Papers by Keyword: Surface Texture

Abstract: Surface modification of metallic materials to impart antibacterial properties has attracted significant attention for practical applications in biomedical and industrial fields. This study aims to characterise the antibacterial surface textures of Ti alloys (Ti-6Al-4V) and investigate their relationship with water repellency, bio-adhesion resistance, and antibacterial performance. Two distinct surface textures were fabricated using chemical (acid treatment for 5 and 20 min) and physical methods (tensile testing). Antibacterial tests revealed 41.6%, 14.6%, and 31% reductions in the viable bacterial counts for the 5-minute acid-treated, 20-minute acid-treated, and tensile-tested samples, respectively, compared to untreated controls. Contact angles of 100.9°, 96.1°, and 79° were observed, indicating varying degrees of water repellency. The acid-treated samples exhibited reduced bio-adhesion, whereas the tensile-tested samples showed increased bio-adhesion. These findings suggest that the surface morphology that inhibits bacterial aggregation is the primary factor contributing to antibacterial properties. Although water repellency and bio-adhesion resistance are often associated with antibacterial surfaces, they serve as functional correlations rather than direct determinants. The surface texture developed in this study exhibited a symmetrical vertical height distribution with Sa = 0.24 µm and featured flat valley regions, rendering it highly suitable for antibacterial applications and promising for use in biocompatible environments.

Abstract: The paper presents the use of integral methods of surface texture evaluation of structural steel samples used in armaments production for the analysis of the functional behaviour of gear surfaces. The aim of the paper is to evaluate the relationship between the quality of the ground surface and the surface after the plasma nitriding process and the functional properties of the surface using unconventional characteristics. These characteristics include Amplitude Distribution and Material Ratio, Autocorrelation Function (ACF), Frequency Spectrum (FS) and Power Spectral Density (PSD). These characteristics can, for example, reveal small changes in surface texture caused by both the cutting tool and surface treatments, such as diffusion nitriding technology, which show only slight changes in standard parameters. Thus, these characteristics can be used as a suitable diagnostic tool for evaluating changes in the functional properties of surfaces. These changes can usually be characterized by wavelength profile inequalities and statistical and spectral properties. In this paper, the surfaces of C45, 15NiCr13, 18CrNiMo7-6 and 16MnCr5 steels after the finishing operation of grinding and further after plasma nitriding are evaluated. Measurement of the standard parameter, i.e. the arithmetic mean height Ra, of ground and nitrided surfaces resulted in the same or slightly higher values after diffusion technology. Using integral characteristics, changes in surface texture were found to be directly related to the functional behaviour of surfaces in interaction and can predict, for example, noise levels, wear and lubrication properties.

Abstract: Elemental analysis by X-ray fluorescence, XRF, is a well-known technique, widely used in laboratories and industrial plants. XRF equipment manufacturers offer accessories and programs to integrate their equipment into automated plants and use it as quality control tools. The relationshipbetween the surface roughness of the samples and the quality of the measurement is studied and its physical principles are known. In this work it is proposed to use an XRF equipment to analyze the surface roughness of the elements produced in chain, and establish a pass/do not pass control of a batch.By integrating the XRF equipment into the chain, and comparing the measurement with a previous measurement considered reference (which can be done with other equipment such as a roughness meter or confocal microscope) it can be determined if the surface roughness of the samples conforms to the established tolerance limits. The advantages of using an XRF equipment are: using equipment that is already in the plant, automating the control process, integrating an XRF into a flexible manufacturing environment and non-contact roughness analysis (surface texture).In this work the authors start from different machined specimens of aluminium alloy perfectly known by spark emission spectrometry to the appropriate dimensions to be measured in an XRF spectrometer. The surface to be evaluated is machined until the desired order of roughness is achieved, its surface finish is determined by optical methods and subsequently measured in the XRF equipment. Different specimens, are produced to determine the changes in the XRF measurements. The intensity of selected elements in each specimen is related to the surface finish and conclusions are drawn.

Abstract: Ti15Mo7Zr15Ta1.00Si titanium alloy contained higher concentration of silicon and better elastic properties, excellent biocompatibility and lower processing cost. To investigate the influence of texture shapes and parameters of joint surfaces on the friction and wear properties under bionic lubrication conditions, three types of texture morphologies (circular, elliptical, and equal-width grating) with the same pit depth and surface coating rate were processed on a Ti15Mo7Zr15Ta1.00Si titanium alloy using a picosecond laser processing system in this study. Then, the "ceramic–metal" friction and wear tests of textured and smooth samples under lubrication with bovine serum protein were performed using a UMT-3 multifunctional friction and wear testing machine. The results showed that the surface micro-texture morphology could improve the anti-friction properties of titanium alloy artificial joint materials. The wear resistance of the circular micro-dimples improved with an increase in the circular diameter. In the elliptical micro-dimple texture morphology, the vertical arrangement of the ellipses could provide the maximum bearing capacity and best friction reduction effect, followed by the elliptical morphology and the transverse ellipse arrangement. The denser the arrangement of the equal-width bars, the better the friction reduction effect was.

