SU1397102A1 - Suspension for producing investment patterns - Google Patents

Abstract

The invention relates to casting materials for casting chemically active and refractory metal-floors and alloys in melted models. The purpose of the invention is to increase the strength of the molds and reduce the consumption of suspension materials. This is achieved in that the suspension contains May. %: condensation product of phenol and formaldehyde in the presence of caustic barium as a catalyst 7-17; Resol-type phenol-formaldehyde resin solution with aceto content of 7-12 wt.% 7-17; acid hardener 16-20; solvent 26-34 and graphite powder - the rest. Such a suspension has a high durability, which allows reducing the consumption of materials and the rejects of castings by increasing the strength of the molds. 2 tab. with% 9 (L

Description

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The invention relates to foundry, in particular, to mold materials for the casting of reactive and refractory metals and alloys in flyable models.

The purpose of the invention is to increase the strength of the molds and reduce the consumption of suspension materials.

The essence of the invention is that in the composition of the suspension containing graphite powder (filler), the binder: the condensation product of phenol and formaldehyde in the presence of barium hydroxide as a catalyst (SFL-309) and a 7-12% solution of phenol-formaldehyde resin Resole type in acetone (SFZH-3016). The use of this mixture of thermo-reactive resins increases the vitality of the suspension and the strength of ceramic forms.

The amount of dry residue in the SFL-309 resin is 70-80%, and in the SFL resin - 55%. The reactivity is indirectly assessed by the content of free phenol in the resin, and the lower the content of the latter, the higher the reactivity of the resin. The content of free phenol in the SFL-309 resin is 20% and in the SFL-301 6 55% resin. The use of a single resin (SFZh-3016) in suspension as a binder due to the low solids content (low degree of condensation) leads to an increase in the porosity of the forms and the formation of a burn

Ethyl alcohol, acetone and other solvents can be used as a solvent in the suspension, which bring the suspension to the required viscosity.

Benzosulfonic acid, Petrov's kerosene contact, hydrochloric acid can be used as a hardener for the rapid hardening of the suspension.

When used as a hardener of sulfonic acids or Petrov’s contact, it is an active hydrogen of a sulfonic group of an NZOZ. The relative amount of sulfo groups in a Petrov contact is less than in sulfonic acids, which explains the increase in the amount of hardener when used in a suspension of Petrova kerosene contact.

 The suspension is prepared as follows.

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Dissolve the binder in 2/3 hours of solvent, load the filler and mix, then dilute 1/3 of the solvent hardener is added with stirring, and the suspension is finally stirred.

Forms and test specimens were fabricated in melted models by successively applying slurry layers, which were then sprinkled. Nine layers were applied, then, after drying, the model was melted and fired for 2 hours at 750-800 ° C. The second firing step was under vacuum for 2 hours. After the final firing, the specimens were tested for flexural strength. Toning is determined by the onset of gelatinization of the slurry.

To obtain forms and samples, suspensions were prepared, the compositions of which are given in table. 1, and the average values of the vitality and strength of the molds are in table. 2,

Compositions 1-6 correspond to the proposed invention, and composition 1-5 - using Petrov's kerosene contact as hardener, and composition 6 - using benzoicolfoacid as hardener.

As can be seen from the table. 1 and 2, the amount of binder (resin mixture) less than 14% does not increase the strength properties of the forms due to the small amount of binder in relation to the filler, and an increase in binder of more than 34% does not provide a significant increase in vitality, as the change in the amount of binder in with respect to the solvent with the same amount of hardener leads to acceleration of the binder polymerization.

The use of the invention allows to increase the survivability of the suspension by 3-10 times and the strength of the forms by 1.3-2.1 times. Increasing the survivability of the suspension reduces the consumption of materials (especially under conditions of small-scale production), as well as the loss of castings due to the increased strength of the molds.

Claims (1)

Invention Formula Suspension for the manufacture of molds for industrial models used in the manufacture of castings from. chem. 3197102, highly active and refractory metals in the following ratio of ingredients and alloys, including graphite iron, May. %: The condensation product of phenol and formaldehyde in the presence of caustic barium as a catalyst 7-17 powder, acid hardener, solvent, condensation product of phenol and formaldehyde in the presence of barium hydroxide as a catalyst and the product of polycondensation is reactive capable monomer with formaldehyde, characterized in that, with the aim of increasing the strength of forms and reducing the consumption of materials, the suspension contains, as a polycondensation product of a reactive monomer with formaldehyde, a solution of a resol phenol-formaldehyde resin with an acetone content of 7-12 wt.% Ingredients Indicators, May. % for suspension formulations IIZIIIETIULlIIZIOE Graphite powder42 44 Fen ol for rmal ryde g id- on resin SFZH-309 5 Phenol formaldehyde-to resin SFZH-3016 5 Petrova kerosene contact 18 sixteen Sol Na Acid Benzosulfonic acid Ethyl alcohol Anetpn thirty 26 30 A solution of phenol-formaldehyde resin of the ash type with an acetone content of 7-12 wt.% Acid hardener Solvent Graphite powder Ta 28 12 12 56 54 28 44 12 12 17 20 7 7 17 7 17 17 20 7 7 17 7 17 18 20 18 16 20 34 30 26 26 34 26 34