JPH0625036B2 - High toughness chromium carbide sintered body - Google Patents
High toughness chromium carbide sintered bodyInfo
- Publication number
- JPH0625036B2 JPH0625036B2 JP63249788A JP24978888A JPH0625036B2 JP H0625036 B2 JPH0625036 B2 JP H0625036B2 JP 63249788 A JP63249788 A JP 63249788A JP 24978888 A JP24978888 A JP 24978888A JP H0625036 B2 JPH0625036 B2 JP H0625036B2
- Authority
- JP
- Japan
- Prior art keywords
- chromium carbide
- sintered body
- crystals
- high toughness
- carbide sintered
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、高靱性炭化クロム焼結体に関するものであ
る。本発明の焼結体は、加熱炉、均熱炉などの工業用炉
の部材や溶融金属に対し優れた耐食性を備えているため
熱電対の保護管等への使用が期待されるものである。TECHNICAL FIELD The present invention relates to a high toughness chromium carbide sintered body. INDUSTRIAL APPLICABILITY The sintered body of the present invention has excellent corrosion resistance to members of industrial furnaces such as heating furnaces and soaking furnaces, and molten metal, and therefore is expected to be used for protective tubes of thermocouples and the like. .
従来、炭化クロム焼結体は炭化クロムに各種の焼結助剤
を添加して製造されている。焼結助剤としては、Co，F
e，Ni，Ni-pなどの金属粉、ホウ化チタン、ホウ化ジル
コニウムなどの硼化物、炭化タンタル、炭化ホウ素、炭
化ケイ素などの炭化物、酸化アルミニウム、酸化クロ
ム、酸化マグネシウムなどの酸化物、リン化鉄、リン化
コバルト、リン化クロムなどのリン化物、窒化クロム、
窒化チタン、窒化アルミニウムなどの窒化物などが提案
されており、その焼結助剤の添加量は炭化クロムに対し
１０重量％以下で、焼成温度は1,500 ℃以下とされてい
る（特開昭５９−107972号公報）。しかし、この先行技
術によっては炭化クロムの針状結晶を有した焼結体は得
られない。炭化クロム焼結体の組織については、これま
で粗大結晶や粒状の結晶が報告されているが、針状ある
いは柱状の結晶の生成あるいはこれの利用といった例は
見られていない（例えば、“Some properties of Chrom
ium Carbide Ceramic Material”，Nippon Tungsten Re
view Vol.１９（１９８６））。Conventionally, a chromium carbide sintered body is manufactured by adding various sintering aids to chromium carbide. As a sintering aid, Co, F
Metal powders such as e, Ni and Ni-p, borides such as titanium boride and zirconium boride, carbides such as tantalum carbide, boron carbide and silicon carbide, oxides such as aluminum oxide, chromium oxide and magnesium oxide, phosphorus Phosphides such as iron oxide, cobalt phosphide, chromium phosphide, chromium nitride,
Nitride such as titanium nitride and aluminum nitride has been proposed. The amount of the sintering aid added is 10% by weight or less with respect to chromium carbide, and the firing temperature is 1,500 ° C. or less (JP-A-59). -107972). However, a sintered body having acicular crystals of chromium carbide cannot be obtained by this prior art. Coarse crystals and granular crystals have been reported so far with regard to the structure of chromium carbide sintered bodies, but no examples of the formation or utilization of needle-shaped or columnar crystals have been found (for example, "Some properties of Chrom
ium Carbide Ceramic Material ”, Nippon Tungsten Re
view Vol.19 (1986)).
炭化クロム系セラミック材料は、耐酸化性、耐スケール
性に優れていることが知られているが、強度、硬度、破
壊靱性及び耐熱衝撃性に問題があることが指摘されてい
る。そのため用途は加熱炉におけるスキツドレールやス
キツドボタン等に限定されているのが現状である。It is known that chromium carbide-based ceramic materials are excellent in oxidation resistance and scale resistance, but it is pointed out that there are problems in strength, hardness, fracture toughness and thermal shock resistance. Therefore, the application is currently limited to skid rails and skid buttons in heating furnaces.
本発明はこれらの点に鑑み、炭化クロムの微細な針状結
晶を生成させることにより改良することを目的としたも
のである。In view of these points, the present invention aims to improve by forming fine needle-shaped crystals of chromium carbide.
