JP3266200B2 - Silicon nitride based sintered body - Google Patents
Silicon nitride based sintered bodyInfo
- Publication number
- JP3266200B2 JP3266200B2 JP00364190A JP364190A JP3266200B2 JP 3266200 B2 JP3266200 B2 JP 3266200B2 JP 00364190 A JP00364190 A JP 00364190A JP 364190 A JP364190 A JP 364190A JP 3266200 B2 JP3266200 B2 JP 3266200B2
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- silicon nitride
- sintered body
- phase
- grain boundary
- based sintered
- Prior art date
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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，窒化珪素基焼結体に関し，更に詳しくいえ
ば靭性等の本質的特性を低下させることなく耐摩耗性を
向上させた窒化珪素基焼結体に関する。本発明は，切削
工具，耐摩耗部品及び摺動部品等に利用される。Description: TECHNICAL FIELD The present invention relates to a silicon nitride-based sintered body, and more particularly, to a silicon nitride having improved wear resistance without deteriorating essential properties such as toughness. It relates to a base sintered body. The present invention is used for cutting tools, wear-resistant parts, sliding parts, and the like.
従来の窒化珪素焼結体としては，耐摩耗性を向上させ
るために，表面に高硬度又は耐摩耗性に優れるセラミッ
ク材料を被覆したものが知られている（特公昭63−1278
号公報）。As a conventional silicon nitride sintered body, a sintered body having a surface coated with a ceramic material having high hardness or excellent wear resistance in order to improve wear resistance is known (Japanese Patent Publication No. 63-1278).
No.).
また，他の窒化珪素焼結体において，母材の改良とし
て高硬度のα−窒化珪素粒を強靭性のβ−窒化珪素粒中
に分散させたものも知られている（特開昭58−185484号
公報）。Further, in another silicon nitride sintered body, there is known a sintered body in which α-silicon nitride grains having high hardness are dispersed in tough β-silicon nitride grains as an improvement of a base material (Japanese Patent Laid-Open No. No. 185484).
［発明が解決しようとする課題］ 上記前者の焼結体においては，被覆セラミック材と窒
化珪素母材との熱膨張又は化学的親和性の相違という問
題により，十分な接着強度が得られにくく，更に費用も
かかり経済性にも問題があり，ほとんど実用化されてい
ない。[Problems to be Solved by the Invention] In the former sintered body, it is difficult to obtain a sufficient adhesive strength due to a problem of thermal expansion or a difference in chemical affinity between the coated ceramic material and the silicon nitride base material. Furthermore, there is a problem in cost and economy, and it is hardly practically used.
上記後者の焼結体は，両相を全体に均一に含むので，
その割合により性能が変化するものであり，その各性能
を十分に発揮できない。即ち一方の性能を十分に高めよ
うとすると，他方の性能を犠牲にせざるをえず，高々そ
の中間性能を示すに過ぎない。Since the latter sintered body contains both phases uniformly throughout,
The performance varies depending on the ratio, and each performance cannot be sufficiently exhibited. That is, if one performance is to be sufficiently enhanced, the performance of the other must be sacrificed, and only an intermediate performance is exhibited at most.
本発明は，上記観点に鑑みてなされたものであり，表
面を改質して耐摩耗性に優れた表面部を形成させて表面
部及び内部の材質特性を十分に発揮させた従来になく優
れた窒化珪素基焼結体を提供することを目的としてい
る。The present invention has been made in view of the above-mentioned point of view, and has an unprecedented superiority which has been achieved by modifying the surface to form a surface portion having excellent wear resistance and sufficiently exhibiting the material properties of the surface portion and the inside. It is an object of the present invention to provide a silicon nitride-based sintered body.
本発明者は，焼結体の耐摩耗性を改善する手段とし
て，表面の改質を種々検討した結果，以下の知見を見出
して本発明を完成したものである。The present inventors have conducted various studies on surface modification as means for improving the wear resistance of a sintered body, and as a result, have found the following findings and completed the present invention.
本発明の第１の視点によれば，一体に形成された表面
部と内部とから成り，内部は窒化珪素，サイアロンの一
種以上を主体とし，表面部は内部に比べ窒化珪素及びサ
イアロン結晶粒子が30vol％以上少ないことを特徴とす
る窒化珪素基焼結体により，上記課題は解決される。According to a first aspect of the present invention, a surface part and an inside are integrally formed, and the inside is mainly composed of at least one of silicon nitride and sialon, and the surface part is made of silicon nitride and sialon crystal grains as compared with the inside. The above-mentioned problem is solved by a silicon nitride-based sintered body characterized by being less than 30 vol%.
本発明の第２の視点によれば，一体に形成された表面
部と内部とから成る窒化珪素基焼結体において，粒界相
の一部又は全てを形成する結晶質化合物の，表面部に対
する内部の含有量比が,X線ピーク強度比法にて0.5未満
であることにより，上記課題は解決される。According to a second aspect of the present invention, in a silicon nitride-based sintered body composed of an integrally formed surface portion and an inside, a crystalline compound forming a part or all of a grain boundary phase is formed with respect to a surface portion. The above problem is solved when the content ratio inside is less than 0.5 by the X-ray peak intensity ratio method.
本発明の第３の視点によれば，粒界相の一部又はすべ
てを形成する結晶質化合物は，表面部において,Si3N4及
びサイアロン粒子の含有量に対し最高Ｘ線強度比法にて
0.3以上含有されていることにより，第１及び第２の視
点に対し，さらに改良される。According to the third aspect of the present invention, the crystalline compound forming part or all of the grain boundary phase is subjected to the highest X-ray intensity ratio method based on the content of Si 3 N 4 and sialon particles at the surface. hand
The content of 0.3 or more further improves the first and second viewpoints.
