Dull Surface Research Articles

Corrosion behaviour of glass-bead blasted stainless steel sheets and other sheets with dull surface finish in a chloride solution

Glass-bead blasted stainless steel sheets are used in recent time for many applications in architecture or design of machines. If chloride can be accumulated on the surface, glass-bead blasted stainless steel show a worse corrosion behaviour than ground stainless steel. The corrosion behaviour of glass-bead blasted stainless steel is characterised by electrochemical, topographic and roughness investigations. The results of glass-bead blasted stainless steel will be compared with results of other surface treated steels like ground, structure rolled, sand-blasted and electropolished stainless steel. It is shown that not only the roughness parameter Ra has an influence on the corrosion behaviour but also the shape of the valleys and peaks, which are produced during different surface treatments. The investigations lead to advices for the use of these materials in practice.

Leaf-fiber lignins of Phormium varieties compared bysolid-state 13C NMR spectroscopy

Abstract Solid-state NMR spectroscopy was used to determine total lignin and to distinguish between the syringyl and guaiacyl components of Phormium leaves. Fibers obtained from the upper (shiny) and lower (dull) surfaces of a P. tenax leaf showed guaiacyl lignin contents of 1.5% and 5.4% by weight, respectively. Guaiacyl lignin is known to have poor photostability, so the analyses supported a traditional view of the upper-surface fibers as the more suitable for textiles. All other analyses involved mixtures of fibers from both upper and lower surfaces. They showed no detectable differences in guaiacyl content between leaves within a ramet, or between ramets in a P. tenax bush, with a mean value of 2.2% for 20 leaves. There were no detectable differences in guaiacyl content between bushes of the variety Taeore grown at different sites, with a mean value of 2.7% for 6 sites. There were detectable differences in guaiacyl content between 15 named varieties grown at a single site, with values as low as 2.3% and as high as 4.5%. Lowest guaiacyl contents were found in varieties traditionally used for textiles. The highest guaiacyl lignin contents, 6.0% and 5.8%, were found in P. cookianum and in a plant grown from stock obtained at Norfolk Island. Syringyl lignin contents were relatively uniform between varieties, with a mean value of 6.7%.

All That Glistens: II. The Effects of Reflective Surface Finishes on the Mouthing Activity of Infants and Toddlers

A number of infants and toddlers have been observed to mouth and to lick the horizontal metal mirrors of toys on their hands and knees in a manner not unlike the way older children drink from rain pools in developing countries. Such mouthing of glistening surfaces by nursing-age children might characterize the precocious ability to recognize the glossy and sparkling features of water long before this information is useful later in development. Two experiments examined the frequency with which infants and toddlers mouthed lightweight 25.4-cm diameter dinner plates during 5 bouts of plate contact. Experiments were conducted in the natural context of toy handling during playtime at 10 day-care facilities in northern California. In the first experiment, 22 children divided into 2 age groups (13 between 6 and 12 months and 9 between 13 and 17 months) were examined as they handled or contacted a stainless steel plate with a mirror finish or a glossy white plastic plate. The stainless steel plate was mouthed at a significantly (p < .0001) larger percentage of plate-contact bouts than the white glossy plate, with no appreciable difference in age. Consistent with observations that some forms of mouthing resembled drinking activity, children mouthed the stainless steel plate on their hands and knees significantly (p < .025) more than the glossy white plate. The 2nd experiment compared teal-blue plastic plates with plates that had glossy and dull surface finishes. Forty-six infants and toddlers in 3 age groups (7-12 months, 13-18 months, and 19-24 months) handled or contacted both plates for 5 bouts. The glossy plate elicited a significantly (p < .05) larger percentage of mouthing than the dull plate, but this effect was restricted to the youngest age group. Mouthing of both plates increased markedly in the oldest age group, a result that likely characterizes the association of dinner plates with eating. Together, the results of these experiments suggest that infants and toddlers have the precocious ability to recognize the optical cues for water as characterized by the gleaming highlights and clear reflections of polished metal. The reduction of mouthing of the teal plate with a dull surface finish provides ideas for thwarting mouthing that endangers children by applying dull surface finishes to potentially hazardous household objects known to have caused incidences of suffocation, choking, and the transmission of pathogens by saliva.

