JPH0451281B2 - - Google Patents
Info
- Publication number
- JPH0451281B2 JPH0451281B2 JP59158096A JP15809684A JPH0451281B2 JP H0451281 B2 JPH0451281 B2 JP H0451281B2 JP 59158096 A JP59158096 A JP 59158096A JP 15809684 A JP15809684 A JP 15809684A JP H0451281 B2 JPH0451281 B2 JP H0451281B2
- Authority
- JP
- Japan
- Prior art keywords
- silicon nitride
- sintered body
- toughness
- sintered
- surface layer
- 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
Links
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 25
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 25
- 238000001816 cooling Methods 0.000 claims description 19
- 239000002344 surface layer Substances 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 239000000919 ceramic Substances 0.000 description 10
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 238000005520 cutting process Methods 0.000 description 6
- 229920002545 silicone oil Polymers 0.000 description 5
- 230000035939 shock Effects 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- MTPVUVINMAGMJL-UHFFFAOYSA-N trimethyl(1,1,2,2,2-pentafluoroethyl)silane Chemical compound C[Si](C)(C)C(F)(F)C(F)(F)F MTPVUVINMAGMJL-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 1
- 238000007545 Vickers hardness test Methods 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000001513 hot isostatic pressing Methods 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B27/00—Tools for turning or boring machines; Tools of a similar kind in general; Accessories therefor
- B23B27/14—Cutting tools of which the bits or tips or cutting inserts are of special material
- B23B27/148—Composition of the cutting inserts
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
- C04B35/584—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride
- C04B35/593—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride obtained by pressure sintering
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/0072—Heat treatment
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Ceramic Products (AREA)
- Cutting Tools, Boring Holders, And Turrets (AREA)
Description
（産業上の利用分野）
本発明は鋳鉄の切削加工、Ni基合金などの難
削性材料の切削加工等の用途に適し、靭性に優れ
かつ耐摩耗性の向上した切削用高靭性窒化珪素質
焼結体工具及びその製造方法に関するものであ
る。
（従来の技術）
現在市販されているセラミツクス工具は主とし
てアルミナ系セラミツク工具とアルミナー炭化チ
タン系セラミツク工具の２種類がある。アルミナ
系セラミツクは高温かつ酸化性雰囲気下で耐摩耗
性に優れているという特徴があるが、一方熱衝撃
によるクラツクが発生し易いなどその靭性に劣つ
ており、高硬度材や断続を含む部位の施削加工、
フライス加工などには使用できない。また、アル
ミナー炭化チタン系セラミツク工具はアルミナに
炭化チタンを添加して靭性を改善したものである
が、施削加工の高能率化と自動化により、より高
い靭性を有しかつ安定して使用できる工具が望ま
れている。この様な現状から近時、窒化珪素を主
成分とするセラミツクスが高温強度が高温硬度が
優れておりかつ熱衝撃性にも強いことから切削工
具用材料として盛んに研究されている。
（発明が解決しようとする問題点）
しかしながら、窒化珪素を主成分とするセラミ
ツク工具はアルミナ系セラミツク工具やアルミナ
−炭化チタン系セラミツク工具と比較して強度及
び熱衝撃性に優れているが、耐摩耗性に劣るとい
う欠点があり、使用条件が限られている。そのた
め、この窒化珪素を主成分として炭化チタン
（TiC）や窒化チタン（TiN）などの硬質粒子を
添加して耐摩耗性を向上させようとする方法があ
るが、この場合窒化珪素本来の靭性が低下する。
また、アルミナ（Al2O3）が窒化アルミニウム
（AlN）などを窒化珪素質母材表面にコーテイン
グする方法があるが、CVDコーテイングでは高
温で塩素などを含む腐食性雰囲気にさらされるた
め、窒化珪素母材の強度劣化を免れず、また、窒
化珪素とアルミナでは熱膨張率の差が大きく窒化
珪素母材表面に極く薄くしかコーテイング膜が付
着せず通常の摩耗量に対応できる効果がない。さ
らに、これらCVD等のコーテイング技術では製
造コストが高くなる欠点がある。
（問題点を解決するための手段）
本発明者は上記の現状に鑑み鋭意研究の結果、
窒化珪素を主成分とする焼結体を一定温度に加熱
後、急冷することにより、該焼結体の表層部の破
壊靭性を中心部の破壊靭性よりも2.0MN／m3/2以
上高くすることが出来、これにより欠損やチツピ
ングの発生が少なくかつ耐摩耗性の向上した窒化
珪素質焼結体工具が得られることを知見した。
したがつて、本発明においては耐摩耗性の向上