本発明の第４の視点によれば，上記第２の視点におい
て，表面部の前記「粒界相を形成する結晶質化合物」は
メリライトである。According to a fourth aspect of the present invention, in the second aspect, the “crystalline compound forming the grain boundary phase” on the surface is melilite.
本発明の第５の視点によれば，第３の視点において，
表面部の前記「粒界相を形成する結晶質化合物」はメリ
ライトである。According to a fifth aspect of the present invention, in a third aspect,
The “crystalline compound forming the grain boundary phase” on the surface is melilite.
以下の好適な態様において，本発明の効果が良く発揮
される。第１の視点において，粒界相はガラス相の場
合，又は粒界相の一部又は全てが結晶化される場合，が
ある。Y2O3を含まない（或いは少い）場合，表面部の粒
界相は，第３相を除きガラス相が主となる。結晶化の処
理を施さない場合も，表面部の粒界相にはガラス相が残
る。この粒界相に含まれる結晶相Si3N4−Y2O3基の化合
物（Si3N4−nY2O3−mX）は，メリライト相（「Ｍ相」と
も略称する）,J相,K相,H相,A相又はこれらの混合相であ
る。これらの相は次の通りのものを言う。In the following preferred embodiments, the effects of the present invention are well exhibited. In the first viewpoint, the grain boundary phase may be a glass phase, or some or all of the grain boundary phase may be crystallized. When Y 2 O 3 is not contained (or is small), the grain boundary phase on the surface is mainly a glass phase except for the third phase. Even when the crystallization treatment is not performed, a glass phase remains in the grain boundary phase on the surface. The crystalline phase Si 3 N 4 —Y 2 O 3 group compound (Si 3 N 4 —nY 2 O 3 —mX) contained in the grain boundary phase is composed of a melilite phase (also abbreviated as “M phase”) and a J phase. , K phase, H phase, A phase or a mixed phase thereof. These phases refer to the following:
Ｍ相（mellilite）Si3Y2O3N4（Si3N4−Y2O3） Ｊ相（wohlerite）Si2Y4O7N2（Si2N2O−2Y2O3） Ｋ相（wollastonite）SiYO2N（Si3N4−2Y2O3−SiO2） Ｈ相（apatite）Si7Y10O N4（Si3N4−5Y2O3−4Si
O2） Ａ相（ − ）Si3Y10Al2O N4（Si3N4−5Y2O3−Al2O
3） 要約すると次式で表わされる。M phase (mellilite) Si 3 Y 2 O 3 N 4 (Si 3 N 4 -Y 2 O 3) J phase (wohlerite) Si 2 Y 4 O 7 N 2 (Si 2 N 2 O-2Y 2 O 3) K Phase (wollastonite) SiYO 2 N (Si 3 N 4 −2 Y 2 O 3 —SiO 2 ) H phase (apatite) Si 7 Y 10 ON 4 (Si 3 N 4 −5 Y 2 O 3 −4Si
O 2 ) A phase (-) Si 3 Y 10 Al 2 ON 4 (Si 3 N 4 -5 Y 2 O 3 -Al 2 O
3 ) Summarized by the following equation.
Si3N4−nY2O3−mX（ｎ＝１〜5,X＝SiO2,Al2O3,m＝０〜４） 即ち，被削材又は相手材のほとんどは鉄系の合金が多
く，これに対して窒化珪素の主構成元素であるSiは化学
的親和性が高いために，耐摩耗性が劣ることを見出し
た。ここで，窒化珪素の焼結は，従来より窒化珪素の分
解揮発を防ぐ工夫がなされていた。本発明は，逆にこの
分解揮発を利用し，表面部の窒化珪素成分のSi含有量の
内部に対する減少率を所定値以上とした窒化珪素基焼結
体が，靭性等を低下させることなく耐摩耗性を向上させ
るという知見を得たことから出発する。Si 3 N 4 -nY 2 O 3 -mX (n = 1 to 5, X = SiO 2 , Al 2 O 3 , m = 0 to 4) That is, most of the work material or the partner material is an iron-based alloy. On the other hand, it was found that Si, which is a main constituent element of silicon nitride, had a high chemical affinity and therefore had poor wear resistance. Here, the sintering of silicon nitride has conventionally been devised to prevent the decomposition and volatilization of silicon nitride. On the contrary, the present invention utilizes this decomposition and volatilization to make the silicon nitride-based sintered body in which the reduction rate of the silicon content of the silicon nitride component in the surface portion with respect to the inside is not less than a predetermined value without deteriorating the toughness and the like. We will start from the fact that we have learned to improve wear properties.
