SU1310090A1 - Suspension for making moulds by investment pattern - Google Patents

Abstract

The invention relates to a foundry, namely, slurry compositions for the manufacture of molds for produced models. The purpose of the invention is to improve the quality of molds by reducing their cracking and scrap due to blockages, as well as reducing the cost of molds. According to the invention, in suspension based on a hydrolyzed solution of ethyl silicate with a content of conditional SiO 11.5–12.0 wt.%, Use is 8–10 May. % phenol-formaldehyde resin and 65-70% by weight of technical alumina. Due to the porosity of alumina, it is impregnated with resin, which, during calcination, decomposes into pyrocarbon. Due to this, the durability of the molds increases, their cracking decreases (twofold), and the scrap of castings in clogs and gas shells decreases by the same amount. 2 tab. / § (L

Description

eleven

The invention relates to a foundry, in particular, to materials for casting on melted models of parts from mechanically active metals and alloys, for example titanium.

The purpose of the invention is to improve the quality of the forms by reducing their cracking and reactivity, improving their permeability and reducing the cost of the forms.

The essence of the invention is as follows.

The suspension consists of two phases: solid technical alumina and liquid - hydrolyzed solution of ethyl silicate and phenol-formaldehyde resin. As g of Linosem use g of the soil of any of the grades G-00, G-0, G-1, G-2 with grain sizes of 0.05 microns or less. Technical alumina differs from electrocorundum (fused alumina) with increased porosity. A hydrolyzed solution of ethyl silicate is prepared from ETS-DO with a content in the final product of 11,; 5–12% conditional silica. As the resin used resin brand SFZH 3016.

Suspension contains substances in the following ratio, mA.Z:

Alumina 65 - 70

Phenol formaldehyde resin 8-10

Hydrolyzed

ethyl silicate solution

In preparing the suspension, the pores of the alumina are filled with resin. During the calcination of the mold formed during thermal decomposition of the resin, pyrolytic carbon precipitates in the pores of the alumina grains and on their surface with a uniform distribution throughout the thickness of the mold. This leads to an increase in the strength of the form and to its chemical inertness to the metal being poured. As a result, the separation and cracking of the mold is reduced, the scrap of castings on clogs and gas shells is reduced, and the depth of the surface layer of metal of increased hardness becomes less. To obtain the forms and samples, suspensions were prepared, the compositions of which are given in Table. one.

In a solution of pre-hydrolyzed ethyl silicate at constant n02

resin was added to the agitation, then alumina and stirred for 0.5–0.6 h until a homogeneous suspension was obtained and its viscosity was measured.

viscometer VZ-4. The viscosity of the suspension was adjusted by adding a hydrolyzed solution of ethyl silicate. The resulting suspension was kept for 0.17-0.25 hours until the gas bubbles were completely removed from it, after which the suspension was ready for use. Molding by produced models was carried out by dipping models made by a known method from

model composition of PS, in suspension, followed by powder with electrocorundum powder of white granulometric fraction O, 16-0, A micron, drying in vacuum-ammonia medium for 0.5 h with detergent in air before and after drying for 0.3-0 , 4 h. Thus, 6-8 layers were applied, after the model was melted at 95-100 ° С for 0.5-0.7 h, the forms were dried at 200-250 s for 1.5-2 , 0 h and calcined in a reducing gas atmosphere (a mixture of hydrocarbon and nitrogen) for 10-11 hours at.

An ingenious form was poured with a VT5L grade titanium alloy heated to 1720–1730 ° C.

The results of technological tests of molds and quality of castings resulted; Deny in tab. 2

The implementation of the invention allows to improve the quality of castings due to

40 improving the quality of the form, provides the economic effect of reducing the rejects of castings and the use of refractories - technical alumina of lower cost than the cost

45 electrocorundum.

Claims (1)

Invention Formula Suspension for making molds Q for melted models for casting parts made of chemically active metals, containing a refractory filler, a hydrolyzed solution of ethyl silicate and a reinforcing additive, which is characterized by the purpose of improving the quality of forms by reducing their cracking and reactivity, improving gas permeability and reducing the cost forms, it contains technical alumina as a refractory filler, and as a hardening additive a phenol-formaldehyde resin at the following ratio of components, wt%: Components Content, wt.% in suspension :: i :: ini ::: i :: i Alumina 70.0 68.0 65.0 Phenol formaldehyde resin 8, 0 9.0 10.0 Solution of hydrolyzed ethyl silicate (SiOj content 11.5–12.0%) 22.0 23.0 25.0 Table2 Indicator Composition izziziz ::::: 8, 9 8.5 8.2 0.16 0.15 .0.15 7.9 7.5 7.4 Compiled by V.Ivanov Editor N.Kshptulynets Tehred A. Kravchuk Proofreader G, Reshetnik Order 1824/9 Circulation 741 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 Alumina Phenol formaldehyde resin Hydrolyzed ethyl silicate solution Tabli