Surface Profiling Instrument Research Articles

Study on the process optimization and wear resistance of electron beam cladding AlCoCrFeNi coating on 253MA austenitic stainless steel surface

This study employs a continuous scanning electron beam to deposit AlCoCrFeNi composite cladding on the surface of 253MA austenitic stainless steel to enhance its surface properties. The characteristics were examined through a scanning electron microscope (SEM), backscattered electron diffraction (EBSD), and white light interferometric three-dimensional surface profile instrument. This study investigated the effect of electron beam process parameters on the surface organization and mechanical properties of 253MA steel. The sample surface was divided into four zones: overlay, bonding, thermal influence, and substrate, according to the results. Coarse columnar and island-shaped crystals composed the overlay zone, while equiaxed austenite grains primarily constituted the substrate. With the increase of the beam current, the microstructure's grain size decreased, the substructures increased, and the BCC phase transformed into the FCC phase. The grain size slightly decreased, substructures changed marginally, and the BCC phase increased as the scanning speed increased. Additionally, the microhardness and mechanical properties of the overlay layer increased significantly, and wear volume and wear rate decreased progressively with the increase in beam current and scanning speed. At a beam current of 18 mA and a scanning speed of 200 mm/min, the surface hardness of 253MA steel reached the maximum value of 520 HV. When the beam current was 24 mA, and the scanning speed was 200 mm/min, the wear volume and wear rate of the overlay sample were minimal, accounting for 37.4% of the original sample's, and its wear resistance was 2.67 times more than that of the substrate.

Machining Performance of TiAlN-Coated Cemented Carbide Tools with Chip Groove in Machining Titanium Alloy Ti-6Al-0.6Cr-0.4Fe-0.4Si-0.01B

In this paper, TiAlN-coated cemented carbide tools with chip groove were used to machine titanium alloy Ti-6Al-0.6Cr-0.4Fe-0.4Si-0.01B under dry conditions in order to investigate the machining performance of this cutting tool. Wear mechanisms of TiAlN-coated cemented carbide tools with chip groove were studied and compared to the uncoated cemented carbide tools (K20) with a scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The effects of the cutting parameters (cutting speed, feed rate and depth of cut) on tool life and workpiece surface roughness of TiAlN-coated cemented carbide tools with chip groove were studied with a 3D super-depth-of-field instrument and a surface profile instrument, respectively. The results showed that the TiAlN-coated cemented carbide tools with chip groove were more suitable for machining TC7. The adhesive wear, diffusion wear, crater wear, and stripping occurred during machining, and the large built-up edge formed on the rake face. The optimal cutting parameters of TiAlN-coated cemented carbide tools were acquired. The surface roughness Ra decreased with the increase of the cutting speed, while it increased with the increase of the feed rate.

Characterization of pavement texture by means of height difference correlation and relation to wet skid resistance

Driving safety is of utmost importance in the automobile industry and is acknowledged by the introduction of the tire wet grip index as part of the EU tire label. The rubber pavement interaction is determined by the viscoelastic properties of the rubber as well as by the pavement texture. Nowadays available optical surface profiling instruments allow for a detailed measurement of surface roughness covering several length scales. This enables the validation of a mathematical statistical description of pavement texture within the framework of self-affine surfaces and hence provides a holistic characterization of surface roughness covering several length scales within a few characteristic parameters. We deduce within this article the correlation between classical surface roughness parameters and the parameter set of self-affine surfaces. These parameters allow for a detailed understanding of the relationship between pavement texture and its wet skid resistance. We present wet skid resistance measurements with the British pendulum and a linear friction tester device on different pavement textures. We demonstrate that the so-called estimated texture depth does not correlate to the surface skid resistance measured with the British pendulum. Finally, we deduce a dependency of wet skid resistance on pavement texture which is supported by current models for hysteresis friction.

A New Method of Processing High-Precision Micro-Hole with the Femtosecond Laser

Based on the femtosecond laser processing technology and PZT driving scanning technology,high-precision micro- manufacturing technology is developed. By adjusting the laser parameters and scanning parameters to get micro-hole machining on the flat or curved surface. Hole’s size and surface morphology is observed by using phase contrast microscopy and scanning electron microscopy observations, and the surface roughness is analyzed by the surface profile instrument. The feasibility of diesel injector nozzle processing is verified in practical industry applications. The results show that this method of making micro hole has significant advantages, such as high precision, good consistency, without burrs, good surface roughness and high efficiency. These characteristics can meet the practical application requirements and can be used in various industrial fields.

