Surface quality evaluation of hot deformed aluminum

2016 ◽  
Vol 1816 ◽  
Author(s):  
L.A. Espinosa Zúñiga ◽  
F.A. Pérez González ◽  
O. Zapata ◽  
N.F. Garza Montes de Oca ◽  
S. Haro
Keyword(s):  
Surface Quality ◽  
Solidification Rate ◽  
Surface Damage ◽  
Compression Tests ◽  
Cooling Rates ◽  
Heat Treated ◽  
Electron Microscopes ◽  
High Cooling Rates ◽  
Scanning Electron Microscopes

ABSTRACTThe surface quality of a heat treatable Al-Si-Mg alloy by means compression tests at 450°C was evaluated. Samples were obtained from an ingot with unidirectional solidification in order to obtain a microstructural gradient influenced by the cooling and solidification rate. The samples were heat treated by homogenization at 520°C for 4 hours prior to deformation by compression. Inverted optical and scanning electron microscopes were used to assess the surface damage of deformed samples.Analysis of deformed surface indicates a greater influence of microstructural refinement on hardening rate. It was found that the samples solidified at high cooling rates showed no defects, but at low cooling rates produced growth of grain size and intermetallic phases and thereby the high incidence of cracks in the surface.

Effect of Thickness and Permeability of Ceramic Shell Mould on In Situ Melted AZ91D Investment Casting

2013 ◽  
Vol 465-466 ◽  
pp. 1087-1092
Author(s):  
Hassan Jafari ◽  
Mohd Hasbullah Idris ◽  
Ali Ourdjini
Keyword(s):  
Surface Quality ◽  
Investment Casting ◽  
Solidification Rate ◽  
Ceramic Shell ◽  
Good Surface ◽  
Melting Technique ◽  
Shell Mould ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

The influence of ceramic shell mould thickness and permeability on investment casting of AZ91D alloy using in-situ melting technique was investigated. AZ91D granules together with melting flux were charged into two different moulds having different thicknesses and four various permeabilities; then were heated at 650°C in order to be melted. Visual inspection and scanning electron microscopes were used to characterise the surface quality of cast samples. Thermal analysis was employed to further analyse the effect of mould thickness on cooling and solidification behaviour of molten metal. The findings of this research showed that thinner mould provided higher solidification rate, which is believed to favour in-situ melting enhancement. It enabled melting of the granules at the investigated temperature resulted in suppressing mould-metal reaction and producing cast samples with good surface quality. The results also showed that the permeability of shell mould was ineffective in suppressing mould-metal reaction.

scholarly journals Dissimilar Metals Laser Welding between DP1000 Steel and Aluminum Alloy 1050

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 102 ◽  
Author(s):  
António Pereira ◽  
Ana Cabrinha ◽  
Fábio Rocha ◽  
Pedro Marques ◽  
Fábio Fernandes ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Laser Welding ◽  
Mechanical Tests ◽  
Welding Parameters ◽  
Dissimilar Metals ◽  
Butt Welding ◽  
Electron Microscopes ◽  
1050 Aluminum Alloy ◽  
Scanning Electron Microscopes

The welding of dissimilar metals was carried out using a pulsed Nd: YAG laser to join DP1000 steel and an aluminum alloy 1050 H111. Two sheets of each metal, with 30 × 14 × 1 mm3, were lap welded, since butt welding proved to be nearly impossible due to the huge thermal conductivity differences and melting temperature differences of these materials. The aim of this research was to find the optimal laser welding parameters based on the mechanical and microstructure investigations. Thus, the welded samples were then subjected to tensile testing to evaluate the quality of the joining operation. The best set of welding parameters was replicated, and the welding joint obtained using these proper parameters was carefully analyzed using optical and scanning electron microscopes. Despite the predicted difficulties of welding two distinct metals, good quality welded joints were achieved. Additionally, some samples performed satisfactorily well in the mechanical tests, reaching tensile strengths close to the original 1050 aluminum alloy.

Research on Subsurface Damage of Lapping Sapphire with Diamond Fixed Abrasive

2020 ◽  
Vol 866 ◽  
pp. 143-151
Author(s):  
Jian Bin Wang ◽  
Yong Qiang Tong ◽  
Ben Chi Jiang ◽  
Da Shu ◽  
Gang Wang
Keyword(s):  
Surface Quality ◽  
Surface Damage ◽  
Subsurface Damage ◽  
Indentation Fracture ◽  
Damage Layer ◽  
Damage Depth ◽  
The Difference ◽  
Fixed Abrasive ◽  
Free Abrasive

The depth of surface/subsurface damage layer is the key index of surface quality of sapphire. In this paper, that depth model of the surface/subsurface damage lay characterized by the crack length was established according to the mechanical theory of indentation fracture. The cutting relation between abrasive and workpiece and the difference of the depth of subsurface damage crack are analyzed. It is preliminarily estimated that the length of sub-surface damage crack of free abrasive sapphire is about 2.46 times that of fixed abrasive when considering only the contact hardness of abrasive grain under static load. Diamond abrasives with size of W20 were adopted to carry out experiments in free and fixed lapping methods. The results show that the surface/subsurface damage depth is 9.87μm and 3.63μm respectively. It is easier to obtain good sub-surface quality by using the fixed abrasive method than free abrasive at the same particle size.

