Showing papers on "Surface roughness published in 1975"
TL;DR: In this paper, the authors describe a study of the adhesion between elastic solids and the effect of roughness on their adhesion, showing that roughness which is small compared with the overall deformation occurring at the region of the rubber-Perspex contact can produce an extremely large reduction in adhesion.
Abstract: This paper describes a study of the adhesion between elastic solids and the effect of roughness in reducing the adhesion. The experiments were carried out between optically smooth rubber spheres and a hard smooth flat surface of Perspex which could be roughened to various degrees. The radius of the rubber spheres was varied by a factor of 8, their elastic modulus by a factor of 10, while the centre line average (c.l.a.)of the roughened Perspex surface was varied from 0.12 to 1.5 μm. The results show that c.l.a. roughnesses which are small compared with the overall deformation occurring at the region of the rubber-Perspex contact can produce an extremely large reduction in adhesion. The effect is more marked for rubbers of higher modulus. On the other hand the curvature of the sphere (over the range examined) has little influence. For this reason and because the analytical problem of a sphere on a rough flat is extremely complicated a theoretical analysis has been developed for the simpler case of a smooth flat in contact with a rough flat surface. As in Greenwood & Williamson (1966) the rough surface is modelled by asperities all of the same radius of curvature and with heights following a Gaussian distribution of standard deviation σ. The overall contact force is obtained by applying the contact theory of Johnson, Kendall & Roberts (1971) to each individual asperity. The theory predicts that the adhesion expressed as a fraction of the maximum value depends upon a single parameter, 1/Δ e ,which is the ratio between a and the elastic displacement δ C that the tip of an asperity can sustain before it pulls off from the other surface. The analysis shows that the adhesion parameter may also be regarded as representing the statistical average of a competition between the compressive forces exerted by the higher asperities trying to prize the surfaces apart and the adhesive forces between the lower asperities trying to hold the surfaces together. Although the theory is derived for two nominally plane surfaces it is found to fit the experimental results for a sphere on a flat reasonably well.
838 citations
TL;DR: In this paper, a theoretical description of the scattering and absorption of electromagnetic radiation induced by roughness on the surface of a semi-infinite medium is presented, where the authors use scattering theory applied to the classical Maxwell equations.
Abstract: In this paper, we present a theoretical description of the scattering and absorption of electromagnetic radiation induced by roughness on the surface of a semi-infinite medium. We approach the problem by the use of scattering theory applied to the classical Maxwell equations. We obtain formulas for the roughness-induced scattering from the surface of an isotropic dielectric for both $s$- and $p$-polarized waves incident on the surface at a general angle of incidence. When the real part of the dielectric constant of the material is negative and its imaginary part small (as in a simple nearly-free-electron metal), we extract from the expressions for the total absorption rate that portion which describes roughness-induced absorption by surface polaritons (surface plasmons). We compare our results with those recently published by Ritchie and collaborators for the case of normal incidence, and we present a series of numerical studies of the roughness-induced scattering and absorption rates in aluminum.
348 citations
TL;DR: In this paper, a model for evaporation as a molecular diffusion process into a turbulent atmosphere is extended by joining it with the similarity models for turbulent transfer in the surface sublayer.
Abstract: A model proposed earlier (Brutsaert, 1965) for evaporation as a molecular diffusion process into a turbulent atmosphere is extended by joining it with the similarity models for turbulent transfer in the surface sublayer. The assumed mechanisms were suggested by available flow visualization studies near smooth and rough walls; the theoretical result is in good agreement with available experimental evidence. The important dimensionless parameters governing the phenomenon near the surface are the Dalton (or Stanton) number (i.e., mass transfer coefficient), the drag coefficient (u*2/U2), the roughness Reynolds number (u*z0/v) (except for smooth surfaces), and the Schmidt (or Prandtl) number (v/k). The proposed formulation allows the evaluation of the effects of some parameters, such as surface roughness or molecular diffusivity, that were hitherto not well understood. An important practical result is that in contrast to the drag coefficient, the Dalton number is relatively insensitive to changes in roughness length Z0.