Numerical simulation of multiple light scattering in layers consisting of opaque particles with a dull surface (geometrical optics approximation)

A numerical model is presented which allows one, in the geometrical optics approximation, to calculate scattering contributions of specified multiplicity in layers comprised of opaque particles with dull surfaces. For definiteness, the particles are assumed to be spherical with the Lambertian law of light scattering by the particle surface. The greatest scattering multiplicity is restricted, in this model, only by computer capacity. In this paper, the scattering multiplicities up to the sixth order inclusively are studied. Layers of moderate optical thickness, as well as the case of a semi-infinite medium with different particle packing densities, are analyzed for different geometries of illumination and observation. It is shown that for conservative scattering by the particle surface, the contribution of higher-order scattering decreases with increasing order number, which is related to the shadow-hiding effect. The scattering indicatrices of higher orders approach the isotropic case. The even and odd scattering orders show a systematic difference between themselves.

Evaluation of the surface roughness of compomer by laser scanning microscopy.

The purpose of this study was to evaluate the effect of alcoholic and low pH soft drinks on the surface roughness of compomer restorative materials. There were five tested materials and four immersion media. Specimens were immersed in test solutions for a 10-day period at a temperature of 37 degrees C. Measurement of the surface texture was carried out using a laser scanning microscope (a non-contact laser stylus tracing method). This was also used to produce the Laser Scanning Microscope Image (LSM Image). Specimens immersed in orange juice and whisky displayed higher values for Ra & Rz than specimens immersed in soft drinks and deionized water. LSM Image showed a difference between the control and the examined side, especially for specimens immersed in low pH soft drinks this could be due to the erosive effect of the media. Alcoholic and low pH soft drinks caused deterioration of the materials surface, which may lead to a clinically detectable rough and dull surface.

First Report of Potato Spindle Tuber Viroid in Costa Rica.

During 1997 to 1998, symptoms of leaf roll, dwarfism, chlorosis, and occasional leaf necrosis were observed on Solanum tuberosum in several plots in Cartago, the principal potato-production region of Costa Rica. Because of the known association between potato leafroll virus (PLRV) and viroids (1) and previous reports of PLRV in Costa Rica, the presence of potato spindle tuber viroid (PSTVd) was suspected. Leaf samples from 122 symptomatic potato plants, cvs. Atzimba, Floresta, Idiafrit, and Birris, were collected from 10 plots. Total nucleic acids (TNAs) were extracted and purified (2) from collected symptomatic samples and six healthy potato controls. TNAs were spotted on nylon membranes and hybridized to a digoxigenin-labeled DNA probe specific for PSTVd. Of 122 symptomatic plants, 71 were positive for PSTVd based on dot blot hybridization. TNAs from 12 positive potato samples, including at least 1 sample from each cultivar, were used to inoculate Lycopersicum esculentum cv. Super Marmande. Eleven of twelve inoculated tomato plants showed symptoms of dwarfism, leaf deformation, and grayish foliage, often with a dull surface. TNAs were extracted from inoculated tomato and hybridized to the PSTVd probe. All inoculated symptomatic plants were positive for PSTVd based on dot blot hybridization. This is the first report of PSTVd in Costa Rica.

Effects of Average Lubricant Velocity and Sliding Velocity on Friction Behavior in Mild Steel Sheet Forming

A series of experiments was carried out using a rolling-type tribometer to investigate the frictional dependence on the average velocity of the lubricant V at the contact zone inlet and the relative sliding velocity ΔV between the roll and workpiece during deformation. Experiments using mild steel strips with a dull surface of 0.63 fxm Ra showed that the friction coefficient decreases with increasing forming velocity, especially at high forming velocity. This variation in the friction coefficient may be due to the increase in ΔV derived from the increase of the forming velocity, because the friction coefficient decreases with increasing ΔV but varies little with increasing V. It was also confirmed that an increase of ΔV or a decrease in V promotes flattening of the workpiece asperities.

