CN113770298A

CN113770298A - Low-gas-evolution precoated sand for casting sand mold of turbine shell

Info

Publication number: CN113770298A
Application number: CN202110861810.6A
Authority: CN
Inventors: 马榕
Original assignee: Wuxi Zhengjie Machinery Technology Co ltd
Current assignee: Wuxi Zhengjie Machinery Technology Co ltd
Priority date: 2021-07-29
Filing date: 2021-07-29
Publication date: 2021-12-10

Abstract

The invention discloses low-gas-evolution precoated sand for a turbine shell pouring sand mold. The components are 91 plus or minus 2 percent of silicon dioxide, 6 plus or minus 2 percent of ferric oxide, 2.5 plus or minus 0.8 percent of phenolic resin, 0.3 plus or minus 0.8 percent of urotropine and 0.2 plus or minus 0.08 percent of calcium stearate. Adding silicon dioxide into a stirring furnace, heating the stirring furnace by burning natural gas, heating the temperature in the stirring furnace to 500 ℃, and stirring for five minutes; adding the phenolic resin into a stirring furnace, and stirring for five minutes at 500 ℃; adding urotropin and calcium stearate into a stirring furnace, and stirring for three minutes at 500 ℃; adding ferric oxide into a stirring furnace, and stirring for three minutes at 500 ℃; and discharging the mixture out of the furnace and cooling to room temperature to obtain the precoated sand. According to the invention, the ferric oxide is added into the precoated sand, so that hydrogen and carbon monoxide are converted into water and carbon dioxide, and the defective rate of castings is reduced.

Description

Low-gas-evolution precoated sand for casting sand mold of turbine shell

The technical field is as follows:

the invention belongs to the technical field of turbine shell production, and particularly relates to low-gas-evolution precoated sand for a turbine shell pouring sand mold.

Background art:

when the existing pouring sand mold is used, if the pouring temperature of a casting exceeds 1450 ℃, the coated sand of the pouring sand mold can release hydrogen and carbon monoxide, and the hydrogen and the carbon monoxide can stay at the thick and large part of the casting, so that the casting forms needle-shaped air holes, and the defective rate of the casting is increased.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

The invention content is as follows:

the invention aims to provide low-gas-evolution precoated sand for a turbine shell pouring sand mold, so that the defects in the prior art are overcome.

In order to achieve the aim, the invention provides low-gas-evolution precoated sand for a turbine shell pouring sand mold, which comprises the following components: 91 plus or minus 2 percent of silicon dioxide, 6 plus or minus 2 percent of ferric oxide, 2.5 plus or minus 0.8 percent of phenolic resin, 0.3 plus or minus 0.8 percent of urotropine and 0.2 plus or minus 0.08 percent of calcium stearate.

A preparation method of low-gas-evolution precoated sand for a turbine shell pouring sand mold comprises the following steps: (1) adding silicon dioxide into a stirring furnace, heating the stirring furnace by burning natural gas, heating the temperature in the stirring furnace to 500 ℃, and stirring for five minutes;

(2) adding the phenolic resin into a stirring furnace, and stirring for five minutes at 500 ℃;

(3) adding urotropin and calcium stearate into a stirring furnace, and stirring for three minutes at 500 ℃;

(4) adding ferric oxide into a stirring furnace, and stirring for three minutes at 500 ℃;

(5) and (4) discharging the mixture obtained in the step (4) and cooling to room temperature to obtain the precoated sand.

Compared with the prior art, the invention has the following beneficial effects:

by adding the ferric oxide into the precoated sand, the ferric oxide reacts with hydrogen and carbon monoxide at high temperature respectively to generate water and carbon dioxide in the pouring process, so that the problem that the hydrogen and the carbon monoxide are accumulated at the thick large part of the casting to form needle-shaped air holes is solved, and the defective rate of the casting is reduced.

The specific implementation mode is as follows:

the following detailed description of specific embodiments of the invention is provided, but it should be understood that the scope of the invention is not limited to the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.

Example 1

The utility model provides a low gas production tectorial membrane sand for turbine housing pouring sand mould, its component is: 91% of silicon dioxide, 6% of ferric oxide, 2.5% of phenolic resin, 0.3% of urotropine and 0.2% of calcium stearate.

A preparation method of low-gas-evolution precoated sand for a turbine shell pouring sand mold comprises the following steps: (1) adding 91 parts of silicon dioxide into a stirring furnace, heating the stirring furnace by burning natural gas, heating the temperature in the stirring furnace to 500 ℃, and stirring for five minutes;

(2) adding 2.5 parts of phenolic resin into a stirring furnace, and stirring for five minutes at 500 ℃;

(3) adding 0.3 part of urotropin and 0.2 part of calcium stearate into a stirring furnace, and stirring for three minutes at 500 ℃;

(4) adding 6 parts of ferric oxide into a stirring furnace, and stirring for three minutes at 500 ℃;

And (3) preparing the precoated sand into a sand mold, pouring molten iron into the sand mold, and reacting the generated hydrogen and carbon monoxide with ferric oxide respectively.

In the pouring process, the ferric oxide at high temperature respectively reacts with hydrogen and carbon monoxide to generate water and carbon dioxide, the water is evaporated at high temperature, the carbon dioxide cannot invade into molten iron like carbon monoxide, the problem that the hydrogen and the carbon monoxide are gathered at the thick large part of the casting to form needle-shaped air holes is solved, and the defective rate of the casting is reduced.

And (3) gas forming amount test: taking 3 groups of precoated sand of the existing sand mold, wherein each group is 10g and marked as A₀、B₀、C₀(ii) a 3 groups of precoated sand of the invention are removed, each group is 10g and marked as A₁、B₁、C₁；A₀、A₁Is a first group, B₀、B₁Is a second group, C₀、C₁And performing gas forming amount test on the three groups in an intelligent initiating tester, wherein the heating temperature of the first group is 500 ℃, the heating temperature of the second group is 1000 ℃, and the heating temperature of the third group is 1450 ℃.

TABLE 1 gas evolution test Table

As can be seen from Table 1, the precoated sand of the present invention significantly reduced gas evolution at high temperature, and at 1450 ℃, gas evolution was reduced by about 20%.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims

1. The utility model provides a low gas production tectorial membrane sand for turbine housing pouring sand mould, its component is: 91 plus or minus 2 percent of silicon dioxide, 6 plus or minus 2 percent of ferric oxide, 2.5 plus or minus 0.8 percent of phenolic resin, 0.3 plus or minus 0.8 percent of urotropine and 0.2 plus or minus 0.08 percent of calcium stearate.

2. The preparation method of the low-gas-evolution precoated sand for the turbine shell pouring sand mold according to claim 1 comprises the following steps: (1) adding silicon dioxide into a stirring furnace, heating the stirring furnace by burning natural gas, heating the temperature in the stirring furnace to 500 ℃, and stirring for five minutes;