Surface Profilometry Techniques Research Articles

Surface characterization of paper products by profilometry with a fractal dimension analysis

A surface profilometry technique was used to characterize the surfaces of paper products. A stylus-contact type profilometer capable of simultaneously generating both surface roughness- and friction-profiles was used. As a stylus for the profilometer, a conical shape whose tip was rounded to have a 0.5 mm curvature radius was designed and successfully employed in both printing & writing (P&W) papers and hygiene papers such as bathroom tissues and kitchen towel. From the profiles, the mean absolute deviation (MAD) from the averages, i.e., R-MAD from the roughness average and F-MAD from the average coefficient of friction, were suggested as the new surface characterization parameters. To elucidate the surface roughness profiles by fractal dimension analysis, the variogram method was applied to get the fractal dimensions of the paper products. Generally, the value of the fractal dimension increased as the surface roughness increased. The surface profilometry technique with the fractal dimension analysis with the variogram method looks promising to gain additional insight on the surface characteristics of paper products.

Laser processing of composite materials for acoustic applications

The consistency of machined components in terms of their final material surfaces is a fundamental aspect of manufacturing. Laser-based non-contact sensors that use non-destructive speckle imaging are challenging the surface profilometry technique as an alternative method for the analysis of surface quality. This paper presents research into the importance of laser techniques in analyzing the surface roughness of composite materials used in the fabrication of acoustic panels. Roughness analyses performed by both the designed laser sensor and the surface profilometry technique were both found to be efficient; however, the speckle imaging method produces better results for most materials. Enhancements in surface roughness were measured and found to be 20% greater than those observed by the stylus method; in addition, the laser technique has low costs for commercial applications while being a scientific-concept-based analytical technique that uses a novel approach. The surface roughness was measured under different conditions by varying the speckle contrast using different positions and laser source orientations. The interactions between photons and phonons were analyzed in depth for a fabricated biomaterial-based-composite to assess its suitability for acoustic applications in different smart devices.

Biomimetic macroscopic hierarchical moire gratings.

Large-scale hierarchical macroscopic moire gratings resembling the surface structure of Peruvian lily flower petals are fabricated on azobenzene molecular glass thin films using a Lloyd's mirror interferometer. It is shown that nanostructured linear and crossed moire gratings can be made with pitch values reaching a few millimeters. Also, using atomic force microscopy, scanning electron microscopy, optical microscopy, and surface profilometry techniques, it is shown that the obtained moire gratings have two-fold or three-fold hierarchical structures fabricated using a simple all optical technique.

The Role of Microstructure on Damage Tolerance in Nano-Bainitic Steels

Three nanostructured bainitic steels have been produced by austempering at 250, 300 and 350°C respectively after a similar austenitization treatment at 950°C. It has been found that a decrease in austempering temperature causes increase in content of bainitic ferrite (BF) as well as refinement of BF and retained austenite (RA) resulting in strengthening of the steel. However, results of sub-critical fatigue crack growth rate tests on these steels revealed that the steel transformed at higher austempering temperature which showed coarser morphology of BF and RA and also higher content of RA are more damage tolerant. It appeared that the thickness of BF plates and its volume fraction in the microstructure plays a major role in enhancing the strength whereas improved damage tolerance has been attributed to higher content of ductile phase RA. Scanning electron microscopy, nano-indentation and surface profilometry techniques revealed that the larger plastic zone size, higher amount of strain energy consumed during austenite to martensite transformation (TRIP effect) and tortuous crack path are the main factors for slower fatigue crack propagation rates in steel with the coarser morphology and higher retained austenite content.

