ASTM D3720-90(2011)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D3720 − 90 (Reapproved 2011)
Standard Test Method for
Ratio of Anatase to Rutile in Titanium Dioxide Pigments by
X-Ray Diffraction
This standard is issued under the fixed designation D3720; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope upon the amount of that substance in the mixture. To a minor
extentthepeakintensityofthecomponentisalsodependenton
1.1 This test method covers the determination of the ratio of
the mass absorption coefficient of other materials present.
anatase to rutile in titanium dioxide pigments. The method is
Since the test method utilizes the ratio of the intensities of
also applicable to pigment mixtures and pigmented coatings
diffraction peaks of two chemically similar materials, it is
containing titanium dioxide.
expected that the effects of other constituents will be the same
1.2 The values stated in SI units are to be regarded as the
for both materials.
standard. The values given in parentheses are for information
3.2 The intensity of the diffraction maxima for anatase and
only.
rutile is measured by X-ray diffractometry. The intensity of the
1.3 This standard does not purport to address all of the
anatase peak is converted to anatase content relative to rutile
safety concerns, if any, associated with its use. It is the
and the rutile content is determined by difference.
responsibility of the user of this standard to establish appro-
3.3 The X-ray diffraction measurement is made on single
priate safety and health practices and determine the applica-
pigments, pigment mixtures, films of pigmented coatings, and
bility of regulatory limitations prior to use.
films prepared from liquid coatings, if interfering materials are
2. Referenced Documents not present. When interfering materials are present, the pig-
ment is separated from the redissolved (or ignited film, or from
2.1 ASTM Standards:
the liquid coating and treated to isolate the titanium dioxide.
D215 Practice for the Chemical Analysis of White Linseed
Oil Paints (Withdrawn 2005)
4. Significance and Use
D2371 Test Method for Pigment Content of Solvent-
Reducible Paints
4.1 This test method is used by titanium dioxide pigment
D2698 Test Method for Determination of the Pigment Con-
manufacturers and users for process control and product
tent of Solvent-Reducible Paints by High-Speed Centri-
acceptance.
fuging
D3925 Practice for Sampling Liquid Paints and Related
5. Interferences
Pigmented Coatings
5.1 Calcium sulfate interferes, but its effect is eliminated by
chemical removal (see Practice D215). It is desirable to assure
3. Summary of Test Method
by analysis that any residual CaSO is considerably less than
3.1 TheX-raydiffractionpatternobtainedfromamaterialis
the level of anatase being sought. The insoluble residue after
characteristic of that material. The intensity of a diffraction
removal of calcium sulfate should be ignited above 700°C.
peak entirely due to one component of a mixture is dependent
Chrome yellow and the valentinite form of antimony trioxide
also interfere if not removed. High amounts of iron render
analysis difficult due to increased background (see Note 1).
This test method is under the jurisdiction of ASTM Committee D01 on Paint
Additives, such as antimony and zinc, and impurities, such as
and Related Coatings, Materials, andApplications and is the direct responsibility of
niobium and zirconium, are generally present in solid solution
Subcommittee D01.31 on Pigment Specifications.
Current edition approved June 1, 2011. Published June 2011. Originally
and thus would not have interfering diffraction peaks. Surface
approved in 1978. Last previous edition approved in 2005 as D3720 - 90 (2005).
treatments such as silica and alumina do not interfere. Extreme
DOI: 10.1520/D3720-90R11.
differences in particle size between the anatase and rutile
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM portions affect the results.
Standards volume information, refer to the standard’s Document Summary page on
NOTE1—Backgroundscatterduetohighironlevelsinasamplemaybe
the ASTM website.
The last approved version of this historical standard is referenced on reduced by use of a cobalt or molybdenum target tube in place of the
www.astm.org. copper target tube. The background may be eliminated for all practical
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D3720 − 90 (2011)
purposes by use of a curved crystal monochromator equipped with a
as isopropyl alcohol and then mixed, followed by air drying.
graphite crystal in conjunction with a copper target tube.
This dry cake is ground up using a mortar and pestle to ensure
homogeneity.
5.2 In the calculation of converting the ratio to percent it is
implicitly assumed that the sum of anatase and rutile is 100 %,
8. Hazards
an assumption normally made in TiO pigment systems. Other
materials present would interfere to the extent that they dilute
8.1 X-ray producing equipment can be dangerous to both
the sample. The third polymorphic form of TiO , brookite,
theoperatorandpersonsintheimmediatevicinityunlesssafety
would have such an effect. However, it reportedly does not
precautions are strictly observed. Refer to the manufacturer’s
occur in commercial titanium dioxide pigments.
instruction manual. Exposure to excessive quantities of
X-radiation may be injurious to health.Therefore, users should
6. Apparatus
avoid exposing any parts of their bodies, not only to the direct
beam, but also to secondary or scattered radiation that occurs
6.1 X-Ray Diffractometer—The principle components of
when an X-ray beam strikes or has passed through any
thisinstrumentare:(a)X-raygenerator,(b)coppertargetX-ray
material. It is strongly recommended that users check the
tube, (c) goniometer, (d) detector, (e) electronic circuit panel,
degree of exposure by film carried on them or by the use of
(f) computer (if used), and (g) strip chart recorder or printer.
dosimeters and that blood counts be made periodically. Before
6.2 Operating Conditions—The X-ray tube voltage and
utilizing the equipment, all persons designated or authorized to
filament current and other settings are selected to record X-ray
operate X-ray instrumentation or supervise its operation,
diffraction peaks of weak intensities.
should have a full understanding of its nature and should also
6.2.1 Nickel Filter, to remove Cu K beta radiation if a
become familiar with established safe exposure factors by a
monochromator is not used. Cu K beta radiation will produce
careful study of the National Bureau of Standards Handbook
a diffraction line from the rutile phase of TiO that appears at
2 “X-Ray Recommendations of the International Roentgen Ray
the same 2θ angle as the anatase analytical line.
Committee on X-Ray Protection” and other standard publica-
tions on the subject. Inquiries should be made of state agencies
6.3 Typical Apparatus Conditions:
as to existing requirements.
6.3.1 High-Voltage Power Supply—Select X-ray tube
voltage, filament current, and other settings so that 0.1 %
9. Specimen Preparation
anatase generates a signal with intensity at least four t
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