SU831331A1 - Complex-curing agent for sand/resin mixtures for producing casting ceramic moulds - Google Patents

Description

The invention relates to a foundry, in particular, to hardeners of resin mixtures, which are cured in a tooling at normal ambient temperatures. In the modern foundry industry, various hardeners are used for cold-hard resin mixtures; orthophosphoric acid, beiso sulfonic acid and other fl. Known hardeners for cold hardening resin mixtures are used at normal ambient temperatures. When used at low ambient temperatures, for example, for the winter season, the required results are not achieved, as the curing of core mixtures slows down dramatically, and consequently, the holding time of the rods in the core boxes decreases, labor productivity decreases and labor costs increase. . Hardeners are also known: on the basis of the water-soluble product, the pyrolysis of wood and hydrochloric acid and on the basis of chemical compounds of aluminum phosphates, for example, aluminum chromophosphate G2,. The closest to the proposed technical essence and the achieved result is a hardener of sand-resin mixtures for the manufacture of casting cores and molds -. herbs of chromatron-based chromatron solution and other acid salts impurities h. However, this hardener provides high-quality rods only at normal ambient temperatures and cures the rods in a short time; at low temperatures from -7, the curing time of the rods and their holding in boxes dramatically increases. The purpose of the invention is to accelerate the curing of the rods and molds from cold-hardening mixtures (HTS) at lower temperatures, the environment is from -7 to + 10 ° C. The goal is achieved by the fact that the complex hardener of sand-resin mixtures for the manufacture of casting cores and molds, including the chromatron etching solution, additionally contains an aluminum-chromophosphate binder in the following ratio of ingredients, wt.%: Etching solution chromatron 50-90 Aluminum-chromophosphate binder 10 -5Р

The hardener chromatre is a by-product of the electrovacuum and radio engineering industry and contains, wt%:

Support iron 75-83

Ferric chloride1-3

Hydrochloric acid. 1Chlorne copper 0.5-1.7

Zinc chloride 0.7-2.0

Chloride tin 0.2-0.8

Aluminum chloride 0,: 5-1,7 Water Else

The initial and working chromatron hardener consistency is 1.49-1.50 g / cm

The aluminum chromophosphate bond (AHPS) is an acidic phosphate salt of aluminum and trivalent chromium, obtained by reacting chromium and aluminum compounds with phosphoric acid.

It is preferable to use AHFS as a technical product in accordance with TUb-18-166-73. The initial and working density of AHFS is 1.58-1, 60 g / cm

When the AHFS content in the complex hardener is lower than the lower (10 wt.%) And higher than the upper limit (50 wt.%), The required acceleration of the hardening of the rods and molds is not achieved at low ambient temperatures and their heat resistance decreases.

The Complex Hardener can be used to cure mixtures with various synthetic resins, however, it is preferable to use it in mixtures with urea-formahyde (urea) resins. when the resin content of 3 wt.%).

A complex hardener is obtained by simply mixing the ingredients of its ingredients under ordinary conditions. It is also possible to separate the introduction of its ingredients.

The mixture is prepared in paddle or screw mixers according to the following mode: the refractory filler is tangled with a complex hardener for 1-2 minutes, then a resin, such as a urea formaldehyde class, is added and mixing is continued for another 1-2 minutes. The total mixing time is 2-4 minutes.

For example. Prepare a cold-hardening mixture containing weight,% Quartz sand 96.4 Resin M.19-623,0

Complex hardener0.6 Table 1 shows the physical and mechanical properties of the mixtures using the proposed complex hardeners and the well-known hardener,

The test data was obtained under conditions of low ambient temperature (from -7 to) possible in the core sections of foundries in the winter season,

Table 2 shows the compositions of cold-hardening mixtures with the proposed complex hardener with the optimal ratio of ingredients (70 wt.% Chromatron and 30 wt.% AHFS

The tab, 3 shows the physicomechanical properties of the mixtures with the proposed hardener of the optimal composition under conditions of low temperature: from –7 to +10 ° C

From the results presented in Tables 1-3, the proposed complex hardener provides curing of resin mixtures at low ambient temperatures with increased speed, which allows a significant increase in labor productivity in the manufacture of rods in winter conditions,

T a b l and c a

Offered 50 50 25 4.0 10.5 Ma 60 40 20 7.2 11.6 70 30 20 8.0 12

21 27 29 Over 12 0.4 Over 12 0.1 Over 12 0.05

80 90

20

15 17

ten

120,100

Quartz sand KO315

Urea resin M 19-62

Complex hardener Humidity,% 1.4 Vitality, min30 Compressive strength, gf / cm after 1 h9.7 2 h11.4 24 hMore than 1 Salability in 24 h,% 0.01 Heat resistance (400 C) in time of resistance of the sample under the action of load, s35

Continued table. one

35 38

10.9 Over 12 0.1 10.0 Over 12 0.24

1.4 Over 12 0.48

17

table 2

96.43

96.4

.3,0

3.0 0.57 0.60

Claims (1)

Table 3 1.31.5 3520 10.611.0. 12,012,0 2 More than 12 more than 0 0,010,10 4243. Invention Formula A complex sand hardening hardener.) Mixtures of dp of fabricating lead rods and molds, including chromatron etching solution, so that, in order to accelerate the hardening of the rods and molds at low ambient temperatures from -7 to It additionally contains an apyumochromophosphate binder at the following ratio of ingredients, wt%:. 831331 50-90 10-50 information during examination C.S., and L.S.S.M. from cold hardened yisasnn, certificate of the USSR 22 C 1/10, 1975. USSR certificate 22 C 1/10, 1975. 8 Etching solution chromatron Aluminum chromophosphate bond