ASTM C791-83(2000)
(Test Method)Standard Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Boron Carbide
Standard Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Boron Carbide
SCOPE
1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade boron carbide powder and pellets to determine compliance with specifications.
1.2 The analytical procedures appear in the following order: SectionsTotal Carbon by Combustion and Gravimetry7-17Total Boron by Titrimetry18-28Isotopic Composition by Mass Spectrometry29-38Chloride and Fluoride Separation by Pyrohydrolysis39-45Chloride by Constant-Current Coulometry46-54Fluoride by Ion-Selective Electrode55-63Water by Constant-Voltage Coulometry64-72Impurities by Spectrochemical Analysis73-81Soluble Boron by Titrimetry82-95Soluble Carbon by a Manometric Measurement96-105Metallic Impurities by a Direct Reader Spectrometric Method106-114
1.3 This method covers the determination of total carbon in nuclear-grade, boron carbide in either powder or pellet form.
1.4 This method covers the determination of total boron in samples of boron carbide powder and pellets. The recommended amount of boron for each titration is 100 10 mg.
1.5 This method covers the determination of the isotopic composition of boron in nuclear-grade boron carbide, in powder and pellet form, containing natural to highly enriched boron.
1.6 This method covers the separation of up to 100 g of halides per gram of boron carbide. The separated halides are measured using other methods found in this standard.
1.7 This method covers the measurement of chloride after separation from boron carbide by pyrohydrolysis. The lower limit of the method is about 2 g of chloride per titration.
1.8 This method covers the measurement of fluoride after separation from boron carbide by pyrohydrolysis. The lower limit of the method is about 2 g of fluoride per measurement.
1.9 This method covers the determination of water in boron carbide in either powder or pellet form. The lower limit of the method is 5 g of water.
1.10 This method covers the determination of 14 impurity elements in boron carbide in either powder or pellet form.
1.11 This method covers the determination of soluble boron in boron carbide. Soluble boron is defined as that boron dissolved under the conditions of the test.
1.12 This method covers the determination of soluble carbon in boron carbide. The lower limit of the method is 0.02 % with a 100-mg sample. Soluble carbon is defined as that carbon oxidized by the sodium dichromate-sulfuric acid solution under the conditions of this method.
1.13 This method is applicable to the determination of metallic impurities in samples of boron carbide powder and pellets. From 20 to 5000 g of many of the impurities per gram of sample can be determined.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: C 791 – 83 (Reapproved 2000)
Standard Test Methods for
Chemical, Mass Spectrometric, and Spectrochemical
Analysis of Nuclear-Grade Boron Carbide
This standard is issued under the fixed designation C 791; 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 must meet certain criteria for assay, isotopic composition, and
impurity content. These methods are designed to show whether
1.1 These test methods cover procedures for the chemical,
or not a given material meets the specifications for these items
mass spectrometric, and spectrochemical analysis of nuclear-
as described in Specifications C 750 and C 751.
grade boron carbide powder and pellets to determine compli-
3.1.1 An assay is performed to determine whether the
ance with specifications.
material has the specified boron content.
1.2 The analytical procedures appear in the following order:
3.1.2 Determination of the isotopic content of the boron is
Sections
made to establish whether the content is in compliance with the
Total Carbon by Combustion and Gravimetry 7-17
Total Boron by Titrimetry 18-28
purchaser’s specifications.
Isotopic Composition by Mass Spectrometry 29-38
3.1.3 Impurity content is determined to ensure that the
Chloride and Fluoride Separation by Pyrohydrolysis 39-45
maximum concentration limit of certain impurity elements is
Chloride by Constant-Current Coulometry 46-54
Fluoride by Ion-Selective Electrode 55-63
not exceeded.
Water by Constant-Voltage Coulometry 64-72
Impurities by Spectrochemical Analysis 73-81
4. Reagents
Soluble Boron by Titrimetry 82-95
Soluble Carbon by a Manometric Measurement 96-105
4.1 Purity of Reagents—Reagent grade chemicals shall be
Metallic Impurities by a Direct Reader Spectrometric 106-114
used in all tests. Unless otherwise indicated, it is intended that
Method
all reagents shall conform to the specifications of the Commit-
2. Referenced Documents
tee on Analytical Reagents of the American Chemical Society,
where such specifications are available. Other grades may be
2.1 ASTM Standards:
used, provided it is first ascertained that the reagent is of
C 750 Specification for Nuclear-Grade Boron Carbide Pow-
sufficiently high purity to permit its use without lessening the
der
accuracy of the determination.