Effect of Surface Topography of Workpiece on Pressure Dependence of Coefficient of Friction in Sheet Metal Forming

In the previous sheet draw tests of Al-Si alloy and aluminum having a dull surface, the authors found that the coefficient of friction was constant in the lower pressure range, whilst in the higher pressure range, it decreased with increasing pressure and the relationship was qualitatively interpreted from results of the direct observation of contact behavior. In the present work, the pressure dependence is examined, changing the surface topography of workpiece by prerolling to different flattening degrees of surface asperities. From the results of direct observation of contact behavior obtained by making use of a newly developed fluorescence measurement method, the contact model can be interpreted 3-dimensionally for better surface control.

The effect of structural heterogeneity on the pitting corrosion behavior of melt-spun amorphous NiZr alloys

The pitting behavior of amorphous NiZr alloys prepared by melt-spinning was thoroughly investigated by placing an emphasis on the effect of the microstructure and surface composition. It was found that the alloy ribbons showed different pitting corrosion behavior along the thickness direction from the dull side to the shiny side in de-aerated 0.5 M H 2SO 4 solution with 0.1 M NaCl. The dull side surface was most susceptible to pitting corrosion, but it became difficult to occur if the as-prepared dull side surface was removed by mechanical polishing. The shiny side surface of all the alloys passivated spontaneously and the pitting potential increased with an increase in alloy zirconium content. TEM observation indicated that all the shiny side surfaces were wholly amorphous, while some microcrystalline phases existed in the amorphous matrix in the dull side. The crystalline phases formed in the dull side were identified as Ni 3Zr and NiZr 2 for the Ni30Zr and Ni70Zr alloys, respectively. The presence of both the microcrystalline phases in the amorphous matrix and the irregular surface morphology of the dull side were responsible for the origin of the pitting corrosion of the dull side surface. The high corrosion resistance of the shiny side surface was attributed to the high protectiveness of the passive film and the structural homogeneity of the alloy.

On-line growth monitoring of InP-based device structures by reflectance anisotropy spectroscopy

Reflectance anisotropy spectroscopy (RAS) has been used to study the metalorganic vapor phase epitaxy growth process for GaxIn1−xAsyP1−y/InP light emitting diodes. The sensitivity of RAS to morphology changes is demonstrated by InP growth on different InP:Fe substrates. RAS reveals not only development of dull surfaces but also detects initial temporary roughness of mirror-like layers. Based on the RAS results the substrate preparation was optimized. RAS spectra measured on n- and p-type InP and p-type GaInAsP during light emitting diodes production are suitable for finger-printing of the growth process. Spectra from InP:Si and InP:Zn layers show characteristic features near 4.3 eV which allow for assessment of doping level at growth temperature (640°C). Correlation of RAS spectra and transients during growth with the quaternary composition was achieved. A change in composition of only Δx=0.01, Δy=0.03 corresponding to a shift of photoluminescence-peak position by 16 nm was detectable in RAS spectra. The results demonstrate the high sensitivity and thus the suitability of RAS for on-line control during growth of device structures.

Pitting Corrosion of Amorphous Ni&amp;ndash;Zr Alloys in Chloride Ion Containing Sulfuric Acid Solutions

The pitting corrosion behavior of the melt-spun amorphous Ni-Zr alloys with 30-75 at% zirconium, the crystalline arc-melted counterparts and the sputter-deposited Ni-Zr alloys with 20-84 at% zirconium was examined by electrochemical measurements in deaerated 0.5 kmol/ m 3 H 2 SO 4 with and without 0.1 kmol/m 3 NaCl at 303 K. In the sulfuric acid solution without Cl - , these alloys were spontaneously passive and their potentiodynamic behavior was similar to each other. In the Cl - -containing solution, all the melt-spun amorphous alloys suffered pitting during anodic polarization and the pitting potential decreased with an increase in zirconium content. On the other hand, the crystalline arc-melted low zirconium alloys suffered pitting but no pitting observed for the crystalline alloys containing 70 at% zirconium or more. In addition, the pitting potential increased with the zirconium content of crystalline alloys. All the sputter-deposited alloys did not suffer pitting regardless of the amorphous and crystalline structures. Therefore, the melt-spun amorphous alloys were the most susceptible to pitting corrosion. A marked difference was observed in the pitting behavior between the shiny side (top side) and the dull side (wheel side) surfaces of the melt-spun ribbon. The pits initiated from the dull side surface. Thus, the dull side surface could be responsible for such an unusual pitting behavior of the melt spun ribbon.