なお、後述のSi減少率は，下記の式により算出され
る： Si減少率＝［（内部Si含有量（重量）− 表面部Si含有量（重量））／ 内部Si含有量（重量）］×100 第１視点の窒化珪素基焼結体は，その表面部のSi3N4
及びサイアロン粒子減少率が内部と比べて30vol％以上
であり，その内部はSi3N4の気化がなくそのままである
ので，表面部の耐摩耗性に優れるという性質と内部の高
靭性等という本質的特性が十分に発揮される。即ち，本
焼結体では，従来のように両性質の中間的特性を示すも
のではない。従って，本焼結体では，その表面改質によ
り，内部の本質的特性を低下させることなく耐摩耗性を
向上させることができる。The Si reduction rate described later is calculated by the following equation: Si reduction rate = [(internal Si content (weight) −surface Si content (weight)) / internal Si content (weight)] × 100 The first viewpoint of the silicon nitride based sintered body is that the Si 3 N 4
In addition, the sialon particle reduction rate is 30 vol% or more compared to the inside, and since the inside is free from vaporization of Si 3 N 4 , it has excellent properties such as excellent wear resistance on the surface and high toughness inside. Characteristic is fully exhibited. That is, the sintered body does not show an intermediate property between the two properties as in the conventional case. Therefore, in this sintered body, the wear resistance can be improved without deteriorating the internal essential characteristics by the surface modification.
また，表面部と内部は一体のため，両者間の接合強度
が高く剥離することもない。In addition, since the surface and the inside are integrated, the bonding strength between the two is high, and there is no peeling.
このSi3N4及びサイアロン粒子減少率を30vol％以上と
するのは,30vol％未満ではその効果が十分でなく，それ
以上の場合は靭性等に優れるという内部の特性を低下さ
せることなく耐摩耗性を向上させることができるからで
ある。尚，この減少率は50vol％以上が好ましい。この
場合は耐摩耗性が一層向上するからである。また，表面
部のSi3N4及びサイアロン粒子がほとんどなくなっても
よく，この場合は耐摩耗性がより一層向上するが，面粗
度が低下するので，脆い化合物が生成しない範囲にする
のが好ましい。If the reduction rate of Si 3 N 4 and sialon particles is 30 vol% or more, the effect is not sufficient if the volume is less than 30 vol%, and if it is more than 30 vol%, the abrasion resistance is reduced without deteriorating the internal characteristics such as excellent toughness. This is because the properties can be improved. The rate of decrease is preferably 50 vol% or more. In this case, the wear resistance is further improved. In addition, the Si 3 N 4 and sialon particles on the surface may be almost eliminated. In this case, the wear resistance is further improved, but the surface roughness is reduced. preferable.
本窒化珪素基焼結体は通常，窒化珪素を主体とするも
のであるが，これに限らずサイアロンであってもよい。
この窒化珪素又はサイアロンとしても，α−，β型を問
わず，目的，用途により選択され，更にそれらの混合で
あってもよい。窒化珪素等以外の成分としては，粒界相
構成成分又は粒界相以外の第３成分とすることができ
る。粒界相構成成分は，ガラス相のみであってもよい
し，ガラス相以外に種々の結晶相を含んでもよう。第３
成分としては，例えば耐摩耗性，靭性向上に有効な成分
とすることができる。このものとしては，例えば，周期
律表第IV a,V a,VI a族遷移金属の炭化物，窒化物及び
酸化物，並びにこれら２種以上の固溶体のうちの１種若
しくは２種以上等を用いることができる。これらの第３
成分は粒状でもよいし針状（例えばウイスカー）又は繊
維状であってもよい。一般的に粒状分散粒子は硬度の向
上に，あるいは粒成長抑制効果からくる靭性の向上に効
果がある。又針状あるいは繊維状分散成分は靭性向上に
著しい効果がある。尚，この第３成分化合物は，焼結体
の靭性を低下させないために,30重量％以下が好まし
い。The silicon nitride-based sintered body is usually mainly composed of silicon nitride, but is not limited to this and may be sialon.
The silicon nitride or sialon may be selected depending on the purpose and application irrespective of the α- or β type, and may be a mixture thereof. The component other than silicon nitride or the like can be a component constituting the grain boundary phase or a third component other than the grain boundary phase. The component of the grain boundary phase may be only the glass phase or may include various crystal phases in addition to the glass phase. Third
The component can be, for example, a component effective for improving wear resistance and toughness. For example, use is made of carbides, nitrides and oxides of transition metals of Groups IVa, Va and VIa of the periodic table, and one or more of these two or more solid solutions. be able to. These third
The components may be granular, needle-like (eg, whiskers) or fibrous. Generally, the granular dispersed particles are effective for improving hardness or toughness resulting from the effect of suppressing grain growth. Needle-like or fibrous dispersion components have a remarkable effect on improving toughness. Incidentally, the content of the third component compound is preferably 30% by weight or less so as not to lower the toughness of the sintered body.
内部とは，表面部を除いた部分であり，本窒化珪素基
焼結体の主要部となり，本焼結体の本質的特性を示す部
分である。この内部は,Si3N4が分解揮発除去（以下，気
化という）されないので，上記窒化珪素等及び粒界相構
成成分更には上記第３成分がそのままで構成される。The inside is a portion excluding the surface portion, is a main portion of the present silicon nitride-based sintered body, and is a portion showing the essential characteristics of the present sintered body. Since Si 3 N 4 is not decomposed and volatilized and removed (hereinafter, referred to as vaporization) in the interior, the above-mentioned silicon nitride and the like, the components constituting the grain boundary phase, and the third component are used as they are.
表面部は,Si3N4が気化されてSi含有量が減少した分,S
i3N4,サイアロン以外の成分が残存し，その成分の相対
的含有率が向上した部分である。表面部の厚さは，目
的，用途及び製造方法等により異なるが，通常，数μｍ
〜0.1mm程度であるが，場合により約1mmにも達する。
尚，本焼結体においては，表面部と内部の境界において
上記組成比が急に変わらない場合即ち連続的に変わる場
合も含まれ，このように少なくとも所定の組成比をもつ
表面部と所定の組成比もつ内部とをもつものであればよ
い。Surface portions, Si 3 min where N 4 is vaporized Si content is reduced, S
Components other than i 3 N 4 and Sialon remain, and the relative content of these components is improved. The thickness of the surface varies depending on the purpose, application, manufacturing method, etc.
