High-frequency infrared carbon and sulfur analyzer analysis of the introduction of perchloric acid - Database & Sql Blog Articles

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High frequency infrared carbon sulfur analyzer

High-frequency infrared carbon and sulfur analyzer is an important instrument for analyzing the content of carbon and sulfur in steel. Some phase analysis of carbides, such as

SiC

The need to take sulfuric acid smoke to remove free carbon and then measure the silicon carbide content. Frequently encountered smoke, smoke has not been defined, in fact, refers to the addition of acid solution to produce some kind of acid gas. The smoke seen generally does not refer to pure acid vapor, but rather to fine mist droplets formed by acid vapor and water vapor.

HCl

with

H ₂ O

Azeotrope compound, under normal pressure

11

0

°C

Boiling, ie

110

°C

Hydrochloric acid.

HNO ₃

with

H ₂ O

Azeotrope compound, under normal pressure

122

°C

Boiling, ie

122

°C

Nitrogen fumes. sometimes

HNO ₃

The smoke is yellow because

HNO ₃

Decomposition generation

NO ₂

.

HCl

with

HNO ₃

The smoke temperature is low, easy to grasp, and it is not easy to have problems. In the dissolution process of insoluble samples, it is mainly

HClO ₄

smoke,

H ₂ SO ₄

Smoke and

H ₃ PO ₄

Smoke, these three kinds of cigarettes are all white, and the temperature of smoking is higher, it is more difficult to master. The following describes the introduction of perchloric acid.

High frequency infrared carbon and sulfur analyzer heating thin

HClO ₄

When the solution is evaporated, water is first evaporated, then dilute acid, and then

476K

The azeotrope of water and perchloric acid can be evaporated. Contain

72%

of

HClO ₄

When the azeotrope is evaporated, it is accompanied by

HClO ₄

Decomposition, the reaction formula is:

Commercially available

HClO ₄

Quality score is

70%-72%

. But taking a risk

HClO ₄

When smoking,

HClO ₄

The content is generally lower than

72%

, the water that evaporates at the beginning, after the inclusion

72% HClO ₄

Azeotrope compound. In the pre-furnace analysis of alloy steel, the commonly observed perchloric acid smoke is

413K

Seeing the smoke in the triangle bottle on the left and right sides, as the temperature gradually rises, the white smoke gradually fills the bottle and then reaches

476K

, the temperature is the same, that is, a constant boiling compound. At this time, the feature is that the bottle is smokeless, and only the bottle mouth smokes. In general, the procedure mentions that the introduction of perchloric acid smoke is

476K

I only see smoke at the mouth of the bottle as the standard, not the liquid smoke at the beginning or the white smoke in the bottle, not the water vapor at the beginning.

In the pre-furnace analysis, when measuring high chromium steel by perchloric acid oxidation, use dissolved acid (

H ₂ O: HCl: HClO ₄ = 4: 1: 20)

After low temperature dissolution, continue to heat to see the following phenomenon: start the liquid surface smoke, then the bottle is filled with white smoke, then only see the bottle mouth smoke, the temperature is

476K

. Temperature remains the same, maintain

30-40s

The sulfuric acid is further added to adjust the acidity, and titrated with ammonium ferrous sulfate in the presence of a chromium indicator. In some chemical analysis procedures, the precautions for this method indicate that the smoke is in

573-673K

,this is not right. because

HClO ₄

in

203

°C

When the compound is azeotrope, the temperature does not change. According to the principles of physical chemistry,

HClO ₄

with

H ₂ O

On the two-phase equilibrium diagram,

476K

For the final evaporation temperature, this time contains

72% HClO ₄

The content does not change and the temperature does not change. The actual measurement results are the same until the perchloric acid is completely exhausted.

Pre-furnace analysis thiocyanate

-

When ascorbic acid colorimetric method is used to determine molybdenum in low, medium and high alloy steels, the sample is dissolved in perchloric acid.

HClO ₄

When smoking, add color ascorbic acid and ammonium thiocyanate. Take a place here

HClO ₄

Smoke, also refers to

HClO ₄

The smoke has risen to the mouth of the bottle, only to see the smoke at the mouth of the bottle. At this time, the temperature is also

476K

. Ammonium persulfate

-

When Ding Erqi colorimetric determination of nickel, use

HCl

with

H ₂ O

Dissolve, add

HClO ₄

Evaporation of smoke, the addition of potassium tartrate complex interference ions, in the presence of ammonium persulfate, in the alkaline solution of nickel and butyl hydrazine to produce a wine red solution colorimetric determination. here

HClO ₄

The requirements and temperature for evaporating smoke are also the above criteria. Only the mouth of the bottle emits smoke, and the temperature is

476K

.

High-frequency infrared carbon and sulfur analyzers are widely used and are of great significance for improving the quality of steel products.