Effect of Heat Treatment on the Structure and Morphology of Amorphous Steel Produced Using Spray Metal Forming

2007 ◽  
Vol 539-543 ◽  
pp. 4185-4190
Author(s):  
A. Srinivasa Rao ◽  
L. Kohler ◽  
L.F. Aprigliano
Keyword(s):  
Heat Treatment ◽  
Steel Ingot ◽  
Small Samples ◽  
X Ray Diffraction ◽  
Structure And Morphology ◽  
Heat Treated ◽  
Amorphous Steel ◽  
Electron Microscopes ◽  
Prolonged Heat ◽  
Scanning Electron Microscopes

In order to investigate the effect of heat treatment on the structure and morphology of spray formed structurally amorphous steel, several small samples were cut from one spray formed amorphous steel ingot (DAR – 35). The samples were heat treated at 700oC in a tube furnace under a constant flow of 99.9% argon for up to 120 hours. The samples were furnace cooled to 300oC. Later they were quenched in water. The structure was investigated using x-ray diffraction and the morphology of the polished and lightly etched samples was examined under both optical and scanning electron microscopes. The results indicate that the spray formed steels were amorphous. However, their microstructure is not homogeneous. The microstructure is composed of three distinctively different phase contrasts (viz. light gray, dark gray and bright white contrasts). The bright white phase contained maximum amount of tungsten and molybdenum, it had the least amount of iron. Both light and dark gray phases contained nearly the compositionally expected amount of iron, and more chromium than compositionally expected. The effect of heat treatment at 700oC had no effect on the three different phase contrasts. However, the heat treatment at 700oC showed some effect on the crystallization of the structure. The heat treatment for up to 24 hours has very little effect on the structure and morphology of the amorphous steel samples. However, if the samples were heat treated at 700oC for more than 24 and below 72 hours, it appears that a partial crystallization of the steel occurs. Significant crystallization of the spray formed amorphous steel occurs due to prolonged heat treatment above 72 hours.

Defect Review at 0.25 Micron Electron Optic Requirements and Practical Examples

1997 ◽  
Vol 3 (S2) ◽  
pp. 447-448
Author(s):  
Bryan Tracy
Keyword(s):  
Process Development ◽  
Stable Process ◽  
Defect Inspection ◽  
Process Technology ◽  
Feature Size ◽  
Modern Development ◽  
Multiple Defect ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

The sub-micron era in 1C process technology has been characterized by ever shrinking device geometries. When the minimum feature size of 0.5 micron was reached, a significant inflection in the usefulness of optical microscopy occurred. Seemingly routine Fab activities such as the use of the optical microscopes to determine the quality of the metal etch were no longer possible. At the same time, an increased use of defect inspection tools such as KLA and Tencor was required to insure stable process quality. These and other factors combined to hasten the introduction of multiple defect review scanning electron microscopes into the modern 1C Fab. This trend has accelerated during the process development of 0.25 micron technology. Accordingly, as leading 1C manufactures introduce production 0.25 devices, it is not unusual to find as many as six such instruments installed in a modern development or fabrication facility. As such, these instruments, commonly called Defect Review Tools (DRT's) constitute an increasing share of the Fab equipment set.

In environmental Scanning Electron Microscopy, the secondary electron signal reveals surface information not accessible by conventional backscattered electron signals

1989 ◽  
Vol 47 ◽  
pp. 78-79
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Vacuum ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Specimen Preparation ◽  
Dynamic Events ◽  
Backscattered Electron ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Environmental scanning electron microscopes (ESEM) operate at high as well as at low vacuum (<2.5 kPa: ~20 Torr) but utilize all advantages of conventional high vacuum SEM (large specimen size, high depth of focus and specimen tilt capability, TV-rate scanning for imaging dynamic events). They have the advantage of imaging wet specimens as well as insulators without the need of any specimen preparation. Previously, environmental scanning microscopy was restricted to the BSE signal collected with BSE detectors. SE signals cannot be collected with the Everhart-Thornley detector because it cannot operate at low vacuum. Using positively biased electron collectors, it is now possible to collect an SE signal. However, the origin and quality of this signal need to be further characterized.An ElectroScan ESEM was used equipped with SE and BSE detectors and operated at 7-30 kV with partial water pressures of 0.1-2.5 kPa (∼1-20 Torr).

