Cu/MoS2 composite material was formed by a novel powder-molding technique, which is termed the compression shearing method at room temperature (COSME-RT). Cu/MoS2 sample mechanical and tribological properties and microstructures were investigated. Samples were prepared using five different MoS2 concentrations between 0 to 20 vol.%. No unwanted compounds were generated by the Cu and MoS2 because a high temperature is unnecessary in COSME-RT. Scanning electron microscopy observations confirmed that the MoS2 particles were dispersed homogeneously in the Cu host matrix. The indentation hardness of Cu/MoS2 with 0, 1.0 and 5.0 vol.% MoS2 was higher than 1.6 GPa, and is higher than that formed by conventional powder metallurgy methods and a pure Cu plate. The indentation hardness of the Cu/MoS2 decreased with increasing MoS2 concentration. In contrast, the lubricating performance of MoS2 became more pronounced at 5.0 vol.% or above. The coefficient of friction of Cu/MoS2 with 5.0, 10 and 20 vol.% MoS2 was ~0.20, and is the same as for MoS2 in air. The sample coefficient of friction was maintained because of lubrication by forming a transferred film of wear debris that contained MoS2. Cu/MoS2 had a low coefficient of friction, but maintained its material strength at 5.0 vol.% MoS2.
The particles contained in the lubricating oil carry detailed and important information about the condition of the machine. The information may be deduced from particle shape, composition, size distribution and concentration. Particles eroded from the surface of an oil wetted component in any centralized lubrication system upon examination give specific and accurate information. The operating wear modes prevailing in the machine are determined with the examination of the lubricant in circulation. Analytical and experimental studies were undertaken to assess the deleterious effect of contaminants present in lubricant on the performance of critical equipment in steel plant. The study involves the findings of typical characteristics developed in the oil wetted components on account of contaminants. Morphology of worn out particles, change in chemistry of lubricant and the presence of contaminants in the centralized system was optimized. The experimental methods include quantification of total ferromagnetic particles through direct reading and analytical ferrography, particle size in a laser diffraction particle counter and deleterious particles present in the lubricant through an Oil View Analyser instrument and an inductive couple plasma unit. The above condition based analytical techniques were used to predict the overall health of the critical equipment located in different units of steel plant.
This work shows new method which controls adhesion strength between acrylic resin and metal mold with electric field. Usage of electric field is considered as a new solution to control adhesion of thermoplastic resin in Carbon-Fiber-Reinforced ThermoPlastic (thermoplastic CFRP) stamping process because this method can prevent CFRP from its degradation. In this work, we establish new adhesion tester which can apply Direct Current (DC) or Alternating Current (AC) field on metal specimens. In the results, when DC −12 V/mm is imposed on metal specimens, adhesion strength increases to 0.81 MPa which is 57% higher than that of no field condition. Negative component of surface energy after imposing DC −12 V/mm on metal specimens is 7.6 mJ/m2. This value is 56% smaller than that of no field condition. When AC electric fields is imposed, adhesion strength decreases from no electric field condition. The most effective AC field condition is AC 10 V/mm with 1 MHz, in which case adhesion strength is 0.29 MPa. This value is 44% lower than that of no field condition.
In this study, the potential of a Micro Slurry-jet Erosion (MSE) test to swiftly evaluate the intrinsic surface strength properties of thin multi-layer coatings is demonstrated. A slurry containing 1.2 μm alumina particles was impacted at high velocity perpendicular to PVD TiN/TiCN (TiCN on top of TiN) and TiN coatings deposited on high-speed steel by a hollow cathode discharge (HCD) or an cathodic arc (CA) method. In addition, nano-indentation and XRD, GDOES analyses were done for the original surfaces. By measuring the variation of erosion depth against test time, the MSE test made it possible to evaluate the individual erosion properties of TiCN and TiN layers independent of the substrate. Although the hardness of TiCN layers, coated by HCD or CA, was measured with nano-indentation and found to be approximately 20% higher than for TiN, the erosion rates of TiCN layers were found to be between 32% and 38% of the erosion rate of TiN. For the HCD coating, the erosion proceeded uniformly and produced a mostly smooth surface. On the other hand, for the CA coating, a pitted surface was observed. The existence of the hollows blemishes which caused by macroparticles i. e. droplets in the coating may affect the difference in the erosion rates between HCD and CA coatings. Consequently, the MSE test may be useful to evaluate the difference of the morphology of coatings as well as the surface strength which are related with the fabrication process.
The present study deals with capillary compensated symmetric hole-entry hybrid journal bearing under couple stress lubricant. Reynolds equation has been modified considering couple stress lubricant in the bearing system. The Galerkin’s Technique has been applied to solve the modified Reynolds equation together with restrictor flow equation. The computation of bearing performance has been made by using couple stress parameter. The bearing operating with couple stress lubricant provides better values of fluid film thickness, rotor dynamic coefficients than similar bearing operating with Newtonian lubricant.
In lubricated systems with textured surfaces cavitation is of importance, therefore, in the present paper, a modified Reynolds equation including wall slip is combined with a cavitation model. A numerical investigation was carried out to study the interaction of wall slip and surface texturing on the lubrication of lubricated MEMS devices. Textured surfaces with different patterns were studied and compared with the results of similar untextured surfaces. The results showed that the presence of wall slip could result in a significant reduction in the coefficient of friction. It is found that slip can improve the load support because the cavitation zone is reduced. This effect was particularly large for untextured surfaces with an optimized slip surface.