一般的にセラミックスの最大の弱点である機械的あるい
は熱的衝撃改善するために繊維強化法が行なわれてい
る。これは数十μｍ〜数百μｍの長さのウイスカーある
いはより長いフアイバーを焼結体中に均一に分散させる
ものである。この方法でもある程度の効果は得られる
が、ウイスカー使用によるコスト高、均一分散させるこ
との製造上の困難さ等から充分に実用化されているとは
言えない。Generally, a fiber reinforced method is used to improve mechanical or thermal shock, which is the greatest weak point of ceramics. In this method, whiskers having a length of several tens to several hundreds of μm or longer fibers are uniformly dispersed in the sintered body. Although some effects can be obtained by this method, it cannot be said that it has been put to practical use because of the high cost of using whiskers and the difficulty in manufacturing it by uniform dispersion.
本発明は、簡単に炭化クロムの針状結晶を焼結体に生成
させることにより、耐衝撃性、耐熱衝撃性、強度、硬度
等の改善に成功したものである。The present invention succeeds in improving impact resistance, thermal shock resistance, strength, hardness and the like by simply forming acicular crystals of chromium carbide in a sintered body.
即ち、本発明は、炭化クロム９９．５〜５０重量％とＡ
ｌＮ０．５〜５０重量％を含む焼結体であって炭化クロ
ムの微細な針状結晶を有してなることを特徴とする高靱
性炭化クロム焼結体である。That is, according to the present invention, 99.5 to 50% by weight of chromium carbide and A
A high toughness chromium carbide sintered body, characterized in that it is a sintered body containing 0.5 to 50% by weight of 1N and has fine needle crystals of chromium carbide.
以下、さらに詳しく本発明について説明する。The present invention will be described in more detail below.
本発明の焼結体は、炭化クロムとＡｌＮを含有してなる
が、その他の成分、例えばZrB2，TiB2，TIC，SiC等も本
発明の焼結体の機能を損わない範囲であれば含有してい
ても何ら差支えがない。The sintered body of the present invention contains chromium carbide and AlN, but other components such as ZrB 2 , TiB 2 , TIC, SiC, etc. may be used as long as they do not impair the function of the sintered body of the present invention. If it contains, there is no problem.
炭化クロムにはCr3C2，Cr7C3，Cr4C等が存在するが一般
的にはCr3C2が使用される。炭化クロムは純度９９％以
上、平均粒径は５μｍ以下好ましくは１μｍ以下であ
る。ＡｌＮも同様に純度９９％以上、平均粒径１０μｍ
以下好ましくは５μｍ以下である。The chromium carbide exists Cr 3 C 2, Cr 7 C 3, Cr 4 C , etc. but is generally used is Cr 3 C 2. Chromium carbide has a purity of 99% or more and an average particle size of 5 μm or less, preferably 1 μm or less. Similarly, AlN has a purity of 99% or more and an average particle size of 10 μm.
It is preferably 5 μm or less.
通常これらの微粉末の混合物はそれぞれの微粉末を均一
に混合することにより得られるが、同時に粉砕混合して
も良い。混合物の粒度としては平均粒径１０μｍ以下好
ましくは１μｍ以下である。粉砕方法としては湿式、乾
式のいずれもが採用される。混合物中の炭化クロムとＡ
ｌＮの割合については、以下に説明する焼成を行えば焼
結体の組成は混合物のそれにほとんど一致するので、目
的とする焼結体組成にしておけばよい。Usually, a mixture of these fine powders is obtained by uniformly mixing the respective fine powders, but they may be pulverized and mixed at the same time. The particle size of the mixture is 10 μm or less, preferably 1 μm or less. Either a wet method or a dry method is adopted as the pulverizing method. Chromium carbide and A in the mixture
With respect to the ratio of 1N, the composition of the sintered body is almost the same as that of the mixture when the firing described below is performed, so that the composition of the desired sintered body may be set.
本発明の焼結体は、以上のようにして調整した混合微粉
末を真空中、アルゴン、ヘリウム、窒素などの中性ある
いは還元性の雰囲気下でホットプレス法かコールドプレ
ス成型後常圧焼結法によって得ることができる。焼成温
度は１６００℃以上が必要であり、それ未満の温度では
針状結晶は生成しない。焼成時間については３０分〜１
２時間が適切である。またＨＩＰ法も有効である。The sintered body of the present invention is obtained by hot-pressing or cold-pressing the mixed fine powder prepared as described above under vacuum in a neutral or reducing atmosphere such as argon, helium, or nitrogen, and then pressureless sintering. Can be obtained by law. The firing temperature must be 1600 ° C. or higher, and needle-like crystals will not be formed at temperatures lower than that. About 30 minutes to 1
2 hours is appropriate. The HIP method is also effective.