した高靭性窒化珪素質工具及びその製造方法を提
供することを目的とする。
本発明によれば窒化珪素（Si3N4）を主成分と
する焼結体であつて、該焼結体の表層部の破壊靭
性が中心部の破壊靭性よりも2.0MN／m3/2以上高
い高靭性窒化珪素質焼結体工具が提供される。
また、本発明によれば窒化珪素（Si3N4）を主
成分として所定形状に焼結成形された焼結体を、
不活性雰囲気中で1300〜1600℃に加熱し、次いで
50〜200℃／秒で冷却するようにした高靭性窒化
珪素焼結体工具の製造方法が提供される。
（作用）
予じめ、ホツトプレス法、熱間静水圧プレス
法、常圧あるいは加圧ガス中焼結法などの任意の
焼成方法により焼成され、所定形状に成形された
窒化珪素質焼結体を1300〜1600℃の不活性雰囲気
中で加熱しなければならない。この場合、1300℃
未満での加熱では冷却時に充分な効果がなく焼結
体の表層部と中心部との破壊靭性の差が
2.0MN／m3/2以上とならず、1600℃を超えて加熱
すると冷却時、焼結体にクラツク等の欠陥が生じ
る。また、加熱された焼結体は50〜200℃／秒で
冷却しなければならない。即ち、50℃／秒未満で
は焼結体表面の破壊靭性が向上せず、200℃／秒
を超えると焼結体に歪が生じ全体にクラツクが生
じるか、または表層部の破壊靭性が向上せず耐摩
耗性及び耐チツピング性が劣下する。さらに焼結
体の表層部の破壊靭性が中心部の破壊靭性よりも
2.0MN／m3/2未満であると、焼結体に欠損やチツ
ピングが発生し、耐摩耗性の向上がみられない。
（実施例）
〓相90％以上の窒化珪素（Si3N4）に対し、
Al2O3，MgO，Y2O3，Ce2O3及び希士類元素の
酸化物から選ばれる１種若しくは複数種の複合焼
結助剤を第１表に示す割合（重量）となるように
秤量し、アルミナポツト中にてイオン交換水を加
えて混合粉砕する。得られた原料を第１表の焼成
条件欄に示す条件にて焼結成形することにより
JIS規格SNGN432（0.2×20゜のチヤンフアーホー
ニング）に基づく形状の各試料No.１〜20を得た。
これらの試料No.１〜20について第１表に示す熱処
理条件、冷却条件及び表層部冷却速度条件に従つ
て加熱及び冷却処理を行つた。得られた各試料No.
１〜20の内部及び外部の破壊靭性（KIC）をビツ
カース圧痕法（予じめ、鏡面研摩した試料表面に
ビツカース硬度計用圧子を押し当て発生したクラ
ツクの長さから破壊靭性を求める測定法）により
測定し、表層部の破壊靭性（KIC）向上量を算出
すると共に、直径150mm、長さ250mmの鋳鉄製円柱
を切削速度350ｍ／mm・切込み２mm，送り0.45
mm／revで各チツプについて100個外周荒削り切削
を行いフランク摩耗量及び刃先のチツピング状態
を観察した。尚、一部試料については欠損などの
ため、加工工数100個未満でテストを中止した。
これらの結果を第２表に示す。
(Field of Industrial Application) The present invention is a high-toughness silicon nitride material suitable for cutting of cast iron, difficult-to-cut materials such as Ni-based alloys, and has excellent toughness and improved wear resistance. The present invention relates to a sintered tool and a method for manufacturing the same. (Prior Art) Ceramic tools currently on the market are mainly of two types: alumina-based ceramic tools and alumina-titanium carbide-based ceramic tools. Alumina-based ceramics are characterized by excellent wear resistance under high temperatures and oxidizing atmospheres, but on the other hand, their toughness is poor, with cracks easily occurring due to thermal shock, and they are used for high-hardness materials and parts with discontinuities. Machining,
Cannot be used for milling etc. In addition, alumina titanium carbide ceramic tools are made by adding titanium carbide to alumina to improve toughness, but due to high efficiency and automation of machining, tools that have higher toughness and can be used stably. is desired. Under these circumstances, ceramics containing silicon nitride as a main component have recently been actively researched as materials for cutting tools because they have excellent high-temperature strength and high-temperature hardness and are resistant to thermal shock. (Problems to be Solved by the Invention) However, although ceramic tools containing silicon nitride as a main component have superior strength and thermal shock resistance compared to alumina-based ceramic tools and alumina-titanium carbide-based ceramic tools, they It has the disadvantage of poor abrasion resistance, and its usage conditions are limited. Therefore, there is a method to improve wear resistance by adding hard particles such as titanium carbide (TiC) or titanium nitride (TiN) to silicon nitride as the main component, but in this case, the inherent toughness of silicon nitride is descend.
