The analysis of carbon and sulfur elements in metal and non-metal materials uses high frequency infrared carbon and sulfur analyzer. During the use of the instrument by the manufacturer, the user is not too familiar with the working principle and operation of the high-frequency infrared carbon and sulfur analyzer, so that there are often situations in which the analysis results are not repeatable or reproducible. The first thing to suspect is the failure of the instrument, but often after inspection of the instrument hardware, it is concluded that the instrument is working properly. In view of this, according to the structural characteristics of the infrared carbon and sulfur analyzer and its working principle, several factors affecting the analysis results of the carbon and sulfur analyzer are
Crucible blank requirements. The crucible must be pre-treated before use, and the appropriate baking temperature and time should be controlled. Generally, it is recommended to bake in a muffle furnace at 1100 ° C for 4 hours, so as to minimize the influence of the crucible blank on the stability of the analysis results.
2.The quality and amount of flux
Another factor that affects the stability of the analysis results is the quality and amount of the flux. The flux is selected from the blank and stable, tungsten particle flux for carbon and sulfur analyzers. The influence of the amount of flux added is very prominent when analyzing low-content samples. For example, when analyzing samples with a carbon and sulfur mass fraction of less than 15μg / g, add 1.5g and 2g flux (carbon and sulfur mass fractions in the flux are ≤8μg / g and ≤5μg / g, respectively), because the amount of flux is usually added It is not involved in the calculation of the analysis results, so the fluctuation of the carbon and sulfur content in 0.5g of flux was introduced between the two analyses. It is assumed that the content of carbon and sulfur in the flux is 3 μg / g, and the sample weighs 0.5 g. Due to the addition of the flux, a deviation of 3 μg / g is introduced. Therefore, when analyzing low-content samples, try to ensure that the amount of flux added is consistent, so as to reduce the uncertainty introduced by the flux.
Different samples weigh different amounts of C and S contained in the sample, resulting in different areas where the analysis results fall on the instrument calibration curve. Due to the limitation of the linear range of the instrument, this difference in the calibration area will cause fluctuations in the analysis results, especially when the upper and lower limits of the analytical instrument are near.
For low-content samples, the results are higher when the sample is weighed larger. For high-content samples, the situation is reversed and results are lower.
In addition, the difference in sample weighing directly affects the high-frequency induction combustion. The combustion temperature and state of the carbon-sulfur meter are not only related to the power of the high-frequency furnace itself, but also to the amount of magnetically-removed material that is induced internally. The combustion temperature is not continuously constant. As the material melts and burns, the amount of induction gradually decreases. For instruments
from different manufacturers, the linear range and calibration curve characteristics are different, and the high-frequency control part is implemented differently. Therefore, the weighing of the sample affects the accuracy and reliability of the analysis results. For specific instruments. You need to be familiar with its characteristics through a large number of experiments, and choose an appropriate weighing sample to avoid the impact as much as possible.
4.Sampling order of samples and flux
The influence of the stacking order of samples and fluxes on the stability of sample analysis results cannot be ignored. During the analysis, the stacking order of samples and fluxes directly affects the combustion results and analysis stability. The co-solvent not only has the effect of increasing the magnetically conductive substance in the sample and the combustion temperature, but also has the effect of increasing the fluidity of the sample and diluting the sample. The sample was placed on the bottom layer, and the tungsten particles were placed on the upper layer. After the analysis, the quartz tube in the combustion chamber was very clean, and there was no metal melt splash on the ceramic thermal protective sleeve, and the analysis result was stable. For example, iron-based samples are directly combusted under high-frequency induction under oxygen, which is reflected violently and splashes severely after melting, easily causing damage to the quartz tube of the combustion chamber and pollution of the ceramic protective sleeve. Replaced with tungsten particles as the base, and the sample was placed on the upper layer. It was found that the quartz tube industry in the combustion chamber was quickly contaminated. A thick layer of iron melt was stuck on the ceramic protective sleeve, which was difficult to clean, which not only affected the combustion tube. The service life also hinders the supply of oxygen, which directly affects the stability of the analysis results.
There are many factors affecting the stability of the analysis results of carbon and sulfur analyzers. During the analysis process, especially when analyzing low-content samples, the influence of these factors can be comprehensively considered to make an accurate evaluation of the analysis results. Avoid affecting the analysis results and progress due to incorrect estimation of the problem, and increase the maintenance cost of the instrument.