High-rate dissolution of copper in cupric-sulfate electrolytes

The mass-transfer-limited dissolution of copper in acidic and binary cupric-sulfate solutions is investigated. The dissolution produces a dull surface with a coarse microtexture. This system has an unusually large limiting-current plateau, where a salt film precipitates. The film is characterized with steady polarization measurements as well as AC-impedance and flow-modulation spectroscopy. A low-field, film-conduction mechanism explains best the high-frequency region of the AC-impedance spectrum. The electrochemical behavior of the system is compared to other high-rate metal-dissolution systems. Shortcomings of present salt-film models are discussed.

Transposon tagging of the maize Glossy2 locus with the transposable element En/Spm.

The Glossy2 (Gl2) locus of maize is required for the formation of the epicuticular wax layer of young plants. gl2 mutant seedlings can be visually identified because of their glossy leaf surface which is different from the dull surface of wild-type seedlings. The Gl2 locus was isolated by transposon tagging. Seven unstable mutations, gl2-m2 to gl2-m8, were induced in a parental strain carrying an active transposable Activator (Ac) element in the unstable wx-m7 allele. Genetic tests on the gl2-m2 allele indicated that it was not caused by the Ac element but by the insertion of the transposable element Enhancer/Suppressor-Mutator (En/Spm). A Sa/l restriction fragment segregating with the mutant phenotype was identified, by Southern analysis, using sequences from the En/Spm element as a probe. Part of the fragment was cloned and was shown to carry part of the unstable gl2-m2 allele. These gl2 sequences were used to identify a genomic fragment carrying the wild-type allele and to isolate its corresponding cDNA sequence. The predicted Glossy2 protein consists of 426 amino acids. No similar amino acid sequence was found in protein data banks and the biochemical function of the Gl2 gene product is still unknown. The wild-type Gl2 transcript is found predominantly in juvenile leaves. The transcript level in the leaves of seedlings homozygous for a stable recessive gl2-ref allele is hardly detectable.

Microstructure of roughened surface in metal rolling

Flat rolled aluminum products have a $25 billion market worldwide annually. The topography of the rolled surface is a key measure of surface quality. A dull surface finish can be generated by non-homogeneous surface deformation when the sheet is rolled under conditions of hydrodynamic lubrication. This is undesirable for some applications where high reflectivity is required, though it improves paintability. Wilson and Schmid have investigated the influence of lubrication conditions on roughening. Although the texture evolution during the hot and cold rolling of aluminum has been studied, the basic mechanisms of the roughening process are not fully understood. The purpose of the present research is to explore the microstructural changes associated with the evolution of surface roughness and to use this information to develop mathematical models which can accurstely describe the surface roughening evolution process.A TEM study of cross-sectional microstructure evolution of aluminum alloy Al 5052-0 material during cold rolling in the presents of a thick lubricant film has been conducted. Commercial aluminum alloy AL 5052-0 as-received was used in the experiments.

Investigation Into Relationship Between Friction Behavior and Plastic Deformation Using a Newly Devised Rolling-Type Tribometer

A new rolling-type tribometer has been devised to investigate the effects on friction behavior of the average velocity of the lubricant at the inlet to the contact zone and the relative sliding velocity during deformation independently. This paper shows the principle of operation of the tribometer and deformation mode of the workpiece, especially considering the relationship between friction and bulk deformation. Experiments using mild steel strips with a dull surface showed that the friction stress on the friction roll, which has a smaller velocity than that of the traction roll, is mainly controlled by lubricating conditions on the friction roll side. The contact pressure is mainly decided by the friction conditions on the traction roll side. It was also revealed that, with an increase of the reduction in the workpiece thickness, the friction stress on the friction roll side remains constant when the friction roll is rotated. The friction stress increases when the friction roll is stopped after a certain reduction in the workpiece thickness.

Tribological Phenomena in Metal Forming at High Speed.

