JPH04238641A - Slurry for manufacturing lost wax mold - Google Patents

Abstract

PURPOSE:To provide a slurry for manufacturing a lost wax mold without any collapse caused by absorbing moisture and slaking it. CONSTITUTION:This slurry for manufacturing the lost wax mold is obtd. by incorporating 10-40wt.% one or two kinds of colloidal calcium carbonate and colloidal calcium hydroxide, and blending and mixing alkaline water calcium compound sol adjusted to pH:9-11 with ammonia to calcium compound powder composed of one or two kinds of calcium carbonate powder and calcium hydroxide powder so as to become 1/9-4/6 weight ratio.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slurry for producing lost wax molds used for casting high melting point metals such as titanium or titanium alloys.

0002

[Prior Art] Generally, a lost wax mold is known as one of the molds for casting high melting point metals such as Ti or Ti alloys.
First, a wax model with an outer surface shape corresponding to the shape of the casting cavity was made, and one layer of colloidal zirconium oxide powder was poured into the wax model.
Contains 0 to 40% by weight, pH: 3 to 5 with hydrochloric acid etc.
1/9 to 4/6 to acidic aqueous zirconia sol adjusted to
It is immersed in a slurry made by blending and mixing so that it has a weight ratio of
Powder scattering and drying are treated as one step, and this step is performed two or more times to form an inner layer, and similarly, immersion in a silica-based slurry, pulling up, coarse powder scattering, and drying are treated as one step, and this step is performed as one step. It is manufactured by performing two or more steps of forming a backup layer on the outside of the inner layer, dewaxing in an autoclave, and then firing in the air at 1300°C for 5 hours.

However, the surface of Ti or Ti alloy castings produced using such zirconia-based lost wax molds is
There was a problem that it became brittle due to contamination. In order to solve this problem, a method of creating a lost wax mold using calcia (CaO) as a mold material has been proposed in recent years. The binder used when creating a lost wax mold using calcia as a mold material (hereinafter referred to as a calcia-based lost wax mold) is a non-aqueous binder, such as a solution of calcium chloride in ethanol, and a slurry. is produced by incorporating calcia flour into the above binder.

[0004] A wax model having an outer surface shape corresponding to the shape of a casting cavity is immersed in this slurry, pulled up, sprinkled with coarse calcia particles, and then dried. ,
Powder scattering and drying are treated as one step, and this step is performed two or more times to form an inner layer, and similarly, immersion in a silica-based slurry, pulling up, coarse powder scattering, and drying are treated as one step, and this step is performed as one step. A backup layer is formed on the outside of the inner layer by performing two or more steps of
Manufactured by firing at a temperature above. For the above-mentioned dewaxing, a dewaxing method such as heat shock is used instead of using an autoclave that uses steam.
Titanium/Zirconium” Vol. 38, No. 2,
Published April 1990, pages 87-93).

[0005]

[Problems to be Solved by the Invention] The above calcia-based lost wax mold uses a non-aqueous binder, such as calcium chloride dissolved in ethanol, as the binder. If left for a long period of time, it will inevitably absorb moisture from the atmosphere, dissolve and disintegrate, and since the ethanol must be handled at the production site, there are problems such as the danger of ignition.

[0006]

[Means for solving the problem] Therefore, the present inventors
As a result of research to develop a lost wax mold that absorbs moisture from the atmosphere, dissolves it, and does not disintegrate even if left for a long period of time, we found that one of colloidal calcium carbonate and colloidal calcium hydroxide or An alkaline aqueous calcium compound sol containing 10 to 40% by weight of two types (hereinafter referred to as colloidal calcium compounds) and adjusted to pH: 9 to 11 with ammonia is mixed with one of calcium carbonate powder and calcium hydroxide powder.
Calcium compound powder consisting of one or two species (hereinafter referred to as
One or two of calcium carbonate and calcium hydroxide is added to a slurry for manufacturing lost wax molds, which is obtained by mixing calcium compound powder (referred to as calcium compound powder) at a weight ratio of 1/9 to 4/6. The lost wax mold obtained by using it as a scattering particle is
It was discovered that the casting surface was not rough, no collapse due to slaking occurred, and the casting surface of castings cast using this lost wax mold was smooth.

[0007] The present invention was made based on this knowledge, and the colloidal calcium compound was
Contains ~40% by weight, pH: 9-1 with ammonia
The slurry for manufacturing lost wax molds is made by blending and mixing an alkaline aqueous calcium compound sol adjusted to 1 with calcium compound powder at a weight ratio of 1/9 to 4/6. be.

If the content of the colloidal calcium compound contained in the alkaline aqueous calcium compound sol used for producing the slurry for producing lost wax molds of the present invention is less than 10% by weight, sufficient mold strength cannot be ensured; If it exceeds 40% by weight, the calcium compound will aggregate, which is not preferable. Therefore, the content of the colloidal calcium compound was set at 10 to 40% by weight. Also, the pH of the same alkaline aqueous calcium compound sol
The reason why the pH was adjusted to 9 to 11 is that when the pH is less than 9, calcium compounds tend to aggregate;
This is because if the amount of ammonia is exceeded, the amount of ammonia becomes relatively too large, and cracks are likely to occur due to evaporation of ammonia during mold drying. Furthermore, the reason why the alkaline aqueous calcium compound sol and the calcium compound powder are blended at a weight ratio of 1/9 to 4/6 is that if the ratio is less than 1/9, the proportion of the calcium compound powder is too small and is not sufficient. This is because mold strength cannot be ensured, and on the other hand, if the ratio exceeds 4/6, the ratio of calcium compound powder becomes relatively too large and the slurry cannot function adequately.