It is about 0.1 mm, but sometimes reaches about 1 mm.
In the present sintered body, the case where the above composition ratio does not change suddenly at the boundary between the surface portion and the inside, that is, the case where the composition ratio changes continuously is also included. What is necessary is just to have the inside with the composition ratio.
本焼結体は表面のSi3N4分を気化させた焼肌にて通常
使用されるので，気化に伴う面粗度の悪化には注意をす
る必要がある。従って，この面粗度は12.5S（JIS Ｂ
0601）以下にするのが好ましい。特に，面粗度を重視す
る用途の場合は，粒界相形成成分が残留し表面を覆うの
が好ましい。Since this sintered body is usually used on a burnt surface where the Si 3 N 4 component on the surface is vaporized, attention must be paid to the deterioration of the surface roughness due to the vaporization. Therefore, this surface roughness is 12.5S (JIS B
0601) It is preferable to set the following. In particular, in applications where surface roughness is important, it is preferable that the components forming the grain boundary phase remain and cover the surface.
本発明の諸視点に共通して，次の事が成立つ。 The following holds true for all aspects of the present invention.
即ち，（１）表面部において，内部よりも粒界相が実
質的に多いこと，及び（２）（粒界相がガラス相である
場合を除き）表面部において内部よりも粒界相の結晶化
度が高いこと，この両者の相乗効果により，耐摩耗性が
極めて向上する。第１〜３の視点に規定される特徴によ
り，耐摩耗性向上に有効な範囲が決められる。That is, (1) the grain boundary phase is substantially more present at the surface than at the interior, and (2) the crystal of the grain boundary phase is greater than the interior at the surface (unless the grain boundary is a glass phase). Due to the high degree of conversion and the synergistic effect of both, the wear resistance is extremely improved. The effective range for improving the wear resistance is determined by the characteristics defined in the first to third viewpoints.
粒界相が結晶質を含む場合，表面粒界相をなす結晶質
化合物のうちメリライトが好ましい。即ち，表面部の粒
界相をSi3N4・Y2O3正方晶化合物（以下，メリライトと
いう）を主として結晶化させかつ内部と比べて多く含有
させると耐摩耗性が極めて向上することを見出した。When the grain boundary phase contains crystalline, melilite is preferable among the crystalline compounds forming the surface grain boundary phase. That is, if the grain boundary phase on the surface part is mainly crystallized with a Si 3 N 4 · Y 2 O 3 tetragonal compound (hereinafter referred to as melilite) and contained more than the inside, the wear resistance is extremely improved. I found it.
更に，被削材又は相手材のほとんどは鉄系の合金が多
く，これに対して窒化珪素の主構成元素であるSiは化学
的親和性が高いために，耐摩耗性が劣り，そのためSi3N
4に比べてSiが少ない分だけその反応が少なくなり，耐
化学的安定性が向上し，ひいては耐摩耗性が向上するこ
とを見出した。ただし，上記メリライト等の粒界相結晶
質Si3N4−Y2O3基化合物が内部にも多く晶出すると，室
温における靭性が低下してしまうので，粒界相結晶質は
表面部に多く内部に少なく存在させることが重要であ
る。Furthermore, most of the work material or counterpart material often alloy iron, whereas for Si has a high chemical affinity which is the main constituent elements of the silicon nitride, poor wear resistance, therefore Si 3 N
It was found that the reaction was reduced by the smaller amount of Si as compared with 4 , and that the chemical stability was improved and the wear resistance was improved. However, if a large amount of the crystalline Si 3 N 4 —Y 2 O 3 -based compound such as the above-mentioned melilite is crystallized inside, the toughness at room temperature is reduced. It is important to have many inside and few.
以上の観点より，本発明はなされたものであり，第１
の観点において,Si3N4及びサイアロン結晶粒子が，表面
部において内部よりも30vol％以上少ないとするが，こ
の差が30vol％未満では，十分な表面改質効果（耐摩耗
性増大）が生じない。In view of the above, the present invention has been made.
From the viewpoint of Si 3 N 4 and Sialon crystal particles, it is assumed that the surface part is 30 vol% or less than the inside, but if this difference is less than 30 vol%, a sufficient surface modification effect (increase in wear resistance) occurs. Absent.
第２の視点において，粒界相結晶質化合物が表面部に
おいて，その内部に対する含有量比がＸ線ピーク強度比
法にて,0.5以上になると，十分な表面改質効果が顕われ
ない。From the second viewpoint, when the content ratio of the grain boundary phase crystalline compound to the inside of the surface portion becomes 0.5 or more by the X-ray peak intensity ratio method, a sufficient surface modification effect does not appear.
第３の視点において，粒界相結晶質化合物が，表面部
において,Si3N4及びサイアロン結晶粒子の含有量に比
し，最高Ｘ線強度比法にて0.3以上あると，第２の視点
において，耐摩耗性改善のため一層好ましい。In the third viewpoint, if the grain boundary phase crystalline compound is 0.3 or more by the maximum X-ray intensity ratio method in the surface part compared to the content of Si 3 N 4 and sialon crystal particles, the second viewpoint Is more preferable for improving wear resistance.
