SU1138228A1 - Suspension for manufacturing ceramic investment moulds - Google Patents

Abstract

SUSPENSION FOR THE MANUFACTURE OF CERAMIC FORMS ACCORDING TO THE MELTED MODELS, including a refractory filler, an aluminum-chromophosphate binder, an anionic surface substance, alkaline earth metal chloride, water, and a hardener, which is important, because of the treatment time, because of the time, because of the trouble, because of the time of the trouble, because of the time of the trouble, because of the time of the trouble, because of the time of trouble, because of the time of the trouble, because of the time of the trouble, because of the trouble, because of the trouble; suspension contains as a hardener 9-11 / o-ny aqueous alkali solution in the following ratio of ingredients, May / o; Alumochromophosphate binder13, 0-20.0 Alkaline earth metal chloride2.0-4.0 Water 12.0-16.0 Anionic surface substance 0.08-0.1 9-11% aqueous alkali thief 2 , 0-8,0 Refractory filler Rest (L

Description

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FIELD OF THE INVENTION The invention relates to foundry, in particular, to obtaining accurate casting in ceramic molds.

A refractory suspension is known, containing an aluminum-chromophosphate binder (AHFS), barium chloride, a surfactant, a surfactant, water, and a refractory filler 1.

The disadvantage of this suspension is the duration of the curing of the coating layer at room temperature (more than 12 hours), since its composition contains a small amount of hardeners that are included in the refractory filler in the form of iron oxides, calcium, magnesium and other substances in the form of impurities.

Closest to the invention to the technical essence and the achieved result is a suspension for the manufacture of ceramic forms, including AHFS, alkaline earth metal chloride, water, surfactant, hardener, refractory filler. As a hardener, the suspension contains shlak ferrochromic production or Al (OH) i 2.

The disadvantages of the known suspension are the duration of the curing process and the low mechanical properties of the coating layer. Due to the fact that hardeners of ferrochromic production or aluminum hydroxide are used as hardeners in the known composition, which are powdered insoluble in this binding material.

The hardener particles aggregate, and in a number of cases they undergo sedimentation, which leads to a decrease in the contact surface with AHFS and, consequently, to a decrease in the activity of the suspension.

The aim of the invention is to accelerate the curing time of the suspension and increase the strength properties of the molds after the model is smelted.

This goal is achieved in that the suspension, which includes a refractory filler, an aluminum-chromophosphate binder, an anionic surface substance, alkaline earth metal chloride, water and a hardener, contains a 9-11% alkali solution as a hardener at the following ingredient ratio, wt.% / A: Alumochromophosphate binder 13.0-20.0

Alkaline earth metal chloride2.0-4.0 Water 12.0-16.0 Anion-active surface substance 0.08-0.1 9-1 F / 0-ny alkaline aqueous solution 2.0-8.0 Refractory filler Rest . 10 1 ° / o-aqueous alkaline hardener solution acts by lowering the pH of the AHFS solution.

The introduction of a 9-11% aqueous alkali solution as a hardener contributes to the initial neutralization of chromium and aluminum dihydrogen phosphates and their conversion into insoluble hydroxides, and upon further alkalinization leads to the formation of soluble aluminum aluminates and sodium chromates by the reaction

CgACNGRO) 6 + 24NaOH - (OH) 4 (HgO) g 4-6Mazr04CH + 12NgO + (OH) 4 (HjO) j. The resulting hydrated complexes easily lose their hydration water and

5 transitions to the dehydrated salts of NaAIOj and NaCrOz, which occurs during the curing of the coating layer.

AHFS after curing gives the shell high strength properties, and alkaline-earth metal chloride gives strength at high temperatures. Water - solvent serves for optimal selection of the density of the binder solution AHFS. Surfactants, increasing the wettability of the refractory filler, increase the strength of the shell and reduce the viscosity of the coating. The refractory filler - the base of the coating forms together with the bonding refractory shell. In order to select the optimum amount of alkali necessary for the reactions to be performed, the following are prepared.

0, different in content, refractory slurry compositions and comparative testing of properties with a known composition.

The suspension is prepared in the following manner.

The prepared aqueous solution of calcium chloride with a density of d l 16 g / cm, which corresponds to 17.8 s / s concentration (May) in a volume of 1 l. To the resulting solution was added 1.5 L of AHFS and stirred for 5-7 minutes. The resulting mixture of solutions has a density of 1.34-1.36 g / cm.

