ASTM D4616-95(2005)
(Test Method)Standard Test Method for Microscopical Analysis by Reflected Light and Determination of Mesophase in a Pitch
Standard Test Method for Microscopical Analysis by Reflected Light and Determination of Mesophase in a Pitch
SIGNIFICANCE AND USE
Sometimes coal tar and petroleum pitches are heat treated thereby forming mesophase spheroids. The mesophase may be partially soluble in quinoline and cannot be estimated by the quinoline insoluble test (Test Method D 2318). This test method provides for the identification, quantitative estimation, and size determination of mesophase spheroids.
The mesophase initially forms as spheroids that may coalesce to form a variety of asymmetrical shapes. The smallest mesophase particle that can be detected with certainty at 400× or 500× magnification is 4 μm in diameter; mesophase particles sizes less than 4 μm should be ignored. If mesophase material less than 4 μm in size is of interest, then magnifications of 1000 to 1800× shall be used and the results should be appropriately identified. This method is limited to determining minor levels of mesophase, that is, ≤20 % mesophase.
SCOPE
1.1 This test method covers laboratory procedures for the preparation of granular and melted samples for microscopic analysis using reflected light to identify and estimate the amount and size of the mesophase.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.3This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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An American National Standard
Designation: D 4616 – 95 (Reapproved 2005)
Standard Test Method for
Microscopical Analysis by Reflected Light and
1
Determination of Mesophase in a Pitch
This standard is issued under the fixed designation D 4616; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 cenospheres—usually a minor component of coal tar
pitch. They are formed by the rapid pyrolysis of unconfined
1.1 This test method covers laboratory procedures for the
coal particles that are carried over from the coke oven to the
preparation of granular and melted samples for microscopic
tar. Microscopically, they appear like hollow spheres or seg-
analysis using reflected light to identify and estimate the
ments thereof (see Fig. 1), and are typically sized from about
amount and size of the mesophase.
10 to 500 µm. In polarized light (crossed polarizers), a
1.2 The values stated in inch-pound units are to be regarded
cenosphere may be optically active.The size of the anisotropic
as standard. The values given in parentheses are mathematical
pattern or mosaic depends upon the rank of the coal carbon-
conversions to SI units that are provided for information only
ized. Cenospheres are harder than the continuous phase and
and are not considered standard.
polish in relief (see Fig. 1).
1.3 This standard does not purport to address all of the
3.1.2 coke-oven-coke—usually a minor component of coal
safety concerns, if any, associated with its use. It is the
tar pitch. It originates in carry-over from the coke oven to the
responsibility of the user of this standard to establish appro-
tar side. It differs from cenospheres only in terms of its shape
priate safety and health practices and determine the applica-
and porosity. Coke-oven-coke is angular and less porous.
bility of regulatory limitations prior to use.
3.1.3 mineral matter—formed when minute particles of the
2. Referenced Documents cokeovenchargearecarriedoverintothecokeovencollecting
2
main during the charging operation. The tiny coal particles are
2.1 ASTM Standards:
digested in the collecting main tar, resulting in a residue that is
D 329 Specification for Acetone
rich in mineral matter. This mineral matter is identified under
D 1160 Test Method for Distillation of Petroleum Products
bright field illumination by its high reflectivity, in the case of
at Reduced Pressures
pyrite, and its low reflectance in the case of clay, quartz, and
D 2318 Test Method for Quinoline-Insoluble (QI) Content
carbonates. The association of mineral matter with insoluble
of Tar and Pitch
organic matter from coal aids in its identification.
D 3104 Test Method for Softening Point of Pitches (Mettler
3.1.4 refractory—usuallyaminorcomponentthatoriginates
Softening Point Method)
from the coke oven walls, doors, and patches due to wear and
D 4296 Practice for Sampling Pitch
degeneration; another component is charge hole sealant. It can
E11 Specification for Wire-Cloth Sieves for Testing Pur-
berecognizedunderthemicroscopethroughopticalproperties,
poses
hardness, shape, and associated minerals.
E 562 Test Method for Determining Volume Fraction by
3.1.5 isotropic phase—usually the predominant, and con-
Systematic Manual Point Count
tinuous, phase. It is a complex mixture of organic aromatic
3. Terminology
compounds composed mainly of carbon and hydrogen. At
room temperature, the isotropic phase is a glass-like solid. It is
3.1 Definitions of Terms Specific to This Standard:
optically inactive in polarized light (see Fig. 1 and Fig. 2).
3.1.6 mesophase—an optically anisotropic liquid crystal
1
This test method is under the jurisdiction of ASTM Committee D02 on
carbonaceous phase that forms from the parent liquor when
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
molecular size, shape, and distribution are favorable. In the
D02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.
early stages of its development, mesophase usually appears as
Current edition approved May 1, 2005. Published May 2005. Originally
approved in 1986. Last previous edition approved in 2000 as D 4616 – 95 (2000).
spheroids. The planar molecules are lined up equatorially as
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
shown schematically in Fig. 3. This equatorial arrangement
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
may be distinguished in crossed polarized light. Under crossed
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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