Rapid and sensitive determination of Pb2+ in water using chromogenic reagent patterned on nail polish modified filter paper

The current strategy extends the analytical utility of colorimetric spot assay for developing a simple one-step determination of Pb2+ in environmental water samples using the chromogenic reagent 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP). The established assay was executed on Whatman filter paper modified with commercially available nail polish (NP). Goniometry analysis revealed that the surface of NP modified cellulose surface harbored hydrophobic character (θ ~111º). Scanning electron microscopy (SEM) and surface profilometry techniques satisfactorily recognized the changes in the morphology as well as the roughness upon surface modification. Under the optimized parameters, the assay could be concluded in less than 10 min upon formation of red-colored Pb-PADAP chelate. The figures of merits of the developed method were as follows; limit of detection (LOD=0.01 μg/mL), and linear dynamic range (LDR=0.5–10.0 μg/mL). The estimated assay sensitivity of the developed assay for Pb2+ determination corresponds to 11.4 ΔI/µg/mLPb2+/cm2. In addition to visual detection, data was also quantitated through scoring color intensity of the assay using image analysis software. Selectivity of the assay towards Pb2++ was greatly improved through addition of CN−, I− and F− that would eliminate the interference from most common diverse ions. The developed assay was satisfactorily extended for trace determination of Pb2+ in tap and wastewater samples. The reputable assay has several advantages; inexpensive modification/platform, low reagent/analyte volume requirement, improved specificity and simple read-out. Hence, the recognized assay can be widely implemented for point-of-use application especially in regions dealing with lead toxicity and limited laboratory facilities.

2500-Channel single-shot areal profilometer using hyperspectral interferometry with a pinhole array

Surface profilometry techniques such as coherent scanning interferometry or focus variation require long scan times and are thus vulnerable to environmental disturbance. Hyperspectral interferometry (HSI) overcomes the problem by recording all the spatial and spectral information necessary to reconstruct a 2D surface height map in a single shot. In this paper, we present a new HSI system that uses a pinhole array to provide the necessary gaps for the spectral information. It is capable of measuring 2500 independent points, twice the previous maximum number, with a maximum unambiguous depth range of ∼825 µm and a larger maximum surface tilt angle of 33.3 mrad. The use of phase information allows height to be measured to a precision of ∼6 nm, an order of magnitude improvement on previous HSI systems.

Optical 3-D Profilometry for Measuring Semiconductor Wafer Surfaces with Extremely Variant Reflectivities

A new surface profilometry technique is proposed for profiling a wafer surface with both diffuse and specular reflective properties. Most moiré projection scanning techniques using triangulation principle work effectively on diffuse reflective surfaces, on which the reflected light beams are assumed to be well captured by optical sensors. In reality, this assumption is no longer valid when measuring a semiconductor wafer surface having both diffuse and specular reflectivities. To resolve the above problem, the proposed technique uses a dual optical sensing configuration by engaging two optical sensors at two different viewing angles, with one acquiring diffuse reflective light and the other detecting at the same time specular surface light for achieving simultaneous full-field surface profilometry. The deformed fringes measured by both sensors could be further transformed into a 3-D profile and merged seamlessly for full-field surface reconstruction. Several calibration targets and industrial parts were measured to evaluate the feasibility and accuracy of the developed technique. Experimental results showed that the technique can effectively detect diffuse and specular light with repeatability of one standard deviation below 0.3 µm on a specular surface and 2.0 µm on a diffuse wafer surface when the vertical measuring range reaches 1.0 mm. The present findings indicate that the proposed technique is effective for 3-D microscale surface profilometry in in-situ semiconductor automated optical inspection (AOI).

Surface profilometry using the incoherent self-imaging technique in reflection mode

In this paper, we introduce a highly sensitive and cost-effective surface profilometry technique based on the Lau self-imaging phenomenon in reflection mode, combined with the Moiré technique. Standard incoherent grating imaging with two Ronchi rulings is deployed to produce localized Fresnel pseudoimages, except that the light wavefront gets modulated after reflecting off the surface under test and before the final image forms. A third grating is superimposed on the pseudoimage to take advantage of the magnification property of the Moiré fringes and enhance the surface-induced modulations. A five-step phase-shifting technique is used to extract the 2D surface profile of the sample from the recorded Moiré patterns. To demonstrate our technique, we measure the profile of a 250 nm step-like metallic sample. The results show a few nanometer uncertainties, very good reproducibility, and agreement with other known optical and mechanical surface profilometry methods.

