JPS6041020B2 - Alumina ceramic with high strength and hardness - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alumina ceramic having both high strength and high hardness.

In general, alumina ceramics have high hardness and excellent wear resistance, corrosion resistance, and electrical insulation properties, so they are used in cutting tools, corrosion-resistant and wear-resistant parts such as various nozzles, and insulating substrates. Used in manufacturing.

However, although this conventional alumina-based ceramic has high hardness as mentioned above, it has poor plowability and has a hardness of 30 to 50k9/
It has a low anti-resistance strength comparable to that of a rock, so although it has future potential, it is actually only used in fields where tensile stress or impact force is not applied much.
Therefore, it is desirable to improve the rutting property of the alumina ceramic and increase its strength, thereby making it possible to apply it in a wide range of fields.
One TIC-based ceramic was proposed, and indeed this AI2
03-TIC ceramics have a high bending strength of about 60 to 90k9/mau, which is a turning point in the field of application, as they can now be used in applications where impact forces are applied, such as cutting edges for milling. It was something that brought about this.

However, this AI2Q-TIC ceramic
For example, when used as a cutting tool, the reliability against chipping of the cutting edge is somewhat lacking, and therefore there is a problem when using it as a cutting tool in an automatically operated machine tool. From the above-mentioned viewpoint, the present inventors conducted research to solve the problems of conventional alumina ceramics and thereby obtain alumina ceramics with high hardness, high strength, and high quality. a - One or more types of carbides, nitrides, and carbonitrides of Ti, Zr, and Hf (hereinafter, these are collectively referred to as Tj, Zr, and Hf charcoal/chamber) to the alumina ceramic. Addition of compounds (called compounds) improves the sardine properties and improves strength.

[b- When the ceramic described in item 'a' above contains one or more of Ca, Y, and oxides of rare elements, these components promote competitive striations. Because it also acts as a retaining agent to suppress grain growth,
Improved sardine quality and strength.

'c) When zirconium oxide (hereinafter referred to as 2 in Z) is added to the ceramic in item 'b' above, the rutting property is further improved, but on the other hand, the hardness is decreased. Therefore, when this is used as a cutting tool, for example, chipping occurs at the cutting edge when cutting hard work materials such as chilled rolls.

[d- However, when aluminum nitride (hereinafter referred to as mountain N) is added to the ceramic of [c-] above,
Hardness increases without loss of toughness, and as a result, even when used as a cutting tool to cut hard work materials, the cutting edge does not chip and provides extremely stable cutting. Become possible.

[e- In addition to the ceramic of [d' item above], V, Nb
, and one or more of the group consisting of Ta carbides, nitrides, and carbides, and Cr and W carbides (hereinafter, these are collectively referred to as V, Nb, Ta, C
When R, and W (referred to as carbon/nitride) are added, the plowability and hardness are further improved.

'f' Furthermore, one or two of Mo and molybdenum carbide (hereinafter referred to as Mo2C) are added to each of the ceramics shown in the above 'd} and [e' terms],
When Ni is added and contained, rice grain properties are further improved.

The findings shown in the above terms 'a} to [f} have been obtained.

This invention has been made based on the above findings, and includes one or more of oxides of mountain N: 0.5 to 5%, ZrO2: 1 to 20%, Ca, Y, and rare elements. Contains two or more types (hereinafter collectively referred to as sintering aid components): 0.1 to 3%, carbon/nitrides of Ti, Zr, and Hf: 2 to 30%, and further contains as necessary. Accordingly, V,
Carbon/nitride of Nb, Ta, Cr, and W: 0.02~
15%, and further, if necessary, one or two of Mo and MQC: 0.1 to 3%,
Contains 0.5 to 3% Ni, with the remainder consisting of aluminum oxide (hereinafter indicated by ridge 203) and unavoidable impurities (all % by volume and % below all mean % by volume). , high hardness, high strength,
It is characterized by alumina-based ceramics having high rice grain properties.

Next, the reason for limiting the component composition range as described above in the ceramic of the present invention will be explained. 'a-NN The NN component has the effect of reducing the surface energy of N203, suppressing grain growth, preventing the decrease in hardness brought about by the addition of Zr02, and improving rice grain quality. If the content is less than 0.5%, the desired effect cannot be obtained; on the other hand, if the content exceeds 5%, nests are likely to occur in the compact, which causes a decrease in strength. The content was determined to be 0.5 to 5%.

