SU772675A1 - Suspension for investment-pattern producing of casting moulds - Google Patents

Description

one

The invention relates to foundry, mainly casting refractory and reactive metals.

Suspensions are known on the basis of Grae-5 phitic powder, thermosetting resin, hardener and solvent for the production of casting molds according to melted models l.

The disadvantage of the molds obtained from these slurries is their low strength and high shrinkage, leading to a distortion of the geometric dimensions of the casting.

Closest to the invention of 15 technical essence and achievable. the result is a suspension for iz. preparing casting molds based on melted models, including graphite powder as a refractory filler, titanium powder, thermosetting resin, organic solvent 2.

However, this suspension has disadvantages. The strength and configurational stability of the form is determined by the conditions for the formation of coke from a thermosetting resin during calcination to 800-900 ° C. Titanium, like the rest of metals of groups IV-VI of periodic system-30

themes (PS), practically does not interact with carbon up to 1000-150os. Coke formed during thermal decomposition of the resin has a high chemical activity and interacts intensively with the metal to form carbides. The carbide formation process is accompanied by a decrease in volume.

In tab. 1 shows the volume effects (shrinkage) of the formation of monocarbides.

From tab. As can be seen in Figure 1, for shrinkage of group IV, the shrinkage is significant and amounts to 11-13%, for elements of the V and VI groups it is less and amounts to only about 5%. As a result, the efficiency of the carbide additive is less significant for elements of groups V and VI of C. However, in the manufacture of complex shapes, due to the large specific weights of metals of groups V and VI, their distribution is uneven, leading to local cracking.

Thus, the formation of carbides in the interaction of metal powder with coke leads to the increase and distortion of forms, and in places of high concentration of the added metal - to cracking and softening.

The purpose of the invention is to improve the quality of forms by reducing their linear shrinkage.

This goal is achieved by the fact that the suspension additionally contains metal carbide powder IV-VI groups P, C in the following ratio of ingredients, wt.%:

Powder titanium 0.6-3.5 Powder metal carbide IV-VI

groups PS0,5-1,5

Thermosetting resin 24,0-30,0

Organic

solvent 35,0-40,5 Graphite

Powder Else

The introduction of metal carbide of these groups slows down the rate of interaction of the cast reactive metal with the carbon residue. In connection with this, the formation of the coke residue proceeds mainly before the formation of carbides, which reduces the percentage of shrinkage of the carbon form.

The effect of introducing titanium carbide into the suspension is illustrated in Table. 2

As can be seen from the table. 2, when carbide is introduced to less than 0.5 wt.%, The shape shrinkage is slightly reduced and there is no hardening effect. The introduction of carbide more than 1.5 wt.% Does not lead to a further reduction of shrinkage and additional strengthening.

The introduction of carbides of the V. Group illustrates the table. 3 on the example of niobium carbide.

The introduction of group VI carbides illustrates the table. 4 using molybdenum carbide as an example. .

As can be seen from the table. 3 and 4, carbides of metals of groups V and VI slightly affect shrinkage and strength, but in the manufacture of forms of complex configuration, the introduction of carbides of metals of groups V and VI of PS is advisable to eliminate local cracking.

To determine the optimal compositions, suspensions with different content of metal carbide are prepared in the usual way. The suspension is applied to the model by dipping, followed by sprinkling with graphite sand and drying at room temperature.

After the model mass is heated, the obtained forms are burned in a container filled with graphite before, then subjected to high-temperature vacuum calcination to 1800 ° C. Linear shrinkage is determined by comparing the length of the model and the length of the mold after calcination. Tests for bending strength expose plates cut from calcined molds.

An experimental batch of castings weighing 2.5 kg of zirconium was obtained by centrifugal casting. In the manufacture of an experimental batch of castings, a reduction in marriage is to be made from pouring zirconium from 40% to 12%.

The economic effect from the implementation of the invention according to preliminary calculations will be 80-100 rubles. for 1 ton of good to pour.

Table

Metal

titanium (powder) 1.5 1., 4 1.6 1.4 1.5 1.5

Phenol-barite resin SFZH-309

Organic solvent (alcohol)

Titia carbide (powder)

Graphite

poruiyuk

Metal

niobium

(powder)

phenol-barite resin

SFZH-309.

Solvent (alcohol)

Niobium carbide

Metal

titanium (powder)

Strength on

bend, kg / cm

Linane

shrinkage,%

Continued table. 2

28

27

28

26

36 39 37.5 38.5 37 0.4 0.5 1.0 1.5 1.7

3.05 28.0 32.5

29.2 3.0

3.0 3.0

3.0

28.0 28.0 29.0 27.0 28.0

.38,6

39.0 37.0

38.0 1.8 1.0 1.5 0.5

4.1

3.8 3.9 4.15 4.20 2.3 2.5 2.5 2.4 2.4 2.3

Claims (2)

SFZH-309 phenol-barite resin Formula that, in order to improve the quality of the forms by reducing their linear shrinkage, the suspension additionally contains powder of metal of group IV-VI of the periodic system when the ratio is and ingredients, wt.%: Table 4 Titanium powder 0.6-3.5 Metal carbide powder IV-VI groups of the periodic system 0.5-1.5 Thermosetting resin 24.0-30.0 Organic solvent35.0-40.5 Graphite powder Else Sources of information attention during examination 1. USSR author's certificate 25079, class, B 22 C 1/01, 1970. 2. Authors certificate of the USSR 01596, cl. B 22 C 1/01, 1962.