GB/T 4698.7-2011 English PDF (GB/T4698.7-2011)

GB/T 4698.7-2011: Methods for chemical analysis of titanium sponge, titanium and titanium alloys -- Determination of oxygen and nitrogen content
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GB/T 4698.7-2011
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.120.50
H 64
Replacing GB/T 4698.7-1996, GB/T 4698.16-1996
Methods for chemical analysis of titanium sponge, titanium
and titanium alloys - Determination of oxygen and nitrogen
content
ISSUED ON: MAY 12, 2011
IMPLEMENTED ON: FEBRUARY 01, 2012
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 General ... 5 
4 Method 1 -- Inert gas melting-infrared method for determination of oxygen content
... 6 
5 Method 2 -- Inert gas fusion-infrared/thermal conductivity method to measure
oxygen and nitrogen contents ... 12 
6 Method 3 -- Distillation separation - Determination of nitrogen content by Nessler
reagent spectrophotometry ... 16 
Appendix A (Informative) Statistical data of oxygen and nitrogen contents as measured
by method 2 ... 22 
Methods for chemical analysis of titanium sponge, titanium
and titanium alloys - Determination of oxygen and nitrogen
content
1 Scope
This Part specifies the method for the determination of oxygen and nitrogen content, in
sponge titanium, titanium, titanium alloys.
This Part applies to the determination of oxygen and nitrogen content, in sponge
titanium, titanium, titanium alloys.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB/T 6682 Water for analytical laboratory use - Specification and test methods (ISO
3696, MOD)
GB/T 12806 Laboratory glassware - One-mark volumetric flasks (ISO 1042, EQV)
GB/T 12808 Laboratory glassware - One mark pipettes (ISO 648, EQV)
GB/T 12809 Laboratory glassware - Principles of design and construction of
volumetric glassware (ISO 384, EQV)
GB/T 12810 Laboratory glassware-Volumetric glassware - Methods for use and
testing of capacity (ISO 4787, IDT)
3 General
3.1 Unless otherwise stated, only confirmed analytical pure reagents are used in the
analysis; the water used is distilled water or deionized water or water of equivalent
purity, which shall comply with the provisions of GB/T 6682.
3.2 The instruments used shall be within the verification period; their performance shall
meet the technical parameters, which are required by the verification; the glass
containers shall be grade A, which is specified in GB/T 12808, GB/T 12809, GB/T
12806; the specific use method shall refer to the requirements of GB/T 12810.
4 Method 1 -- Inert gas melting-infrared method for
determination of oxygen content
4.1 Measurement range
The measurement range of oxygen content is 0.020% ~ 0.40% (mass fraction).
4.2 Principle
The sample is added with a flux (metal platinum or nickel); placed in a graphite crucible;
heated and melted in a pulsed electrode furnace under an inert atmosphere (He or Ar);
the released oxygen is combined with carbon to form carbon monoxide. Carbon
monoxide is oxidized to carbon dioxide; or part of it still exists in the form of carbon
monoxide. The mixture is loaded into the infrared detector by the inert gas.
When carbon monoxide or carbon dioxide passes through the detector, infrared
absorption occurs; the oxygen content in the sample is measured, by comparing it with
the infrared absorption curve, which is established by the titanium standard sample.
4.3 Reagents
4.3.1 Anhydrous magnesium perchlorate
It is used in instruments to absorb moisture. Use the purity, which is required by the
instrument manual.
4.3.2 Clay sodium hydroxide
It is used in some instruments, to absorb carbon dioxide. Use the purity, which is
required in the instrument manual.
4.3.3 Copper oxide
It is used in some instruments, to oxidize carbon monoxide to carbon dioxide. Use the
purity, which is specified in the instrument manual.
4.3.4 Helium or argon
Use the purity and type, which are specified in the instrument manual.
4.3.5 Nickel pickling solution
75 mL of glacial acetic acid + 25 mL of nitric acid + 2 mL of hydrochloric acid.
4.5.1 Sample preparation
The preparation procedures of sponge titanium, titanium, titanium alloys shall be
consistent with the relevant standard methods, that have been issued.
4.5.2 Preparation of specimens
4.5.2.1 The best specimen shall be a cylindrical specimen (about 5 mm in diameter,
about 0.06 g ~ 0.14 g in weight), OR a block specimen (about 3 mm in edge length,
about 0.06 g ~ 0.14 g in weight).
