Papers by Keyword: Textured Surface

Abstract: Surface texturing is a process of fabricating specific patterns on a surface to enhance surface properties such as friction, contact area, air aspiration, wear, hydrophobicity, etc. Fabricating surfaces with planned micro features is an effective method to improve tribological performance of the interacting surfaces. Laser surface texturing process is one of the best suitable processes for producing micro-patterns. Micro textures are imparted on HSS discs using CO₂ laser, varying the shape and dimensions of the resulting dimples affecting the frictional coefficient and wear. Experiments have been accomplished to determine effects of textural variations such as areal density of dimples, dimple shape, area of dimples and depth of dimples on the Coefficient of Friction (COF) and Wear. Effects of lubrication conditions (Dry and Wet), pin material (MS, SS, EN31), applied load (25N, 50N, 75N) and Sliding velocity (400 rpm, 800 rpm and 1200 rpm) are evaluated on COF and Wear. Tests have been performed on pin-on-disk apparatus along guidelines of Taguchi L18 Orthogonal Array, keeping constant sliding distance of 940 m (about 10,000 cycles). Experimentally, it is found that wet lubricated, circular shaped dimples, with areal density 7.5%, dimple area 0.09 mm² with MS material pin provides best results. This experimental analysis has been performed to test the applicability, efficiency and reliability of the textured surfaces.

Abstract: On the basis of transient thermal hydrodynamic lubrication (TTHL) simulation and isothermal hydrodynamic lubrication (IHL) simulation of textured piston ring/cylinder liner, main factors influencing oil film temperature, distribution of the maximum temperature, and comparison between two models were discussed. The results show that texturing improves hydrodynamic lubrication situations, and velocity of piston ring and applied load are two important factors affecting oil film temperature. Apart from that, sever temperature elevation is located at the export of oil film and textured areas. Although change trends of the maximum of pressure and the minimum of oil film thickness are basically the same, the values of them are different. Temperature is a necessary element for analyzing the lubricant situations of piston ring/cylinder liner.

Abstract: This work proposes the investigation of nanosized Titanium Aluminum Nitride (TiAlN) on the Stainless Steel (316L) substrate. A chromium interlayer has been applied over the modified surface which will act as an interlayer between the substrate and hard composite coating. The composite coating was prepared by Magnetron Sputtered-Physical Vapour Deposition (PVD) on chromium coated lapped and textured surfaces of stainless steel substrate. Scratch test was performed to characterize the adherence of the coatings on the substrate. TiAlN surface coating over the textured surface exhibits higher adherence than the lapped surface coating surface. The tribological performance of the wear resistant coatings on lapped and textured surfaces was experimentally investigated by pin on disc tribometer at dry sliding contact conditions under various normal loads. The testing results were compared and the results showed that TiAlN coating on textured surfaces exhibited lower friction coefficient and wear rate than lapped coating surfaces under same testing conditions. Sliding wear characteristics such as coefficient of friction and specific wear rate were investigated.

Abstract: Molecular dynamic simulation for Fe sliding on Fe substrate with textured surface is investigated in this work. The textured surfaces on sliding are discussed to elucidate the physics of friction at the small scale. The modified embedded-atom method many-body potential is modeled to describe the interaction of Fe-Fe atoms. We find that a textured surface can reduce the friction because the former can entrap wear particles, effectively reducing the contact area. In addition, the friction force increases almost linearly in the low sliding speed with the increasing of sliding speeds. However, the friction force decreased as the increasing speed exceeds the 300 m/s.

Abstract: Coupled molecular dynamics simulation and finite element method, a multiscale method is used to model nanoscale sliding contacts problems. According to an experimental sample, 4 textured surfaces with different asperity shapes are designed. Through the friction forces comparisons between smooth surface and textured surfaces, the effects of texture shapes are investigated, and 2 better textured surfaces are discovered to reduce friction forces.

Abstract: The Ga-doped ZnO (GZO) films were prepared by DC magnetron sputtering at different substrate temperature, followed by etching in 0.5%HCL solution for 15s to obtain textured surface. Optical and electrical properties, structural and surface morphology of thin films were investigated. The results indicated that the transmittance rate decreased and the C-axis preferred orientation of films enhanced with the increase of the substrate temperature. When temperature increased from room time (RT) to 200°C, the resistivity decreased and the quality crystal became better, while substrate temperature above 250°C, the resistivity increased,the deterioration of crystallinity emerged. For the textured film deposited at 200°C, it obtained the minimum resistivity of 0.84×10^-3/(Ω•cm) and had a good light trapping ability.

Abstract: High quality textured ZnO:Al electrode can improve the energy conversion efficiency of silicon based thin film solar cells. Two groups of ZnO:Al films were fabricated under different sputtering powers. Different textured surfaces were got when corroding ZnO:Al films with diluted HCl solutions of different concentration. The transmission spectrum and square resistance of the samples were measured. The dependence of sputtering power and corrosion time on the resistivity, transmittance and surface texture of the samples were studied. The results showed that the density of the ZnO:Al film was mainly affected by sputtering power. The compactness of the film increases with the increase of sputtering power. The corrosion rates of the samples with different compactness follow different rules. High quality textured ZnO:Al electrode was obtained when the ZnO:Al film deposited under sputtering power of 200W was corroded by diluted HCl solution of 0.5%.

Abstract: A multiscale method coupled molecular dynamics simulation and finite element method is used to investigate two dimensional nanoscale sliding contacts between a rigid cylindrical tip and an elastic face centered cubic copper substrate with textured surface, in which adhesive effects are considered. Two series of nanoscale surface textures with different asperity shape, different asperity heights and different spacing between asperities are designed. Through the friction forces comparisons between smooth surface and textured surfaces, a better shape is advised to indicate that asperity shape plays an important role in friction force reduction. With proper asperity height and proper spacing between asperities, surface textures can reduce friction forces effectively.