A calculated amount of a 10-1% aqueous solution of alkali (NaOH) of mark x4, GOST 4326-47, refractory filler marschalite of grade PK-3, GOST 9077-59, the calculated amount of which is 4.5 kg and 4 ml of surfactant. The suspension is stirred with water cooling for 20-30 minutes. The shortest time to transfer AHFS to

0 complex salts occur when using 10 ° / of the alkali solution within + 1%, i.e. 9-110 / 0.

As anionic surface substances, black neutralized 5 rectified contact (KCNR) according to TU-38-3022-74 and sulfonol according to TU-6-01-1001-75 are introduced into the suspension.

Other variants of suspensions are prepared in the same way.

In tab. 1 shows the compositions 1-5 of the proposed suspensions and the composition of the 6 known suspensions.

Four-layer specimens are made from suspensions for ceramics bending tests using a well-known technique. To determine the curing time of the coating layer, the slurry is applied to wax models and destroyed after a certain time.

In tab. Figure 2 shows the results of shell studies.

From the data table. 2 it follows that suspensions of compositions 2-4 have the best properties, i.e. those in which a 10 + 1% alkaline aqueous solution is introduced in an amount of 2-8% by weight.

The vitality of the proposed suspension is high (although somewhat lower than that of the known) and satisfies any production. The strength of the cheese is significantly higher than that of the known suspension, and the deformation of the shells at 900 ° C is practically unchanged.

With a content of 9–11 ° C / l of an aqueous solution of wormwood in suspension less than 2 Bes.%, The curing time of the coating layer is cured, which results only in a partial hemming of the slurry solution and, consequently, incomplete conversion of AHFS to a soluble form. When the alkali solution is mixed with 8 wt.%, No further acceleration of the curing process is observed and, in addition, there is a deterioration in the mechanical properties.

Examples of the use of anion-active surface substances introduced into the refractory suspension with justification of their boundary values, for example, KCNR according to TU38-3022-74, and sulfonol (TU-6-01-1001-75), are given in Table. 3 and 4, and in table. 5 presents the results of studies of the properties of the shells.

Thus, when the surfactant content is less than 0.08%, the durability of the shell decreases at room temperature, and when the surfactant content is more than 0.10%, the strength decreases both at room temperature and at high temperature due to foaming of the suspension.

The implementation of the invention makes it possible to reduce the curing time by 40% and improve the mechanical properties of the ceramic forms in the raw state by 1.4-1.6 times.

Table 1

10 Chloride of alkaline earth metal1 10 Slag of ferrochromic production water solution of 1 alkali 0.05 76.95 Refractory filler 1317202218 23455 1214161815 25810 0.050.0505050505050 70.9560.9551.9544.9561.45 The strength limit for static bend at room temperature after separation from the model (without melting), kgf / cm 43 59 Tensile strength in the wet state (after model overhead in water) under static bending at 20 ° C, KGS / CM244 57 Deformations of the shell during 2 hours of exposure, mm 0.5 Sustainability of the suspension at 20-25 ° С, day 45 41 Curing time of coating layer 1.0, h

Strength at

static bend at

900С, КГС / СМ237

AHFS

X

Alkaline earth metal chloride

Water

9% alkali solution

Surfactant (KCHNR)

table 2

44

44

0.7

43

1.2

28

26

thirty

33 31

Ta.b faces 3

17

20

22

13 73 60 47 71 61 47 0.6 0.6 0.7. 0.7 40 37 28 0.60 0.5 0.62 0.9

Strength at static bending at 20 ° С

The curing time of the coating layer, h

Strength at static bending at 900 ° С

Table 4

42/44 55/57 69/71 63/61 -48/44

1.2 / 1.1 0.75 / 0.60 0.55 / 0.53 0.60 / 0.64 0.91 / 0.85

35/38 34/34 30/32 28/29 27/24

Claims (1)

SUSPENSIONS FOR THE PRODUCTION OF CERAMIC FORMS BY MELECTED MODELS, including refractory filler, alumochromophosphate binder, anionic surface substance, alkaline earth metal chloride, water and hardener, characterized in that, in order to accelerate the time of its solidification, the suspension forms and increases the strength as a hardener, 9–11 ° / o-aqueous alkali solution in the following ratio of ingredients, wt.%: Aluminum chromophosphate yawning 13.0-20.0 Alkaline earth chloride th metal 2.0-4.0 Water Anionic on top of 12.0-16.0 bone substance 0.08-0.1 9-11% aqueous plant 2.0-8.0 G alkali thief SS Refractory filler Rest ω a oo QO yu QO>