JPH01179759A - Ceramic member for cutting tool - Google Patents

Abstract

PURPOSE:To obtain a ceramic member for a cutting tool capable of exhibiting excellent cutting performance for a long period by allowing both aluminum oxide and oxide of Mg, Y or Zr to be incorporated and allowing the balance to consist of double carbide of Ti and Hf at a specified rate. CONSTITUTION:The title ceramic member incorporates 10-45wt.% aluminum oxide and 0.5-8wt.% one or more kinds selected from among oxides of Mg, Y and Zr and consists of the balance 51-90wt.% double carbide of Ti and Hf and inevitable impurities and the above-mentioned double carbide of Ti and Hf has composition satisfying (2/8-9.5/0.5) Ti/Hf by weight ratio. This double carbide of Ti and Hf has action for improving thermal shock resistance of the member and furthermore has action for keeping hardness and wear resistance of the member in a high state by holding fine particles size even after sintering. However since the above-mentioned actions can not be recognized in the content less than 51% and on the other hand, when the content exceeds 90%, wear resistance at a time of high-speed cutting in a dry state is especially lowered, the content is regulated to 51-90%.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention is applicable to cast iron and steel, especially general cast iron and ductile cast iron that require high strength, excellent wear resistance and thermal shock resistance. The present invention relates to a ceramic member that exhibits excellent cutting performance when used as a cutting tool in wet cutting at a cutting speed of .

[Conventional technology]

Conventionally, when cutting general cast iron, WCC cemented carbide parts were used at cutting speeds of 200 rn/min or less, or 200 m/min.
At high speeds higher than n, aluminum oxide (hereinafter referred to as Ag2O3
The A11203-based ceramic members are used as cutting tools, and although the conditions of use are limited because the A11203-based ceramic members do not have sufficient strength, they can also be used for cutting ductile cast iron. It is well known.

[Problem that the invention seeks to solve]

However, the cutting speed of the above WCC cemented carbide member is 200%.
If the tool is used at a high speed of 250 m/min or higher, the tool life will be significantly shortened, and if the cutting speed is 250 m/min or higher, it will not be practical. Attempts have been made to perform high-speed cutting, but in this case chipping and chipping are likely to occur, and although Aρ203-based ceramic members are suitable for high-speed cutting, they do not have sufficient strength. Because of this, chipping is likely to occur when cutting with a large depth of cut, and chipping is likely to occur during wet cutting due to strong thermal shock during cutting.Furthermore, even when wet cutting ductile cast iron, which has high strength, chipping is likely to occur. There are problems such as the inability to put it into practical use.

[Means for solving problems]

Therefore, from the above-mentioned viewpoint, the present inventors have determined that the cutting speed of general cast iron and ductile cast iron in particular is 200 rn/mi.
As a result of our research to develop a material for cutting tools that exhibits excellent cutting performance not only in cutting at n or higher, but also in wet cutting, we found that, in weight% (hereinafter % indicates weight%), A II! 20 a ・10 to 45%, one of the oxides of Mg, Y, and Zr (hereinafter referred to as MgO, YO, and ZrO2, respectively, and collectively referred to as metal oxides) species or two or more species, 0.5 to 8%, and the remainder consists of 51 to 90% of a double carbide of Ti and Hf [hereinafter referred to as (Ti, Hf)C] and inevitable impurities, and (Ti, Hf')C is a ceramic member having a composition satisfying a weight ratio of Ti/Hf: 2/8 to 9.510.5, which has high strength and excellent wear resistance and thermal shock resistance. However, it has excellent performance when used as a cutting tool for general cast iron, ductile cast iron, and steel that require these characteristics, as well as high-speed dry cutting of steel at a cutting speed of 200 m/ll1 inch or more, as well as high-speed wet cutting. We have obtained knowledge that it will be effective over a long period of time.

Therefore, this invention has been made based on the above knowledge, and the reason why the component composition is limited as described above will be explained below.

(a) Ag2O3 8Ω203 has the effect of improving the wear resistance of parts, but if its content is less than 10%, the desired excellent wear resistance cannot be secured; is 45%
If the content exceeds 10%, the thermal shock resistance particularly in wet cutting will deteriorate, so the content was set at 10% to 45%.

(b) Metal oxides These components have the effect of improving sinterability and significantly increasing the strength of parts, and if their content is less than 0.5%, sintering using the hot press method will not work. Although it is possible to secure high strength, ordinary sintering or sintering using hot isostatic pressing (HIP) method results in insufficient sintering, making it difficult to secure the desired high strength. On the other hand, if the content exceeds 8%, not only the wear resistance but also the chipping resistance will decrease.
Its content was determined to be 0.05 to 8%.