基体となる焼結体は，通常，一般的な常圧焼結法によ
り製造されるが，ガス圧焼結法又は熱間静水圧焼結法
（HIP法）により製造することもできる。焼結雰囲気
は，基本的には窒素を含有した雰囲気で行うことが必要
で，表面部のSi3N4及び／又はサイアロン結晶粒子の減
少の仕方の一例として圧力は窒化珪素が適当量気化する
条件であればよく，減圧から数千気圧まで変化させるこ
とができる。焼結温度は，通常,1550〜1800℃の範囲を
用い，好ましくは1600〜1750℃である。The sintered body serving as the base is usually produced by a normal atmospheric sintering method, but can also be produced by a gas pressure sintering method or a hot isostatic sintering method (HIP method). The sintering atmosphere is basically required to be performed in an atmosphere containing nitrogen. As an example of the method of reducing the Si 3 N 4 and / or sialon crystal particles on the surface, the pressure is such that silicon nitride is vaporized in an appropriate amount. Any conditions can be used, and the pressure can be changed from reduced pressure to several thousand atmospheres. The sintering temperature is usually in the range of 1550-1800 ° C, preferably 1600-1750 ° C.
本焼結体の製造方法は，例えば，次の如くして行うこ
とができる。The method for producing the present sintered body can be performed, for example, as follows.
まず，窒化珪素粉末，所定の焼結助剤等を所定組成に
配合し，混合，粉砕する。焼結助剤としては，窒化珪素
の常圧焼結（ガス圧焼結,HIP焼結も含む）用の助剤であ
ればよく，好ましくはSi元素を含まないものがよい。こ
のものとして，例えばAl2O,Y2O3,AlN,MgO若しくはCaO,
又はY2O3等の希土類酸化物等がある。この素地は，必要
形状に加圧成形され焼結される。この焼結時において，
表面のSi3N4を気化させる方法としては，例えば，窒素
分圧,Si分圧を下げたり，還元雰囲気を用いたりするこ
とができる。First, a silicon nitride powder, a predetermined sintering aid and the like are blended in a predetermined composition, mixed and pulverized. The sintering aid may be any one for normal pressure sintering (including gas pressure sintering and HIP sintering) of silicon nitride, and preferably does not contain Si element. For example, Al 2 O, Y 2 O 3 , AlN, MgO or CaO,
Or a rare earth oxide such as Y 2 O 3 . This base is pressed into a required shape and sintered. During this sintering,
As a method of vaporizing Si 3 N 4 on the surface, for example, a nitrogen partial pressure, a Si partial pressure can be reduced, or a reducing atmosphere can be used.
典型的には，出発原料粉末素地は次の如く調整され
る。Typically, the starting material powder base is prepared as follows.
Si3N4 50〜95wt％，好ましくは60〜90wt％より好まし
くは64〜86wt％ 焼結助剤＊ ５〜30wt％，好ましくは７〜20wt％より好
ましくは10〜20wt％ 第３成分＊＊ 30wt％以下，好ましくは25wt％以下＊ 焼結助剤:Al2O3,AlN,Y2O3,MgO,CaO,AlON,YN,希土類酸
化物＊＊ 周期律表IV a（Ti,Zr,Hf）,V a（V,Nb,Ta）及びVI
a（Cr,Mo,W）族の化合物（酸化物，炭化物，窒化物
等），その針状（ウィスカ）又は繊維状結晶を含む。Si 3 N 4 50 to 95 wt%, preferably 60 to 90 wt%, more preferably 64 to 86 wt% Sintering aid * 5 to 30 wt%, preferably 7 to 20 wt%, more preferably 10 to 20 wt% Third component ** 30 wt% or less, preferably 25 wt% or less * Sintering aid: Al 2 O 3 , AlN, Y 2 O 3 , MgO, CaO, AlON, YN, rare earth oxide ** Periodic Table IVa (Ti, Zr, Hf), Va (V, Nb, Ta) and VI
a (Cr, Mo, W) group compounds (oxides, carbides, nitrides, etc.) and their acicular (whisker) or fibrous crystals.
出発原料粉末素地（混合物）は，平均粒径５μｍ以下
が好ましく，より好ましくは２μｍ以下である。The starting material powder base (mixture) preferably has an average particle size of 5 μm or less, more preferably 2 μm or less.
製造工程は，次のように要約される。 The manufacturing process is summarized as follows.
（ａ）出発原料粉末素地を所定組成とする，混合（通例
同時粉砕を行う）を含む。(A) Mixing (usually simultaneous pulverization) of a starting material powder base having a predetermined composition is included.
（ｂ）所定形状に成形する。(B) Form into a predetermined shape.
（ｃ）成形体を，焼結体表面でSi減少が生ずるよう，窒
化珪素が表面で気化される条件下にて所定の温度で焼結
する。(C) The molded body is sintered at a predetermined temperature under conditions in which silicon nitride is vaporized on the surface so that Si reduction occurs on the surface of the sintered body.