248 citations
237 citations
TL;DR: In this paper, the capacitance of the edge orientation (plane perpendicular to the basal one) of stress-annealed pyrolytic graphite and glassy carbon have been studied in concentrated aqueous solutions using an a.c. impedance bridge.
187 citations
01 Jan 1975
TL;DR: In this paper, a scalar theory of surface scattering phenomena has been formulated by utilizing the same Fourier techniques that have proven so successful in the area of image formation, and an analytical expression has been obtained for a surface transfer function which relates the surface micro-roughness to the scattered distribution of radiation from that surface.
Abstract: A scalar theory of surface scattering phenomena has been formulated by utilizing the same Fourier techniques that have proven so successful in the area of image formation. An analytical expression has been obtained for a surface transfer function which relates the surface micro-roughness to the scattered distribution of radiation from that surface. The existence of such a transfer function implies a shift-invariant scattering function which does not change shape with the angle of the incident beam. This is a rather significant development which has profound implications regarding the quantity of data required to completely characterize the scattering properties of a surface. This theory also provides a straight-forward solution to the inverse scattering problem (i.e., determining surface characteristics from scattered light measurements) and results in a simple method of predicting the wave length dependence of the scattered light distribution. Both theoretical and experimental results will be presented along with a discussion of the capabilities and limitations of this treatment of surface scatter phenomena.© (1977) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
182 citations
TL;DR: The roughness length of any scalar admixture depends not only on the nature of the surface but also on the intensity of surface shear stress and on the molecular diffusivity and the viscosity as discussed by the authors.
Abstract: An expression is presented for the roughness length of water vapor (or sensible heat, etc) that is the surface value intercept of the straight line resulting from a semi-logarithmic plot of the mean specific humidity (or potential temperature, etc) profile in the dynamic sublayer The derivation is based on the standard assumption of continuity in the mean profile at the interface between the interfacial transfer sublayer and the fully turbulent surface sublayer It is found that the resulting formulation yields similar results for a number of empirical and theoretical equations for the interfacial transfer that are available in the literature The roughness length of any scalar admixture depends not only on the nature of the surface but also on the intensity of the surface shear stress and on the molecular diffusivity and the viscosity In meteorological applications under rough flow conditions this roughness length may be considerably smaller than the aerodynamic roughness length Z0, whereas
179 citations
TL;DR: Two speckle patterns produced from the same rough surface by two different illuminations are correlated and the theoretical calculations have been performed for a normally distributed surface, in good agreement with theory.
Abstract: Two speckle patterns produced from the same rough surface by two different illuminations are correlated. The correlation depends on the surface roughness. The two illuminations were obtained here by varying the angle of incidence of a coherent plane wave on the surface. The speckle patterns are recorded on the same film by double exposure. By placing this film in a convergent laser beam, Young fringes are observed in the Fourier plane. The correlation of the speckle patterns is obtained by measuring the visibility of the fringes. The theoretical calculations have been performed for a normally distributed surface. The experimental results are in good agreement with theory.
172 citations
TL;DR: In this article, all aspects of surface form can be considered to reflect surface roughness, including texture and grain, while vertical variation is discussed under relief, texture, and relief.
Abstract: All aspects of surface form can be considered to reflect surface roughness. Horizontal variation includes the concepts of texture and grain, while vertical variation is discussed under relief. The ...
164 citations
TL;DR: The residual surface roughness of diamond-turned optics is expected to contain significant periodic components and the optical properties of such surfaces are explored as a special case of Rayleigh-Rice vector scattering theory applied to periodic roughness with vertical amplitudes much smaller than the wavelength of light.
Abstract: The residual surface roughness of diamond-turned optics is expected to contain significant periodic components. The optical properties of such surfaces are explored as a special case of Rayleigh-Rice vector scattering theory applied to periodic roughness with vertical amplitudes much smaller than the wavelength of light. Expressions are given for the interpretation of differential-scatter, total-integrated-scatter, reflectometry, and ellipsometric measurements in the limit of a highly conducting. surface. In general, such measurements give varying degrees of information about the two-dimensional power spectral density of the surface roughness within the nominal range from the wavelength of light to the diameter of the probing beam spot. Such information may be useful for the practical characterization of mirror surfaces.