C 751 Specification for Nuclear-Grade Boron Carbide Pel-
4.2 Purity of Water—Unless otherwise indicated, references
lets
to water shall be understood to mean reagent water conforming
D 1193 Specification for Reagent Water
to Specification D 1193.
E 115 Practice for Photographic Processing in Optical
Emission Spectrographic Analysis
5. Safety Precautions
E 116 Practice for Photographic Photometry in Spectro-
5.1 Many laboratories have established safety regulations
chemical Analysis
governing the use of hazardous chemicals and equipment. The
E 130 Practice for Designation of Shapes and Sizes of
users of these methods should be familiar with such safety
Graphite Electrodes
practices.
3. Significance and Use
6. Sampling
3.1 Boron carbide is used as a control material in nuclear
6.1 Criteria for sampling this material are given in Specifi-
reactors. In order to be suitable for this purpose, the material
cations C 750 and C 751.
These test methods are under the jurisdiction of ASTM Committee C-26 on
Nuclear Fuel Cycle and are the direct responsibility of Subcommittee C26.03 on
Neutron Absorber Materials Specifications.
Current edition approved Feb. 28, 1983. Published April 1983. Originally “Reagent Chemicals, American Chemical Society Specifications,” Am. Chemi-
published as C 791 – 75. Last previous edition C 791 – 80. cal Soc., Washington, D.C. For suggestions on the testing of reagents not listed by
Annual Book of ASTM Standards, Vol 12.01. the American Chemical Society, see “Reagent Chemicals and Standards,” by Joseph
Annual Book of ASTM Standards, Vol 11.01. Rosin, D. Van Nostrand Co., Inc., New York, N.Y., and the “United States
Annual Book of ASTM Standards, Vol 03.05. Pharmacopeia.”
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 791
TOTAL CARBON BY COMBUSTION AND 10.6.3 Flowmeter (C) —The total system has two flowme-
GRAVIMETRY ters, one located before the furnace (Fig. 3) and one after the
absorption bulb (Fig. 2). This arrangement helps to detect leaks
7. Scope
in the system.
10.7 Oxygen Purification System—The letters in parenthe-
7.1 This method covers the determination of total carbon in
ses refer to the components shown in Fig. 3.
nuclear-grade, boron carbide in either powder or pellet form.
10.7.1 Gas Regulator (A), for oxygen.
8. Summary of Test Method
10.7.2 Drying Tubes —The three tubes are filled as fol-
lows: the first (B ) with magnesium perchlorate to dry the
8.1 The sample mixed with a flux material is burned in an 1
oxygen; the second (B ) with anhydrous calcium sulfate to
oxygen atmosphere at a temperature not lower than 1400°C. 2
indicate when trap B is spent; the third tube (B ) with sodium
The carbon dioxide product is passed through a gas-treatment 1 3
hydrate-asbestos to remove carbon dioxide.
train to ensure that any carbon monoxide formed is converted
10.7.3 Gas Flow-Regulating Valve (C).
to carbon dioxide and to remove dust, sulfur dioxide, and
10.7.4 Flowmeter (D).
moisture. The carbon dioxide is absorbed and weighed (1,2).
10.8 Sieve, No. 100 (150-μm), U.S. Standard Sieve Series,
9. Interferences 3-in. diameter, brass or stainless steel.
9.1 At the specification limits usually established for
11. Reagents
nuclear-grade boron carbon, interferences are insignificant.
11.1 Calcium Sulfate, Anhydrous, indicating.
10. Apparatus
11.2 Copper, granules, 30 mesh.
11.3 Copper, rings.
10.1 Analytical Balance, capable of weighing to 6 0.1 mg.
11.4 Cupric Oxide, reagent grade, used in the catalyst
10.2 Crucible, zircon ceramic.
furnace (Fig. 1) to assure that any carbon monoxide formed
10.3 Crucible Covers, porous, ceramic.
during combustion is converted to carbon dioxide.
10.4 Mortar, diamond (Plattner), or boron carbide mortar.
11.5 Iron, chips.
10.5 Combustion System—The letters in parentheses refer
11.6 Magnesium Perchlorate, anhydrous.
to the components shown in Fig. 1.