焼結は，成形体を焼結するに十分な時間（好ましくは
0.5〜5hr,より好ましくは１〜3hr）行う。所望焼結条件
は，特別な雰囲気により，所定の減圧窒素及び／又はSi
分圧，或いは（特に，これらの減圧分圧に加えて）CO2
及び／又はCO含有雰囲気等により，達成される。一般的
に，焼結条件は，組成及び焼結温度に応じて可変であ
る。即ち，焼結雰囲気は，所定温度に対応して所定組成
について適当であると考えられるN2及び／又はSi分圧よ
りも僅か低い分圧で，設定される（例えば，第５図を参
照して）。このようにして,Si及びＮの適当量が表面部
のSi3N4から，粗面を形成しない範囲内にて，分解気化
される。Sintering is carried out for a time sufficient to sinter the compact (preferably
(0.5 to 5 hours, more preferably 1 to 3 hours). The desired sintering conditions are as follows: depending on the special atmosphere, a predetermined vacuum nitrogen and / or Si
Partial pressure, or (especially in addition to these reduced partial pressures) CO 2
And / or CO-containing atmosphere. Generally, sintering conditions are variable depending on the composition and the sintering temperature. That is, the sintering atmosphere, corresponding to a predetermined temperature at a slightly lower partial pressure than the N 2 and / or Si partial pressure is considered to be suitable for a given composition, is set (for example, with reference to FIG. 5 hand). In this manner, appropriate amounts of Si and N are decomposed and vaporized from Si 3 N 4 on the surface within a range where a rough surface is not formed.
かく得られる焼結体の表面部は，主として焼結助剤及
び／又はその反応生成物（化合物）であって,Si及び／
又はＮを固溶体として含むものから成る（或いはさらに
第３成分を含む）。Si及びＮの気化により，表面部には
残る粒界相及び第３成分の比率が，内部に比べて高くな
り，密度及び硬度に変化を生ずる（硬度は増大）。窒化
珪素及び／又はサイアロンの表面部内における量は,30v
ol％以上内部よりも少い（最大100vol％少い）。The surface part of the obtained sintered body is mainly a sintering aid and / or its reaction product (compound),
Or, it comprises N as a solid solution (or further contains a third component). Due to the vaporization of Si and N, the ratio of the grain boundary phase and the third component remaining on the surface becomes higher than that inside, causing a change in density and hardness (hardness increases). The amount in the surface of silicon nitride and / or sialon shall be 30 v
ol% or more and less than the inside (up to 100vol% less).
第４の視点において，表面部と内部ではそれを構成す
るメリライトの含有量比（Ｘ線ピーク強度比）が異なる
ことを特徴とする。この［内部／表面部］比を0.5未満
とするのは,0.5以上ではその効果が十分でなく，それ未
満では靭性等に優れるという内部の特性を低下させるこ
となく耐摩耗性を向上させることができるからである。The fourth viewpoint is characterized in that the content ratio (X-ray peak intensity ratio) of melilite constituting the surface portion is different from that in the inside. If the [internal / surface portion] ratio is less than 0.5, the effect is not sufficient if the ratio is 0.5 or more, and if it is less than 0.5, the wear resistance can be improved without deteriorating the internal characteristics such as excellent toughness. Because you can.
更に，第５の視点にて，表面部における，窒化珪素及
びサイアロン含有量に対するメリライト含有量の最高Ｘ
線強度比は0.3以上である。この場合，メリライトの含
有量の増大を確保できかつSi含有量を減少させることが
できるので，耐摩耗性改善を確実に確保でき，更にそれ
を一層向上させることができるからである。Furthermore, from the fifth viewpoint, the maximum X of the melilite content with respect to the silicon nitride and sialon content in the surface portion.
The line intensity ratio is 0.3 or more. In this case, the increase in the content of melilite can be ensured and the content of Si can be reduced, so that the improvement of the wear resistance can be reliably ensured, and it can be further improved.
本窒化珪素基焼結体は通常，窒化珪素を主体とするも
のであるが，本発明においてメリライト等の粒界相結晶
質化合物を内部よりも表面部により多く含有させるとい
う表面改質のためには，既述の通り，これに限らずサイ
アロン又は両者の混合であってもよい。この窒化珪素又
はサイアロンとしても，α−，β型を問わず，目的，用
途により選択され，更にそれらの混合であってもよい。The present silicon nitride-based sintered body is usually mainly composed of silicon nitride. However, in the present invention, the surface modification is carried out so that a grain boundary phase crystalline compound such as melilite is contained more in the surface than in the interior. Is not limited to this, but may be Sialon or a mixture of both. The silicon nitride or sialon may be selected depending on the purpose and application irrespective of the α- or β type, and may be a mixture thereof.
本発明において，粒界相に結晶質化合物を含む場合,Y
2O3の組成成分量（配合量）は，通常１〜20重量％であ
り，好ましくは１〜15重量％，より好ましくは１〜10重
量％である。これは，メリライト等の粒界相結晶質化合
物の構成元素である「Ｙ」を供給するにはY2O3が最も好
ましく，これには１重量％以上が必要であり，又，多く
なると粒界相の増加に伴う高温特性の低下が起こるため
である。尚，「Ｙ」は，酸化物以外の窒化物，珪化物等
の他化合物にて添加してもよい。このときの添加量はY2
O3に換算した量が適用される。In the present invention, when a crystalline compound is contained in the grain boundary phase, Y
The amount (composition amount) of 2 O 3 is usually 1 to 20% by weight, preferably 1 to 15% by weight, more preferably 1 to 10% by weight. This is because Y 2 O 3 is most preferable for supplying “Y”, which is a constituent element of the crystalline compound of the grain boundary phase such as melilite, which requires 1% by weight or more. This is because high-temperature characteristics decrease with an increase in the interphase. Incidentally, “Y” may be added as a compound other than an oxide, such as a nitride or a silicide. The addition amount at this time is Y 2
The amount converted to O 3 applies.
