dyz
第5楼2010/09/25
我们这里的4460全都带N通道,不过都是远紫外波长的,Fe基中低合金钢标样,>20ppm的数据完全可信,5-20ppm的数据对操作、氩气纯度和仪器维护要求很严格,一般座位参考。
转一下操作要求:
===========
D.1 Microalloyed Steels - CNOPS
Note: CNOPS is the abbreviation of Carbon – Nitrogen – Oxygen – Phosphorus – Sulphur.
D.1.1 General Consideration
The analyses of microalloyed steels (CNOPS) require the special VUV option hardware. Therefore you must
also consult the manual dedicated to this option (VUV Line Analysis) for the handling and maintenance of the
VUV hardware.
D.1.2 Working Constraints
The analyses of microalloyed steels (CNOPS) need the use of absolutely clean stainless steel argon pipes,
with irreproachable sealing of all connections and fittings.
For the analysis of oxygen, milling is mandatory because polishing and grinding are contaminating the sam-
ple surface by adding a supplementary oxide layer. For carbon and nitrogen, the results are usually satisfac-
tory with grinding, but are nevertheless better by milling. Milling is necessary for the analysis of ultra low
carbon concentration (ULC). The pure samples used for calibration and standardisation must also be milled.
The surface quality is important too, the sample must be perfectly flat and the abrasive paper used in case of
polishing must be is a good state.
The analysis of the oxygen imposes the hard metal disk to be glued on the analytical table. This constraint
makes the daily maintenance more difficult, because the table must be removed for the cleaning of the
sparking chamber.
The analysis of the carbon, nitrogen and oxygen at very low concentrations is very sensitive to the accumu-
lation of dust in the sparking chamber, in argon exhaust pipes and to the clogging of the entrance of the out-
put argon filter. The reproducibility of these elements becomes sensibly degraded if the routine maintenance
is not done very regularly.
Moreover for the oxygen, the analysis spots must not crossover: black halos around the sparking area must in
no way be superposed. After the run of a badly positioned sample (sample not flat or analysis hole not com-
pletely recovered), iron oxide powder is blown on part or the entire sample surface. This powder affects the
oxygen results: the sample needs to be surfaced again.
The content of impurities depends on the sparking positioning between the centre of the sample (inhomoge-
neous by definition) and the periphery sensitive to micro-leaks. The best position for the sample corresponds
to a sparking zone so that the exterior of the black halos are situated at around 3-4 mm from the sample edge.
D.1.3 Particular Procedures
For the cleaning procedures of the components of the stand, the ordinary procedures (see Routine
Maintenance chapter) can be followed. However they must be applied f more often or the reasons explained
in the previous section Working Constraints.
D.1.3.1 Before Every Run
♦ Electrode, top of the table and hard metal disk
Clean the electrode with the small steel brush (yellow) before every analysis. Then clean the table surface
and the disk with a tissue paper in order to remove all the dust as well as fingertips.
If the time interval between two analyses is long (5 minutes or more), the oxygen value is higher on the first
run because of the stand contamination during the idle time. This first run must be eliminated from the
average.
D.1.3.2 Partial Maintenance
♦ Hard metal disk, insulator, sparking chamber
Once a day is a strict minimum. In case of shift work, it must be done at each shift change at least, or every
400 runs.
If the disk is not glued, you can also remove it quickly and aspirate the dust accumulated into the insulator. If
the disk is glued, the table must absolutely be removed in order to aspirate the dust inside the sparking
chamber. Remove the table with care, so as not breaking the insulator.
♦ Argon exhaust, pipes, filter entrance
At the same time you clean the chamber, the exhaust argon pipe must also be cleaned and the end at the oil
filter entrance side cleaned out. To do that, the pipe must be released from the filter entrance. Use a cotton
pad or a pipe cleaner for cleaning into the elbow fitting. Then aspirate wit a vacuum cleaner at the pipe end
and inside the elbow fitting. Put back the pipe into the fitting.
After a partial maintenance, 15 runs are necessary to decontaminate the stand from the oxygen
lead in during the handlings.
D.1.3.3 Full Maintenance
♦ Inside, table, supporting block, cylinder
Once a week is a strict minimum. In case of high sample throughput or if a large amount of dust is generated
the rate must be increased. If the instrument operates 24 hours a day, this maintenance may become daily.
The analytical program must be completely standardised after every full maintenance because of P and S
elements.
After a full maintenance, 50 runs are necessary to decontaminate the stand from the oxygen lead
in during the handlings.
A 5 l/min flush during 1 to 2 hours before starting analyses helps to recover quicker the
performances on oxygen.
D.1.3.4 Argon Output Filter
The ordinary maintenance of the VUV output filtering device must be done at least once a week.
D.1.3.5 Lens Cleaning
Consult the VUV Line Analysis manual for the handling and maintenance of the lens.
For CNOPS lines, the lens contamination is not significant as long as the instrument is standardised every
eight hours.
The problem of the lens appears only after the maintenance of the lens, the highest drift is observed just after
that maintenance.
D.1.3.6 Standardisation
For all the reasons developed in this chapter a daily standardisation is at least required. In case of shift
working, a standardisation at the beginning of each shift change should be done. However the other required
maintenance operations must be executed before the standardisation.
D.1.3.7 Calibration
If you intend to calibrate yourself new microalloyed programs, it is essential to proceed first to a full mainte-
nance including cleaning of the inside of the stand, the pipes, the output filter and the lens.
After that maintenance, run analyses during at least one hour before starting the calibration.
D.1.3.8 Other Subjects
For all the other maintenance subjects not explicitly described in this appendix, refer to the Routine
Maintenance chapter and its Summary Table section.