SU663473A1 - Solution for treating ceramic moulds - Google Patents

Description

The invention relates to foundry, in particular, to the manufacture of multilayer shell molds, and can be used in the production of casting on melted models. In the production of casting on melted models, aqueous solutions of alkaline earth metal chlorides and aluminum are widely used for chemical processing. ceramic molds on the liquid glass binder 1. F1) the frames are processed for curing; 1 and drying is done in layers or after applying all the layers. When processing a liquid glass coating, chlorides of alkaline earth metals and aluminum enter into chemical interaction with liquid glass, partly destroying its 3 drying times of the treated liquid glass layer, which slows down the process of making shell forms. In addition, the solution has a reduced rate of penetration into the pores of dry shells due to insufficient wetting of the latter, impairing the impregnation of multilayer forms. The aim of the invention is to accelerate the process of making shell molds and increase their strength after calcination. This is achieved by the fact that the treatment solution for shell forms on a liquid glass binder, including a hardener and water. The hardener contains glycine in the following ratio of components, wt.%: Glycine 10-18 Water 82-90 Glycine is an internal salt (bipolar ion) GOST 5860-51. MHZ-CHg Like other compounds with mixed functions, glycine exhibits the properties of acids and amines. The bipolar glycine ion in the acidic medium behaves as a cation, since the dissociation of the carboxyl group is suppressed, and in the alkaline medium it is anion, 7VH-CH-COOH Nn, -CH, -COOB, which is processed with a solution of glycine of a ceramic form, made using liquid glass binder, hardening of the shell is completed in 15-30 seconds without breaking the liquid glass. The mechanism of curing (drying) can be explained as follows. With the introduction of glith in a liquid-glass sol, negatively charged particles,) / VtfV2x / V, the electrokinetic potential decreases, resulting in the stability of liquid glass being disturbed and the particles of the lyophobic sol coagulate into a solid, dense gel. The decrease in the electro-kinetic potential caused by the compression of the diffusion layer under the influence of the electrostatic interaction of the bipolar NH-CH2-COd ions causes the transition of the liquid glass micelles to an isoelectric state with a complete loss of aggregative stability. Thus, during drying, a coagula-colloidal liquid-glass system under the scheme takes place in the treated shell: a sol gel-n-spruce, as well as the transfer of the solvent from the bast layers to the surface, evaporating it from the surface. In the untreated casing during the drying process proceeds hundreds of times slower. In tab. 1 shows examples of the composition of the proposed solution; in tab. 2 - their physico-mechanical and technological properties.

Hydroxychloride

24-19 aluminum

Glycine

5 95 Water

81-86

Table 1

20 80

18 82

15 85