Trend Of Surface Roughness Research Articles

Statistical characteristics and logarithmic EWMA control method of bearing raceway's surface roughness by superfinishing

The bearing raceway is the main working surface of the bearing and good surface integrity is required. Since superfinishing is an important method for achieving high surface quality, it is usually used as the last processing to play a very essential part in improving the surface integrity of bearing raceway. In this paper, we proposed a superfinishing surface quality control method, by which we could determine whether there were systematic factors that caused surface quality anomalies by measuring and analysing the roughness data without directly measuring process parameters and environmental indicators. Firstly, we verified through experiment that the surface roughness by superfinishing did not obey the normal distribution but obeyed the logarithmic normal distribution. We interpreted this statistic characteristics by the mechanism of the relationship between roughness and random factors in the superfinishing. Then, according to above findings, and considering the possible trend of surface roughness during continuous processing, we designed a logarithmic exponentially weighted moving average (EWMA) method to test the surface roughness and judge whether it was under control. Finally, the effectiveness of this surface quality control method in superfinishing was verified by applying it to the actual bearing raceway outer ring machining.

Laser Direct-Part Marking of Data Matrix Barcodes on the Surface of Metal Alloy Material

The influences of laser processing parameters on the symbol contrast and surface roughness of Data Matrix barcodes were studied by single factor experiments using a Q-switched lamp pumped Nd:YAG laser. The orthogonal experiments were carried out to further study the relationship between laser parameters and surface roughness. Multivariate nonlinear regression analyses were performed based on the orthogonal experimental results and a mathematical relationship between parameters and surface roughness was established. The results show that the change trend of surface roughness is similar to symbol contrast with the increase of laser parameters. Both the average power and two different overlaps are important factors affecting the surface roughness and symbol contrast. But the current intensity has an insignificant impact on the surface roughness. The developed regression model can be used to predict the roughness of Data Matrix barcodes. This study can improve industrial application of laser direct part marking technology on titanium alloy substrates.

Prologue to the Special Issue on “Recent Trends in Surface Roughness”

Prologue to the Special Issue on “Recent Trends in Surface Roughness”

Quantifying trends in surface roughness and the effect on surface wind speed observations

Many studies analyzing surface wind speed observations find a decrease in wind speed over the last 30 to 50 years. A cause sometimes proposed is increasing surface roughness, although to date the evidence that this is the primary factor is still inconclusive. In this study, changes in surface roughness are investigated for 20 stations in the Netherlands and 137 stations in 7 other European countries. From the Dutch data set, local aerodynamic roughness lengths were calculated from hourly gust factors. Trends in wind speed for individual stations and wind direction sectors correlate negatively with trends in surface roughness. For 1962–2009, typically a doubling of the local roughness length was found, with the strongest increase after 1981. An accompanying average decrease in wind speed by 3.1% (0.13 m/s) per decade was found for 1981–2009. A conceptual boundary layer model was used to show that 70% of the wind speed trend can be attributed to surface roughness changes; the remaining 30% of the trend remains unresolved. Changes in land use, including urbanization, forestation, and a decrease in pasture land area, are probable causes for the increasing surface roughness. For the European station data from the European Climate Assessment and Dataset (ECA&D) and the Swiss Federal Office of Meteorology and Climatology (MeteoSwiss), the analysis was restricted to daily gust factors. Observed trends in wind speed at stations correlate negatively with trends in gust factors. Averaged over all stations, the wind speed decreased 1.2% (0.05 m/s) per decade over 1982–2009, consistent with increasing surface roughness.

Real time spectroscopic ellipsometry on ultrathin (<50Å) hydrogenated amorphous silicon films on Si(100) and GaAs(100)

Real time spectroscopic ellipsometry was used to determine the time evolution of the dielectric function, bulk thickness, and surface roughness during hot-wire chemical vapor deposition of hydrogenated amorphous silicon (a-Si:H). The amorphous silicon films were deposited on native-oxide-covered c-Si(100) and GaAs(100) substrates at temperatures in the range from 70to350°C. Data analysis by a three layer optical model, consisting of substrate, bulk, and surface roughness layer, revealed that the dielectric function of the a-Si:H film changes in the initial growth regime (d<50Å), which can be attributed to a higher optical band gap for films with a smaller thickness. It is argued that the origin of this higher band gap lies most likely in quantum confinement effects of the electron wave function in the ultrathin film, with possibly a small contribution of a higher hydrogen content in the ultrathin film. In addition, we show that the trends in surface roughness and bulk thickness are only marginally affected, regardless of whether the change in dielectric function with film thickness is incorporated in the data analysis.

Toward the Improvement of the Microstructure of Chemical Vapor Deposited Aluminum on Silicon Carbide

This paper presents results on the chemical vapor deposition of aluminum on silicon carbide starting from triisobutylaluminum. The deposited films show important systematic trends in surface roughness and porosity. Considering literature information on the deposition of aluminum on silicon, pretreatments of the deposition surface with hydrofluoric acid and/or titanium tetrachloride have been tested. They lead to films with a smoother morphology and stronger adhesion with the substrate than in the case of an untreated surface. Different heteroelements are observed at the interface under these conditions. A short thermal activation of the nucleation process following these pretreatments does not unambiguously improve the characteristics of the aluminum films. The obtained results can be considered for the modification of surface characteristics of silicon carbide particles which are used in discontinuously reinforcement aluminum composite materials with the aim to improve their mechanical properties and corrosion resistance as well as their fabrication process. © 2001 The Electrochemical Society. All rights reserved.

Trends in surface roughness

The recent past of roughness measurement and characterisation is briefly reviewed and some interesting unresolved problems are discussed.Gaps in the present instrumental coverage of range-resolution space are identified.Progress of in-process and inspection techniques is reviewed, and it is noted that existing measurement techniques are restricted to single-valued surfaces.The lack of compatibility of proprietary software packages is deplored and timely development of soft gauges is advocated. Support is expressed for current proposals for a consolidated 3D parameter set. Finally two remaining problem areas of 3D characterisation are identified as the description of lay and the connectedness of surface features.

Structure and Morphology of Biaxially Oriented Films of Polyethylenes

Biaxially oriented films of commercial polyethylenes were investigated using X-ray diffraction in directions transverse and perpendicular to the film plane. The surface morphology of the inner and outer faces of these films were studied in two directions by (a) transmission election microscopy employing replication procedures, (b) by atomic force microscopy (tapping mode) down to nanometer resolution, (c) scanning electron microscopy of ion-etched metal coated surfaces, and (d) small-angle X-ray scattering measurements obtained from the bulk films. Discernible differences in morphological features were found for the inner and outer film faces that experienced different conditions during blow extrusion. The mean surface roughness of the films was measured and correlated with the haze parameters of these polyolefin materials. Trends in surface roughness with crystallinity (assessed from other measurements) are attributed to surface lamellar-like crystallization.