In addition, there is a method in which alumina (Al 2 O 3 ) is coated with aluminum nitride (AlN) or the like on the surface of a silicon nitride base material, but in CVD coating, silicon nitride is exposed to a corrosive atmosphere containing chlorine etc. at high temperatures. The strength of the base material inevitably deteriorates, and the difference in coefficient of thermal expansion between silicon nitride and alumina is large, and the coating film is only attached very thinly to the surface of the silicon nitride base material, making it ineffective to cope with normal wear. Furthermore, these coating techniques such as CVD have the disadvantage of increasing manufacturing costs. (Means for solving the problem) In view of the above-mentioned current situation, the inventor has conducted extensive research and found that
By heating a sintered body whose main component is silicon nitride to a constant temperature and then rapidly cooling it, the fracture toughness of the surface layer of the sintered body is made higher than the fracture toughness of the center by 2.0 MN/m 3/2 or more. It has been found that this makes it possible to obtain a silicon nitride sintered tool with less occurrence of fractures and chipping and improved wear resistance. Therefore, an object of the present invention is to provide a high toughness silicon nitride tool with improved wear resistance and a method for manufacturing the same. According to the present invention, the sintered body is a sintered body mainly composed of silicon nitride (Si 3 N 4 ), and the fracture toughness of the surface layer of the sintered body is 2.0 MN/m 3/2 higher than the fracture toughness of the center part. A silicon nitride sintered tool with high toughness as described above is provided. Further, according to the present invention, a sintered body made of silicon nitride (Si 3 N 4 ) as a main component and sintered into a predetermined shape,
heated to 1300-1600℃ in an inert atmosphere, then
A method for manufacturing a high-toughness silicon nitride sintered tool is provided, which is cooled at a rate of 50 to 200°C/second. (Function) A silicon nitride sintered body is fired in advance and formed into a predetermined shape by any firing method such as hot pressing, hot isostatic pressing, normal pressure or pressurized gas sintering. Must be heated in an inert atmosphere at 1300-1600°C. In this case, 1300℃
Heating at temperatures lower than
If the temperature is not 2.0 MN/m 3/2 or higher and it is heated above 1600°C, defects such as cracks will occur in the sintered body when it is cooled. Further, the heated sintered body must be cooled at a rate of 50 to 200°C/sec. In other words, if the temperature is less than 50°C/sec, the fracture toughness of the surface of the sintered body will not improve, and if it exceeds 200°C/sec, the sintered body will become distorted and cracks will occur in the entire body, or the fracture toughness of the surface layer will not improve. However, wear resistance and chipping resistance deteriorate. Furthermore, the fracture toughness of the surface layer of the sintered body is higher than that of the center.
If it is less than 2.0 MN/m 3/2 , defects and chipping will occur in the sintered body, and no improvement in wear resistance will be observed. (Example) For silicon nitride (Si 3 N 4 ) with a phase of 90% or more,
One or more types of composite sintering aids selected from Al 2 O 3 , MgO, Y 2 O 3 , Ce 2 O 3 and rare element oxides in the proportions (weight) shown in Table 1. Weigh the mixture, add ion-exchanged water, and mix and grind in an alumina pot. By sintering and shaping the obtained raw material under the conditions shown in the sintering conditions column of Table 1.
Each sample No. 1 to No. 20 having a shape based on JIS standard SNGN432 (0.2×20° channel honing) was obtained.
These samples Nos. 1 to 20 were subjected to heating and cooling treatments according to the heat treatment conditions, cooling conditions, and surface cooling rate conditions shown in Table 1. Each sample No. obtained
The internal and external fracture toughness (KIC) of 1 to 20 is measured by the Vickers indentation method (a measurement method that determines the fracture toughness from the length of the crack that is generated by pressing an indenter for a Vickers hardness tester onto a sample surface that has been mirror-polished in advance). In addition to calculating the improvement in fracture toughness (KIC) of the surface layer, a cast iron cylinder with a diameter of 150 mm and a length of 250 mm was cut at a cutting speed of 350 m/mm, depth of cut of 2 mm, and feed rate of 0.45.
