Kai Feng Zhang

The Improved Friction Properties of Bonded MoS2 Films by MAO Treating of Al Substrate

The bonded MoS2 films are widely used as solid lubricants in aerospace mechanisms due to their excellent tribological properties. Traditionally, the MoS2 was directly bonded on the Al substrate that was only treated by the technique named of sandblast. For improving the tribological properties of MoS2 films, micro arc oxidation (MAO) instead of sandblast was introduced as a new technique for treating of Al substrate. In this article, the tribological properties of MoS2 films which were bonded on different surface of Al substrate as mentioned above were discussed, respectively. It was concluded from the test results that the MoS2 films bonded on substrate treated by MAO have better tribological properties than those samples treated by sandblast. The endurance life against abrasion of the former is as high as twenty times of the latter by the stand test method of ball on disk using the UMT Multi-Specimen Test System. This test results could be illustrated by the following reasons. The first is the porous microstructures of MAO ceramic coatings on the Al substrate. The coatings have numerous pits to be good at increasing the binding force with the MoS2 films, and the pits can also provide a MoS2 lubricants reservoir during processes of friction. Both of them improved the MoS2 film’s ability of wear-protective. The second is that hardness of the coating is higher than the Al, and this ensures well wearing resistance, especially in practical application to big load-supporting moving parts, such as bearing, gear, etc…

Study of Tribological Properties of Micro-Arc Oxidation Ceramic Coatings Prepared with Different Impulse Frequency on Aluminum Alloy

The ceramic coatings, on the substrate of LY12 Al alloy, were prepared by micro-arc oxidation (MAO) technique with different electrical source parameters. The microstructure and tribological properties of the resulting micro-arc oxidation ceramic coatings(MAOC) were tested and analyzed by Nano-scratch tester, Micro-hardness tester and ball-on-disk friction tester etc. The results indicate that the thickness, roughness, micropore sizes and wear-resistance of MAOC increase with impulse frequency decreasing, however, the porosity is correspondingly reduced.

Synthesis of Highly-Ordered V2O5 Nanowires by AAO Template and its Electrocatalytic Activity for Dopamine Electro-Oxidation

Highly-ordered V2O5 nanowires were prepared by sol-gel strategy using anodic aluminum oxide (AAO) as a template. The morphologies, structures and components of the nanowires were characterized by XRD, SEM and XPS. The results indicated high-ordered and uniformly distributed V2O5 nanowires were obtained, and the length and diameter were dependent on the diameter and the thickness of the applied AAO template. The V2O5 nanowires modified glassy carbon electrode (GCE) was used to investigate the electrochemical properties of dopamine (DA), V2O5 nanowires exhibited an excellent electrocatalytic behavior on DA.

Effects of Duration on Wear Rate of a PTFE Composite

A type of PTFE/MoS2/glass fiber composite has been used as bearing cage material. To study the friction properties, the tests have been performed under various parameters on block-on-ring. The experimental results were as follows: Wear rate of the polymer composites was dramatically affected by test duration. With increase of test duration, the wear rate rapidly decreased. At the sliding velocity of 1.83m/s and load of 45N, the highest wear rate was 8.85×10-15m3/N·m in the test of duration 0.5h, while the lowest was 0.88×10-15m3/N·m in the test of duration 10h (the minimum and maximum times examined).

A Facile Method for Improving the Process of Porous Anodic Aluminum Oxide Film Preparation

A new and facile method for improving the procedure of anodic aluminum oxide (AAO) film preparation was presented, which was based on an electrochemical detachment procedure. The detachment and pore-opening were performed just through one step in a solution of HClO4 and C2H5OH at a voltage of 40V. The as-obtained AAO film was characterized by scanning electron microscopy (SEM) and scanning probing microscopy (SPM). The process of detachment and pore-opening was also discussed.

Applications of Nanostructured Materials as Additives in Space Fluid Lubricants

With an extended service life expectancy of space crafts, fluid lubricants attracted intense interests of the fields of tribology, due to their long life under EDH conditions, higher thermal conductance, lower frictional and torque noise, and rapid processing compared to the solid lubricants. However, there are still some disadvantages of fluid lubricants, such as finite vapor pressure, narrow range of operating temperature, degradation of some oils, viscosity temperature-dependence and so on. So far, there have existed some space fluid lubricants, such as PFPE, MAC, PAO and mineral oil based lubricants. It seems that there will be a challenge for a new type of fluid lubricants to come out without any limits above. Recent arisen nanostructured materials assisted in improvement of the research of space fluid lubricants, and the results indicated that some nanostructured materials exactly promoted the tribological properties of fluid lubricants. This paper reviewed recent development of nanostructured materials as additives in space fluid lubricants.