WO2017114065A1

WO2017114065A1 - Method for preparing environmentally friendly casting material

Info

Publication number: WO2017114065A1
Application number: PCT/CN2016/107863
Authority: WO
Inventors: 张建勋; 侯晓翠
Original assignee: 张建勋
Priority date: 2015-12-29
Filing date: 2016-11-30
Publication date: 2017-07-06
Also published as: CN105618677A

Abstract

A method for preparing environmentally friendly casting material, comprising the steps of preparing a wax mould, preparing a surface layer coating, surface sand suspension, preparing a rear layer coating, rear sand suspension, steam dewaxing, and baking; fine sawdust and crop straw fibre are used as shell-making materials, reducing the amount of fire-resistant materials used and being environmentally friendly, and a reasonable proportion being used; breathability is increased whilst ensuring moulding cast strength, and using porous attapulgite is beneficial for ventilation, reducing casting pore defects, increasing the yield of finished products, and reducing the weight of the mould shell.

Description

Preparation method of environmentally friendly casting material

Technical field

The invention belongs to the technical field of metal investment precision casting, and in particular relates to a preparation method of environmentally friendly casting materials.

Background technique

Mold precision casting is an advanced casting forming process, which is used to realize complex, thin-walled and precision casting. It has great advantages in precision jewellery, aero-engines and other precision molded parts. The traditional investment casting process is used. Fusible materials (such as wax) are made into a fusible model (abbreviated as investment), which is coated with several layers of special refractory coatings, dried and hardened to form a monolithic module, and then melted from the module. A method of melting a mold to obtain a hollow mold shell, then subjecting the mold shell to high temperature sintering, and finally casting a molten metal therein. At present, in the production process of investment casting, ceramic sand is often used. The mold shell broken after casting has difficulty in recovery of sand and has great environmental pollution. Therefore, it is necessary to find a high-performance and environmentally-friendly mold preparation method. very necessary.

Summary of the invention

Based on the above technical problems, the present invention discloses a method for preparing an environmentally friendly casting material, which can efficiently obtain a casting mold shell, and adopts environmentally friendly materials to protect the environment and resources.

The complete technical solution of the present invention includes:

A method for preparing an environmentally friendly casting material, comprising the steps of:

(1) preparing a wax mold, preparing a corresponding wax mold, a casting system and bonding into a wax module according to the shape of the desired casting, and a set of casting system with four castings;

(2) preparation of the top layer coating, the fine corundum powder, ethyl silicate, fine wood chips, n-butanol, cobalt aluminate are mixed and stirred to obtain a surface coating, the fine corundum powder has a particle size of 300 mesh, fine wood particle size For 240 mesh, the weight ratio of the above coating components is: fine corundum powder: ethyl silicate: fine wood chips: n-butanol: cobalt aluminate = 1900: 150: 150: 1.5: 2;

(3) noodles sand: the wax module is immersed in the surface coating pool, and then taken out, and the surface is blown to make it evenly coated under rotating conditions, the blowing time is 30s-60s, preferably 40s; Following the rotation condition The surface sand is sprinkled down to the surface, the surface sand component is alumina sand and fine wood chips, and the weight ratio is alumina sand: fine wood chips = (10-15): 1, and the size of the alumina sand is 80- 100 mesh, the fine wood chip size is 160-200 mesh; the wax module coated with the surface sand is dried for 12-18h, preferably 15h;

(4) preparation of back layer coating, mixing attapulgite powder, mullite powder, crop straw fiber, ethyl silicate hydrolyzate to obtain a back layer coating, the attapulgite powder particle size is 240 mesh, Molai The stone particle size is 240 mesh, the straw fiber diameter of the crop is 2-3 mm, and the silica content of the ethyl silicate hydrolyzate is 20%. The weight ratio of the above coating components is: attapulgite powder: mullite powder: crop straw Fiber: ethyl silicate hydrolyzate = (350-500): (1800-2000): (50-120): (2-4);

(5) Hanging the sand, immersing the dried wax module in step (3) into the back coating tank, and then taking it out, blowing it to the surface under rotation to make it evenly coated, the blowing time is 40s -80s, preferably 60s; then sprinkle back sand on the surface under rotating conditions, the back sand component is mullite coarse powder and crop straw fiber, and the weight ratio is mullite coarse powder: crop straw fiber =(10-15):1, the particle size of the mullite coarse powder is 40-60 mesh, the diameter of the crop straw fiber is 4-6 mm; the wax module coated with the back sand is dried for 12-18 h, preferably 15 h;

(6) repeating step (4) and step (5) 2-4 times until the thickness of the mold shell reaches 6-10 mm, preferably 8 mm, and is dried after sealing;

(7) The mold shell after the step (6) is dried by steam dewaxing and calcined, and the furnace is cooled to obtain an environmentally friendly casting material.

