Surface roughness measurements of vanadium-contaminated fluidized cracking catalysts by atomic force microscopy

1996 ◽  
Vol 54 ◽  
pp. 866-867
Author(s):  
H. Kinney ◽  
M.L. Occelli ◽  
S.A.C. Gould
Keyword(s):  
Surface Roughness ◽  
Zeolite Y ◽  
Atomic Level ◽  
Microporous Structure ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Roughness Measurements ◽  
Cracking Catalysts

For this study we have used a contact mode atomic force microscope (AFM) to study to topography of fluidized cracking catalysts (FCC), before and after contamination with 5% vanadium. We selected the AFM because of its ability to well characterize the surface roughness of materials down to the atomic level. It is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting that the surface corrugation could play a key role in the FCCs microactivity properties. To test this hypothesis, we chose vanadium as a contaminate because this metal is capable of irreversibly destroying the FCC crystallinity as well as it microporous structure. In addition, we wanted to examine the extent to which steaming affects the vanadium contaminated FCC. Using the AFM, we measured the surface roughness of FCCs, before and after contamination and after steaming.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.

scholarly journals Atomic force microscopy comparative analysis of the surface roughness of two posterior chamber phakic intraocular lens models: ICL versus IPCL

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Juan Gros-Otero ◽  
Samira Ketabi ◽  
Rafael Cañones-Zafra ◽  
Montserrat Garcia-Gonzalez ◽  
Cesar Villa-Collar ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Atomic Force Microscopy ◽  
Intraocular Lenses ◽  
Posterior Chamber ◽  
Anterior Surface ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Phakic Intraocular Lenses ◽  
Roughness Measurements

Abstract Background To compare the anterior surface roughness of two commercially available posterior chamber phakic intraocular lenses (IOLs) using atomic force microscopy (AFM). Methods Four phakic IOLs were used for this prospective, experimental study: two Visian ICL EVO+ V5 lenses and two iPCL 2.0 lenses. All of them were brand new, were not previously implanted in humans, were monofocal and had a dioptric power of − 12 diopters (D). The anterior surface roughness was assessed using a JPK NanoWizard II® atomic force microscope in contact mode immersed in liquid. Olympus OMCL-RC800PSA commercial silicon nitride cantilever tips were used. Anterior surface roughness measurements were made in 7 areas of 10 × 10 μm at 512 × 512 point resolution. The roughness was measured using the root-mean-square (RMS) value within the given regions. Results The mean of all anterior surface roughness measurements was 6.09 ± 1.33 nm (nm) in the Visian ICL EVO+ V5 and 3.49 ± 0.41 nm in the iPCL 2.0 (p = 0.001). Conclusion In the current study, we found a statistically significant smoother anterior surface in the iPCL 2.0 phakic intraocular lenses compared with the VISIAN ICL EVO+ V5 lenses when studied with atomic force microscopy.

Analysis of fluidized cracking catalysts by Atomic Force Microscopy

1995 ◽  
Vol 53 ◽  
pp. 424-425
Author(s):  
S.A.C. Gould ◽  
M.L. Occelli
Keyword(s):  
United States ◽  
Atomic Force Microscopy ◽  
Liquid Fuel ◽  
Zeolite Y ◽  
The United States ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Percentage Difference ◽  
Cracking Catalysts

In the United States, five million barrels of oil per day or one third of all processed crude oil is catalytically converted with fluidized catalysts, a process which requires 500 tons of catalyst daily. Given these immense quantities, a small percentage difference in the efficiency of the oil conversion to liquid fuel can result in a savings of many millions of barrels of oil annually. In this study we have used a contact mode atomic force microscope (AFM) to study to topography of a set of fluidized cracking catalysts (FCC) from the μm level down to the atomic. We selected this technique because it is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting a surface which contains numerous pores, something the AFM can well characterize.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.

Suppression of SiC surface roughening during high-temperature annealing by atmospheric control using purified Ar gas

2010 ◽  
Vol 25 (4) ◽  
pp. 708-710 ◽  
Author(s):  
Atsushi Ogura ◽  
Daisuke Kosemura ◽  
Shingo Kinoshita
Keyword(s):  
Surface Roughness ◽  
High Temperature ◽  
Surface Roughening ◽  
Annealing Atmosphere ◽  
High Temperature Annealing ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Furnace Tube ◽  
Ar Gas

4H-silicon carbide (SiC) wafers were annealed at 1300 and 1600 °C for 30 min and 60 min in a conventional and purified Ar atmosphere. The surface roughness before and after annealing was evaluated by atomic force microscopy. The surface roughness before annealing was approximately 2.37 nm in root mean square. The roughness, after annealing for 30 min at 1300 and 1600 °C in a conventional Ar furnace, was increased to 4.53 and 14.9 nm, respectively. The roughness, after annealing for 60 min, was 5.01 and 19.1 nm, respectively. In this study, the G3 grade Ar gas (99.999%) was supplied in the conventional furnace tube. When the Ar gas was purified to an impurity concentration of less than 1 ppb, and it was supplied in the leak-tight furnace tube, the roughness after 30-min annealing improved 4.27 and 6.93 nm at 1300 and 1600 °C, respectively. The roughness after 60-min annealing was also reduced to 3.54 and 9.28 nm, respectively. We assume that a significant reduction of H2O concentration in the annealing atmosphere might play an important role in suppressing surface roughening of SiC during high-temperature annealing.