Dynamic modelling of the fidelity of random surface measurement by the stylus method

A numerical simulation has been used to systematically investigate the characteristics of a stylus surface profiling instrument. The model bridges together previously used concepts to incorporate both tip size and tip dynamics. The dynamics incorporate a tip flight phenomenon, inferring detachment from zero value of the reaction force and the trajectory from a free vibration solution to a second order system. Tip shape is handled by a rigid kinematic model. Following brief discussions of the modelling and the process for generating test profiles with defined correlation lengths, the influences of the inherent parameters of the stylus instrument and the testing method on the measurement fidelity are examined. The tip shape effect of the stylus instrument is also considered in the dynamic measurement. It is noted that the finite tip size can increase the critical scanning speed to avoid tip flight, but decreases the signal fidelity of the measurement due to the bridging effect.

A simple model for the short-time evolution of near-surface current and temperature profiles

A simple analytical/numerical model has been developed for computing the evolution, over periods of up to a few hours, of the current and temperature profile in the upper layer of the ocean. The model is based upon conservation laws for heat and momentum, and employs an eddy diffusion parameterisation which is dependent on both the wind speed and the wind stress applied at the sea surface. Other parameters such as the bulk-skin surface temperature difference and CO$_2$ flux are determined by application of the Molecular Oceanic Boundary Layer Model (MOBLAM) of Schluessel and Soloviev. A similar model, for the current profile only, predicts a temporary increase in wave breaking intensity and decrease in wave height under conditions where the wind speed increases suddenly, such as, for example, during gusts and squalls. The model results are compared with measurements from the lagrangian Skin Depth Experimental Profiler (SkinDeEP) surface profiling instrument made during the 1999 MOCE-5 field experiment in the waters around Baja California. SkinDeEP made repeated profiles of temperature within the upper few metres of the water column. Given that no tuning was performed in the model, and that the model does not take account of stratification, the results of the model runs are in rather good agreement with the observations. The model may be suitable as an interface between time-independent models of processes very near the surface, and larger-scale three-dimensional time-dependent ocean circulation models. A straightforward extension of the model should also be suitable for making time-dependent computations of gas concentration in the near-surface layer of the ocean.

A study on the laser marking process of stainless steel

A Q-switched Nd:YAG laser was used in the laser marking process of stainless steel. The influence of the pulse frequency of the laser beam on the mark depth, width and mark contrast have been studied in this paper. The mark contrast is the ratio of the apparent brightness between the mark and unmarked areas which shows the clearance degree of the mark. An optical microscope, scanning electron microscope and surface profile instrument were used to measure the effects of pulse frequency on the mark depth and width. An image-analysis system with a frame-grabber card and a charged-couple-device (CCD) was used to measure mark contrast. It has been found that the mark depth, width and mark contrast depend on the interaction process of the laser beam and the material, which was influenced dramatically by the pulse frequency. The pulse frequency of the laser has a significant effect on the mark quality. There is maximum mark depth when the pulse frequency is about 3 kHz, while mark width almost keeps constant at different pulse frequency. With the pulse frequency increasing, evaporation of material becomes less, and at the same time oxidization becomes more significant, which leads to the improvement of mark contrast. The highest mark contrast could be obtained when the pulse frequency of laser was about 8 kHz.

Hemolytic effect of surface roughness of an impeller in a centrifugal blood pump.

The present study investigates how the surface roughness of an impeller affects hemolysis in the pivot bearing supported Gyro C1E3 pump. This study focuses on particular areas of the impeller surface in the impeller type centrifugal pump. Seven Gyro C1E3 pumps were prepared with smooth surface housings and different impeller parts with different surface roughnesses. The vanes, top side, and backside of the impeller were independently subjected to vapor polishing, fine sand blasting, or coarse sand blasting to produce three different grades of surface roughness. These surfaces were then examined by a surface profile instrument. Using these pumps with different impellers, in vitro hemolysis tests were performed simulating cardiopulmonary bypass (5 L/min, 350 mm Hg). The findings of this study conclusively proved that surface roughness of the back side of the impeller has the greatest effect on hemolysis, followed by the top side and then the vanes. The following are reasons for these findings. First, the shear rate may be greater on the back side than on the top side because of the smaller gap between the back and the housing and the greater relative speed against the impeller. Second, the fluid beneath the impeller may have a longer exposure time because there is little chance for the fluid to mix beneath the impeller. Third, the shear rate may be greater on the top side of the impeller than on the vanes because a vortex formation occurs behind the vanes.

Effect of surface roughness on hemolysis in a pivot bearing supported Gyro centrifugal pump (C1E3).

