The effect of oxygen on the processing of mesocarbon microbeads to high-density carbon

Carbon ◽  
2006 ◽  
Vol 44 (9) ◽  
pp. 1673-1681 ◽  
Author(s):  
Changjun Zhou ◽  
Paul J. McGinn
Keyword(s):  
High Density ◽  
Mesocarbon Microbeads ◽  
Effect Of Oxygen

scholarly journals The Effect of Oxygen Content in Binderless Cokes for High-Density Carbon Blocks from Coal Tar Pitch

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1832
Author(s):  
Seungjoo Park ◽  
Seon Ho Lee ◽  
Song Mi Lee ◽  
Jin-Woo Park ◽  
Sung-Soo Kim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Oxygen Content ◽  
Flow Rate ◽  
Coal Tar ◽  
High Density ◽  
Coal Tar Pitch ◽  
Air Flow Rate ◽  
Carbon Block ◽  
Effect Of Oxygen

High-density carbon blocks are much lighter than metals and have excellent mechanical properties and are one of the materials garnering attention to replace existing metal parts. In this study, a binderless coke was produced by changing the flow rates of nitrogen and air as a carrier gas during heat treatment of coal tar pitch and using this, a green body was formed at 150 MPa and carbonized to produce a high-density carbon block. We express the binderless coke produced in this way by N10A0, N7A3, N5A5, N3A7, N0A10 according to the ratio of nitrogen and air, and in the case of carbon block, we have added CB in front of it. We then considered the effect of oxygen content in the binderless cokes on the optical, chemical, and mechanical properties. It was observed that the produced binderless cokes develop into a dense mosaic structure with a small particle size as the air flow rate increased. To survey the change in oxygen content of the produced binderless coke, O1s and C1s regions were measured using X-ray photoelectric spectroscopy (XPS), and O1s/C1s was calculated. The O1s/C1s ratio steadily increased as the air flow rate increased, and in the case of N0A10, it increased about twice as much as that of N10A0 to 11.20%. β-resin has a very large effect on the mechanical strength of the carbon block in addition to air in the pitch. And in the case of CB-N0A10, it shows the best mechanical strength with a density of 1.72 g/cm3, bending strength of 87 MPa, and shore hardness of 93 HSD.

The Microstructures and Properties of Carbon and Graphite Materials Prepared from Mesocarbon Microbeads by Different Molding Methods

2016 ◽  
Vol 849 ◽  
pp. 831-837
Author(s):  
Zu Qiong Zhang ◽  
Hong Wan ◽  
Xing Yu Cheng
Keyword(s):  
Flexural Strength ◽  
Open Porosity ◽  
Bending Strength ◽  
High Strength ◽  
High Density ◽  
Mesocarbon Microbeads ◽  
Carbon And Graphite ◽  
One Step ◽  
Uniaxial Compaction ◽  
Molding Methods

Mesocarbon microbeads (MCMBs) are the prominent precursors for high-strength and high-density carbon and graphite materials (CGM). The microstructures and properties of CGM prepared by different compaction techniques using raw powders or pelleted powders of MCMBs with low content of β-resins was investigated in the present study. The green blocks by one-step uniaxial compaction at 230MPa were carbonized at 1200°C, forming carbon blocks with density of 1.84g/cm3 and bending strength of 76.9MPa. After graphitizing at 2700°C the carbon blocks are with density of 1.91g/cm3 and flexural strength of 70.5MPa. One-step cold isotropic pressing can improve the moldability of green blocks and increase open porosity of graphite blocks to 12.64vol%, with density of 1.87g/cm3. The green blocks with no cracks prepared by multistep cold isotropic pressing exhibit density of 1.84g/cm3 and bending strength of 81.7MPa. However, the flexural strength of these carbon and graphite artifacts decreased by 11.6~32.0MPa with comparison to the ones directly prepared from MCMBs.

