SU697244A1 - Coating composition for gasified patterns - Google Patents

Description

(54) COATING FOR GASIFIED MODELS

The invention relates to foundry, namely to coatings for foundry gasification models. In the foundry industry, the coating for gasified models based on alcohol and water-soluble polymeric materials is known. This lyvieeT coating has improved strength properties after drying, but using them as an dispersion medium as an ether-oxidizing fraction, and as a binder — as resin, makes it almost impossible to use them applying to the foam models by dipping in a fluidized bed to preserve the integrity of the models. The closest in technical essence and the achieved result to the invention is a coating comprising a refractory filler, a 0.5-2% aqueous solution of polyvinyl alcohol, hydrolyzed ethyl silicate, asbestos, portleshded cement, 2-cerin 2. However, this coating does not allow uuluchit machinability castings. The invention is improved by and:; razabivaemost castings. The goal is achieved by the fact that the coating additionally contains silicon powder with the following ratio of ingredients, wt.%: 0.5-2% aqueous solution of polyvinyl alcohol33-55 Hydrolyzed ethyl silicate3, 3-5.1 Glycerol 0.16-0.28 Asbestos0 , 33-0.56 Portland cement 0.03-0.06 Silicon powder 3,18-35 Refractory fillerErestal Zircon powder can be used as a refractory filler, and ETS 40 as a hydrolyzed ethyl silicate. Powdered silicon reduces the solubility of carbon in austenite. The preparation of the coating is carried out as follows. Glycerin and hydrolyzed ethyl silicate are added to the calculated amount of a 0.5-2% aqueous solution of alcohol. After thorough mixing, asbestos is added and kept for 1.5-2 hours at 18-25 seconds until complete binding of the binder. Then, the calculated amounts of Portland cement, powdered silicon and zircon powder are introduced and mixed in a mixer with a speed of 1500-2000 rpm for 3-5 minutes.

The invention is illustrated in tables 1, 2 and 3, in which the compositions, properties of the coatings and the characteristics of the microstructures of the castings are given respectively.

The amount of Portland cement is reduced in comparison with the known coating due to exposure for 1.5-2 hours at 18-25 seconds with an aqueous solution of polyvinyl alcohol, hydrolysis and hydrolyzed ethyl silicate until complete gelation.

The use of coatings with silicon allows 6 wide limits to regulate the structure of the surface layer of steel castings obtained by the method of casting by gasifiable models. Coating 2 can be used if necessary to complete surface treatment of castings , 0 33.0 32.0

5.75.1 4.293.37 3.3 2.52

0.30.28 0.220.2 0.16 0.15

0,50,56 0,45,0,39 0,33 0,30

0.10.06 0.040.04 0.03 0.03

Silicon PORSCH1KOVY 37.3 35.0 23.0 .11.0 3.18

Refractory filler

17 24

Viscosity, with Vitality, h

steel can be used for the manufacture of steel gears with a molded tooth, if necessary, such castings can be processed with a tool from high-speed steel. Covers 4-5 can be used for parts that are operated under conditions of intense abrasive and hydroabrasive wear, for example, for agricultural machine cutting machine fingers. In addition, to obtain differentiated surface properties within one casting, it is possible to use different coatings within the surface of one foam model. So,. For example, coating 3 should be used to paint the foam model of a gear with a cast tooth for the ring gear, and coating 2 for the hole in the hub to be machined. The implementation of the invention will significantly expand the range of parts manufactured by this method using standard methods; heat treatment with tooling from high speed steel.

Table 1

4.0 27.0 46.0 60.0 65.0

Table

17 24

17 24

17

17 24 24 Quality of castings, Prigar over the entire quantity of a burned surface Surface cleanness Mchcrohardness N., distance from the surface, mm: 140-160 180-190 200-220 170-190

Coating compositions

Proposed

A ferrite-graphite mixture is fixed in the surface layer with a thickness of 1.5-1.8 mm. According to GOST 3443-57, the area occupied by graphite in the structure is less than 3%, the score is 1-Гш02. The size of the largest diameter-inclusions graph-ta less than 25 microns; score 1-gshd1. The pattern of distribution of graphite inclusions is a point interdendritic, a score of 8-Gr8. The form of graphite inclusions is spherical in combination with a lamellar one, a score of 3-Grsh-3. The transition from layer to core is clearly pronounced without a noticeable transition zone. In the core - ferrite-pearlite structure of hypoeutectoid steel.

The same at a depth of 0.8-1.2 mm.

2. 3.

Continuation of table 2

Table

Characteristics of the microstructure In the surface layer with a thickness of 0.8-1 mm free graphite is not detected, the layer structure is perlite. In the transition zone, the perlite-ferritic mixture with the transition to the structure of the core. Unknowing No No No No No, no chitie-stick-stick 210 250-270250-270 170-190170-190 170-190 170-190170-190 Coating compositions 4.

5. At a depth of 0.2-0.4 mm P €: a smooth structure with a needle chain on the borders and inside the grain, then. perlite with the transition to the main structure of the core.

Famous

6. a depth of 0.4-0.6 mm pearlite structure with large-needle cementite along the boundaries and inside the grain, then pearlite with the transition

in the structure of the core.

Claims (1)

Claims of the Invention: Hydrated Ethyl Rolling Coating for Gasifiable Mode-Silicate 3.3-5.1 leu, including refractory fill; -Glycerin 0.16-0.28 Tay, 0,5-2% aqueous solution of poly- Asbestos0,33-0,56 viyl alcohol, hydrolysis of Portland cement 0.03-0.06 et lsilicate, asbestos, portland cement. Silica powder3,18-35 glycerin, different refractory filler rest the fact that, in order to improve the machinability of castings, it is an additional source of information, NO contains silicon powder at 30: taken into account, when examining the following ratio of ingredients, weight USSR author's certificate 0.5-2% WATER plant. 4,67779, CL B 22 C 3/00, 1974. polyvinyl alcohol thief es USSR Certificate of Authorship ta33-55 -35} j 554929, cl. В 22 С 3/00, 1975. 697244. 8 Characteristics of the microstructure In the surface layer of tolgdine 0.8-1, mm - pearlite structure with separate. inclusions of cementite along the grain boundaries, then perlite with transition to the main structure of the core. P Rodol and wife ab.3