The blood contacting surface quality is an important pump parameter for blood compatibility and cell damage. This study investigates the surface roughness and the effect it has on hemolysis in a centrifugal blood pump. In vitro hemolysis tests were performed with a pivot bearing supported Gyro centrifugal pump (C1E3) simulating cardiopulmonary bypass (CPB; 5 L/min, 350 mm Hg) and left ventricular assist device (LVAD; 5 L/min, 100 mm Hg) conditions. To produce 4 different grades of surface roughness, the impellers and housings were subjected to vapor polishing, sand papering, fine sand blasting, or coarse sand blasting. Seven pumps were assembled with different impeller and housing surfaces. These surfaces were then examined by a surface profile instrument and a scanning electron microscope. The results of this study are as follows. First, the effect of surface roughness on hemolysis was significantly greater in the CPB condition than in the LVAD condition. Second, surface roughness, regardless of whether it is the impeller or pump housing, had little effect on hemolysis in the LVAD condition. Third, in the CPB condition, the surface roughness of the pump housing has a greater effect on hemolysis than does that of the impeller. From a hemolytic point of view, an extremely smooth pump housing is required for use of an impeller type centrifugal pump as a CPB device. In contrast, it is conceivable that a smooth surface is not always essential for an impeller type centrifugal pump that is used as an LVAD.

Quantitative phase imaging in confocal microscopy by optical differentiation

The technique of optical differentiation is applied to confocal microscopy for the purpose of quantitative phase imaging. One-dimensional absorptive filters are placed in the pupil of the microscope objective to produce images related to the local phase slope in the object. With suitable signal processing and integration, a quantitative phase profile is obtained. This method is demonstrated in a reflection-based surface-profiling instrument.

The contact between opposing fault surfaces at Dixie Valley, Nevada, and implications for fault mechanics

Well‐exposed normal fault surfaces from Dixie Valley, Nevada, provide a unique opportunity to study the contact properties of fault surfaces, because it is possible to examine both the hanging wall and footwall surfaces of a fault zone which was once seismically active. The topography of the individual surfaces, as well as the aperture, or gap between the two surfaces, was measured using surface profiling instruments and a resin replication technique. These measurements enable frictional parameters of the surfaces, most notably the characteristic decay distance, Dc, to be calculated using contact theory. Although the individual surfaces are approximately self‐similar and fractal, the aperture between the opposing surfaces is a stationary quantity because the surfaces are well correlated at dimensions larger than approximately 2 mm. Consequently contact theory can be used to calculate an average size for contact spots between the surfaces, and by inference, a characteristic decay distance, Dc, for frictional slip between the surfaces. Direct inspection of resin replicas of the aperture allows an independent estimate of average contact spot size. Both approaches give contact spot diameters of ≈0.16 mm, and Dc of 0.01–0.1 mm. Because the individual surfaces of the fault are fractal and approximately self‐similar, correlation between the surfaces should decrease significantly during slip events, particularly if slip rates are high (seismic events). Decreased correlation between the surfaces should lead to larger contact spot sizes and hence larger Dc. Thus critical slip distances for natural faults should evolve concurrently with seismic fault slip.

Figure and finish of grazing-incidence mirrors

Great improvement has been made in the past several years in the quality of optical components used in synchrotron-radiation (SR) beam lines. Most of this progress has been the result of vastly improved metrology techniques and instrumentation permitting rapid and accurate measurement of the surface finish and figure on grazing-incidence optics. A significant theoretical effort has linked the actual performance of components used at X-ray wavelengths to their topological properties as measured by surface-profiling instruments. Next-generation advanced light sources will require optical components and systems to have sub-arcsec surface figure tolerances. We will explore the consequences of these requirements in terms of manufacturing tolerances to see if the present manufacturing state-of-the-art is capable of producing the required surfaces. It is now possible to routinely measure figure and finish on meter-long optical surfaces in our laboratory with a long trace profiler of our own design and with a commercial microinterferometer profiler. Our instrumentation allows us to analyze surface profile data in terms of the power spectral density function over the range of spatial periods that are of relevance to X-ray mirror performance: 1 m to 5 μm. We have been able to recognize several classes of problems in the manufacture of grazing-incidence optics from the results of our measurements. In some cases we have been able to provide feedback to the manufacturer, who has then been able to modify and improve his process. Results from our analyses of mirror figure and finish measurements will be presented and their impact on the design of high-resolution soft-X ray SR systems will be discussed.

Scanning capacitance microscopy

A novel mechanically scanned and non-contacting surface profiling instrument has been developed in which a fine wire probe is raster scanned over the surface of the sample under examination. Measurement of the modulated capacitance between the probe and the vibrated sample is used to maintain the probe just above the surface. In the prototype instrument described, an in-plane resolution better than 2 mu m is achieved by the use of an etched tungsten wire probe, while the perpendicular resolution is 6 nm. Both insulating and conducting samples may be scanned and the technique makes it possible to measure electrical properties of the surface under the probe as well as the surface microtopography.

Stylus profiling instrument for measuring statistical properties of smooth optical surfaces

A surface profiling instrument is described which produces digitized surface profiles and other statistical data. Sharp styli are available that can give height resolution of the order of 1-2 A and lateral resolution of a few tenths of a micrometer on smooth surfaces. The stylus loading can be adjusted so that no permanent marks are left on the surface. Representative surface profiles and autocovariance functions are shown for various materials, and roughnesses measured with the instrument are compared with values obtained using other techniques.