SU914022A1 - Sun plant for preparing liqid fodder - Google Patents

Description

914169 with gas evolution, Corundum-based materials {9399,

5% ΑΙ1Ο3) or based on rutile (T10 ₇ ) 5

The gas-generating materials used in this method must withstand the calcination temperature of the form Т _{pr <? (<} = '= 700-900 ° С without significant decomposition or dissociation. 10

The degree of dissociation of such materials at the calcination temperature of the mold should be 10-100 times less than when interacting with high-temperature liquid alloys (T _SPA = 1b73 ~ 15

1973 ° C)

Such materials may be substances of the type Ca ₃ (A10 ^) ^ - tricalcium aluminate, Co ^ О ^ - cobalt oxide, MDSC - magnesium sulfate, 20

RVOC - lead sulfate.

For these substances, the type of decomposition reaction is monomolecular (type AVFA + B), the rate constant of such a reaction is determined by the dependence 25 'i-Л ¢ - а ^к - ν ^{КГ1 а-} х' where V is the reaction time; a is the initial amount of substance, x is the amount of substance decomposed during this time.

Thus, for example, by the decomposition of one half under calcination (average for 5 hours) and other polovi- ₃₅ us in contact with the liquid metal (average during 0.05 h) the decomposition rate constants, respectively:

! <

PR ^to zag

0.693

0.693

0.05 = 0.14 g = 14 g ¹

In the case of other ratios of the amount of decomposed material, 45 mo is necessary so that the difference between K _pp and K changes upward.

The dissociation pressure range is chosen in such a way that sufficient pressure is generated in the profit for supplying 50 castings.

So, during the decomposition of С03О4, the pressure developing at 1073 K and at 1243 ° K is 1333 and 102 -1 0 ^b Pa, respectively.

The method for producing ceramic molds using investment casting has been experimentally tested in the manufacture of castings made of 10x18 * 9 T steel.

Wax models with a profitable part are made from PS 50-50 and assembled in blocks in the usual way.

Before applying the ceramic shell to the elements of the models that form. the profitable feeding part of the casting, corundum is installed either from rutile-based material caps with gas-generating material 4 previously applied to the cap walls.

Cobalt oxide, magnesium sulfate or lead, as well as tricalcium aluminate in powder form, which is mixed with liquid glass prior to application to the inner surface of the cap and used to fix the composition on the walls of the caps, are used as the gas-creating material. Then, the processes are carried out: applying a refractory ceramic shell (5 layers) by dipping a suspension of ethyl silicate with an electrocorundum filler and sprinkling with electrocorundum, drying the shell and melting the model mass followed by annealing the mold at T = 1073 ~ 1O23 ° K for 5 hours and pouring metal at T = 1823-1853 ° K · Caps with gas-containing material remain molded inside the ceramic mold 1.

When the mold is poured at the moment of contact of the liquid metal with the gas-generating material (or after heating to the decomposition temperature, if the gas-generating material is covered with a protective layer), its decomposition or dissociation begins with the formation of gases, the pressure of which is completely transferred to the liquid metal due to the gas tightness, which ensures efficient casting nutrition during hardening.

This method can also be used in the manufacture of ceramic molds with closed gas profits, which undergo preliminary calcination before casting metal (casting on burnable models, Show process).

A comparative analysis of the castings obtained in the molds according to the invention and the known 14] show that the castings have a lower mass profit by an average of 8-12%, which is associated

914169 8 with improved nutrition. ’In castings, shrinkage defects were sharply reduced by 55-65%.

The implementation of the invention allows, by creating conditions for efficient 5th power supply of castings during solidification, to increase the usable yield up to 4550% and reduce casting defect to 8 -0%.

The method has the greatest advantages in the manufacture of castings in vacuum <40 vacuum plants, where it is impossible to provide the required conditions for metal feed from profits.

The expected economic effect per 1 ton of suitable casting is 5, 5,875 rubles.

Claims (3)

Claim 1. A method of manufacturing a casting mold obtained by investment casting, including layer-by-layer ceramic coating on the investment casting block and the casting system, removal of the investment casting, subsequent calcination and placement in the profits of the gating system of the gaseous material, characterized in that In order to improve the casting quality, on the profit model of the gating system before applying the ceramic coating, caps from a gas-tight material having a temperature coefficient of linear identical expansion with a ceramic coating, and gas-bearing material is applied to the inner surface of the cap and has a decomposition reaction rate and dissociation pressure during calcination of the mold 10-100 times less than when it interacts with a liquid metal. 2. The method of pop. ^ characterized in that as a gas-tight material use material based on corundum or rutile. 3. The method of pop. 1, characterized in that as the gaseous material using tricalcium aluminate or cobalt oxide, or magnesium sulfate, or lead sulfate.