また,Y2O3と同時にAl2O3,AlNを配合することもでき，
これらはメリライト等のSi3N4・Y2O3基化合物の結晶化
に重要な役割をもつ。Al2O3は１〜10重量％,AlNは１〜1
0重量％添加することが好ましい。この場合,AlNはAl2O3
より多めに添加すれば，より好ましい結果が得られる。
尚，その他，通常のSi3N4の常圧焼結用助剤，例えば,Mg
O,SiO2,ZrO2及び希土類酸化物等のうち少なくとも１種
を用いることもできる。It is also possible to mix Al 2 O 3 and AlN simultaneously with Y 2 O 3 ,
These have an important role in crystallization of Si 3 N 4 .Y 2 O 3 group compounds such as melilite. Al 2 O 3 is 1 to 10% by weight, AlN is 1 to 1
It is preferable to add 0% by weight. In this case, AlN is Al 2 O 3
More addition results in more favorable results.
In addition, other normal-pressure sintering aids for Si 3 N 4 such as Mg
At least one of O, SiO 2 , ZrO 2 and rare earth oxides can be used.
窒化珪素の一部を，例えば耐摩耗性，耐欠損性改善に
有効な成分（第３成分）で置換してもよい。このものと
しては，例えば，周期律表第IV a,V a,VI a族遷移金属
の炭化物，窒化物及び酸化物，並びにこれら２種以上の
固溶体のうちの１種若しくは２種以上等を用いることが
できる。尚，この置換化合物は，焼結体の靭性等を低下
させないために，全体の30重量％以下が好ましい。Part of the silicon nitride may be replaced with a component (third component) effective for improving wear resistance and fracture resistance, for example. For example, use is made of carbides, nitrides and oxides of transition metals of Groups IVa, Va and VIa of the periodic table, and one or more of these two or more solid solutions. be able to. Incidentally, this substitution compound is preferably not more than 30% by weight of the whole so as not to lower the toughness of the sintered body.
内部とは，表面部を除いた部分であり，本窒化珪素基
焼結体の主要部となり，本焼結体の本質的特性を示す部
分である。The inside is a portion excluding the surface portion, is a main portion of the present silicon nitride-based sintered body, and is a portion showing the essential characteristics of the present sintered body.
第２の視点においての表面部は，メリライト等のSi3N
4−Y2O3基化合物の相対的含有率が向上した部分であ
る。表面部の厚さは，目的，用途及び製造方法等により
異なるが，通常，数μｍ〜0.1mmから1mm以下程度であ
る。Si3N4−Y2O3基結晶質化合物が多量に表面部に晶出
し表面全体を覆う場合，表面を覆っている層はSi3N4及
び／又はサイアロン粒子をほとんど含まない状態（但し
第３成分＝分散相は含む）であり,100vol％減状態とな
り，この（100vol％減状態の）厚さは焼結体全体の強度
低下を防止するために,5μｍ以下が好ましい。尚，本焼
結体においては，表面部と内部の境界において上記組成
比が急に変わらない場合即ち連続的に変わる場合も含ま
れ，このように少なくとも所定の組成比をもつ表面部と
所定の組成比をもつ内部とをもつものであればよい。The surface from the second viewpoint is made of Si 3 N such as melilite.
The relative content of 4 -Y 2 O 3 group compound is a portion improved. The thickness of the surface portion varies depending on the purpose, application, manufacturing method and the like, but is usually about several μm to 0.1 mm to about 1 mm or less. When a large amount of the Si 3 N 4 -Y 2 O 3 group crystalline compound is crystallized on the surface and covers the entire surface, the layer covering the surface contains little Si 3 N 4 and / or sialon particles (however, The third component = including the disperse phase), which results in a reduced state of 100 vol%, and the thickness (in the reduced state of 100 vol%) is preferably 5 μm or less in order to prevent a reduction in the strength of the entire sintered body. In the present sintered body, the case where the above composition ratio does not change suddenly at the boundary between the surface portion and the inside, that is, the case where the composition ratio changes continuously is also included. What is necessary is just to have the inside which has a composition ratio.
本焼結体の第４の視点の製造方法は，既述の通りであ
る。なお，表面部における窒化珪素の適当量の気化条件
下で焼結することが好ましいが，必ずしもそれに限定さ
れない。The manufacturing method according to the fourth aspect of the present sintered body is as described above. It is preferable to sinter the silicon nitride on the surface under an appropriate amount of vaporization conditions, but the present invention is not limited to this.
この焼成雰囲気は，基本的に窒素含有雰囲気下で行わ
れ，この圧力は通常の焼成に用いられる窒素分圧（減圧
から数千気圧）が用いられる。This sintering atmosphere is basically performed in a nitrogen-containing atmosphere, and the pressure is a nitrogen partial pressure (reduced pressure to several thousand atmospheres) used for normal sintering.
この焼結時において，上記本発明の表面を形成させる
には，粒界相をメリライト等のSi3N4−Y2O3基化合物と
して結晶化させることが好ましい。そのためには，焼結
時に1400〜1700℃，好ましくは1500〜1650℃で一定時間
保持する，又は冷却速度を遅くする等が行われる。更
に，この所定温度保持は，一度通常焼成（第１の視点参
照）をした後に上記温度に再加熱してもよいし，焼結工
程と連続的に行ってもよい。この結晶時には，表面のみ
ならず内部の粒界相にもメリライト等のSi3N4−Y2O3基
化合物が晶出するので，過度の熱処理には注意が必要で
ある。内部より表面部のメリライトの晶出を多くする方
法としては，焼成時の雰囲気制御即ち窒素分圧，酸素分
圧の制御を行ったり，表面より晶出しやすい組成原料で
覆ったりする方法を用いることができる。At the time of this sintering, in order to form the surface of the present invention, it is preferable to crystallize the grain boundary phase as a Si 3 N 4 —Y 2 O 3 group compound such as melilite. For this purpose, sintering is carried out at a temperature of 1400 to 1700 ° C., preferably 1500 to 1650 ° C. for a certain period of time, or a cooling rate is reduced. Further, the predetermined temperature may be maintained by performing normal firing once (see the first viewpoint) and then reheating to the above temperature, or may be performed continuously with the sintering step. At the time of this crystallization, Si 3 N 4 —Y 2 O 3 -based compounds such as melilite are crystallized not only on the surface but also in the internal grain boundary phase. As a method of increasing the crystallization of melilite on the surface from the inside, a method of controlling the atmosphere during firing, that is, controlling the partial pressure of nitrogen and oxygen, or covering with a composition material that is easily crystallized from the surface is used. Can be.