Study on Arithmetic of Surface Damage Ratio in High Speed Machining of Graphite Based on Matlab Image Processing

2013 ◽  
Vol 652-654 ◽  
pp. 2196-2199
Author(s):  
Li Zhou ◽  
Yu Zhong Li ◽  
Cheng Yong Wang
Keyword(s):  
Image Processing ◽  
Surface Quality ◽  
High Speed ◽  
Quantitative Description ◽  
Surface Damage ◽  
Projection Area ◽  
High Speed Machining ◽  
Machined Surface ◽  
Stereo Microscope

The surface quality of graphite cannot be completely evaluated only by the roughness value Ra measured by profilometer. The surface damage ratio Sc is presented to give quantitative description of surface quality of graphite, which was calculated as the ratio of the projection area of fracture craters to the overall area of free surface. The machined surface was observed and taken photo by use of the stereo microscope with CCD image acquisition system. Matlab image processing tool was used to convert the color photo to binary image, in which fracture craters were shown as black pixels and the other surfaces as white pixels. The surface damage ratio is the result of the sum of black pixels divided by the overall pixels. Under the same conditions of high speed machining experiments for verification, the surface damage ratio was calculated in comparison with the Ra values measured by profilometer. The variation tendency of surface damage ratios exhibited good coherence to the measured roughness.

scholarly journals Effects of thermal treatment before plane sanding on the surface quality of Corymbia citriodora wood

BioResources ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. 2576-2583
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Surface Quality ◽  
Treated Wood ◽  
Average Roughness ◽  
Abrasive Grains ◽  
Surface Finishes ◽  
Heat Treated ◽  
Corymbia Citriodora

Wood sanding is one of the most expensive processes in the woodworking industry, and little is known about the factors that influence the final quality of wooden parts. For this reason, studies involving different wood treatments, such as thermal treatment, have been developed to produce better surface qualities. The objective of this work was to verify the influence of thermal treatment of the wood species Corymbia citriodora before the sanding process on the surface quality of the wood pieces. The surface finishes of the sanded natural and heat-treated wood were compared. Sanding was performed using two sandpaper grades, 80 mesh and 120 mesh, with abrasive grains of aluminum oxide. The sanding process was performed by flat horizontal sanding parallel to the fibers. Six specimens were used for each sandpaper grade. Initially the specimens were heat-treated at 120 °C, 160 °C, and 200 °C for 2 h, and then they were subjected to sanding. For the analysis of the surface quality of the wood pieces, the average roughness was used. From the obtained results, it was concluded that the heat treatment considerably reduced the roughness of the wood for both sandpaper grit sizes, and it facilitated the final finishing of the wood pieces.

Advances in Scanning Electron Microscopy

MRS Bulletin ◽  
1991 ◽  
Vol 16 (3) ◽  
pp. 41-45 ◽  
Author(s):  
K. Sujata ◽  
Hamlin M. Jennings
Keyword(s):  
Electron Beam ◽  
X Rays ◽  
Backscattered Electrons ◽  
Scanning Transmission ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Television Image ◽  
Focused Beam ◽  
Scanning Electron

Scanning electron microscopes offer several unique advantages and they have evolved into complex integrated instruments that often incorporate several important accessories. Their principle advantage stems from the method of constructing an image from a highly focused electron beam that scans across the surface of a specimen. The beam generates backscattered electrons and excites secondary electrons and x-rays in a highly localized “spot.” These signals can be detected, and the results of the analysis are displayed as a specific intensity on a screen at a position that represents the position of the electron spot. As with a television image, after a given period, information about the entire field of view is displayed on the screen, resulting in a complete image. If the specimen is thin, the same type of information can be gathered from the transmitted electrons, and a scanning transmission image is thus constructed.The scanning electron microscope is highly versatile and widely used. The quality of the image is related to its resolution and contrast, which, in turn, depend on the diameter of the focused beam as well as its energy and current. Because electron lenses have inherently high aberrations, the usable aperture angles are much smaller than in a light microscope and, therefore, the electron beam remains focused over a relatively large distance, giving these instruments a very large depth of focus.Scanning electron microscopes are versatile in their ability to detect and analyze a lot of information. As a result, modern versions of these instruments are equipped with a number of detectors. Developments are sometimes related to placing the detectors in a geometrically attractive position close to the specimen.

scholarly journals Monitoring Carbon in Electron and Ion Beam Deposition within FIB-SEM

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3034
Author(s):  
Nicholas T.H. Farr ◽  
Gareth M. Hughes ◽  
Cornelia Rodenburg
Keyword(s):  
Secondary Electron ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Chemical Surface ◽  
Bonding State ◽  
Ion Beam Deposition ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Beam Deposition

It is well known that carbon present in scanning electron microscopes (SEM), Focused ion beam (FIB) systems and FIB-SEMs, causes imaging artefacts and influences the quality of TEM lamellae or structures fabricated in FIB-SEMs. The severity of such effects depends not only on the quantity of carbon present but also on its bonding state. Despite this, the presence of carbon and its bonding state is not regularly monitored in FIB-SEMs. Here we demonstrated that Secondary Electron Hyperspectral Imaging (SEHI) can be implemented in different FIB-SEMs (ThermoFisher Helios G4-CXe PFIB and Helios Nanolab G3 UC) and used to observe carbon built up/removal and bonding changes resulting from electron/ion beam exposure. As well as the ability to monitor, this study also showed the capability of Plasma FIB Xe exposure to remove carbon contamination from the surface of a Ti6246 alloy without the requirement of chemical surface treatments.

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