Comparison of principles and methods of the most h

Comparison of principles and methods of "ningsifen" carbon sulfur analyzer

carbon and sulfur are important elements to determine the specification and quality of steel products. Those with carbon content higher than 1.70% are called cast iron, and those with carbon content lower than 1.70% are called steel. Generally, steel with carbon content higher than 0.60% is called high carbon steel, steel with carbon content between 0.25% and 0.60% is called medium carbon steel, steel with carbon content less than 0.25% is called low carbon steel, and steel with carbon content less than 0.04% is called industrial pure iron

carbon plays an important role in the properties of steel: with the increase of carbon content, the hardness and strength of steel increase, and its toughness and plasticity decrease; On the contrary, if the carbon content decreases, the hardness and strength decrease, while the toughness and plasticity increase. Carbon sulfur analyzer is a commonly used measuring instrument in the physical and chemical analysis room of enterprises. Jis1 sample also describes the relevant experimental methods and other content instruments. It is used for quantitative analysis of the content of carbon and sulfur in metallic and non-metallic materials. It is widely used in metallurgy, which will not only affect the company's sales gold, casting, machinery, vehicles, pumps and valves, ores, environmental protection, quality inspection and other industries and fields, but also facilitate the acceptance of raw materials Analyze and test at the stages of pre furnace analysis and finished product inspection, and then loosen the nut

the presence of sulfur in iron and steel will deteriorate the quality of iron and steel, reduce its mechanical properties and corrosion resistance. It can be welded by the pressure testing machine directly controlled by computer. In particular, if the sulfur in steel exists in the state of iron sulfide, due to its low melting point (about 1000 ℃), it will cause the "hot brittleness" phenomenon of steel, that is, thermal deformation, cracks will occur when working at high temperature, affecting the quality and service life of products. Therefore, the lower the sulfur content in steel, the better. Generally, the sulfur content in ordinary steel is less than 0.050%, that in tool steel is less than 0.045%, and that in high-quality steel is less than 0.020%

in view of the important role of carbon and sulfur content in steel quality and performance, it is of great significance to detect the carbon and sulfur content in steel, that is, carbon and sulfur analysis

carbon and sulfur in steel are burned by oxygen at high temperature (1200 ℃ ~ 1400 ℃). Both can be converted into gas to generate CO2 and SO2, which is the basis of carbon and sulfur analysis by combustion method

the principle of carbon and sulfur analysis is to burn the sample with oxygen in a high-temperature furnace (such as resistance furnace, also known as tubular furnace, electric arc furnace, high-frequency induction combustion furnace, etc.), generate and escape CO2 and SO2 gas, use this method to realize the separation of carbon and sulfur elements from metal elements and their compounds, then measure the content of CO2 and SO2, and then calculate the content of carbon and sulfur in the sample. The general determination methods are as follows:

1 Infrared photometry: the carbon and sulfur in the sample are oxidized to carbon dioxide and sulfur dioxide after high temperature heating under oxygen enriched conditions. After treatment, the gas enters the corresponding absorption pool to absorb the corresponding infrared radiation, which is transmitted by the detector as a signal, and the computer processes and outputs the results. This method has the characteristics of accuracy, speed and high sensitivity. Both high and low carbon and sulfur contents are used. The infrared carbon and sulfur analyzer using this method has a high degree of automation and high price. It is suitable for occasions requiring high analysis accuracy

2. Volumetric method: commonly used methods include gas volumetric method and non-aqueous titration for measuring carbon, iodometry and acid-base titration for measuring sulfur. In particular, the gas volumetric method for measuring carbon and iodine is fast and accurate. It is the most commonly used method for the joint determination of carbon and sulfur in China. The accuracy of the carbon sulfur analyzer using this method, with the lower limit of carbon content of 0.050% and the lower limit of sulfur content of 0.005%, can meet the needs of most occasions

3. Gravimetric method: commonly used alkali asbestos absorbs carbon dioxide, and the carbon content is calculated from the "increment". Sulfur is usually measured by wet method. The sample is decomposed and oxidized by acid and converted into sulfate. Then barium chloride is added to hydrochloric acid medium to generate barium sulfate. After precipitation, filtration, washing, burning, weighing, the sulfur content is finally calculated. The disadvantage of gravimetric method is that the analysis speed is slow, so it can not be used for on-site carbon and sulfur analysis of enterprises. The advantage is that it has high accuracy. It is still recommended as a standard method at home and abroad, and is suitable for standard laboratories and research institutions

4. Conductivity method: the conductivity method is used to determine carbon and sulfur, which is characterized by accuracy, rapidity and sensitivity. It is mostly used for the determination of low carbon and low sulfur

5. There are also ICP method, direct reading spectrometry, X-ray fluorescence method, mass spectrometry, chromatography, activation analysis method, etc. to determine the content of carbon and sulfur in metals, which have their own advantages and scope of application

at present, carbon and sulfur analyzers are widely used in China, mainly including the following categories:

infrared carbon and sulfur analyzer, high-speed carbon and sulfur analyzer, and non-aqueous carbon and sulfur analyzer. Nanjing No.4 Analytical Instrument Co., Ltd. produces the above types of carbon and sulfur analyzers. Users can choose according to their own needs and the advantages and disadvantages of various carbon and sulfur analyzers. (end)