Abstract: The aim of this study is to determine whether the effective medium approach (EMA) is suitable to model black silicon structures. The present study focuses on comparing EMA paired with 1D FDTD simulations to full 3D FDTD simulations. Comparison was done for ordered cylindrical and hemispherical b-Si nanostructures. From the simulation results, the 1D simulation seems to underestimate the transmittance and overestimate the reflectance for these structures. This was attributed to the failure of the EMA to capture scattering and diffraction effects that were present in the nanostructures. The absorptance spectrum was comparable for both 1D and 3D simulations, hence it was concluded that the simplification may be suitable for simplifying problems where calculating the absorption of light is desired.

Abstract: Currently the measurement of surface texture in mechanical engineering is traditionally carried out using profilometers. Modern profilometers do not allow measuring of surfaces with complex shapes. This is due to the different sensitivity of the sensor and the discreteness of the movements along the axes of the Cartesian coordinate system. Coordinate Measuring Machines are devoid of such a drawback. However, stylus of the coordinate measuring machine has a diameter many times larger than the diamond stylus of the profilometer. Therefore, there is a mechanical filtering effect, that affects the results of measuring the parameters of the surface texture. In this paper a mathematical model of the contact of the spherical stylus and a rough surface based on analytical geometry is proposed. Influence of the diameter of the spherical stylus on the maximum measurement errors of a amplitude parameters are investigated. Seven amplitude parameters Rp, Rv, Rz, Ra, Rq, Rsk, Rku of the surface texture are modeled. Coordinate measuring machine and profilometer with stylus diameter of 2 μm measurement results are compared. it was concluded that the stylus diameter of the coordinate measuring machine when measuring the surface texture should be no more than 20 μm.

Abstract: Friction happens everywhere. Abrasives generated in tribological process will result in secondary wear. Abrasive wear is a kind of rather common but harmful wear, which is the main reason for the damage of fifty-percent mechanical components by friction. Surface texturing is an effective method to improve the tribological and lubricating performance of tribo-pairs. In this paper, with different-size diamond particles added into the lubricant and a surface of the tribo-pairs textured by different parameters (diameter and depth) with femtosecond laser, the relationship between the surface texture and the abrasive wear was researched, and the influence of the texture on the abrasive wear was analyzed. The friction experiments were carried out on UMT3. The microstructures were tested and analyzed by SEM, microscope and White Light Interferometer respectively. The experimental results showed that the size of the surface texture, compared with that of abrasives, is the main factor which determines the friction coefficient. As the size of the surface texture is much bigger than that of the abrasives, the texture can accommodate the abrasives efficiently, and thus the friction coefficient is reduced efficiently.

Abstract: In this paper, the influence of texture on wear and temperature rise is studied by comparing experiments at the normal temperature. Firstly, the preparation of experimental samples and the design of experimental methods are introduced. Secondly, based on the observation and analysis of two groups of experiment, the effects of surface texture on friction coefficient, temperature rise and wear are discussed respectively. The main reasons of surface texture on temperature rise are analyzed from the energy point of view, which lays a foundation for quantitative analysis of temperature rise mechanism.

Abstract: The effect of tribological properties of laser-textured with different surface coverage and diameters on HA/ZrO2 coating is studied. Under the bovine serum lubrication conditions, the effect of load and speed on anti-friction mechanism is tested. Experiments show that the surface texture has an excellent morphology, its tribological property is significantly better than that of the un-textured coating, surface coverage 10%,Φ250μm coating showed the optimum tribological characteristics.

Abstract: Tribological properties of textured surfaces fabricated using a discontinuous microcutting process were investigated. Aluminum cast alloy (AC8A) discs were used for the specimens. The texturing process was carried out using a CNC machining center with a cutting edge with a novel geometry. The resulting surface morphology consisted of micro dimples with a diameter of 200-300 μm and a depth of 5-10 μm, with controlled area fractions of 10 and 40% and a top region finished with a milling cut. The tribological properties were evaluated using a ring-on-disc type testing apparatus under lubricated conditions, and showed that the friction coefficient of the textured surfaces was low and stable from the beginning of the experiment. A dependence of the friction coefficient on the area fraction was also found. Further reductions in the friction coefficient were achieved on a textured surface with a polished top region. It can be concluded that the proposed discontinuous micro cutting process is an effective means of fabricating a micro texture for the reduction and stabilization of frictional resistance.