SU1115834A1 - Moulding sand for making moulds and cores used for castings from chemically active refractory alloys - Google Patents

Abstract

MIXTURE FOR MANUFACTURE strength, the mixture contains as a hardener sulfonated coal in the following ratio of ingredients, wt.%: Phenol-formaldehyde or in furan resin12-20 Sulfonated 5-8 Graphite powderErest

Description

: l

eo so

4: 1 1 The invention relates to the production of glass. A mixture of ethyl silicate and hardener is known. Form1.1 it and such a mixture, when receiving casting from refractory alloys, interact with the alloy to form a strong burner C. A mixture is known for making casting molds used in the preparation of titanium casting, containing graphite powder, refractory filling, Lenol-bary resin, alcohol, hardener and metallic titanium C21. However, the kerosene contact of Petrova, has a very low coke residue, which causes low strength and shrinking of the molds after firing. Closest to the invention | technical essence and the achieved result is a mixture for the preparation of molds and cores used in the manufacture of casting from refractory alloys, containing the following ingredients, May. %: Furan resin 25-28 Hardener Contact Petrov 1 Graphite Powder Else C31 phenol-formaldehyde resin can be used instead of furan resin. The purpose of the invention is to reduce cast rejects by reducing the shrinkage of the mixture and increasing its strength. The goal is achieved by the fact that the mixture for the production of casting molds and cores used in the preparation of castings from chemically active refractory alloys, including graphite powder, phenol-formaldehyde or furan resin, a hardener, contains hardener as the hardener in the following ratio of ingredients, wt. resin 12-20 Sulfonated coal 5-8 Graphite powder Remaining Forms and rods are made by pressing at specific pressures up to 100 dyn / cm. The filler may be graphite or another refractory material that is inert to the metal being poured. g As a thermosetting binder, furan or phenol-formaldehyde resins can be used, and fine hardened sulfone powder (GOST 5696-74) can be used as a hardener. The amount of hardener introduced depends on the amount of binder. The amount of sulfonate less than 5 wt.% Does not provide the necessary strength of products, and as a sulfonate more than 8 wt.% Does not lead to a further increase in strength. Hardening of products occurs during their calcination. In the process of heating the hardener, a coke residue is formed, which provides the structural bonds with the filler and the carbon binder code, which increases the strength of the molds and reduces their shrinkage. The coke residue of contact between Petrov and sulfonic acids is 2.5-2.8%, and the coke residue of sulfone coal, 70%. The low coke residue of the above hardeners causes low strength and shrinking of the molds after firing due to the presence of voids (defects), while the high coking residue of the sulfonated coal during firing will provide greater strength. Dp of obtaining molds and cores are made of mixtures of various compositions (Table 1). Graphite, a powder with an average grain size of 0.2 mm, is used as a filler. As a binder, phenol-formaldehyde resin SFZH-309 GOST 20907-75. Mixtures are prepared as follows. The graphite powder and the sulfougle powder are thoroughly mixed, then the resin is added and again mixed until homogeneous. Then the resulting refractory mixture is pressed into the mold and get the raw form. The form is fired in a graphite lining at C for 6-8 hours, and then in vacuum at 1400 ° C for 2 hours. After firing, the samples are tested for compressive strength and bending, shrinkage measurements are made, as well as strength characteristics.

Mixture compositions are listed in Table 1.

In composition 7, Petrov's contact was used as a hardener, and in composition 8 - ti-toluene sulfonic acid, composition 9 corresponds to the mixture according to t 31,

In tab. 2 shows the properties of mixtures whose compositions are listed in table. one.

As can be seen from the table. 2, the porosity and gas permeability of the molding mixtures depends on the amount of binder and the type of catalyst, but varies only slightly. Porostocht and gas permeability of mixtures when using

Sulfonic acid is somewhat higher due to their low coke residue.

Weight loss during the calcination of these mixtures is also higher, due to the same reasons.

The best strength properties and the least shrinkage have a mixture of 3 - 6.

A decrease in the shape shrinkage and an increase in strength of 1.2-1.3 times will lead to a decrease in casting rejects by 12-15%.

The expected economic effect from the implementation of the invention according to preliminary calculations will be 25-30 thousand rubles. compared with the basic object G21.

Table 1

Phenol-formaldehyde sm111112115 la (SFZH-309) 4956 Sulfonated coal Contact Pet - O-Toluensul phonic acid Compressive strength, kgf / cm at 20 s 98 106 115 130

Strength at

bending, kgf / cm,

at 20 6 D 67 70 75

table 2

55 57 32

71

74 77.020 20 25 7886--8- 5 -Б125 120 90 96 82 Indicators 3 Flexural strength, kgf / cm, at 950 C 66 68 72 78 Linear shrinkage,% for raw form 0.4 0.5 0.4 0 , 45 for fired form 1.9 2.6 1.9 2.05 for general form + metal 2.8 3.5 2.8 2.9 Porosity,% 28 34 29 30 Gas permeability, unit, 132 156 144 142 Loss weight when calcined,% 5.2 9.6 6.4 7.1

and I 58346

Continuation of the table.2 Composition 45678 77 74 56 59 39 0.5 0.5 0.5 0.5 0.5 0.5 2.2 2.4 2.4 3.0 2.8 3.3 3.3 3.1 3.3 3.9 3.7 4.1 31 32 35 35 36 150 154 162 157 165 8.4 9.3 14.1 12.3 14.5

Claims (1)

MIXTURE FOR MANUFACTURE OF CASTING FORMS AND RODS USED WHEN PRODUCING CASTINGS FROM CHEMICALLY REACTIVE REFINING ALLOYS, including graphite powder _f phenol-formaldehyde or furan resin, hardener, which reduces the strength, reducing the mixture, because it reduces the strength, it reduces the strength of the mixture, contains as a hardener sulfonated coal in the following ratio of ingredients, wt.%: Phenol formal dehydrated or furan S resin 1 2-20 / Sulfonated charcoal 5-8 G Graphite FROM powder Rest I and* AND* I I 15834