11.7 Manganese Dioxide.
10.5.1 Induction Furnace (A) —Caution: Contact with the
11.8 Oxygen, ultra high purity grade or equivalent.
high-frequency induction coil will produce severe electrical
11.9 Sodium Hydrate-Asbestos, 8 to 20 mesh.
shock and may cause burns.
11.10 Tin, Granular.
10.5.2 Combustion Tube (B), fused silica.
10.5.3 Dust Trap (C).
12. Precautions
10.5.4 Catalyst Furnace (D).
10.5.5 Drying Tubes —The first tube (E ) is filled with 12.1 Care should be taken to avoid carbon contamination of
magnesium perchlorate and the second tube (E ) is filled with reagents and laboratory equipment. Prior to making the initial
anhydrous calcium sulfate. These tubes prevent water re- analysis, condition the furnace tube and absorption bulb by
leased from the sample from entering the absorption bulb. taking a sample from 15.1-15.13 without making any measure-
10.5.6 Sulfur Trap (F). ments (omit 15.2, for example).
10.6 Gravimetric System—The letters in parentheses refer
13. Sample Preparation
to components shown in Fig. 2.
10.6.1 Nesbitt Absorption Bulb (A), may be modified with
13.1 Crush a pellet with a mortar. Important: when using the
12/5 socket joints on both the entrance and exit port. The bulb
diamond (Plattner) mortar, crush with a few, light hammer
is filled as shown in Fig. 2.
blows.
10.6.2 Drying Tube (B), filled with magnesium perchlo-
NOTE 1—Do not crush and grind the boron carbide extensively in the
rate, anhydrous calcium sulfate, and sodium hydrate-asbestos
diamond mortar because significant iron contamination can occur, which
to prevent any back-diffusion of water and carbon dioxide into
will require an iron correction in the analysis.
the absorption bulb.
13.2 Pass the crushed sample through a metal No. 100 sieve.
13.3 Repeat 13.1 and 13.2 until the whole pellet has passed
through the sieve.
The boldface numbers in parentheses refer to the list of references appended to
13.4 Thoroughly mix the sieved sample.
these methods.
Leco No. 528–035 or equivalent.
Leco No. 528–042 or equivalent.
Leco No. 521–000 or equivalent.
10 18
Leco No. 550–122 or equivalent. Manostat No. 1044B or equivalent.
11 19
Leco No. 501–010 or equivalent. Matheson No. 32 or equivalent.
12 20
Leco No. 507–000 or equivalent. Leco No. 550–184 or equivalent.
13 21
Kimble No. 46010 or equivalent. Leco No. 501–077 or equivalent.
14 22
Drierite has been found satisfactory for this purpose. Leco No. 501–060 or equivalent.
15 23
Leco No. 503–033 or equivalent. Matheson Gas Data Book, The Matheson Co. Inc., East Rutherford, N. J.,
Kimble No. 16010 or equivalent. Fourth Edition, 1966.
17 24
Ascarite has been found satisfactory for this purpose. Leco No. 501-076 or equivalent.
C 791
14. Blank 15.14 Close the absorption bulb and remove it from the
apparatus.
14.1 A blank should be determined at least once in each 8-h
15.15 Weigh the bulb using exactly the same technique used
shift in which total carbon analyses are made. The long-term
in 15.16.
average blank less than 1.5 % of the long-term average amount
15.16 Weighing Absorption Bulb:
of carbon dioxide weighed in the analyses. If any individual
15.16.1 Wipe the closed absorption bulb thoroughly and
blank varies from the long-term average by more than 6 20 %,
evenly with a moist chamois, being careful not to touch the
investigate and correct the cause before continuing the analysis
bulb with the hands.
of samples. Use the long-term average blank in calculating the
concentration of carbon in samples.
NOTE 12—Wiping the absorption bulb with a moist chamois minimizes
the adverse effects on weighing produced by static charges.
15. Procedure
15.16.2 Place the bulb on the balance pan with the balance
15.1 Add2gof tin, 3 copper rings (m1.8 g), and 1.2 g of
door open.
copper granules (30 mesh) to a crucible.
NOTE 13—If a single-pan balance with two doors is used, open both
NOTE 2—To determine a blank, perform 15.1-15.15, omitting 15.2 and
doors.
15.3.