AFM Study of Untreated and Treated Fibers of Mongolian Goat Cashmere

2009 ◽  
Vol 610-613 ◽  
pp. 175-178 ◽  
Author(s):  
Namsrai Javkhlantugs ◽  
Enkhbaatar Ankhbayar ◽  
Khishigjargal Tegshjargal ◽  
Damdin Enkhjargal ◽  
Chimed Ganzorig
Keyword(s):  
Surface Roughness ◽  
Atomic Force Microscopy ◽  
Fine Structure ◽  
Ambient Conditions ◽  
Bleaching Process ◽  
Surface Change ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
The Difference

The morphological surface change of untreated and treated fibers of the Mongolian goat cashmere was investigated by atomic force microscopy (AFM) at ambient conditions. The cuticle scale heights of the Mongolian goat cashmere fibers were measured by the AFM for the fibers before and after treatment. The experimental results showed that the difference between the fine structure of the cuticle and surface roughness of untreated and treated fibers. We found that the surface morphological change of the cashmere fibers was strongly degraded after the bleaching process.

STUDY OF THE MORPHOLOGICAL MODIFICATIONS INDUCED BY LASER ANNEALING OF PREAMORPHIZED SILICON

2001 ◽  
Vol 08 (05) ◽  
pp. 441-445 ◽  
Author(s):  
Y. F. CHONG ◽  
K. L. PEY ◽  
Y. F. LU ◽  
A. T. S. WEE ◽  
A. SEE
Keyword(s):  
Surface Roughness ◽  
Laser Fluence ◽  
Laser Annealing ◽  
Periodic Structures ◽  
Threshold Fluence ◽  
High Fluence ◽  
Force Microscopy ◽  
Atomic Force ◽  
Laser Anneal ◽  
Roughness Measurements

Atomic force microscopy was employed to characterize the morphological modifications induced by laser annealing of preamorphized silicon. Laser irradiation was performed at different fluence with fixed pulse durations of 23 ns. In all cases, the laser fluence used is above the threshold fluence that is needed to melt the preamorphized layer. Roughness measurements show that the surface roughness of the silicon samples increases when the laser fluence increases. Since the laser anneal was performed in air, the changes in morphology may be associated with the surface oxide formed. When a high fluence was employed, the extension of melting was sufficient to remove all surface features of the as-implanted sample but apparently there was not enough time to completely redistribute the material upon solidification. As a result, ripple-like periodic structures are formed on the surface. Therefore, a low laser fluence should be used whenever possible in the annealing of silicon samples.

scholarly journals Nonprescription Bleaching versus Home Bleaching with Professional Prescriptions: Which One is Safer? A Comprehensive Review of Color Changes and Their Side Effects on Human Enamel

2019 ◽  
Vol 13 (04) ◽  
pp. 589-598
Author(s):  
Farhana Omar ◽  
Zuryati Ab-Ghani ◽  
Normastura Abd Rahman ◽  
Mohamad Syahrizal Halim
Keyword(s):  
Surface Roughness ◽  
Over The Counter ◽  
Microscopic Appearance ◽  
Significance Level ◽  
Force Microscopy ◽  
Colorimetric Measurement ◽  
Color Changes ◽  
Atomic Force ◽  
Human Enamel ◽  
Before And After

Abstract Objectives This study evaluates the efficacy and safety of the professionally prescribed and nonprescription over-the-counter (OTC) bleaching agents. Materials and Methods Extracted human upper central incisors were prepared and stained with red wine for 14 days before being subjected to four different bleaching agents: professionally prescribed opalescence PF 15%, VOCO Perfect Bleach 10%, nonprescription OTC Crest 3D Whitestrips, and Whitelight Teeth Whitening System. Colorimetric measurement was performed with Vita Easyshade Handheld Spectrophotometer, enamel surface microhardness measured using Vickers Hardness machine, and surface roughness was evaluated with profilometer, before and after bleaching. Scanning electron microscope (SEM) evaluation and atomic force microscopy were conducted postbleaching. Statistical Analysis The data were analyzed with t-test, two-way ANOVA, one-way ANOVA, and Turkey’s test at a significance level of 5%. Results All bleaching products have the same efficacy to whiten stained enamel. Opalescence PF 15% showed significant increase in the microhardness (92.69 ± 68.316). All groups demonstrated significant increase in surface roughness (p < 0.05). SEM evaluation showed that Opalescence PF 15% resulted in same microscopic appearance as unbleached enamel, while VOCO Perfect Bleach 10%, Whitelight Teeth Whitening System and Crest 3D Whitestrips demonstrated mild to moderate irregularities and accentuated irregularities, respectively. Conclusion Professionally prescribed bleaching agent of Opalescence PF 15% is effective tin whitening the teeth, while the other bleaching products may be effective but also have deleterious effects on the enamel.