4.5.2.2 A mechanical device shall be used, to cut the processed specimen from the
experimental sample; no lubricating fluid shall be used; overheating of the specimen
shall be avoided.
4.5.2.3 Clean the surface of the specimen, according to a), b) or c):
a) Put the specimen into the filter device. Immerse it in the titanic pickling solution
(4.3.6.1), at about 20 °C, until the surface is clean. The time is about 50 s.
Immediately use tweezers to take out the specimen. Use water to wash it twice.
Then use ethanol and acetone to wash it once. Dry it. Store it in a desiccator for
later use. At this time, the weight of the specimen is about 0.05 g ~ 0.13 g.
b) Use a filter device, to immerse the specimen in the titanic pickling solution
(4.3.6.2). Continue for 5 s from the violent reaction between the specimen and
the acid solution. Immediately use tweezers to take out the specimen. Use water
to wash it twice. Use ethanol to wash it once. Use acetone to wash it once. Dry it
naturally. Store in a desiccator for later use. At this time, the weight of the
specimen is about 0.05 g ~ 0.13 g.
c) File or cut off the outer surface of the specimen, to keep the surface fresh. Use
acetone to wash it once. Dry it naturally. At this time, the weight of the specimen
is about 0.05 g ~ 0.13 g.
4.5.2.4 Weigh the specimen, accurate to 0.1 mg.
4.6 Analytical procedures
4.6.1 Number of tests
As far as possible, measure at least two sets of specimens, under identical conditions.
4.6.2 Instrument Preparation
Install the equipment, according to the requirements of the manual. Check and connect
the water and electricity.
Place the graphite crucible (4.4.2) on the support of the furnace. Heat it to a temperature
above the sample degassing temperature, for degassing.
Continue heating, until the specimen is completely melted AND oxygen extraction is
complete. Record the detector's readout signal. Repeat this process, until the detector
reading stabilizes.
Check whether the glass wool filter (4.4.3) is clean. Replace it, if necessary.
If the power is turned off for a long time, the device shall be preheated and stabilized,
according to the requirements of the manual, before using it again.
After replacing the filter (4.4.3) or reagent (4.3.1, 4.3.2, 4.3.3), repeated tests are
required to make the equipment reach a stable state. The test results of this process are
discarded. Before the formal analysis of the sample, prepare for the blank, calibration,
test process, according to the procedures of 4.6.3, 4.6.4, 4.6.5.
Note: The temperature, which is suitable for specimen melting and crucible degassing, is
determined by the instruments of each manufacturer.
When the equipment has the function of computer system control, the establishment of
the working curve, the calibration (drift correction, normalization, recalibration), the
measurement of oxygen content, shall be carried out in accordance with the
requirements of the computer software operating instructions.
4.6.3 Blank detection
Before testing, the following blank test shall be repeated several times:
No sample is added to the crucible, only nickel or platinum for analytical fluxing (the
same flux of the same mass shall be used during sample analysis), to carry out the
analysis, according to the procedure of 4.6.5. Get the reading of the blank test.
Compared with the content in the specimen, the average value of the blank test shall be
sufficiently low. If the blank value is abnormally high, find and eliminate the
contributing factor. If the blank value is normal, enter the blank value, that shall be
deducted, in the relevant setting column of the instrument.
4.6.4 Calibration
Before testing, perform the following calibration procedure:
Use the titanium reference material/sample (4.3.10) as the test sample, to perform the
procedure of 4.6.5.
Subtract the blank value in 4.6.3 from the analyzed readout signal.
Repeat the above process several times.
5.3.7 Pure copper wire.
5.3.8 High-pure soda asbestos.
5.3.9 Nickel basket pickling solution: The ratio is: 75 mL of glacial acetic acid (C2O2H4)
+ 25 mL of nitric acid (HNO3) + 2 mL of hydrochloric acid (HCl).
5.3.10 Titanium specimen pickling solution: The ratio is: 3 parts of 30% H2O2 + 1 part
of 48% HF. The HNO3 can replace 30% H2O2.
5.3.11 Titanium standard material/sample.
5.3.12 Nickel flux
Generally, a nickel basket, which is made of high-purity nickel wire, is used. The
surface contamination needs to be removed, before the nickel basket is used. Immerse
the nickel basket in the nickel pickling solution (5.3.9), for 50 s ~ 60 s. After taking it
out, rinse it under running water for 2 min ~ 3 min. Then pour it into a tower-shaped
paper tube, to absorb excess water. Then put it into a ground glass bottle. Use the
acetone (5.3.1) to clean it. Soak the nickel basket in a new acetone solution. Take it out
to dry it naturally, before use.