'b) Zr○2 In the Zn2 component, Zr02 itself transforms from tetragonal to monoclinic in the cooling process after competitive bonding, and the volume change at this time causes fine cracks in the grain boundaries of peaks 203. Even if a large crack occurs in the ceramic during use, the stress at the tip is relaxed by the fine cracks, so the large crack can be prevented from propagating. If the content is less than 1%, the desired effect cannot be obtained; on the other hand, if the content exceeds 20%, many fine cracks will be present in the ceramic, which will actually lead to a decrease in quality. Not only does this increase the hardness, but also the hardness decreases significantly, so the content was set at 1 to 20%.

'c' Dawn coagulation aid component These components promote the dawn supply of AI203 and contain N.
It has a uniform effect of suppressing the grain growth of No. 203 and thereby improving toughness and strength, but if the soil content is less than 0.1%, the desired effect cannot be obtained, whereas if the soil content exceeds 3%, the desired effect cannot be obtained. If this is done, the amount of brittle glass phase or spinel phase generated at the grain boundaries of AI203 grains will increase, resulting in a decrease in strength.
%.

'd' Ti, Zr, and Hf carbon/nitride These components have a uniform effect of significantly suppressing grain growth of AI203 and thereby improving strength and hardness, but when the content is 2% If the content is less than 30%, the desired effect cannot be obtained, while if the content exceeds 30%, the coagulation property will decrease and it will be difficult to obtain a dense Akatsuki compact. It was set at ~30%. {c-V, Nb, Ta, Cr,
and W carbon/nitride These components have the same effect of further increasing strength and hardness, so these properties are strong and they are added as required, but if the content is 0.
．． If the content is less than 0.02%, the desired effect of improving the above-mentioned action cannot be obtained, while if the content exceeds 15%, the silkiness will deteriorate, so the content is set at 0.02 to 15%. Ta.

{f' Mo, Mo2C, and Ni Mo and Mo2C components, in coexistence with Ni, uniformly disperse Ni in the ceramic and improve the scaling property as well as improve the strength of the ceramic, while the Ni component
It assists the grain quality improvement effect of 2, and contributes to improving the grade of ceramic, which is a brittle body, and this quality improvement effect is due to M
Since it has the effect of mutually improving the coexistence with Mo and Mo2C, it is added and contained especially when high strength and high axiality are required.
When the content of 2C is less than 0.1% and the content of Ni is less than 0.5%, the desired effect of improving the above action cannot be obtained.
If the content exceeds Mo and Mo2C: 3% and Nj: 3%, the crystallization property will deteriorate, so the respective contents are set to Mo and Mo2C: 0.1 to 3%, Ni:
It was set at 0.5-3%.

In addition, the ceramic of the present invention can be produced by using conventional powder metallurgical methods, especially two of the carbon/nitrides of Ti, Zr, and Hf, and the carbon/nitrides of V, Nb, Ta, Cr, and W. When containing more than 1 species, these solid solution powders may be used as raw material powders, and a green compact formed from a mixed powder with a predetermined composition is sintered in a non-oxidizing atmosphere or in a vacuum. It is best manufactured by hot isostatic pressure firing after forming a non-porous sintered silk body, and it can also be manufactured by hot pressing the above mixed powder in a similar atmosphere. .

Next, the alumina-based ceramic of the present invention will be explained using examples and comparing with comparative examples. As raw material powder, Q-Yama 203 powder having an average particle size of 0.4 mm, same as 1.
Ca○, Y203, La203, each having needle N powder of 1 mm and needle Z of 0.8 μm, both having needles of 0.3 mm.
, and Ce203 powder, both of which are 1.3 to 1
．． TIC, ZrC, with an average particle size within the range of 8 mm
HfC, TIN, ZrN, Hikake, TICN, ZnON,
HICN, VC, NbC, TaC, VN, NbN, Ta
N, TaCN, VCN, NbCN, TaCN, Cr3C
2, WC and Mo2C powder, 1.5 mountain m of Mo
Prepare 2.1m of Ni powder, mix these raw powders to the composition shown in Table 1, add methyl alcohol as a solvent, mix in a ball mill for 3 days, and dry. , in a nutritious atmosphere, temperature: 1
Ceramic 1 of the present invention, which has substantially the same final component composition as the blended composition, is produced by hot pressing at 700°C, pressure: 200k9/h, and holding time: 30 minutes.
~1 & comparative ceramics 1-8, and subordinate ceramics 1
, 2 were manufactured, respectively. In addition, comparative ceramics 1 to 8
All of these have compositions in which the content of one of the constituent components (marked with * in Table 1 and listed in Table 1 and Table 2) is outside the scope of the present invention.

