JPH0686332B2 - Manufacturing method of sialon-based ceramic tool for cutting cast iron - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has high strength and high toughness, and also has excellent wear resistance, and is particularly suitable for use as a cutting tool for cutting cast iron. The present invention relates to a method for manufacturing a ceramic tool.

[Conventional technology]

Conventionally, a sialon-based ceramic tool has been used as a cutting tool for cutting cast iron, and this sialon-based ceramic tool has an average particle size of 0.7 to 1.5 μm prepared as raw material powder.
With a silicon nitride (hereinafter, referred to as Si ₃ N ₄ ) powder having a mean particle size of 2 μm or less, and titanium nitride (hereinafter, referred to as TiN) powder as a grain growth suppressing component: 5 to 30
% By weight (hereinafter% means% by weight) and aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) powder as a sialon forming component, or Al ₂ O ₃ powder and aluminum nitride (hereinafter referred to as AlN) powder, or Al ₂ O ₃ powder and Si ₃ N ₄ -Al ₂ O _{3 in} Fig. 1
Sialon intermediate powder such as 21R powder or 8H powder in -SiO ₂ -AlN4 ternary phase diagram: a 1-20%, (indicated by Y ₂ O ₃₎ oxide yttrium as binder phase forming component powder, magnesium oxide (hereinafter (Indicated by MgO) and one or more of rare earth element oxide powders: 0.5 to 15% are mixed, mixed and pressed into a green compact, and then in a nitrogen atmosphere at 1 atm or more. , Manufactured by sintering at a temperature of 1700-1800 ° C.

[Problems to be solved by the invention]

However, in the above conventional sialon-based ceramic tool, TiN is used for the purpose of suppressing grain growth of sialon crystals.
However, its effect is still insufficient and satisfactory high strength and high toughness have not been obtained.As a result, even in continuous cutting of cast iron, in continuous cutting, the service life is reached in a relatively short time, and there are intermittent interruptions. The current situation is that the cutting blade feed is relatively small in cutting.

[Means for solving problems]

Therefore, the present inventors, from the above viewpoints, as a result of conducting research to improve the strength and toughness of the conventional sialon-based ceramic tool, the average particle size: 1μ
the Si ₃ N ₄ powder having the following m, isopropyl orthotitanate {Ti [(CH _{3) 2} · CHO] _4}, titanium ethoxide _{{Ti (OC 2 H 5)} 4}, or titanium octadecyl oxide {Ti [ A Ti-alkoxide such as CH ₃ (CH ₂ ) ₁₇ O] ₄ is mixed in a proportion of ₃ to 15% in terms of TiN, and then agglomerates (secondary particles) of the Si ₃ N ₄ powder are loosened to obtain a fine powder. In order to distribute in the state of, mix with crushing action is carried out, and this is 1000 to 1250 ℃ in a nitrogen atmosphere of 1 atm or more.
When Si ₃ N ₄ powder having a surface coated with a TiN layer, which is produced by heat treatment at a temperature of
The coating layer significantly suppresses the grain growth of sialon crystals, and the tool has a fine structure in combination with the fine Si ₃ N ₄ powder having an average grain size of 1 μm or less, which results in high strength and high toughness. We have obtained the knowledge that it will have excellent wear resistance, and that it will exhibit excellent cutting performance when used as a cutting tool for cast iron.

The present invention has been made based on the above findings, and the Si ₃ N having an average particle diameter of 1 μm or less prepared as a raw material powder is used.
_{3 to 4} powders with Ti-alkoxide converted to TiN
After blending and mixing 15%, in a nitrogen atmosphere of 1 atm or more,
Heat treatment is performed at a temperature of 1000 to 1250 ° C to form Si ₃ N ₄ powder whose surface is coated with TiN. Then, this surface-coated Si ₃ N ₄ powder is mixed with Al ₂ O ₃ powder as a sialon forming component. , Or Al ₂ O ₃ powder and AlN powder, or Al ₂ O ₃ powder and sialon intermediate powder: 1 to 20%, Y ₂ O ₃ powder as a binder phase forming component, MgO powder, and oxide powder of rare earth element One or more of the above: 0.5-
After blending and mixing 15%, press-molding into green compact, 1
Sintering at a temperature of 1700 to 1800 ° C in a nitrogen atmosphere at atmospheric pressure or higher (in this case, it is possible to carry out sintering at a low temperature using the hot press method or HIP method), It is characterized by a method of producing a sialon-based ceramic tool for cutting cast iron which has high toughness and excellent wear resistance.

Next, the reason why the manufacturing conditions are limited as described above in the method of the present invention will be described.

(A) Si ₃ N ₄ gives the particle size of the average particle size ceramic sialon crystal powder Si ₃ N ₄ Effect of particle size of the powder is large, the average particle size the Si ₃ N ₄ powder is 1μm
If it exceeds, it is not possible to secure a fine structure in the ceramic after sintering, so the average grain size was defined as 1 μm or less.

(B) Ti-alkoxide compounding amount If the compounding amount is less than 3%, the TiN coating layer is not sufficiently formed and the desired grain growth suppressing effect cannot be obtained.
If it exceeds 15%, the TiN content in the ceramic tool becomes too large, resulting in a decrease in strength and toughness. Therefore, the content was determined to be 3 to 15%.