本発明の焼結体中に炭化クロムの微細に針状結晶を生成
させるためには適切量のＡｌＮの使用と温度1,600℃以
上における焼成が必要である。炭化クロム針状結晶の大
部分、具体的には２０％以上好ましくは５０％以上を直
径０．１〜１０μｍ、長さ０．２〜３０μｍ程度のもの
にするには、炭化クロムとＡｌＮの混合物中のＡｌＮの
割合を０．５〜５０重量％、好ましくは５〜３０重量％
とし、焼成条件をコントロールするのが望ましい。混合
物中のＡｌＮの含有量が０．５重量％未満では充分な針
状結晶が得られず、また、５０重量％をこえては炭化ク
ロム本来の特質を損われる。In order to form fine needle-like crystals of chromium carbide in the sintered body of the present invention, it is necessary to use an appropriate amount of AlN and perform firing at a temperature of 1,600 ° C or higher. A mixture of chromium carbide and AlN is used in order to make most of the needle-shaped crystals of chromium carbide, specifically 20% or more, preferably 50% or more, to have a diameter of 0.1 to 10 μm and a length of 0.2 to 30 μm. The content of AlN is 0.5 to 50% by weight, preferably 5 to 30% by weight
Therefore, it is desirable to control the firing conditions. If the content of AlN in the mixture is less than 0.5% by weight, sufficient needle-shaped crystals cannot be obtained, and if it exceeds 50% by weight, the original properties of chromium carbide are impaired.
本発明の焼結体は、高耐食性、高硬度、高強度かつ高靱
性であり、特に破壊靱性値は常温で５MPa・m1/2以上を示
すものである。The sintered body of the present invention has high corrosion resistance, high hardness, high strength and high toughness, and in particular, has a fracture toughness value of 5 MPa · m 1/2 or more at room temperature.
実施例１ 純度９９％以上の炭化クロム粉末（平均粒径４〜５μ
ｍ）とＡｌＮ（平均粒径３〜４μｍ）を所定量計量後ボ
ールミルで混合した後ＣＩＰ（２．７ton/cm2，３分
間）成型し、真空雰囲気下において、1,650℃の温度で
３６０分間常圧焼成した。得られた焼結体の物性を表−
１に示す。また、実験No.６（本発明例）と実験No.１
（比較例）の焼結体の結晶構造を示す倍率5,000倍のＳ
ＥＭ写真をそれぞれ第１図と第２図に示す。Example 1 Chromium carbide powder having a purity of 99% or more (average particle size 4 to 5 μm)
m) and AlN (average particle size 3 to 4 μm) are weighed in a predetermined amount and mixed in a ball mill, and then CIP (2.7 ton / cm 2 , 3 minutes) molding is performed, and in a vacuum atmosphere, the temperature is 1,650 ° C. for 360 minutes. Pressure fired. The physical properties of the obtained sintered body are shown in Table-
Shown in 1. Experiment No. 6 (Example of the present invention) and Experiment No. 1
S showing a crystal structure of the sintered body of (Comparative Example) at a magnification of 5,000.
EM photographs are shown in FIGS. 1 and 2, respectively.
なお表の物性は次のようにして測定した。The physical properties in the table were measured as follows.
(1)破壊靱性KICはＩＭ法で測定（常温）した。(1) Fracture toughness K IC was measured by the IM method (at room temperature).
(2)耐熱衝撃性は急冷温度測定法で求めた。供試体は３
×４×４０mmの曲げ強度試験片を用い、電気炉内で所定
温度加熱し、一定時間（１時間）保持後炉の下に設置し
てある０℃の水中へ降下させて試験片を急冷させた。そ
の試験片の曲げ強度を測定し強度が低下したときの加熱
温度と水の温度（０℃）との差をΔＴとした。(2) Thermal shock resistance was determined by a quenching temperature measurement method. 3 specimens
Using a bending strength test piece of × 4 × 40 mm, it is heated at a predetermined temperature in an electric furnace, held for a certain time (1 hour), and then lowered into water at 0 ° C. installed under the furnace to rapidly cool the test piece. It was The bending strength of the test piece was measured, and the difference between the heating temperature and the water temperature (0 ° C.) when the strength decreased was defined as ΔT.