155 citations
TL;DR: In this paper, the effects of surface roughness on the low-cycle fatigue life of Type 304 stainless steel at 593°C in air have been investigated, and it was observed that, at a strain rate of 4 × 10−3 s−1 and a total strain range of 1 pct, the fatigue life (Nf cycles) decreases with an increase in surface rougheness.
Abstract: The effects of surface roughness on the low-cycle fatigue life of Type 304 stainless steel at 593°C in air have been investigated. It is observed that, at a strain rate of 4 × 10−3 s−1 and a total strain range of 1 pct, the fatigue life (Nf cycles) decreases with an increase in surface roughness. Information on crack growthvs strain cycles has been generated, as a function of surface roughness, by the measurement of striation spacing on fractured surfaces of specimens tested to failure. Crack propagation follows the Ina ∞N (wherea is the crack length afterN strain cycles) relation for longer specimen fatigue lives (Nf > 2700 cycles) and departs from Ina ∞N for shorter fatigue lives. A quantitative estimate is made of the number of cycles No(r) to generate a crack length equal to 0.1 mm (≈ 1 grain diam). The initial surface roughness significantly affects only the initiation component of specimen life time. The effect of roughness on crack initiation is described byN0(R) = 1012R−0.21, whereR is the surface roughness (root-mean-square value) in microns.
TL;DR: In this paper, a quantitative relation between the practical breakdown threshold and gas pressure times maximum surface roughness is derived, based on the streamer theory of breakdown, which is applied to microscopic field regions associated with roughness.
Abstract: Electrode surface roughness can cause a large reduction of the threshold for break down in SF 6 insulated apparatus. This effect is discussed by applying the streamer theory of breakdown to the microscopic field regions associated with surface roughness. A quantitative relation is derived between the practical breakdown threshold and gas pressure times maximum surface roughness.
TL;DR: The surface spectral density function (SDF) has been calculated from measurements of the light scattered out of a reflected He-Ne laser beam and allows examination of roughness as a function of spatial frequency, which is important for many applications.
Abstract: Characterization of surface roughness has generally been limited to rms deviation from the mean and occasionally the autocorrelation length. By considering the surface to be a superposition of many sinusoidal gratings, the surface spectral density function (SDF) has been calculated from measurements of the light scattered out of a reflected He-Ne laser beam. By rotating the sample, the SDF can be found for anisotropic surfaces (such as machined surfaces). The SDF allows examination of roughness as a function of spatial frequency, which is important for many applications. Interferometric and scattering results are compared for a rough (350-Arms) machined surface, and finally a smooth (50-Arms) diamond machined surface is characterized.
IBM1
TL;DR: In this article, a series of wear experiments utilizing a ball-plane configuration was performed to determine the influence of both the magnitude and anisotropy of the surface roughness on wear.
TL;DR: In this paper, the contrast of a polychromatic speckle pattern can be calculated from the spectral coherence of the scattered amplitude, and the analytical relationship between the contrast and r.m.s. surface roughness is derived.
Abstract: It is shown how the contrast of a polychromatic speckle pattern can be calculated from the spectral coherence of the scattered amplitude. For gaussian surfaces and relatively narrow spectral profiles an analytical relationship between speckle contrast and r.m.s. surface roughness is derived. The theoretical results are compared with available experimental data and discrepancies are explained.
TL;DR: In this article, an exact quantum formalism for atom scattering from a sinusoidal hard-wall surface is presented, which results in an infinite-dimensional matrix equation for the Fourier coefficients of the scattering kernel which can be solved in a finite-dimensional limit to convergence.
