面摩擦性能的不稳定性，使得不同条件下在云母表面上测得的摩擦力信号有较大的变化。为此，需要通过对云母表面摩擦性能的系统研究，建立一个以云母为AFM/FFM摩擦力测试参考样品实验规范。实验结果表明，云母样品的摩擦特性受其解理时间的长短湿度以及测试针尖的变化等多种因素的影响。不同针尖在云母表面的摩擦力信号大约在±15%的范围内波动；新针尖在云母表面作摩擦实验时，摩擦力信号随磨损次数的增加逐渐增大，然后趋于稳定。对于新鲜解理的云母表面，其摩擦力信号随解理时间的增长而逐渐增大并逐步趋于稳定。由于云母表面的亲水性，其摩擦力信号随湿度的增大而逐渐减小。

使用原子力/摩擦力显微镜在5%-9%的相对湿度范围，研究了二氧化硅和二氧化硅基体上十八烷基三甲氧基硅烷自组装膜（简称OTEsAM/siO2）表面摩擦力和粘着力随湿度的变化规律实验表明叫OTE SAM/SiO2，不仅能明显改善二氧化硅基体表面的摩擦性能，而且在200nN（接触区HPnz压力约为0.8GPa）的载荷条件下表现出良好的抗磨性能由于强的亲水性，二氧化硅表面的摩擦力随湿度的增大先逐渐增大，然后急剧减小相反，OTE SAM/SiO2由于其良好的斥水性，表面的摩擦力在高湿度条件下略有减小，它可望成为微型机械和高速磁记录系统中较为理想的边界润滑剂。