(C) Heat treatment conditions In order to form the TiN coating layer on the surface of the fine Si ₃ N ₄ powder as uniformly as possible, it is preferable that the heat treatment is performed at a relatively low temperature for a long period of time. If the atmospheric pressure is less than 1 atm or the temperature is less than 1000 ° C, the reaction is too slow to be practical, while if the temperature exceeds 1250 ° C, the reaction proceeds too fast and TiN easily aggregates. Not only this, but also grain growth is likely to occur, so the conditions were set to a nitrogen atmosphere pressure of 1 atm or higher and a temperature of 1000 to 1250 ° C.

(D) Other conditions The average particle size of the raw material powders other than the Si ₃ N ₄ powder is set to 2 μm or less, because if the average particle size exceeds 2 μm, it becomes difficult to manufacture a ceramic having a fine structure. The content of the sialon-forming component was limited to 1 to 20% because the formation of sialon was insufficient if the content was less than 1%, while if the content exceeded 20%, The reason for this is that the ceramic component will be left in a large amount and the ceramic characteristics will deteriorate, and the content of the binder phase forming component was further limited to 0.5 to 15%.
If the content is less than 0.5%, the amount of liquid phase during sintering is too small and the sintering does not proceed, while if it exceeds 15%, the glass phase formed during sintering increases. This is because it becomes too soft and the strength is lowered.

The sintering conditions are ordinary conditions, and by satisfying these conditions, a desired ceramic tool can be manufactured.

〔Example〕

Next, the method of the present invention will be specifically described by way of Examples.

First, Si ₃ N ₄ powder having an average particle size of 0.7 μm was used, and from this, the surface-coated Si ₃ N ₄ powder was used under the conditions shown in Table 1.
A powder is produced, which is then combined with this surface-coated Si ₃ N ₄ powder, both having a mean particle size in the range from 0.6 to 1 μm and of the sialon-forming components and binder phase-forming powders of the type shown in Table 1. As the raw material powder, and
By blending to the blending composition shown in the table, wet mixing for 72 hours in a ball mill and drying, press-molding into a green compact under normal conditions, and then sintering under the same conditions as shown in Table 1. Then, the ceramic tools 1 to 10 of the present invention were manufactured.

For the purpose of comparison, Daitsute the surface coating Si ₃ N ₄ powder, average particle diameter: Si ₃ N ₄ powder having a 0.7 [mu] m, and the 2μm of T
Using iN powder, and further using the above-mentioned sialon forming powder and binder phase forming powder, these were compounded to the compounding compositions shown in Table 2 and wet-mixed for 72 hours in a ball mill,
After drying, the conventional ceramic tools 1 to 3 were respectively manufactured by press-molding into a green compact under normal conditions and then sintering under the conditions shown in Table 2. I made it.

Next, the present invention ceramic tools 1 to 10 obtained as a result
For the purpose of evaluating the strength and toughness of the conventional ceramic tools 1 to 3, the JIS standard three-point bending resistance was measured, and the work material: FC25 round bar, cutting speed: 350 m / min, feed: 0.45 mm / rev., Cast iron continuous high-speed cutting test under conditions of depth: 2 mm, Work material: FC25 square bar, Cutting speed: 150 m / min, Feed: change, depth of cut: Cast iron under conditions of 2 mm An intermittent cutting test was performed. In the former test, the cutting time until the flank wear width of the cutting edge reaches 0.3 mm was measured, and in the latter test, the feed amount at which the cutting edge was broken was measured. The results are shown in Table 3.

〔The invention's effect〕

From the results shown in Table 3, the ceramic tools of the present invention 1 to
It is clear that all of 10 show higher strength and toughness than the conventional ceramic tools 1 to 3, and further show excellent cutting performance even when cutting cast iron.

As described above, according to the method of the present invention, using Ti-alkoxide, by using the Si ₃ N ₄ powder whose surface is coated with TiN as a raw material powder, it has high strength and high toughness, In addition, it is possible to manufacture sialon-based ceramic tools with excellent wear resistance, and especially when it is used as a cutting tool for cutting cast iron, it is industrially useful, such as exhibiting excellent cutting performance over a long period of time. The effect is brought about.

[Brief description of drawings]

FIG. 1 is a quaternary phase diagram of Si ₃ N ₄ —Al ₂ O ₃ —SiO ₂ —AlN.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Koyama 1-297 Kitabukuro-cho, Omiya City, Saitama Prefecture Central Research Laboratory, Mitsubishi Metals Co., Ltd. (56) Reference JP-A-59-3073 (JP, A)

Claims (1)

[Claims] 1. A silicon nitride powder having an average particle size of 1 μm or less prepared as a raw material powder is mixed with 3 to 15% by weight in a ratio of Ti-alkoxide converted to titanium nitride, and after mixing, 1
In a nitrogen atmosphere at atmospheric pressure or higher, heat treatment is performed at a temperature of 1000 to 1250 ° C. to form a silicon nitride powder whose surface is coated with titanium nitride. Then, the surface-coated silicon nitride powder has an average particle size of Diameter: 2 μm or less, aluminum oxide powder as a sialon forming component, aluminum oxide powder and aluminum nitride powder, or aluminum oxide powder and sialon intermediate powder: 1 to 20 wt% and yttrium oxide as a binder phase forming component Powder, magnesium oxide powder, and rare earth element oxide powder, one or more kinds: 0.5 to 15% by weight are mixed, mixed and pressed into a green compact, and then a nitrogen atmosphere of 1 atm or more Medium, 1700-18
A method for producing a sialon-based ceramic tool for cutting cast iron having high strength and high toughness, characterized by sintering at a temperature of 00 ° C.