Abstract: An exact quantum formalism for atom scattering from a sinusoidal hard- wall surface is presented. The Lippmann-Schwinger equation is solved for a scattering kernel consistent with the hard-wall boundary conditions on the Schrodinger equation. It results in an infinite-dimensional matrix equation for the Fourier coefficients of the scattering kernel which can be solved in a finite- dimensional limit to convergence. The results show either rainbow or specular patterns depending on the surface roughness and incident k vector, as predicted by semiclassical and coupled-channel calculations. Bragg-like structure is present with the periodicity of the amplitude of the sinusoidal hard wall and the effects of multiple scattering are evidenced at large surface amplitudes. (AIP)
TL;DR: In this article, the amplitudes of diffracted fields from a rough surface, for light of general polarization and incidence angle, are found by the classical method of Rayleigh and Fano.
Abstract: The amplitudes of the diffracted fields from a rough surface, for light of general polarization and incidence angle, are found by the classical method of Rayleigh and Fano. Explicit formulas are then obtained for the differential reflected intensity of $P$- and $S$-polarized light as well as for the decrease in reflection coefficient of $S$, $P$, and circularly polarized light due to the excitation of surface plasmons. The results are valid to first order in the surface roughness and are confirmed by additional calculations based on other perturbative methods, both classical and quantum mechanical. The discrepanies found in some cases with the recent results of Maradudin and Mills are analyzed and explained.
TL;DR: In this paper, the authors derived expressions for the rate at which radiation is scattered and absorbed because of surface roughness on a semi-infinite material, in the presence of a dielectric overlayer.
Abstract: We derive expressions for the rate at which radiation is scattered and absorbed because of surface roughness on a semi-infinite material, in the presence of a dielectric overlayer. We confine our attention to the case of normal incidence. A formalism developed in an earlier paper by the present authors is utilized in the discussion. We also present a series of numerical calculations which explore the roughness-induced scattering and absorption of electromagnetic radiation for aluminum overcoated by aluminum oxide, in the ultraviolet region of the spectrum. The position of the reflectivity dip produced by roughness-induced coupling to the surface plasmon is found to shift toward the visible as the thickness of the oxide layer increases. The size of the dip is controlled strongly by the degree of correlation between the roughness on the vacuum-oxide interface, and that on the oxide-substrate interface. Under conditions discussed in the text of the paper, the presence of the oxide layer can greatly enhance the coupling between the incident radiation and surface plasmons.
Patent•
19 May 1975TL;DR: In this paper, an improved interlayer for laminated safety glass is presented, characterized by having at least one surface which is more printable without sacrificing the surface roughness required to prevent blocking of the sheet and to facilitate de-airing of laminates prepared from the interlayer.
Abstract: Disclosed herein is an improved interlayer for laminated safety glass. The improved interlayer is characterized by having at least one surface which is more printable without sacrificing the surface roughness required to prevent blocking of the sheet and to facilitate de-airing of laminates prepared from the interlayer.
TL;DR: In this paper, a simple model is presented which approximates the turbulent shear flow over a well-defined rough surface as a series of attached and separated flow regions, and an elementary analysis applied to the model provides values for the well-known momentum and heat-transfer roughness functions R(h+ ) and g(h+, Pr), respectively.
Abstract: A simple model is presented which approximates the turbulent shear flow over a well-defined rough surface as a series of attached and separated flow regions. An elementary analysis applied to the model provides values for the well-known momentum- and heat-transfer roughness functions R(h+ ) and g(h+ , Pr), respectively. In order to use the calculation method the exact shape and distribution of the roughness elements are required together with a form drag coefficient and a characteristic separation length. These may be found in the literature for many roughness shapes of interest.
TL;DR: In this paper, the authors investigated the actual locus of failure by 14C labelling of the epoxy polymer and also by Auger spectroscopy profile analysis, which indicated a residual film of polymer a few hundred angstroms thick on the aluminium surface.