Transverse rupture strength was measured for the obtained ceramics of the present invention 1 to 18, comparative ceramics 1 to 8, and conventional ceramics 1 and 2 for the purpose of evaluating the theoretical density ratio, Rockwell hardness (A scale), and strength. As a result, the results shown in Table 2 were obtained.

As shown in Table 2, inventive ceramics 1 to 18 all have extremely high density, hardness, and strength, whereas comparative ceramics 1 to 8 have at least one of these properties. Furthermore, it is clear that Ceramics 1 to 18 of the present invention all have superior strength compared to conventional ceramics.

Next, regarding the present invention ceramics 1 to 18 and conventional ceramics 1 and 2, workpiece material: chilled roll (Shore hardness 84), chip shape: SNG432 (chamber honing: 0.1 skin x -25o), cutting speed: 5 enemy h/m
A cutting test was conducted under the following conditions: in, feed: 0.2 skin/rev, depth of cut: 0.5 skin, and cutting time: Shin, and the number of chipping occurrences among 5 mysterious cutting edges was measured.

These results are shown in Table 2. As is clear from the results shown in Table 2, the ceramic of the present invention exhibits excellent cutting performance without any occurrence of chipping, whereas most conventional ceramics exhibit chipping and It was less reliable.

As mentioned above, the alumina ceramic of the present invention has high hardness, high strength, and high quality, so it can be applied in a wide range of fields such as cutting tools, corrosion-resistant and wear-resistant parts such as various nozzles, and insulating substrates. It is possible, and moreover, when used, it has industrially useful properties such as extremely excellent performance.

Claims (1)

[Claims] 1 Aluminum nitride: 0.5 to 5%, Zirconium oxide: 1 to 20%, One or more of Ca, Y, and rare earth element oxides: 0.1 to 3 %, one or two of carbides, nitrides, and carbonitrides of Ti, Zr, and Hr
An alumina-based ceramic having high strength and hardness, characterized in that it has a composition consisting of 2 to 30% of carbon dioxide and more, and the remainder (volume % or more) of aluminum oxide and unavoidable impurities. 2 Aluminum nitride: 0.5-5%, Zirconium oxide: 1-20%, Ca, Y, and one or more of oxides of rare earth elements: 0.1-3%, Ti, Zr, and one or two of carbides, nitrides, and carbonitrides of Hf
Seed: 2 to 30%, one or more of the group consisting of carbides, nitrides, and carbonitrides of V, Nb, and Ta, and carbides of Cr and W: 0.02 to 15
%, aluminum oxide and unavoidable impurities: The remainder is (volume % or more) an alumina-based ceramic having high strength. 3 Aluminum nitride: 0.5-5%, Zirconium oxide: 1-20%, Ca, Y, and one or more oxides of rare earth elements: 0.1-3%, Ti, Zr, and one or two of carbides, nitrides, and carbonitrides of Hf
More than one species: 2 to 30%, one or two of Mo and molybdenum carbide: 0.1 to 3%, Ni: 0.5 to 3%
, aluminum oxide and unavoidable impurities: an alumina-based ceramic having high strength and high hardness, the remainder being (more than % by volume). 4 Aluminum nitride: 0.5-5%, Zirconium oxide: 1-20%, Ca, Y, and one or more of oxides of rare earth elements: 0.1-3%, Ti, Zr, and one or two of carbides, nitrides, and carbonitrides of Hf
Species or more: 2 to 30%, carbides of V, Nb, and Ta,
One or more of the group consisting of nitrides, carbonitrides, and carbides of Cr and W: 0.02 to 15
%, one or two of Mo and molybdenum carbide: 0.1 to 3%, Ni: 0.5 to 3%, aluminum oxide and unavoidable impurities: the remainder (or more by volume %). Alumina ceramic with high strength and hardness.