ASTM D3720-90(1999)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D3720–90(Reapproved 1999)
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 D 3720; 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 3.2 The intensity of the diffraction maxima for anatase and
rutile is measured by X-ray diffractometry. The intensity of the
1.1 This test method covers the determination of the ratio of
anatase peak is converted to anatase content relative to rutile
anatase to rutile in titanium dioxide pigments. The method is
and the rutile content is determined by difference.
also applicable to pigment mixtures and pigmented coatings
3.3 The X-ray diffraction measurement is made on single
containing titanium dioxide.
pigments, pigment mixtures, films of pigmented coatings, and
1.2 This standard does not purport to address all of the
films prepared from liquid coatings, if interfering materials are
safety concerns, if any, associated with its use. It is the
not present. When interfering materials are present, the pig-
responsibility of the user of this standard to establish appro-
ment is separated from the redissolved (or ignited film, or from
priate safety and health practices and determine the applica-
the liquid coating and treated to isolate the titanium dioxide.
bility of regulatory limitations prior to use.
4. Significance and Use
2. Referenced Documents
4.1 This test method is used by titanium dioxide pigment
2.1 ASTM Standards:
manufacturers and users for process control and product
D 215 TestMethodforChemicalAnalysisofWhiteLinseed
acceptance.
Oil Paints
D 2371 Test Method for Pigment Content of Solvent-
5. Interferences
Reducible Paints
5.1 Calcium sulfate interferes, but its effect is eliminated by
D 2698 Test Method for Determination of the Pigment
chemical removal (see Test Method D 215). It is desirable to
Content of Solvent-Reducible Paints by High Speed Cen-
2 assure by analysis that any residual CaSO is considerably less
trifuging
than the level of anatase being sought. The insoluble residue
D 3925 Practice for Sampling Liquid Paints and Related
2 after removal of calcium sulfate should be ignited above
Pigmented Coatings
700°C. Chrome yellow and the valentinite form of antimony
3. Summary of Test Method trioxide also interfere if not removed. High amounts of iron
render analysis difficult due to increased background (see Note
3.1 The X-ray diffraction pattern obtained from a material is
1). Additives, such as antimony and zinc, and impurities, such
characteristic of that material. The intensity of a diffraction
as niobium and zirconium, are generally present in solid
peak entirely due to one component of a mixture is dependent
solution and thus would not have interfering diffraction peaks.
upon the amount of that substance in the mixture. To a minor
Surface treatments such as silica and alumina do not interfere.
extentthepeakintensityofthecomponentisalsodependenton
Extreme differences in particle size between the anatase and
the mass absorption coefficient of other materials present.
rutile portions affect the results.
Since the test method utilizes the ratio of the intensities of
diffraction peaks of two chemically similar materials, it is
NOTE 1—Backgroundscatterduetohighironlevelsinasamplemaybe
expected that the effects of other constituents will be the same
reduced by use of a cobalt or molybdenum target tube in place of the
copper target tube. The background may be eliminated for all practical
for both materials.
purposes by use of a curved crystal monochromator equipped with a
graphite crystal in conjunction with a copper target tube.
5.2 In the calculation of converting the ratio to percent it is
This test method is under the jurisdiction of ASTM Committee D-1 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
implicitly assumed that the sum of anatase and rutile is 100 %,
Subcommittee D01.31 on Pigment Specifications.
an assumption normally made in TiO pigment systems. Other
Current edition approved May 25, 1990. Published July 1990. Originally
materials present would interfere to the extent that they dilute
published as D 3720 – 78. Last previous edition D 3720 – 84.
Annual Book of ASTM Standards, Vol 06.01. the sample. The third polymorphic form of TiO , brookite,
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3720
would have such an effect. However, it reportedly does not X-radiation may be injurious to health.Therefore, users should
occur in commercial titanium dioxide pigments. avoid exposing any parts of their bodies, not only to the direct
beam, but also to secondary or scattered radiation that occurs
6. Apparatus when an X-ray beam strikes or has passed through any
material. It is strongly recommended that users check the
6.1 X-Ray Diffractometer—The principle components of
degree of exposure by film carried on them or by the use of
thisinstrumentare:(a)X-raygenerator,(b)coppertargetX-ray
dosimeters and that blood counts be made periodically. Before
tube, ( c) goniometer, (d) detector, ( e) electronic circuit panel,
utilizing the equipment, all persons designated or authorized to
(f) computer (if used), and (g) strip chart recorder or printer.
operate X-ray instrumentation or supervise its operation,
6.2 Operating Conditions—The X-ray tube voltage and
should have a full understanding of its nature and should also
filament current and other settings are selected to record X-ray
become familiar with established safe exposure factors by a
diffraction peaks of weak intensities.
careful study of the National Bureau of Standards Handbook
6.2.1 Nickel Filter, to remove Cu K beta radiation if a
“X-Ray Recommendations of the International Roentgen Ray
monochromator is not used. Cu K beta radiation will produce
Committee on X-Ray Protection” and other standard publica-
a diffraction line from the rutile phase of TiO that appears at
tions on the subject. Inquiries should be made of state agencies
the same 2u angle as the anatase analytical line.
as to existing requirements.
6.3 Typical Apparatus Conditions:
6.3.1 High-Voltage Power Supply—Select X-ray tube volt-
9. Specimen Preparation
age, filament current, and other settings so that 0.1 % anatase
generates a signal with intensity at least four times the noise
9.1 Powder Samples:
level.
9.1.1 Packing the specimen in the specimen holder to obtain
6.3.2 Detector—Scintillation detector operating at optimum
a planar surface is one of the most important phases in X-ray
voltage.
analysis. Ripples or indentures in the specimen surface cause
6.3.3 Pulse Height Analyzer—Settings will depend on in-
variations in the test because of an err
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