Rough cutting of the outer periphery of 100 pieces of each chip was performed at mm/rev, and the amount of flank wear and the chipping state of the cutting edge were observed. In addition, due to defects in some samples, the test was stopped when less than 100 pieces were processed. These results are shown in Table 2.
【表】【table】
【表】【table】
【表】
試料No.１，２，及び５〜12は本発明の範囲外
（実験例）のものであり、試料No.１及び２は夫々
20℃の水中と粘度10cStで20℃の油中に投下して
表層部の冷却速度200℃／秒を超えて冷却したも
ので冷却速度が早すぎ焼結体にクラツクが発生し
て使用に耐えないか表層部と中心部とに充分な破
壊靭性の差が生じないため耐摩耗性及び耐チツピ
ング性に劣る。試料No.７〜12は冷却条件が強制空
冷（窒素風量大、小）、窒素ガス中放置及び粘度
50cStのシリコンオイル投下である。また、この
場合表層部冷却速度が50℃／秒未満であるか、焼
結体の熱処理温度が1300℃未満であるので、焼結
体の表層部と中心部とに2MN／m3/2以上の破壊
靭性の差が生じておらず、また表層部の靭性が充
分向上していない。また、焼結体に欠損やチツピ
ングが発生し、フランク摩耗量が0.49mm以上とな
り耐摩耗性が劣化している。
尚、試料No.５及び６は熱処理条件及び表層部冷
冷速度が本発明の範囲であるのに焼結体の表層部
の破壊靭性（KIC）向上量が充分でなくフランク
摩耗量も0.50mm以上となつている。これは冷却条
件におけるシリコンオイルの粘度が1000cStと高
いためと考えられる。試料No.４の冷却条件におけ
るシリコンオイルの粘度が500cStである場合は本
発明を充分備えていることからして少なくともシ
リコンオイル投下の場合は600cSt前後程度までは
本発明の特性に影響はないものと考えられる。ま
た、冷却条件における該実施例を見るかぎり、シ
リコンオイル投下の場合は表層部冷却速度が略50
〜500℃／秒に制御し易いのに比べ他の冷却条件
の場合表層部の冷却速度が著じるしく高いか低い
かの何れかで不安定であるものと考えられる。
一方、これに対し試料No.３，４，及び13〜20の
ものは本発明の範囲内のものであり、何れも焼結
体の表層部の破壊靭性が2MN／m3/2以上であり、
かつ欠損やチツピングの発生がなく、フランク摩
耗量も少なくとも0.45mm以下と本発明の範囲外の
ものと比べ少なく耐摩耗性が向上していることが
理解される。
（発明の効果）
叙述の如く、本発明の窒化珪素質焼結体工具
は、表層部の破壊靭性が中心部の破壊靭性よりも
2.0MN／m3/2以上大であつて、これにより窒化珪
素を主成分とするセラミツク工具の本来保有する
優れた強度及び熱衝撃性に加え、高度の耐摩耗性
が付与され、従つて従来のこの種工具を遥かに綾
ぐ特性を保有することになり、高硬材料の切削加
工等厳しい条件下での使用にも充分耐用し得るも
ので、その実用上の価値は極めて大である。亦、
この優れた工具は、窒化珪素質焼結体に上記の如
く特定された条件の加熱及び冷却処理を施すだけ
で得られるから頗る簡易であり、従つて製造上の
メリツトも大きく、この両発明により得られる利
益は極めて大である。[Table] Samples No. 1, 2, and 5 to 12 are outside the scope of the present invention (experimental examples);
It was dropped into water at 20℃ and oil at 20℃ with a viscosity of 10cSt, and the cooling rate of the surface layer exceeded 200℃/sec.The cooling rate was too fast and cracks occurred in the sintered body, making it unusable. Otherwise, there is no sufficient difference in fracture toughness between the surface layer and the center, resulting in poor wear resistance and chipping resistance. The cooling conditions for samples No. 7 to 12 were forced air cooling (large and small nitrogen airflow), leaving in nitrogen gas, and viscosity.
