ASTM C1494-01

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Designation:C1494–01
Standard Test Methods for
Determination of Mass Fraction of Carbon, Nitrogen, and
Oxygen in Silicon Nitride Powder
This standard is issued under the fixed designation C 1494; 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 E 1569 Standard Test Method for Determination of Oxygen
in Tantalum Powder
1.1 These test methods cover the determination of mass
E 1806 Practice for Sampling Steel and Iron for Determi-
fraction % of carbon, nitrogen and oxygen in silicon nitride
nation of Chemical Composition
powder having chemical compositions within the following
E 1941 Determination of Carbon in Refractory and Reac-
limits:
tive Metals and Alloys
Element Mass Fraction % Range
3. Significance and Use
Carbon 0.05 to 5.0
Nitrogen 30 to 45
3.1 Thesetestmethodsareforthechemicalanalysisofmass
Oxygen 0.1 to 1.5
fraction of carbon, nitrogen and oxygen in silicon nitride
1.2 Two test methods appear in this standard.
powder. It is assumed that all who use these test methods will
1.2.1 Total Carbon by the Direct Combustion-Infrared Mea-
be trained analysts, capable of performing common laboratory
surement Method.
proceduresskillfullyandsafely.Itisexpectedthatworkwillbe
1.2.2 Nitrogen and oxygen by the Inert Gas Fusion-Thermal
performed in a properly equipped laboratory.
Conductivity Measurement Method.
4. Apparatus and Reagents
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4.1 The procedure was written with commercial carbon and
responsibility of the user of this standard to establish appro-
nitrogen/oxygen analyzers in mind. For any other analyzer, the
priate safety and health practices and determine the applica-
instrument manual specific to that analyzer shall be consulted
bility of regulatory limitations prior to use. Specific hazard
for instrument set-up.
statements are given in Section 6.
4.2 Specific apparatus and reagents required for each deter-
minationarelistedinseparatesectionsprecedingtheprocedure
2. Referenced Documents
.
2.1 ASTM Standards:
E 29 Practice for Using Significant Digits in Test Data to 5. Sampling
Determine Conformance with Specifications
5.1 Procedures for sampling the materials refer to those
E 50 Practices for Apparatus, Reagents, and Safety Precau-
partsofPracticeE 1806pertainingtosolidformsamplesofthe
tions for Chemical Analysis of Metals
type used for instrumental analysis.
E 1019 Standard Test Methods for Determination of Car-
6. Hazards
bon, Sulfur, Nitrogen, and Oxygen in Steel and in Iron,
Nickel, and Cobalt Alloys
6.1 For hazards to be observed in the use of certain reagents
E 1409 Standard Test Method for Determination of Oxygen
in this test method, refer to Practice E 50.
in Titanium and Titanium Alloys by the Inert Gas Fusion
6.2 Use care when handling hot crucibles and operating
Technique
furnaces to avoid personal injury by either burn or electrical
shock.
These test methods are under the jurisdiction of ASTM Committee C28 on
7. Total Carbon in Silicon Nitride Powder by Direct
Advanced Ceramics and are the direct responsibility of Subcommittee C28.03 on
Combustion—Infrared Detection Method
Physical Properties and Performance.
Current edition approved April 10, 2001. Published May 2001.
7.1 Scope—This test method covers the determination of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
carbon in concentrations from 0.05 to 5.0 % mass fraction.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C1494–01
7.2 Summary of Test Method —The carbon is converted to (e) Enter blank value following routine outlined in opera-
carbon dioxide by combustion in a stream of oxygen. The tor’s instruction manual.
amount of carbon dioxide is measured by infrared (IR) 7.7 Instrument Calibration Procedure:
absorption. 7.7.1 This procedure was written specially for a carbon
7.3 Apparatus—This test method is written for use with analyzer.Thetypeandamountsofacceleratortobeaddedshall
commercial carbon analyzers, equipped to carry out the analy- be adjusted according to the manufacturers recommendations
ses operations automatically and calibrated using steel stan- for the other instrumentation.
dards with known concentrations of carbon. The operating 7.7.2 Weigh 0.1 to 0.5 g of calibration standard to the
principles, specifications and descriptions of commercial car- nearest mg into a prebaked ceramic or similar refractory
bon analyzers are given in the Practice of E 1019. crucible and enter appropriate weight into weight stack.
7.4 Reagents and Materials: 7.7.3 Add approx. 1.0 6 0.005 g of tungsten/tin accelerator
7.4.1 Crucibles—Expendable ceramic (alumina) or similar and approx. 1.0 6 0.005 g of iron chips accelerator.
refractory crucibles as specified by commercial carbon analyz- 7.7.4 Place crucible on pedestal and analyze.
ers’ manufacturers. Both the crucible and cover, if used, must 7.7.5 Repeattheabovesteps7.7.2-7.7.4aminimumofthree
be prebaked for a sufficient time to produce constant blank times for each standard, and calibrate the instrument following
values. Use the prebake schedule recommended by the instru- the auto calibration procedure as outlined in the operator’s
ment manufacturer. instruction manual.