5.4 Instrumentation
5.4.1 Analytical balance: Accurate to 0.1 mg.
5.4.2 Inert gas fusion, thermal conductivity/infrared oxygen and nitrogen analyzer. (It
includes an electrode furnace, carrier gas purification and analytical gas flow
conversion system, oxygen infrared detector, nitrogen thermal conductivity detector,
computer and software control system.)
5.5 Specimen
5.5.1 The best specimen shall be a cylindrical specimen, which has a diameter of about
5 mm, OR a block specimen of the same volume, which has a mass of about 0.06 g ~
0.15 g.
5.5.2 Immerse the specimen in the titanium specimen pickling solution (5.3.10), to
clean it. It usually takes about 5 s, after the sample and solution start to react.
Immediately use tweezers to take out the specimen in the reaction. Use water and
acetone to clean it, respectively. Then let it dry naturally. The mass of the specimen, at
this time, shall be about 0.100 g ~ 0.140 g.
5.5.3 Another method is to file or cut off all exposed parts of the outer surface of the
specimen. Keep the new surface. Finally use acetone to clean it. Dry it naturally. At this
time, the mass of the specimen is about 0.050 g ~ 0.140 g.
5.5.4 The treated specimen shall not have any other contamination, before subsequent
analysis and testing. Picking shall be done by the use of clean tweezers.
5.6 Analytical procedures
5.6.1 Instrument preparation
Check the connection of all components, according to the requirements of the
instrument manual. Ensure that the power supply, carrier gas, water supply are well
connected. Replace the chemical reagent tubes and filter device, according to the
instructions of the instrument.
5.6.2 Instrument warm-up
The instrument shall be fully warmed up, before analysis, so that the indicators of the
instrument reach the set value.
5.6.3 Instrument leak detection
Use instrument leak detection procedures or other auxiliary equipment, to confirm that
the instrument is free of air leaks.
5.6.4 Blank detection
Add the nickel basket (5.3.12) to the crucible. Carry out the operation of 5.6.6, without
adding the sample. Carry out at least 3 blank value determinations. The mass of the
nickel basket flux used meets the requirements of the instrument specification
(generally the mass ratio of nickel basket to sample is greater than 7:1). Replace a new
crucible each time. The blank value, which is displayed by the instrument, shall be
stable; meanwhile three consecutive blank values shall not exceed: oxygen
0.0005%/nitrogen 0.00007%. Take the average value of the respective blanks. Deduct
the blanks for oxygen and nitrogen, according to the blank compensation procedure.
5.6.5 Calibration procedure (any calibration procedure can be used)
5.6.5.1 Single standard point calibration procedure
5.6.5.1.1 Select a titanium reference material/sample (5.3.11), whose oxygen/nitrogen
content is higher than or close to that of the unknown sample, AND does not exceed the
detection range of this method.
5.6.5.1.2 Perform the single standard point calibration procedure, according to the
requirements of the instrument manual. Analyze the reference material/sample, at least
3 times. Take the average value, to determine the calibration slopes for oxygen and
nitrogen, respectively.
5.6.5.1.3 Use this reference material/sample as a specimen, for analysis, to verify
calibration. The results of oxygen and nitrogen are all within the uncertainty range of
the standard value of the titanium reference material/sample. Carry out the procedure
nitrogen content by Nessler reagent spectrophotometry
6.1 Measurement range
The measurement range of nitrogen content is 0.008% ~ 0.10% (mass fraction).
6.2 Principle
The sample is dissolved in hydrofluoric acid. The nitrogen is distilled and separated in
the form of ammonia, in a strong alkaline medium, to form a colored complex with
Nessler reagent. The absorbance is measured, at a wavelength of 420 nm, by a
spectrophotometer.
6.3 Reagents
6.3.1 Hydrofluoric acid (ρ = 1.15 g/mL): Excellent pure.
6.3.2 Hydrogen peroxide (ρ = 1.10 g/mL): Excellent pure.
6.3.3 Boric acid saturated solution: Excellent pure.
6.3.4 Sulfuric acid c(H2SO4) = 0.01 mol/L.
6.3.5 Sodium hydroxide solution (500 g/L): Weigh 500 g of sodium hydroxide
(excellent pure). Place it in a 1000 mL flask. Add 800 mL of wat...