This paper describes the development of an original tribometer to study the effects of the average speed V, average of friction roll speed and workpiece speed at the entrance of a contact zone, and of the relative sliding speed δV during deformation on frictional behavior in metal forming. The configuration used two rollers and herce rolling may be simulated. Mild steel sheets with a dull surface were used as workpieces. It was revealed that the friction coefficient decreases with an increase of δV or with a decrease of V. It was also confirmed that the increase of δV and the decrease of V promote flattening of the workpiece surface and yieid good performance of the lubrication film.

Surface and bulk crystallization mechanisms in the Metglas Fe 78B 13Si 9 investigated by Mössbauer spectroscopy

The amorphous-to-crystalline transformation of the as-recieved Metgals ∗ 2605S2) was studied by transmission and reflection Mössbauer spectroscopy in order to compare shiny and dull surfaces and bulk crystallization mechanisms. In agreement with previous results, the onset of crystallization occurs on both surfaces, simultaneously to the out-of-plane anisotropy. Higher kinetics of crystallization is observed at dull surface. Then, primary and eutectic crystallization processes seem to be evidenced for the shiny and dull surfaces respectively. It is proposed that these different phenomena originate from the presence of structural and chemical inhomogeneities induced during the solidification process.

The crystallization of a Pd 60Ti 20Si 20 metallic glass

The kinetics and mechanism of crystallization have been followed in a Pd 60Ti 20Si 20 metallic glass by means of a combination of experimental techniques. As quenched alloys contain a variable population of crystals and/or nuclei. Oxide islands were found mostly on the dull (wheel-side) surface of the ribbon, favouring partial crystallization around 710 K. The glass transition temperature, T g , is manifest in DSC and low-frequency internal friction measurements from heating rates of 1 K/min upwards, prior to the main crystallization event (761 and 772 K at 20 K/min heating rate, respectively). Isothermal crystallization in the temperature range from 739.0 to 758.7 K occurred in two steps because of a different population of quenched-in nuclei in various parts of the ribbon. A Johnson-Mehl-Avrami analysis of the DSC isothermal output gave an Avrami exponent of 3, indicating growth on preexisting nuclei, as shown by microscopy observations. The activation energy and the preexponential factor for growth are very high: 566 ± 20 kJ/mol and 10 36ms −1 respectively. This finding is discussed with reference to analogous data for diffusion in metallic glasses.

Ground surface finishes in carbonized resorcinol/formaldehyde foam

Low-density resorcinol/formaldehyde foams developed by Pekala are stabilized by carbonizing (CRF). These delicate foams require machining for critical applications in the Inertial Confinement Fusion program at LLNL. The machining was preformed by first diamond-point turning and then grinding to final dimension. The first several grinding passes removed about 10 (μm per pass, several more passes were made at about 5 (μm per pass, and as the part approached final dimensions, the grinding depth was decreased to about 2 μ.m, and several passes were made at each setting. The final surface finish could be controlled to some extent by adjusting a scraper nozzle that removed grinding debris from the grinding wheel to leave a slight amount of debris on the wheel. During preliminary studies, inconsistencies were observed in the visual appearances of machined surfaces. Some specimens had moderately reflective surfaces, but others had a dull, flat appearance. Therefore, ground CRF surface microstructures were examined to determine the cause of the differences in reflectivity. Secondary-electron images of the specimens were obtained with a Hitachi S-800 FESEM at 25 kV; the specimens were uncoated. Specimens chosen for this study had dull, partially reflective, and reflective surfaces.

Transverse conduction electron focusing and specular reflection in aluminium single crystals

Transverse electron focusing (TEF) of the second-zone hole surface orbits in aluminium single crystals has been observed and used to investigate the probability (p) of specular reflection of conduction electrons at sample surfaces for the three principal crystallographic planes-(100), (110) and (111). The p-values obtained range from 0 to 0.61+or-0.05 depending on both the crystallographic plane and the geometry of the orbit when the surfaces are electrochemically polished like a mirror. Even on the chemically etched dull surface, up to a quarter of conduction electrons are specularly reflected. For specific orbits, the signal shapes are compared with those computed from the four-OPW Fermi surface model.