NOTE 3—Prefiring of the crucibles is recommended to minimize blanks. 15.16.3 Wait 3 min and close the door.
NOTE 4—These quantities of flux and coupler, including the3gof iron
NOTE 14—Leaving the balance door open decreases the amount of time
chips added in 15.4, have been found satisfactory. Since furnaces may
required for the absorption bulb to come to equilibrium after it has been
have different power outputs and coupling characteristics, the quantities of
wiped with the moist chamois. The length of time required to reach
flux and coupler and iron chips required may differ among furnaces.
equilibrium depends upon the relative humidity in the laboratory.
15.2 Weigh the crucible and its contents to 6 0.1 mg.
15.16.4 Weigh the bulb to 6 0.1 mg.
15.3 Add 200 mg of sample in powder form to the weighed
15.16.5 Repeat 15.16.1-15.16.4 until constant weight
crucible and reweigh to 6 0.1 mg.
(6 0.1 mg) is obtained.
NOTE 5—If a sample is in pellet form, crush to a powder using the
procedure given in Section 13.
16. Calculation
15.4 Cover the sample with3gof iron chips.
16.1 Calculate the grams of carbon, C, weighed as follows:
15.5 Cover the crucible with a porous ceramic cover.
C 5 W 2 W 2 W 2 W 0.2729 (1)
@~ ! ~ ! #~ !
2 1 s 2 1 b
15.6 Load the crucible into the induction furnace.
15.7 Purge the crucible and its contents with oxygen for 2
where:
min. W = weight of absorption bulb after combustion
(15.15),
NOTE 6—The flow rate of the gas should be about 0.5/min.
W = weight of absorption bulb before combus-
15.8 Weigh the closed absorption bulb, using the weighing
tion (15.8),
technique given in 15.16.
(W −W ) = weight of CO from sample, g, and
2 1 s 2
(W −W ) = blank measurement.
2 1 b
NOTE 7—Before taking the initial weight of the absorption bulb,
16.2 Calculate the weight percent of carbon, C,inthe
condition it by purging with oxygen for1hat 0.5/min. a
NOTE 8—Important—After obtaining the initial weight of the absorp- sample as follows:
tion bulb, do not touch it with the hands until all analyses have been
C 5 C/ S 2 S ! 3 100 (2)
@ ~ #
a 2 1
completed. Lintless nylon gloves or their equivalent should be used to
handle the absorption bulb.
where:
C = amount of carbon weighed from the sample, g,
15.9 Place the absorption bulb into position in the appara-
S = weight of crucible plus sample (15.3), g, and
tus.
S = weight of crucible (15.2), g.
NOTE 9—Use dry (no grease) ball and socket joints. Greased joints add
to the problem of reproducing weighings.
17. Precision and Accuracy (3)
15.10 Open the absorption bulb to the system and readjust
NOTE 15—Please see Ref (3) for all precision and accuracy statements.
the oxygen flow to 0.5/min, if necessary.
17.1 Precision—The relative standard deviation is 0.50 %.
15.11 Turn on the induction furnace.
17.2 Accuracy—The average percent recovery obtained
NOTE 10—The induction furnace should be preset at its highest grid
from the analysis of boron carbide control standards over a
current setting so that the maximum temperature can be obtained. Follow
two-year period was 100.2 %. Those standards were prepared
the manufacturer’s recommended procedure for operating the furnace.
and certified by the Los Alamos Scientific Laboratory (LASL).
15.12 Burn the sample.
TOTAL BORON BY TITRIMETRY
NOTE 11—If the combustion is incomplete after 8 min by visual
inspection, investigate the flux and coupler conditions to determine
conditions that will give complete combustion. 18. Scope
15.13 Turn off the furnace and wait an additional 22 min, 18.1 This method covers the determination of total boron in
allowing the oxygen to continue flowing through the entire samples of boron carbide powder and pellets. The recom-
system. mended amount of boron for each titration is 100 6 10 mg.
C 791
19. Summary of Method 23.2 The periodic determination of a blank to check for
boron contamination is advisable, particularly whenever a new
19.1 Powdered boron carbide is mixed with sodium carbon-
bottle of any reagent is used. Titrating reagents alone does not
ate and this mixture is fused to decompose the boron carbide.
give a true blank, however (4). A given amount of boric acid
The melt is dissolved in water, filter
...
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