Surface Morphology of Nanoscale TiSi2 Epitaxial Islands on Si(00l)

1996 ◽  
Vol 448 ◽  
Author(s):  
Woochul Yang ◽  
F.J. Jedema ◽  
H. Ade ◽  
R.J Nemanich
Keyword(s):  
Surface Roughness ◽  
Atomic Force Microscopy ◽  
Strain Field ◽  
Island Size ◽  
Island Formation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Size Uniformity ◽  
Rough Substrate

AbstractThe morphologies of nanoscale epitaxial islands of TISi2 are studied. The islands are prepared by deposition of ultrathin Ti (3-20Å) on both smooth and roughened.Si(001) substrates. The island formation is initiated by annealing to 800-1000°C. The roughened substrates are prepared by etching with atomic H produced in a plasma. The morphologies of the substrate before and after island formation are examined by atomic force microscopy (AFM). In particular, the influence of surface-roughness on both the formation of islands and the size distribution of islands is investigated. On a rough substrate islands with a lateral dimension of ~350Å and a vertical dimension of ~25Å were observed with size uniformity of ~20%. Also it was observed that the roughness of the surface reduced the island size and affected the island distribution. The results are discussed in terms of surface energy and the strain field around the islands.

Nanoscale Surface Modifications by Magnetic Field-Assisted Finishing

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Raul E. Riveros ◽  
Jared N. Hann ◽  
Curtis R. Taylor ◽  
Hitomi Yamaguchi
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Microelectromechanical Systems ◽  
Clear Understanding ◽  
X Ray ◽  
Surface Features ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Process Material

A magnetic field-assisted finishing (MAF) process has been developed to reduce the sidewall surface roughness of the 5–20 μm wide curvilinear pores of microelectromechanical systems micropore X-ray optics to <1 nm Rq. Although the feasibility of this process has been demonstrated on these optics, a clear understanding of the MAF process' material removal mechanisms has not been attained. In an attempt to discover these mechanisms, the MAF process is applied to a flat workpiece, allowing for direct observation and tracking of changes to distinctive surface features before and after MAF. Atomic force microscopy, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy are used to analyze the surface morphology and composition with respect to finishing time. These observations suggest that the MAF process modified the surface, reducing surface roughness (from 0.8 nm to 0.6 nm Rz on silicon) by removing relatively low-wavelength surface features. Moreover, the MAF process appears to modify the surface mechanically.

scholarly journals Effect of Hydrofluoric Acid Surface Treatments on Surface Roughness and Three-Point Flexural Strength of Suprinity Ceramic

2020 ◽  
Author(s):  
Nazanin Keshmiri ◽  
Homayoon Alaghehmand ◽  
Faraneh Mokhtarpour
Keyword(s):  
Surface Roughness ◽  
Flexural Strength ◽  
Hydrofluoric Acid ◽  
Testing Machine ◽  
Etching Time ◽  
Control Group ◽  
Force Microscopy ◽  
Atomic Force ◽  
Significant Difference ◽  
Before And After

Objectives: This study aimed to evaluate the effects of hydrofluoric acid (HF) concentration and etching time on the surface roughness (SR) and three-point flexural strength of Suprinity and to analyze the surface elements before and after etching. Materials and Methods: To measure the SR, 70 specimens of Suprinity (2×4×5mm3) were assigned to seven groups (n=10). Six groups were etched for 20, 60, and 120 seconds with 5% and 10% HF and 7th group was the control group. Specimens were evaluated using atomic force microscopy (AFM). One specimen from each group was used to analyze the surface elements using scanning electron microscopy (SEM). For measuring the three-point flexural strength, 60 specimens were divided into six groups (n=10) and etched as previously described. The flexural strength was measured using a universal testing machine. T-test, one-way analysis of variance (ANOVA), and two-way ANOVA were used for statistical analyses (P<0.05). Results: The 10% concentration of HF caused higher SR compared to the 5% HF. The effect of HF concentration on the flexural strength was significantly different in the 20- and 60-second etching groups. Different etching times had no significantly different effect on the SR. With 5% HF, the flexural strength was significantly higher for 20-second etching time than for the etching times of 60 and 120 seconds. With 10% HF, there was a significant difference in flexural strength between etching times of 20 and 120 seconds. The atomic percentage (at%) of silica was enhanced by increasing the etching time. Conclusions: The best surface etching protocol comprises 10% HF used for 20 seconds.

Sign in / Sign up

Export Citation Format

Share Document