SU490830A1 - Protective coating for cast iron treatment - Google Patents

Description

one

The invention relates to the field of ferrous metallurgy and foundry production and can be used to introduce metallic magnesium into cast iron in order to produce high-strength nodular cast iron.

Various formulations of protective coatings of low-boiling additives for the treatment of cast iron on the basis of refractory material are known.

The disadvantages of the known compositions of protective coatings are, firstly, low mechanical strength and a tendency to cracking when they are immersed in liquid iron and the evaporation of the additive, secondly, the excessive duration of the process of iron processing due to the low thermal conductivity of black iron and, as a result, cooling down processed melt.

The aim of the invention is to provide increased mechanical strength and thermal conductivity and a protective coating during the entire process of introducing low-boiling risk into liquid iron.

For this purpose, iron shavings and an alkali metal salt, whose sublimation or decomposition temperature is not more than 1000 ° C, are additionally introduced into the composition of the proposed protective coating. The content of the protective coating components in weight is given below. %:

2

Iron cast L glass

(beats weight 1.48 g / cm Potassium Chamotte

Cast iron chips increase the thermal conductivity of the protective coating and its mechanical strength. Potassium chloride, when heated, provides an increase in the porosity of the coating, which allows the low boiling vapors to pass freely through the wall of the coating without destroying it.

A low boil briquette with a protective coating is prepared as follows.

Chamotte (size 0.5-4 mm), iron shavings and potassium chloride are simultaneously loaded into the mixer, which are mixed to obtain a homogeneous dry mass. Liquid glass is then applied and mixing continues until it is evenly distributed throughout the entire mixture. The finished mixture of protective composition is fed to the molding. The dimensions of the briquette form are determined by the amount of insertion at a protective coating thickness of 10-30 mm. A sample of low-boiling additive is molded in the middle of the briquette. Ready briquette passes

short-term drying at a temperature of 100-150 ° C and, gaining strength sufficient for transportation, enters the processing area of liquid iron. The briquette is forced to sink to the bottom of the ladle with liquid iron. The protective coating is not destroyed and, through the pores present, passes gradually forming, and a pair of the injected additive.

The protective coating was tested on the example of introducing metallic magnesium into cast iron. Stable results were obtained on the absorption of magnesium by cast iron at an absorption coefficient of 767 °.

Subject invention

The hard coating of an additive for the treatment of cast iron, containing chamotte and water glass, is characterized in that, in order to increase the mechanical strength of the coating and shorten the duration of its heating, cast iron chips and potassium chloride are introduced into it, with the following ratio of components, in weight. %;

Cast iron chips

10-20 Liquid glass

(spd. weight 1.48 g / cm)

Potassium chloride 3 5 Shamot Else