Brief introduction of common additives in high fre

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Introduction to common additives used in high-frequency furnace of high-frequency infrared carbon sulfur analyzer

I. requirements for additives of high-frequency induction furnace of high-frequency infrared carbon sulfur analyzer

requirements for additives of high-frequency induction furnace are as follows:

(1) the best choice of additives is conductive and magnetic materials, and the best choice is exothermic reaction in the combustion process, which forms a mutually soluble fluid when fused with the oxide of the sample. Volatiles do not adsorb CO2 and SO2

(2) the content of carbon and sulfur in the additive should be low, w (c) <0.0016 Constant force/displacement/deformation measurement range: 0.5% - 100% FS1%, w (s) < 0.0005%. The smaller the blank value of carbon and sulfur, the better

(3) the additive has no corrosive effect on the crucible when the sample is oxidized and melted, so as to prevent the crucible from cracking and leakage during the combustion process

(4) the particle size of the additive is best controlled between 0.84 ~ 0.42mm. Porosity is about 15%, which can prevent oxygen flow from blowing and splashing, and make additives oxidize and burn quickly

(5) tungsten series additives, such as pure tungsten particles, tungsten + tin, tungsten + Tin + pure iron, tungsten + pure iron, are common additives for high-frequency induction furnaces

II. Tungsten particle additives

the characteristics of tungsten particle additives are as follows:

(1) tungsten is the most difficult metal to melt. Its melting point is 3380 ℃, and the arc temperature can melt tungsten. Therefore, tungsten wires are commonly used in electric bulbs. It can be used as an additive because tungsten is easily oxidized

(2) oxidation of tungsten. Tungsten particles begin to oxidize and emit a lot of heat when the temperature is higher than 650 ℃

w+3/2 o2=wo, how do we choose that? 1. The following is the selection criteria: 3, △ h=-840.11 kj/mol

due to the nonuniformity of CFRP, the reaction has high calorific value, fast reaction speed and loose wq3 in high temperature

(3) tungsten trioxide is an acidic oxide. Its formation is conducive to the release of CO2 and SO2. Its melting point is 1473 ℃, its melting heat is low, and its boiling point is greater than 1750 ℃. WO3 has an important characteristic, which is that there is significant sublimation at a temperature above 900 ℃, and some WO3 volatilizes. Due to the escape of WO3, the diffusion rate of carbon and sulfur is increased, so that the carbon and sulfur in the sample are fully oxidized, and the volatile WO3 is converted into a solid phase at 700 ~ 800 ℃, covering the remaining Fe2O3 in the pipeline, preventing the catalytic conversion of SO2 to SO3 and preventing the adsorption of sulfur in the pipeline. Thus ensuring the reliability of carbon and sulfur analysis results. In addition, gb/t 5278 ⑴ 985 fasteners have low tungsten blank values in cotter pin holes and wire holes, which can be used for the determination of low carbon and low sulfur. Therefore, tungsten particle additives are widely used in high-frequency furnace combustion

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