Compared with the prior art, the invention adopts fine wood chips and crop straw fiber as the shell material, reduces the use amount of the refractory material, is beneficial to environmental protection, and adopts a reasonable ratio, and increases the ventilation under the premise of ensuring the strength of the shell. The attapulgite in the back layer coating is a porous material, which is favorable for exhausting, reduces the porosity defects of the casting, increases the yield, and at the same time reduces the weight of the mold shell, and the raw materials are easily available.

detailed description

The present invention will be further described below in conjunction with specific embodiments.

Example 1:

(1) preparing a wax mold, preparing a corresponding wax mold, a pouring system, a riser according to the shape of the casting to be obtained, and bonding into a wax module;

(2) preparation of the top layer coating, using ethyl silicate as a binder, mixing fine corundum powder, ethyl silicate, fine wood chips, n-butanol and cobalt aluminate to obtain a surface coating, the fine The corundum powder has a particle size of 300 mesh and the fine wood particle size is 240 mesh. The weight ratio of the above coating components is: fine corundum powder: ethyl silicate: fine wood chips: n-butanol: cobalt aluminate=1800:140:100: 1:2;

(3) Noodle sand: The wax module is immersed in the top coating pool, then taken out, and blown to the surface under rotation to make it evenly coated, the blowing time is 30 s; then under rotating conditions The surface is sprinkled with sand, the surface sand is made of alumina sand and fine wood chips, and the weight ratio is alumina sand: fine wood chips = 10:1, alumina sand has a particle size of 80 mesh, fine wood chips The particle size is 160 mesh; the wax module coated with the facial sand is dried 12;

(4) preparation of back layer coating, mixing attapulgite powder, mullite powder, crop straw fiber, ethyl silicate hydrolyzate to obtain a back layer coating, the attapulgite powder particle size is 240 mesh, Molai The stone particle size is 240 mesh, the straw fiber diameter of the crop is 2-3 mm, and the silica content of the ethyl silicate hydrolyzate is 20%. The weight ratio of the above coating components is: attapulgite powder: mullite powder: crop straw Fiber: ethyl silicate hydrolyzate = 350: 1800: 50: 2;

(5) Hanging the sand, immersing the dried wax module in step (3) into the back coating tank, and then taking it out, blowing it to the surface under rotation to make it evenly coated, the blowing time is 40s -80s; then sprinkle sand on the surface under rotating conditions, the back sand component is mullite coarse powder and crop straw fiber, the weight ratio is mullite coarse powder: crop straw fiber = 10:1 The particle size of the mullite coarse powder is 40 mesh, and the diameter of the straw fiber of the crop is 4 mm; the wax module coated with the back sand is dried for 12 hours;

(6) repeating step (4) and step (5) 2-4 times until the thickness of the mold shell reaches 6 mm, and drying after sealing;

(7) The mold shell after step (6) is dried by steam dewaxing, the dewaxing pressure is 0.4 MPa, the dewaxing time is 6 min, sent to a high temperature resistance furnace, and the temperature is raised to a temperature increase rate of 2 ° C / min to 300 ° C, heat preservation 1.5h, then heat up to 750 ° C at 6 ° C / min heating rate, heat 1.5h, then heat up to 1100 ° C at 2 ° C / min heating rate, heat 4h, with the furnace cooling, get environmentally friendly casting materials .

Example 2:

(2) preparation of the top layer coating, using ethyl silicate as a binder, mixing fine corundum powder, ethyl silicate, fine wood chips, n-butanol and cobalt aluminate to obtain a surface coating, the fine The corundum powder has a particle size of 300 mesh and the fine wood particle size is 240 mesh. The weight ratio of the above coating components is: fine corundum powder: ethyl silicate: fine wood chips: n-butanol: cobalt aluminate=2000:160:200: 2:5;

(3) Noodle sand: The wax module is immersed in the top coating pool, then taken out, and blown to the surface under rotation to make it evenly coated, the blowing time is 60 s; then under rotating conditions The surface is sprinkled with sand, the surface sand is made of alumina sand and fine wood chips, and the weight ratio is alumina sand: fine wood chips = 15:1, alumina sand has a particle size of 100 mesh, fine wood chips The particle size is 200 mesh; the wax module coated with the surface sand is dried for 18 hours;