Drop 50cSt of silicone oil. In addition, in this case, the cooling rate of the surface layer is less than 50℃/second, or the heat treatment temperature of the sintered body is less than 1300℃, so the surface layer and center of the sintered body are 2MN/m 3/2 or more. There is no difference in fracture toughness, and the toughness of the surface layer has not been sufficiently improved. In addition, cracks and chipping occurred in the sintered body, and the flank wear amount was 0.49 mm or more, deteriorating the wear resistance. Although sample Nos. 5 and 6 had heat treatment conditions and surface cooling rates within the range of the present invention, the improvement in fracture toughness (KIC) of the surface layer of the sintered body was insufficient and the flank wear amount was 0.50 mm. That's all. This is thought to be because the viscosity of silicone oil under cooling conditions is as high as 1000 cSt. If the viscosity of the silicone oil under the cooling conditions of sample No. 4 is 500 cSt, the present invention is sufficiently provided, so at least when silicone oil is poured, the characteristics of the present invention are not affected until about 600 cSt. it is conceivable that. In addition, as far as the examples under cooling conditions are concerned, in the case of dropping silicone oil, the cooling rate of the surface layer was approximately 50%.
Although it is easy to control the cooling rate to ~500°C/sec, it is considered that under other cooling conditions, the cooling rate of the surface layer is either significantly high or low and unstable. On the other hand, samples Nos. 3, 4, and 13 to 20 are within the scope of the present invention, and all have fracture toughness of the surface layer of the sintered body of 2 MN/m 3/2 or more. ,
Moreover, it is understood that there is no occurrence of chipping or chipping, and the amount of flank wear is at least 0.45 mm or less, which is less than those outside the scope of the present invention, and the wear resistance is improved. (Effects of the Invention) As described above, the silicon nitride sintered tool of the present invention has a fracture toughness in the surface layer that is higher than that in the center.
2.0 MN/m 3/2 or more, which gives a high degree of wear resistance in addition to the excellent strength and thermal shock resistance originally possessed by silicon nitride-based ceramic tools. It possesses characteristics far superior to other tools of this type, and can withstand use under severe conditions such as cutting of high-hardness materials, and its practical value is extremely great. also,
This excellent tool is extremely simple because it can be obtained by simply subjecting a silicon nitride sintered body to heating and cooling treatments under the conditions specified above, and therefore has great manufacturing advantages. The benefits obtained are extremely large.
Claims (1)
あつて、該焼結体の表層部の破壊靭性が中心部の
破壊靭性よりも2.0MN／m3/2以上高いことを特徴
とする高靭性窒化珪素質焼結体工具。 ２ 窒化珪素（Si3N4）を主成分として所定形状
に焼結成形された焼結体を、不活性雰囲気中で
1300〜1600℃に加熱し、次いで50〜200℃／秒で
冷却することを特徴とする高靭性窒化珪素質焼結
体工具の製造方法。[Claims] 1. A sintered body mainly composed of silicon nitride (Si 3 N 4 ), wherein the fracture toughness of the surface layer of the sintered body is 2.0 MN/m 3 higher than the fracture toughness of the center part. A high toughness silicon nitride sintered tool characterized by a toughness of /2 or higher. 2 A sintered body made of silicon nitride (Si 3 N 4 ) as a main component and sintered into a predetermined shape is sintered in an inert atmosphere.
A method for manufacturing a high toughness silicon nitride sintered tool, which comprises heating to 1300 to 1600°C and then cooling at 50 to 200°C/sec.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15809684A JPS6138803A (en) | 1984-07-27 | 1984-07-27 | High strength sintered material tool of nitrified silicon quality and its manufacture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15809684A JPS6138803A (en) | 1984-07-27 | 1984-07-27 | High strength sintered material tool of nitrified silicon quality and its manufacture |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6138803A JPS6138803A (en) | 1986-02-24 |
| JPH0451281B2 true JPH0451281B2 (en) | 1992-08-18 |
Family
ID=15664213
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15809684A Granted JPS6138803A (en) | 1984-07-27 | 1984-07-27 | High strength sintered material tool of nitrified silicon quality and its manufacture |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6138803A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0276607A (en) * | 1988-09-13 | 1990-03-16 | Sumitomo Electric Ind Ltd | Silicon nitride base cutting tool |
| JP4642956B2 (en) * | 1999-12-28 | 2011-03-02 | 株式会社東芝 | Bearing ball, bearing, and method of manufacturing bearing ball |
-
1984
- 1984-07-27 JP JP15809684A patent/JPS6138803A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6138803A (en) | 1986-02-24 |
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