7.4.2 Crucible Tongs—Capable of handling recommended 7.7.6 Check calibration by analyzing the calibration stan-
crucibles with respect to their sizes, shape and temperature. dard again if it is not within the reported range. If it is not,
7.4.3 Accelerators—Carbon free (or containing a known repeat steps 7.7.2-7.7.4.
amount of carbon) granular tungsten/tin and iron chip accel- 7.8 Sample Analysis Procedure:
erators shall be used. 7.8.1 Weigh 0.1 to 0.5 g of sample to the nearest mg into a
7.4.4 Carbon Standard Material—NIST SRM 8j prebaked expendable ceramic or a similar refractory crucible
(0.081 %C), SRM 1 lh (0.2 %C), SRM 12h (0.407 %C), and and add appropriate weight to the weight stack.
NIST RM 8983 (0.107 %C). 7.8.2 Repeat steps 7.7.3 and 7.7.4 in the calibration proce-
7.4.5 Oxygen—Ultra High Purity (99.95 % minimum pu- dure.
rity) or Regular grade (99.5 %) purified by passing over heated 7.8.3 Each sample shall be analyzed in triplicate and record
CuO and through CO /H 0 absorbents. (When the instrument the integral values of the sample.
2 2
has a built in purifier, regular grade oxygen can be used.) 7.9 Calculation—Most commercially available instruments
7.5 Preparation of Apparatus—Follow the operating in- calculate percent concentration directly. If the instrument does
structions for the specific equipment used. After having prop- not give percent concentration, please follow the manufactur-
erly set the operating controls of the instrument system, er’s directions to ensure all the essential variables in the
condition the apparatus by combustion of several blanks calculation of analysis results have been included.
prepared with sample crucible and accelerator in the amounts Or perform the following calculation to determine percent
to be used with the test specimen analyses. Successive blanks concentration (% mass):
should achieve a steady state value. a. Calibration Constant:
7.6 Blank Determination:
G 3 P/100
K 5 (1)
7.6.1 Prebake ceramic crucibles in a muffle or tube furnace
A – A
c b
at 1350° C for not less than 15 min or at 1000° C for not less
where:
than 40 minutes. The crucibles shall be removed from the
K = calibration constant (g/integral value),
furnace, allowed to cool for 1-2 min and placed in a desiccator
G = mass of calibration sample (g),
for storage. If the crucibles are not used within four hours, they
P = total carbon content of the calibration sample (%
must be prebaked again. This prebaking procedure is to burn
mass),
off any organic contaminates.
A = integral value of the calibration sample (7.7.6), and
c
7.6.2 Prepare instrument as outlined in the operator’s in-
A = integral value of the blank (7.6.3e).
b
struction manual.
b. Total Carbon Content:
7.6.3 Determine the instrument blank.
~A – A ! 3 K 3 100
(a) Enter 1.000 g weight into weight stack. s b
C 5 (2)
m
(b)Add1.000g(60.005g)oftungsten/tinacceleratorand
1.000 g (6 0.005 g) of iron chip accelerator.
where:
(c) Place crucible on furnace pedestal and analyze.
C = carbon content (mass %),
(d) Repeat steps 7.6.3a through 7.6.3c a minimum of three
A = integral value of the sample (7.8.3),
s
times.
A = integral value of the blank (7.6.3e),
b
The test method procedure was adapted from (a)ASTM E 1019-94 , “Standard
Test Methods for Determination of C, S, N, and O in Iron, Nickel and Cobalt The weight of sample is chosen based on the expected amount of carbon
Alloys” and (b) Application Bulletin: “Carbon and Sulfur in Ceramic and Similar present and so the CO produced will fall within the detection range of the IR
Materials,” LECO Corp., St. Joseph, MI. detector.
C1494–01
8.2 Summary of Test Method —The specimen, contained in
K = calibration constant (g/integral value), and
a small single-use graphite crucible, is fused under a flowing
m = mass of the sample (g).
helium atmosphere at a minimum temperature of 1900° C
7.10 Report—Report carbon concentration as mass fraction
which is sufficient to release oxygen, nitrogen and hydrogen
percentage to the desired decimal places as directed in Practice
from the sample. The oxygen combines with carbon from the
E 29, as well as times of replication of analysis and any
crucibletoformcarbonmonoxide(CO)whichiscarriedbythe
deviations from the standard analysis procedure.
helium inert gas stream to a thermal conductivity (TC) detec-
7.11 Precision and Bias:
tor. Nitrogen present in the sample is released as molecular
7.11.1 Precision:
nitrogen into the flowing helium stream. The nitrogen is
separated from other liberated gases such as hydrogen and
7.11.1.1 Reproducibility—Three laboratories cooperated in
carbon monoxide and is finally measured in a thermal conduc-
testing this method and obtained reproducibility data for SRM
tivity cell.