Effects of shear stress on the erosion‐corrosion behaviour of X-65 carbon steel: A combined mass-loss and profilometry study

A combined mass-loss and profilometry techniques was undertaken with the goal of understanding the role of high shear stress on the erosion‐corrosion behaviour of X65 carbon steel in a submerged impingement jet (SIJ) system. Computational fluid dynamics (CFD) enabled an accurate prediction of a range of shear stresses (80, 280, 570Pa) and particle tracking (0, 200, 500mg/L) across the sample surface with inhibitor concentration (0, 100ppm). The results demonstrated the suitability of combining mass–loss and surface profilometry techniques for quantifying and predicting general and localized corrosion of X65 pipeline material in an erosion–corrosion environment.

The Surface Finish of Thermally Aged Carbon Fibre Reinforced Composites Using E-glass as a Surface Barrier

This work investigated the effect of woven E-glass mass (25 g/m2, 50 g/m2, 85 g/m2, 135 g/m2) on the painted surface finish of various thermoset (EPIKOTETM RIM935, EPIKOTETM 04434, Ultratec LpTM ES300, Ultratec LpTM SPV6035) carbon fibre composite laminates, before and after aging at 95 °C for 168 h. The as-moulded laminate surfaces were evaluated using surface profilometry techniques and the painted and aged surfaces were evaluated using a wave-scan distinctness of image (DOI) instrument. It was found that the 25 g/m2 E-glass surface layer assisted with reducing the roughness of the as-moulded surfaces and the long-term waviness of the painted surfaces due to the increase in resin-richness at the surface. The EPIKOTETM 04434 resin system that contained diglycidyl ether of bisphenol F (DGEBF) epoxy had the least change in long-term waviness with thermal aging due to the rigid fluorene-based backbone in comparison to the diglycidyl ether of bisphenol A (DGEBA) systems.

Digital differential confocal microscopy based on spatial shift transformation.

Differential confocal microscopy is a particularly powerful surface profilometry technique in industrial metrology due to its high axial sensitivity and insensitivity to noise. However, the practical implementation of the technique requires the accurate positioning of point detectors in three-dimensions. We describe a simple alternative based on spatial transformation of a through-focus series of images obtained from a homemade beam scanning confocal microscope. This digital differential confocal microscopy approach is described and compared with the traditional Differential confocal microscopy approach. The ease of use of the digital differential confocal microscopy system is illustrated by performing measurements on a 3D standard specimen.

Instability of Plastic Flow in the Microstructure of Alkali Halide Crystals

Spatial localization of deformation bands in LiF and KCl single crystals caused by instability of plastic flow in the strain rate range from 5 × 10−6 to 2 × 10−4 s−1 was studied experimentally. The geometrical parameters of localized shift bands (LSB) were studied as a function of strain rate and temperature. To study the LSB relief, a surface profilometry technique was used for the first time, which made it possible to determine the LSB parameters at the early stages of plastic flow (for strains in the range from 0.5 to 2%). The formation and branching of LSB steps on the surface of a deformed crystal due to the generation and motion of dislocations were found to be scaled. It was shown experimentally that the LSB formation is a thermally activated process that occurs through dislocation glide and is limited by dislocation creep.

Visualization and measurement of nanometer dimension surface features using dental impression materials and atomic force microscopy

The resolving ability of polyvinyl siloxane impression material at a submicron scale was tested in order to determine its ability to reproduce the topographical features of worn contact surfaces such as those found in the food processing industry. Three impression materials were tested against three surfaces with standardized surface features. Cryo scanning electron microscopy and atomic force microscopy were used to provide high magnification images of the surfaces and impressions of the surfaces. Dimensional information was also provided by surface profilometry techniques using a solid stylus and a laser profilometer. Although the three impression materials accurately reproduced the line spacing of the largest scale test specimen, the least viscous material gave the most satisfactory surface reproduction, although a degree of vertical relief was lost. This material has been used to monitor wear of food contact surfaces in situ. Such information enables further research into the effect of increased or altered substratum surface roughness upon microbial and organic soil retention.