(4) preparation of back layer coating, mixing attapulgite powder, mullite powder, crop straw fiber, ethyl silicate hydrolyzate to obtain a back layer coating, the attapulgite powder particle size is 240 mesh, Molai The stone particle size is 240 mesh, the straw fiber diameter of the crop is 3 mm, and the silica content of the ethyl silicate hydrolyzate is 20%. The weight ratio of the above coating components is: attapulgite powder: mullite powder: crop straw fiber: Ethyl silicate hydrolyzate = 500:2000:120:4;

(5) Hanging the sand, immersing the dried wax module in step (3) into the back coating tank, and then taking it out, blowing it to the surface under rotation to make it evenly coated, the blowing time is 80s Then, the sand is sprinkled on the surface under the rotating condition. The back sand component is mullite coarse powder and crop straw fiber, and the weight ratio is mullite coarse powder: crop straw fiber=15:1, Mo The particle size of the rough stone powder is 60 mesh, and the diameter of the straw fiber of the crop is 6 mm; the wax module coated with the back sand is dried for 18 hours;

(6) repeating step (4) and step (5) 2-4 times until the thickness of the mold shell reaches 10 mm, and drying after sealing;

(7) The mold shell after the step (6) is dried by steam dewaxing, the dewaxing pressure is 0.8 MPa, the dewaxing time is 8 min, and sent to a high temperature electric resistance furnace, and the temperature is raised to a heating rate of 4 ° C / min to 450 ° C, holding for 1.5h, then heating to 800 ° C at a heating rate of 10 ° C / min, 1.5 h, followed by heating at 4 ° C / min to 1250 ° C, 4 h, with the furnace cooling, to obtain environmentally friendly casting materials .

Claims

A method for preparing an environmentally friendly casting material, comprising the steps of:

(1) preparing a wax mold, preparing a corresponding wax mold, a casting system and bonding into a wax module according to the shape of the desired casting, and a set of casting system with four castings;

(2) preparation of the top layer coating, the fine corundum powder, ethyl silicate, fine wood chips, n-butanol, cobalt aluminate are mixed and stirred to obtain a surface coating, the fine corundum powder has a particle size of 300 mesh, fine wood particle size For 240 mesh, the weight ratio of the above coating components is: fine corundum powder: ethyl silicate: fine wood chips: n-butanol: cobalt aluminate = 1900: 150: 150: 1.5: 2;

(3) noodles sand: the wax module is immersed in the surface coating pool, and then taken out, and the surface is blown to make it evenly coated under rotating conditions, the blowing time is 30s-60s, preferably 40s; Subsequently, the surface sand is sprinkled under the rotating condition, the surface sand component is alumina sand and fine wood chips, and the weight ratio is alumina sand: fine wood chips = (10-15): 1, alumina sand The particle size is 80-100 mesh, the fine wood chip size is 160-200 mesh; the wax module coated with the facial sand is dried for 12-18h, preferably 15h;

(4) preparation of back layer coating, mixing attapulgite powder, mullite powder, crop straw fiber, ethyl silicate hydrolyzate to obtain a back layer coating, the attapulgite powder particle size is 240 mesh, Molai The stone particle size is 240 mesh, the straw fiber diameter of the crop is 2-3 mm, and the silica content of the ethyl silicate hydrolyzate is 20%. The weight ratio of the above coating components is: attapulgite powder: mullite powder: crop straw Fiber: ethyl silicate hydrolyzate = (350-500): (1800-2000): (50-120): (2-4);

(5) Hanging the sand, immersing the dried wax module in step (3) into the back coating tank, and then taking it out, blowing it to the surface under rotation to make it evenly coated, the blowing time is 40s -80s, preferably 60s; then sprinkle back sand on the surface under rotating conditions, the back sand component is mullite coarse powder and crop straw fiber, and the weight ratio is mullite coarse powder: crop straw fiber =(10-15):1, the particle size of the mullite coarse powder is 40-60 mesh, the diameter of the crop straw fiber is 4-6 mm; the wax module coated with the back sand is dried for 12-18 h, preferably 15 h;

(6) repeating step (4) and step (5) 2-4 times until the thickness of the mold shell reaches 6-10 mm, preferably 8 mm, and is dried after sealing;

(7) The mold shell after the step (6) is dried by steam dewaxing and calcined, and the furnace is cooled to obtain an environmentally friendly casting material.