(3)針状結晶（直径０．１〜１０μｍ、長さ０．２〜３
０μｍ）の生成割合はＳＥＭ観察により分類した。○…
…５０％以上、△……４９〜２０％、×……２０％未
満。(3) Needle-like crystals (diameter 0.1 to 10 μm, length 0.2 to 3)
The generation ratio of 0 μm) was classified by SEM observation. ○…
… 50% or more, △ …… 49 to 20%, × …… less than 20%.
(4)相対密度はアルキメデス法を測定した。(4) Relative density was measured by Archimedes method.
表−１より、本発明例（実験No.４〜１１）は比較例
（実験No.１〜３）に比べて高靱性で耐熱衝撃性に優れ
ていることが示された。 Table 1 shows that the inventive examples (Experiment Nos. 4 to 11) have higher toughness and excellent thermal shock resistance than the comparative examples (Experiment Nos. 1 to 3).
実施例２ 実施例１の実験No.７について焼成温度を変えて焼結体
を製造し実施例１と同様にしてその物性を試験した。そ
の結果を表−２に示す。Example 2 For Experiment No. 7 of Example 1, a sintered body was manufactured by changing the firing temperature, and its physical properties were tested in the same manner as in Example 1. The results are shown in Table-2.
表−２より、１６００℃以上の焼成温度でないと針状結
晶が生成しないことが確められた。 From Table-2, it was confirmed that needle-like crystals were not formed unless the firing temperature was 1600 ° C or higher.
本発明の焼結体は、高靱性で、かつ高強度、耐熱衝撃
性、導電性等に優れているので従来の炭化クロム系セラ
ミック焼結体と比べ幅広い分野、例えば熱電対の保護
管、金属加工用ダイス、ヒーター、温度センサー等に使
用することができる。特に高強度耐食部材や高温高強度
部材などへの利用が期待される。また、金属と同様に放
電加工ができるので複雑形状にも容易に対応することが
できる。Since the sintered body of the present invention has high toughness and high strength, thermal shock resistance, conductivity, etc., it is used in a wider range of fields than conventional chromium carbide-based ceramic sintered bodies, for example, thermocouple protection tubes and metal. It can be used for processing dies, heaters, temperature sensors, etc. In particular, it is expected to be used for high-strength corrosion resistant members and high-temperature high-strength members. Further, since it is possible to perform electric discharge machining like metal, it is possible to easily cope with complicated shapes.
図面は、炭化クロム焼結体の結晶構造を示す倍率5,000
倍のＳＥＭ写真であり、第１図は実験No.６（本発明
例）、第２図は実験No.１（比較例）の焼結体である。The drawing shows the crystal structure of the chromium carbide sintered body at a magnification of 5,000.
2A and 2B are SEM photographs, and FIG. 1 shows a sintered body of Experiment No. 6 (invention example), and FIG.
Claims (2)
０．５〜５０重量％を含む焼結体であって、炭化クロム
の微細な針状結晶を有してなることを特徴とする高靱性
炭化クロム焼結体。1. Chromium carbide 99.5 to 50% by weight and AlN
A high toughness chromium carbide sintered body, which is a sintered body containing 0.5 to 50% by weight and has fine needle-like crystals of chromium carbide.
１〜１０μｍ、長さ０．２〜３０μｍからなることを特
徴とする特許請求の範囲第１項記載の高靱性炭化クロム
焼結体。2. Most of needle-shaped crystals of chromium carbide have a diameter of 0.
The high-toughness chromium carbide sintered body according to claim 1, which has a length of 1 to 10 µm and a length of 0.2 to 30 µm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63249788A JPH0625036B2 (en) | 1987-10-06 | 1988-10-05 | High toughness chromium carbide sintered body |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62-250729 | 1987-10-06 | ||
| JP25072987 | 1987-10-06 | ||
| JP63249788A JPH0625036B2 (en) | 1987-10-06 | 1988-10-05 | High toughness chromium carbide sintered body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01201077A JPH01201077A (en) | 1989-08-14 |
| JPH0625036B2 true JPH0625036B2 (en) | 1994-04-06 |
Family
ID=26539490
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63249788A Expired - Lifetime JPH0625036B2 (en) | 1987-10-06 | 1988-10-05 | High toughness chromium carbide sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0625036B2 (en) |
-
1988
- 1988-10-05 JP JP63249788A patent/JPH0625036B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01201077A (en) | 1989-08-14 |
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