The present invention will be specifically explained based on examples.

0010

[Example 1] As shown in Table 1, a pH-adjusted alkaline aqueous calcium compound sol containing calcium carbonate was mixed with particle size: -325 so that the composition shown in Table 1 was obtained. Slurries 1 to 5 of the present invention were prepared by blending and mixing calcium compound powders consisting of one or two of mesh calcium carbonate powder and calcium hydroxide powder.

Outer diameter: 5 in slurries 1 to 5 of the present invention
0mm, inner diameter: 44mm, and after pulling it up, sprinkled with coarse calcium compound powder, and naturally drying it in the atmosphere for 3 hours.
The inner layer is formed by repeating this process, and then both are immersed in alumina slurry, pulled up, sprinkled with coarse alumina, and naturally dried in the atmosphere for 1.5 hours. A backup layer was formed by repeating this step, and then dewaxing was performed in an autoclave at a temperature of 150° C. and a pressure of 8 atmospheres. The lost wax mold obtained in this manner was left in the air for 72 hours, and the lost wax mold was checked for collapse due to slaking, and it was confirmed that there was no collapse. Baked under the conditions,
Ti-6% Al was then melted by skull arc melting method.
-4% V molten metal was cast, and the surface roughness of the resulting casting was examined, and the results are shown in Table 2.

0012

[Table 1]

[0013]

[Table 2]

[Example 2] As shown in Table 3, particle size: -325 was added to an alkaline aqueous calcium compound sol containing calcium hydroxide and having adjusted pH so as to have the composition shown in Table 3. Slurries 6 to 10 of the present invention were manufactured by blending and mixing calcium compound powders consisting of one or two of mesh calcium carbonate powder and calcium hydroxide powder.

Using slurries 6 to 10 of the present invention, a lost wax mold was manufactured in exactly the same manner as in Example 1, and after the obtained lost wax mold was left in the air for 72 hours, whether or not it collapsed due to slaking was determined. Molten Ti-6%Al-4%V melted by the skull arc melting method was cast into the fired lost wax mold, and the surface roughness of the resulting casting was examined. The results are shown in Table 4.

[0016]

[Table 3]

[0017]

[Table 4]

[Example 3] As shown in Table 5, a product containing calcium carbonate and calcium hydroxide and p
Particle size: -32 was added to the alkaline aqueous calcium compound sol with adjusted H so as to have the composition shown in Table 5.
Calcium compound powder consisting of one or two of 5-mesh calcium carbonate powder and calcium hydroxide powder is blended and mixed to make slurry 11-1 of the present invention.
5 was manufactured.

Using slurries 10 to 15 of the present invention,
A lost wax mold was manufactured in exactly the same manner as in Example 1, and the resulting lost wax mold was left in the air for 72 hours, and then the presence or absence of collapse due to slaking was checked to confirm that there was no collapse, and the lost wax was fired. A molten Ti-6% Al-4% V melted by the skull arc melting method was cast into a mold, and the surface roughness of the resulting casting was examined. The results are shown in Table 6.

[0020]

[Table 5]

[0021]

[Table 6]

[Conventional Example] A conventional calcia slurry is produced by placing calcia flour in a binder in which 4% by weight of calcium chloride is dissolved in ethanol, and an external shape corresponding to the shape of the casting cavity is formed in this slurry. The wax model containing the wax model was immersed in calcia slurry, pulled up, and then sprinkled with high-purity fused calcia (CaO) powder with a coarse grain size of -325 mesh, and heated in the atmosphere for 30 minutes.
Allowed to air dry for an hour. This slurry immersion, pulling,
Powder scattering and drying are treated as one step, and this step is performed two or more times to form an inner layer, and similarly, immersion in a silica-based slurry, pulling up, coarse powder scattering, and drying are treated as one step, and this step is performed as one step. A backup layer was formed on the outside of the inner layer by carrying out two or more steps, and air-dried for 1.5 hours in the atmosphere. Then, dewaxing was performed using a heat shock method.

[0023] After the conventional calcia lost wax mold obtained in this way was left in the atmosphere for 72 hours, the presence or absence of collapse due to dissolution was examined, and collapse due to dissolution was confirmed on a part of the cavity surface of the mold. It was done.

[0024]

Effects of the Invention: Lost wax molds made using conventional calcia slurry collapse due to slaking when left in the atmosphere for a long time, but as shown in Tables 1 to 6, the present invention It can be seen that the lost wax mold made using the slurry does not collapse due to slaking even if it is left in the air for a long time.

Therefore, when a lost wax mold is made using the slurry of the present invention, since one or both of stable calcium carbonate and calcium hydroxide are used as raw materials, it can be left in the atmosphere for a long period of time. There is no need to worry about absorbing moisture, dissipating, and disintegrating, making it easy to manage at the manufacturing site, and providing excellent industrial effects.

Claims (1)

[Claims] Claim 1: One or two of colloidal calcium carbonate and colloidal calcium hydroxide
Contains 0-40% by weight, and pH: 9-40% by ammonia
The alkaline aqueous calcium compound sol adjusted to a concentration of A slurry for manufacturing lost wax molds characterized by being mixed.