(c) (Ti, Hf)C (Tj, 1Hf)C has the effect of improving the thermal shock resistance of the component, and also maintains its fine grain size even after sintering, increasing the hardness and wear resistance of the component. It has the effect of maintaining a high condition, but if the content is less than 51%, the above effect cannot be confirmed, while if the content exceeds 90%, the wear resistance, especially during high-speed dry cutting, will deteriorate. Therefore, the content was set at 51 to 90%.

In addition, in order to ensure the effects brought about by the above-mentioned (Ti, Hf)C, the ratio (weight ratio) of Ti and Hf in (Ti, Hf')C should be 278 to 9.510.
It is necessary that the ratio is within the range of 9.
．． If it exceeds 510.5, the ratio of Ti will substantially increase too much compared to If, so the ratio of (Ti, Hf
) It becomes difficult to reduce the average particle size of C to 1.5 mm or less and to obtain a dense sintered body, and this tendency becomes noticeable when ordinary sintering method or HIP method is applied. On the other hand, if the ratio is less than 2/8, the Hf ratio increases, resulting in a significant increase in cost, and the effects are saturated and no further improvement effects can be achieved. Note that 0.35 to 0.65 is Ti
/Hf is the most desirable range.

-8- [Example] Next, the ceramic member of the present invention will be explained with reference to an example.

As raw material powders, each has an average particle size of 1.0 μs, and the Ti/Hf weight ratio is 3/7°4/e, respectively.
6/4. 7/3. 9/1. and 1010 6 types of (Ti, Hf)C powder, average particle size: 0.6 Aρ
203 powder, MgO powder of the same one, and Y of the same two
O powder and Zr O2 powder were prepared, and these raw material powders were blended into the composition shown in Table 1, wet pulverized and mixed in a ball mill for 72 hours, dried, and then molded into a green compact. The green compact was sintered under the conditions that the atmosphere at the start of heating was a vacuum, the temperature was raised from 300°C and the atmosphere for sintering was an Ar gas atmosphere of 1 atm or less, and the temperature was maintained at 1770°C for 3 hours. , further in Ar gas atmosphere, pressure crab 1500 atm, temperature: ][i00°C1 holding time:
Ceramic members 1 to 9 of the present invention and comparative ceramic members 1 to 5 having substantially the same composition as the blended composition were manufactured by performing HIP treatment for 1 hour.

In addition, comparative ceramic members 1 to 5 are all made of (Ti
, Hf) The composition or content of the constituent components of C is outside the scope of this invention, and Table 1 does not include * in the relevant place.
Marked.

Next, regarding the various ceramic members obtained as a result, work material: Fe12, cutting speed: 300 m /
min.

Feed: 0.25mm/rev, Depth of cut: 1.5
mm.

A continuous high-speed wet cutting test was conducted on general cast iron under the following conditions: Work material: FCD50, Cutting speed: 210 m/min
.

Feed: 0.25mm/rev, Depth of cut: 1.5
A continuous high-speed wet cutting test of ductile cast iron was conducted under conditions of +n11, and in each test, the cutting time until the flank wear width of the cutting edge reached 0.3 mm was measured.

In addition, if chipping or chipping occurred on the cutting edge during cutting, the usable life was determined to have expired at the time when this occurred, and the cutting time up to that point was indicated.

〔Effect of the invention〕

From the results shown in Table 1, the ceramic member 1 of the present invention
- 9 are all out of the scope of the present invention due to their high strength and either the composition of (Ti, Hf)C or the content of the constituent components, as seen in the ceramic members 1 to 5. It is clear that the desired cutting performance is not exhibited and the usable life is reached in an extremely short period of time.

As mentioned above, the ceramic member of the present invention exhibits excellent cutting performance when used as a cutting tool for not only dry high-speed cutting of cast iron such as general cast iron and ductile cast iron, but also for wet high-speed cutting of steel. It has industrially useful properties such as being able to exhibit its properties for an extremely long period of time.

Claims (1)

[Claims] (1) Contains aluminum oxide: 10-45%, one or more of the oxides of Mg, Y, and Zr: 0.5-8%, and the remainder is 51-90% Ti and The double carbide of Ti and Hf is composed of a double carbide of Hf and unavoidable impurities, and the double carbide of Ti and Hf has a weight ratio of Ti/Hf: 2/8 to 9.5/0.
A ceramic member for a cutting tool, characterized in that it has a composition (the above weight %) that satisfies the following.