Abstract: Aluminium-epoxy adhesive specimens constructed with the bond at 45‡ to the direction of loading appear to fail very close to the interface. The actual locus of failure was investigated by14C labelling of the epoxy polymer and also by Auger spectroscopy profile analysis. Both techniques indicated a residual film of polymer a few hundred angstroms thick on the aluminium surface. The fracture energy of these specimens was determined and found to be affected by the surface roughness of the aluminium. The mixed-mode fracture energy (GI,II) C45° of these specimens in the absence of any surface roughness effect (polished surfaces) was 140 J m−2 compared to 136 J m−2 for the same polymer in simple opening-modeGI C adhesive fracture. The “interfacial” failure and the effect of surface finish on fracture are discussed in terms of the applied stress directing the failure toward the interface but the approach of the crack to the boundary being limited by the size of the crack tip deformation zone.
TL;DR: In this article, the relationship between the normal approach and load for a variety of rough flat surfaces has been considered experimentally and theoretically, and the experimental values of normal approach measured by a capacitance technique correlate well with the theoretical values based on the measured surface parameters.
TL;DR: In this article, a statistical expression for the fractional reduction in fatigue life at full film conditions due to the competition between asperity induced fatigue and fatigue due to indigenous surface defects and subsurface inclusions is presented.
Abstract: A statistical expression, showing as a function of the film parameter (film thickness/surface roughness or h/σ) the fractional reduction in fatigue life at “full film” conditions due to the competition between asperity induced fatigue and fatigue due to indigenous surface defects and subsurface inclusions, is presented. Several sources of endurance test data relating the fatigue life of a rolling bearing to the film parameter are reviewed. To unify the experimental data a “relative” fatigue life raised to the power of e, the Weibull dispersion parameter, is plotted against the film parameter. Comparisons between the theoretical and experimental results are then made which reveal that the increase in bearing fatigue life due to the film parameter can be described by the theoretical model with a “reference” film parameter value of 1.5 for h/σ > 0.5. For h/σ < 0.5, the variation of h/σ explains only a minor portion of the scatter of the fatigue lives. Presented at the 29th Annual Meeting in Cleveland, Ohio, ...
TL;DR: The adhesion of a polymer film to selected tablet substrates was studied and a film-coating solvent having a solubility parameter close to that of the polymer was found to produce a stronger adhesional bond than a solvent having lower surface tension.
TL;DR: In this paper, the influence of surface roughness on Auger electron spectroscopy (AES) was investigated by measuring the Auger signal from gold films on smooth glass and rough ceramic substrates.
TL;DR: The statistical properties of speckle intensity variations produced by coherent light in the diffraction field of diffusely transmitting objects are investigated experimentally with intimate relation to their surface roughness as mentioned in this paper.
TL;DR: In this paper, the wear behavior of composite coatings consisting of TiC and Ti-carbonitrides of varying composition is considered, and it is shown how roughness and surface structure of TiN layers produced by the CVD method vary in dependence of the deposition temperature but at equal deposition rate.
Abstract: Cemented carbide parts coated with several‐micron‐thick layers of hard material are now used in large quantities in machining, particularly for turning and milling. Applications for jewelry purposes are assuming increasing importance. Following a brief survey of wear mechanisms in machining, the wear behavior of homogeneous coatings of TiC, TiN, and Al2O3 is discussed. Some conclusions concerning the wear‐reducing effect of these coatings are derived. It is found that a complex interrelationship of several factors, such as diffusion barriers, reduction of friction, thermal conductivity, and others, play an important part. Effects of hardness and chemical behavior of hard‐material coatings, especially of TiC and TiN layers on the wear decrease, are mentioned. The wear behavior of composite coatings consisting of TiC and Ti‐carbonitrides of varying composition is then considered. By incorporation of these hard materials into multiple, inhomogeneous layers, significant improvements over homogeneous single‐layer coatings are achieved. In addition to great hardness, the application of hard material layers for jewelry demands corrosion resistance, an attractive color, and good polishing characteristics. Examples for the corrosion resistance of TiC and TiN and the colors of Ti‐carbonitrides are presented. The polishing characteristics of hard‐material layers greatly depend on surface roughness. It is shown how roughness and surface structure of TiN layers produced by the CVD method vary in dependence of the deposition temperature but at equal deposition rate. Some important requirements for coatings applied to tools and jewelry articles and possible methods for their production are mentioned.