SU814547A1 - Self-hardening sand for producing casting moulds and cores - Google Patents

Description

(54) SELF-DEFINING MIXTURE FOR THE MANUFACTURE OF CASTING FORMS AND RODS.

As a material based on oxide and ferrous oxide, the mixture contains an iron magnetite concentrate, and as a polyhydric alcohol it contains glycerin.

When the glycerol content is less than the lower limit, the specified increase in final strength and decrease in fritability is not achieved, and when its content is higher than the upper limit, the mixture has increased survivability and low hardening rate, which limits its applicability under mass production conditions and increases the cost of the mixture.

As iron ore concentrate, it is advisable to use magnetite concentrate of iron ore with a specific surface of 25003000 and a content of ferrous oxide of at least 27-30%.

Increasing the content of iron ore concentrate and ortho-phosphoric acid in the mixture above the upper limit is not economically feasible, since the achieved final strength properties of the mixture satisfy the conditions for the production of castings of a wide range of weight and wall thicknesses, and reducing them above the lower limit cannot be recommended due to sharp deterioration of the strength characteristics of the molds and cores; quartz sand can be used as a refractory filler

distensillimanite zircon, rutile, etc.

The order of introduction of the ingredients during the preparation of the mixture is as follows.

Magnetite concentrate of iron ore is introduced into the sand and mixed for 1.5-2 minutes, then a pre-prepared composition of glycerol and concentrated orthophosphoric acid is introduced and mixed for 40-60 seconds, after which the mixture is poured into a core box and compacted with a vibration, vibropress or another method.

Formation of strength in the mixture

5 occurs due to the interaction of ferrous oxide of iron ore concentrate with concentrated phosphoric acid, and high-strength iron phosphates are formed. The introduction of glycerol in the mixture

0 allows to significantly increase the strength at the final stages of hardening and reduce the crushability of the mixture. This positive effect is achieved by increasing the adhesion of St 5 composition to quartz grains of the filler. Glycerin, modifying concentrated orthophosphoric acid, reduces its activity in relation to nitrous oxide, ez, and low

0 the water content of the acid contributes to the hardening of solid iron phosphates and to an increase in their binding ability, which is crucial for increasing

5 strength of the molding mixture.

The compositions of the proposed and known mixtures

Quartz sand 0315B Karasorskogo career

Quartz sand 1 L02 Lyuberetsky

Magnetic concentrate of iron ore Iron oxide scale specific surface 2500 cm Vr Concentrated orthophosphoric acid specific gravity of 1.72 g / cm

Glycerin Ethylene Glycol

Table

92.95 86.8 81.6

92

ten

eight

6.8 3

3 0.2 0.4

Claims (3)

0.05 5 Test results It follows from the presented data that the proposed self-hardening mixture provides a significant 25 increase in strength at the final stages of curing (after 24 hours) and a sharp decrease in friability. The high heat resistance and strength of the mixture allows it to be used for the production of both medium and heavy shaped castings of iron and steel. Claim 35 1. A self-hardening mixture for the manufacture of casting molds and cores, including a refractory filler, a material based on oxide and iron oxide, concentrated phosphoric acid and a polyhydric alcohol, in order to increase the strength of the forms and cores on the final stage hard, and reduce the fallout, it contains the ingredients in the following ratio, weight,%: sch ri ri it to the number of the number in the proposed and known mixtures 814547. 6 Table2 Material based on nitrous oxide 4.0–10.0 and iron oxide Concentrated 3.0–8.0 orthophosphoric acid 0.05–0.40 Polyhydric alcohol Refractory base 2. Mixed mixture according to claim 1, that, as a material on the basis of oxide and ferrous oxide, and contains iron ore magnetic concentrate. 3. The mixture according to claim 1, differs from the fact that, as a polyhydric alcohol, it contains glycerin. Sources of information that are considered in the examination 1.- Copyright certificate of the USSR 339090, cl. B 22 C 1/00, 1968, 2. Foundry production, 1977, 9, 13-14. 3. Authors certificate of USSR 339091, cl. B 22 C 5/04, 22 C 1/00, 1970.