Scale effects in abrasive wear of composite sol–gel alumina coated light alloys

Chemically-bonded composite sol–gel (CB-CSG) coatings have been developed that incorporate calcined ceramic powder particles (filler) dispersed in a sol–gel (SG) matrix (binder). As a result, they have significantly reduced densification strains compared to conventional SG coatings. The CB-CSG coatings, which are several orders of magnitude thicker than typical micron-thick SG films, can be produced easily by spray depositing onto Al and Mg alloys, followed by a short low temperature (300°C) heat treatment. The abrasive wear performance was determined for Al 2O 3(binder)/Al 2O 3(filler), Al 2O 3(binder)/Al 2O 3-SiC (fillers) and a hybrid Al 2O 3(binder)/Al 2O 3(filler)+Al (40 μm particle filler) coatings on commercial Al and Mg alloys. In two-body abrasion tests, the coated alloys were abraded by bonded SiC abrasives of increasing coarseness with comparative experiments also being performed on the uncoated substrate alloys. Coating wear rates exhibited an order of magnitude increase when the scale of indentation increased above a critical depth, whereupon wear rates approached those of the substrate alloy. Similar observations were made in three-body microabrasion experiments using a ball-cratering technique to abrade the coatings with very fine and coarse alumina slurries. The modes and mechanisms of coating damage were characterized by SEM and optical surface profilometry techniques. Normalized parameters for hardness, abrasive wear and indentation depth, were used in interpreting and comparing coating tribological performance.

Cutting ability of an ultrasonic retrograde cavity preparation instrument.

The aim of this study was to investigate the cutting ability of a working ultrasonic instrument designed for surgical endodontic use (Neosonic, Amadent Corp, Cherry Hill, NJ, USA). Three designs of tip, designated CT 1 to CT 3 were calibrated by measuring their displacement amplitudes in air using light microscopy over a range of power settings. Extracted teeth were sectioned longitudinally and polished to produce a smooth dentine surface onto which the tips were applied for 1 minute over the above range of power settings at a load of approximately 20 g. The depth of cut in the dentine surface was measured using a two dimensional surface profilometry technique. Results showed that a raising of the power setting produced an increase in displacement amplitude and cutting ability for all tip designs. This increase was linear, with minimal cutting occurring at lower power settings. In conclusion the ultrasonic tips could be successfully used to remove dentine, and medium to high power settings optimised their efficiency.

Friction and wear properties of partially stabilized zirconia with solid lubricant

The friction and wear properties of partially stabilized zirconia (PSZ) lubricated with copper powder, copper film or CuO film were studied. The wear rate of unlubricated PSZ increased with normal loads. When loads were over 20 N, a transition from mild to severe wear (wear rate > 1 × 10 −5 mm 3 (Nm) −1) occurred. The CuO film, which was formed by high-temperature chemical diffusion, effectively prevented PSZ from severe wear. Even at a load of 35.6 N the wear rate was essentially zero. It was very difficult to measure any wear by the surface profilometry technique used in the study. The friction coefficients of PSZ were reduced from 0.40 to 0.20, 0.17 and 0.14 for copper powder, copper films and CuO films, respectively. A scanning electron microscope was used to study the mechanisms of friction and wear of PSZ.

Evaluation of Cavitation Damage Characteristics Using a Profilometer

The ability to make quantitative statements concerning cavitation damage should involve appropriate measurements of both material loss and material damage. This study investigates the extent to which surface profilometry techniques can be used to determine cavitation damage characteristics by obtaining the surface profiles of test specimens before and after cavitation. Based on the maximum depth of penetration obtained from the surface profiles, the velocity exponent for maximum damage is determined. This value of the exponent agrees favourably with previously published values obtained from weight loss measurements.