8j, 1 lh, and 12h which are summarized in Table 1. Since the
8.3 Apparatus—This test method is written for use with
reference value with uncertainty of RM 8983 is determined
commercial nitrogen/oxygen analyzers, equipped to carry out
during this round robin study, no reproducibility is reported.
the analyses operation automatically and calibrated using
7.11.1.2 Repeatability—Three laboratories cooperated in
standardswithknownmassfraction%ofnitrogen/oxygen.The
testing this method and obtained repeatability data for SRM 8j,
operating principles, specifications and descriptions of com-
1 lh and 12h which are summarized in Table 1. Since the
mercial nitrogen/oxygen analyzers are given in the Practice of
reference value with uncertainty of RM 8983 is determined
E 1019.
during this round robin study, no repeatability is reported.
8.4 Reagents and Materials:
7.11.2 Bias—No bias of this test method is established,
8.4.1 High Temperature Graphite Crucible (resistance
since insufficient number of laboratories have participated this heated) as recommended by the manufacturer of the instru-
round robin study.The accuracy of a reading may be judged by ment.
8.4.2 Graphite Crucible (sacrificial heated) as recom-
comparingvaluesobtainedwithNISTreferencestandardssuch
mended by the instrument manufacturer.
as listed in Table 1 to their reference values and uncertainty.
8.4.3 Crucible Tongs capable of handling recommended
crucibles and capsules with respect to their sizes, shape and
8. Determination of Total Nitrogen and Oxygen in Silicon
temperature.
Nitride Powder by Direct Inert Gas Fusion-Thermal
8.4.4 TinCapsules asrecommendedbythemanufacturerof
Conductivity Method
the instrument.
8.1 Scope—This test method covers the determination of
8.4.5 Nickel Baskets (Flux) as recommended by the instru-
nitrogen (N) in concentrations from 30 to 45 % mass fraction.
ment manufacturer.
This test method also covers the determination of oxygen (O)
8.4.6 Inert Gases (Helium, Compressed Air, Nitrogen or
in concentrations from 0.1 to 1.5 % mass fraction.
Argon)—Use type and purity specified by the instrument
manufacturer.
8.4.7 Calibration Standards:
TABLE 1 Statistical Information for Carbon Analysis (Mass
8.4.7.1 Oxygen—Select standards with appropriate concen-
Fraction %)
trations.
Carbon
8.4.7.2 Nitrogen—Select standards with appropriate con-
Test Repeatability Reproducibility
Reference Found
A B
Specimen Limit Limit
centrations.
Value
8.4.7.3 Oxygen and Nitrogen—NIST RM 8983, Silicon
C
Bessemer Steel 0.081 6 0.001 0.0796 0.0089 0.0066
Nitride Powder.
(NIST SRM 8j)
D
Open-Hearth Steel 0.200 6 0.001 0.2038 0.0022 0.0126 8.5 Preparation of Apparatus and Samples:
(NIST SRM 11h)
8.5.1 Follow the operating instructions for the specific
E
Open-Hearth Steel 0.407 6 0.003 0.4211 0.0055 0.0383
equipment used. After having properly set the operating
(NIST SRM 12h)
F
Silicon Nitride 0.107 6 0.015 . . .
controls of the instrument system, condition the apparatus by
(NIST RM 8983)
analysis of several blanks prepared with sample crucibles and
A
The 95 % repeatability limit is defined as 1.96* U which is the
repeatability
flux in the amount to be used with the test specimen analyses.
uncertainty of a difference of two averages, each based on 3 repeated measure-
Successive blanks should approach a constant value, allowing
ments at one laboratory. This U is also called repeatability standard
repeatability
deviation.
for normal statistical fluctuations.
B
The 95 % reproducibility limit is defined as 1.96* U which is the
reproducibility
8.5.2 The powder sample to be analyzed shall be dry and
uncertainty of a difference of two averages, each of which is based on 3 repeated
uniform with a particle size distribution of 100 mesh or finer.
measurements from two different laboratories. This U is also called
reproducibility
reproducibility standard deviation.
Ifthesampleisinbulkform,thesamplecrushingshallbedone
C
The SRM 8j Certificate reports 4 determinations which have a standard
without adding oxygen to the sample. Avoid using an Agate
deviation of 0.001.
D
The SRM 11h Certificate reports no deviation from the reference value by
more than 61 in the last significant figure.
E
The SRM 12h Certificate reports 5 determination
...