Carbon disc of high density and strength prepared from synthetic pitch-derived mesocarbon microbeads

Carbon ◽  
1999 ◽  
Vol 37 (7) ◽  
pp. 1049-1057 ◽  
Author(s):  
Yong-Gang Wang ◽  
Yozo Korai ◽  
Isao Mochida
Keyword(s):  
High Density ◽  
Mesocarbon Microbeads

Planar defects in ordered (Ga,In)P

1988 ◽  
Vol 46 ◽  
pp. 902-903
Author(s):  
S. McKernan ◽  
C. B. Carter ◽  
D. Bour ◽  
J. R. Shealy
Keyword(s):  
Electron Diffraction ◽  
Vapor Phase ◽  
Growth Direction ◽  
High Density ◽  
Ordered Structure ◽  
Planar Defects ◽  
Diffraction Patterns ◽  
Ternary Semiconductors ◽  
Anion Species ◽  
Metallic Vapor

The growth of ternary III-V semiconductors by organo-metallic vapor phase epitaxy (OMVPE) is widely practiced. It has been generally assumed that the resulting structure is the same as that of the corresponding binary semiconductors, but with the two different cation or anion species randomly distributed on their appropriate sublattice sites. Recently several different ternary semiconductors including AlxGa1-xAs, Gaxln-1-xAs and Gaxln1-xP1-6 have been observed in ordered states. A common feature of these ordered compounds is that they contain a relatively high density of defects. This is evident in electron diffraction patterns from these materials where streaks, which are typically parallel to the growth direction, are associated with the extra reflections arising from the ordering. However, where the (Ga,ln)P epilayer is reasonably well ordered the streaking is extremely faint, and the intensity of the ordered spot at 1/2(111) is much greater than that at 1/2(111). In these cases it is possible to image relatively clearly many of the defects found in the ordered structure.

Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling

1995 ◽  
Vol 53 ◽  
pp. 512-513
Author(s):  
L. Mulestagno ◽  
J.C. Holzer ◽  
P. Fraundorf
Keyword(s):  
Sample Preparation ◽  
Milling Time ◽  
High Density ◽  
Low Density ◽  
Ion Milling ◽  
High Quality ◽  
Variable Angle ◽  
Major Disadvantage ◽  
Induced Defects

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).

Using the scanning electron microscope for failure analysis of high density magnetic media

1987 ◽  
Vol 45 ◽  
pp. 392-393
Author(s):  
Evelyn R. Ackerman ◽  
Gary D. Burnett
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Failure Analysis ◽  
High Density ◽  
Magnetic Media ◽  
Specific Data ◽  
Retrieval Systems ◽  
Operating Environments ◽  
The Media ◽  
Scanning Electron

Advancements in state of the art high density Head/Disk retrieval systems has increased the demand for sophisticated failure analysis methods. From 1968 to 1974 the emphasis was on the number of tracks per inch. (TPI) ranging from 100 to 400 as summarized in Table 1. This emphasis shifted with the increase in densities to include the number of bits per inch (BPI). A bit is formed by magnetizing the Fe203 particles of the media in one direction and allowing magnetic heads to recognize specific data patterns. From 1977 to 1986 the tracks per inch increased from 470 to 1400 corresponding to an increase from 6300 to 10,800 bits per inch respectively. Due to the reduction in the bit and track sizes, build and operating environments of systems have become critical factors in media reliability.Using the Ferrofluid pattern developing technique, the scanning electron microscope can be a valuable diagnostic tool in the examination of failure sites on disks.

A TEM study of the effect of oxygen on nanocavity formation and precipitation in rapid - solidified Fe-16Ni-9Cr stainless steels

1994 ◽  
Vol 52 ◽  
pp. 700-701
Author(s):  
S. Wisutmethangoon ◽  
T. F. Kelly ◽  
J.E. Flinn
Keyword(s):  
Stainless Steels ◽  
High Mobility ◽  
Hot Extrusion ◽  
Extrusion Ratio ◽  
Gas Atomization ◽  
Cavity Formation ◽  
Nucleation Sites ◽  
Heat Treated ◽  
Different Types ◽  
Effect Of Oxygen

Vacancies are introduced into the crystal phase during quenching of rapid solidified materials. Cavity formation occurs because of the coalescence of the vacancies into a cluster. However, because of the high mobility of vacancies at high temperature, most of them will diffuse back into the liquid phase, and some will be lost to defects such as dislocations. Oxygen is known to stabilize cavities by decreasing the surface energy through a chemisorption process. These stabilized cavities, furthermore, act as effective nucleation sites for precipitates to form during aging. Four different types of powders with different oxygen contents were prepared by gas atomization processing. The atomized powders were then consolidated by hot extrusion at 900 °C with an extrusion ratio 10,5:1. After consolidation, specimens were heat treated at 1000 °C for 1 hr followed by water quenching. Finally, the specimens were aged at 600 °C for about 800 hrs. TEM samples were prepared from the gripends of tensile specimens of both unaged and aged alloys.

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