SU764827A1 - Suspension for making moulds by lost-pattern technique - Google Patents

Description

one

The invention relates to foundry production, namely, suspensions for the manufacture of molds for produced models, with

In the manufacture of molds on produced models, the oxygen content of the air and the composition of the suspension affect the amount of the decarbonized layer. At the time of pouring the metal and during the solidification process-Q, in order to reduce the decarbonized layer in the working cavity of the mold, either a neutral 1 or a reducing atmosphere and supply is created; H corresponding gas from special devices.

A protective atmosphere in the form can be created by introducing special technological additives into the suspension.

Closest to the proposed 20 tagging solution is suspensil for the manufacture of molds on melted models, including a hydrolyzed solution of ethyl silicate, powdered quartz, and a technological additive that reduces the depth of a decarburized layer of castings

As a technological additive, the known suspension contains charcoal, which, when poured and 0

the cooling of the castings decomposes to produce flue gases. With the introduction of up to 10 wt.% Of charcoal into the suspension, the size of the decarbonized layer decreases from 0.78 to 0.64 mm. Increasing the coal content in the slurry reduces the surface cleanliness of the castings.

The purpose of the invention is to increase the effectiveness of reducing the decarburized layer.

This goal is achieved by the fact that the suspension according to the described invention contains sodium nitrate as a technological additive in the following ratio of ingredients, weight. %:

Hydrolyzed Ethyl Silicate Solution 20-35

Sodium nitrate 0.3-0.5 Pvc quartz Else The essence of the invention is that sodium nitrate, decomposed in the casting process, creates a protective atmosphere around the surface of the castings, a sphere consisting of nitrogen. Due to the even distribution of the nitrogen-containing salt throughout the ceramic shell, a protective atmosphere is formed

evenly over the entire surface of the casting.

To prepare the suspension, the refractory filler — Velikodvorsky Dust Quartz PC-3 — is poured into the mixer of the design of the NIITAVTOPROM with the ready binder — an hydrolyzed solution of ethyl silicate — and stirred for 60 minutes at a speed of 1400 min. Suspension contains, wt%: about 30%, filler 70.

Additionally, ten suspension formulations were prepared, differing dichc from each other with nitrogen; sodium sulfate, equal in each composition in series, by weight,%: 0.1; 0.2; 0.3; 0.4j 0.5; 0.6; 0.7; 0.8; 0.9; 1.0 For cooking

of these compounds in a mixer with a suspension containing 30% by weight of a hydrolyzed solution of ethyl silicate and 70% by weight of quartz PC-3 is added sodium nitrate and stirred for 5 minutes

From the obtained suspensions, molds are made on melted models. After the g & a separate composition is melted, the molds are calcined in flasks with quartz sand with sand as a reference filler at 900 ° C for 10 hours. After calcining the mold, 55 L and 40XL steel are cast into the mold at a melt temperature of 15 ° -1590 C.

The table shows the effect of sodium nitrate content in suspension on the thickness of the surface decarbonized layer of castings and the strength of the shells during bending.

Claims (1)

It can be seen from the table that the addition of sodium nitrate to the slurry to obtain ceramic shells reduces the thickness of the surface non-carbon layer of the castings. Optimal soda, the sprinkling of sodium nitrate in suspension makes up 0.3-0.5 wt.%, The thickness of the surface decarburized is printed, the layer of castings is small, and the strength of ceramic shells meets the requirements of production. Addition of sodium nitrate does not affect the survivability of the suspension. The introduction of sodium nitrate into the suspension does not impair the cleanliness of the surface of the castings. Due to the introduction of sodium nitrate into the composition of the refractory slurry in an amount of 0.3-0.5 wt.%, The thickness of the surface decarbonized layer on castings is reduced by 2-3 times, the scrap of castings is reduced by 0.8%. The suspension for the manufacture of ceramic shells when casting on melted models, containing 0.30, 5% by weight sodium nitrate, provides good protection of the surface of the castings from decarburization. Claims of the Invention Suspensions for the manufacture of molds in up to e ftam models, containing guid5 7648276 ethyl silicate solution, py-1. Austria patent number 286517, Levid quartz and technological. 31 G 5, 1970. Harbor, characterized by that, in order to increase efficiency2. V. Aleksandrov. Preventing the decarburized layer, the des-carbonization of steel pulping contains the quality of technological equipment on the smelted, model m. with the following ratio of ingredients7 .3. Ermilov A.I. About some facts, Bec.% Jtorah, affecting the value of the decarbonated hydrolyzed mortar-bearing layer. Proceedings of the Moscow Institute of Dusty Quartz The rest of the Earthquad engineers geodesy, aerial photography Sources of information, survey and cartography, 1970, no. 57, taken into account in the examination. 130-134.