なお，表面部におけるM,J,K,H,A相の晶出の状況は,Y2
O3成分の量と焼結時間の調節によって基本的に影響をう
ける。The state of crystallization of the M, J, K, H, and A phases on the surface is based on Y 2
It is basically influenced by adjusting the amount of O 3 component and sintering time.
本発明の場合，表面部において成分の気化により複雑
な組成の変動が生じ，雰囲気の変化によっても，或いは
冷却過程における成分偏析によっても，生成結晶相は影
響を受ける。しかし，局部的には,SiO2−Si3N4−Y2O3三
元状態図（第11図），（F.F.Lange他,J.Am.Ceram.Soc.6
0（５−６）,p249−252（1977）より），及び林，楊等
の文献（「粉体および粉末冶金」34（１）p26〜31のFi
g.3）に記載の関係が参考となる。In the case of the present invention, a complicated composition change occurs due to the vaporization of components at the surface portion, and the generated crystal phase is affected by a change in atmosphere or by component segregation in the cooling process. However, the local, SiO 2 -Si 3 N 4 -Y 2 O 3 ternary phase diagram (FIG. 11), (FFLange other, J.Am.Ceram.Soc. 6
0 (5-6), pp. 249-252 (1977)) and references by Hayashi and Yang (“Powder and Powder Metallurgy”) 34 (1)
The relationship described in g.3) is helpful.
以下，実施例により本発明を具体的に説明する。 Hereinafter, the present invention will be described specifically with reference to examples.
実施例1.（第１〜３の視点） 表面部のSi含有量を内部より減少させ，或いは更に表
面部において，粒界相結晶質化合物（Si3N4−Y2O3基化
合物）を晶出させて，その効果を調べた。Example 1. (1st to 3rd viewpoints) The Si content in the surface portion was reduced from the inside, or further, the grain boundary phase crystalline compound (Si 3 N 4 —Y 2 O 3 group compound) was further reduced in the surface portion. After crystallization, the effect was examined.
まず，原料粉末として，平均粒径0.6μｍのSi3N4（α
化率90容量％以上）粉末，同0.5μｍのAl2O3若しくはMg
O,同1.3μｍのAlN粉末，同1.2μｍのY2O3粉末，同0.4μ
ｍのZrO2粉末，同1.2μｍのTiN粉末，同1.7μｍのHfN粉
末，同2.0μｍのWC粉末を，各々表に示す配合組成に配
合し，湿式ボールミルで48時間混合した後，成形助剤を
添加して乾燥した。First, as raw material powder, Si 3 N 4 (α
Powder, 0.5 μm Al 2 O 3 or Mg
O, 1.3 μm AlN powder, 1.2 μm Y 2 O 3 powder, 0.4 μm
m ZrO 2 powder, 1.2 μm TiN powder, 1.7 μm HfN powder, and 2.0 μm WC powder were mixed in the composition shown in the table, and mixed for 48 hours in a wet ball mill. Was added and dried.
この粉末を用いて金型成形し,1650〜1750℃，窒素圧
0.7〜10気圧，一部は炭酸ガスを併用した雰囲気中で焼
成して焼結体を製造した。尚，表面部の厚さは，研削に
よる表面削除及び微小領域Ｘ線回折により測定した所，
いずれも約0.01〜0.1mm程度であった。Molding using this powder, 1650-1750 ℃, nitrogen pressure
The sintered body was manufactured by firing at 0.7 to 10 atmospheres, partly in an atmosphere using carbon dioxide gas. The thickness of the surface was measured by surface removal by grinding and X-ray diffraction in a small area.
Each was about 0.01 to 0.1 mm.
この焼結体は,SNMN432（JISB4103）の寸法に仕上げ
た。但し，この仕上加工は，上下面のみ研削加工を行い
側面は焼肌のままとし，これをテストピース（チップ）
２とした。その寸法はプレス成形時に調整した。以下に
示す３つの方法による評価（特にテスト1,2は耐摩耗
性，テスト３は強度）を行い，その結果を表１及び第１
図に示した。This sintered body was finished to the dimensions of SNMN432 (JISB4103). However, in this finishing process, only the upper and lower surfaces are ground and the side surfaces remain as burnt skin, and this is used as a test piece (chip).
And 2. Its dimensions were adjusted during press molding. The following three methods were used to evaluate (especially, test 1 and 2 wear resistance, test 3 strength).
Shown in the figure.
テスト1,2,3の各条件は以下の通りである。尚，テス
ト２は小括弧内，テスト３は中括弧内に示した。また，
テスト１における寿命は，以下に述べるように欠損まで
の時間をとっている。この場合，欠損の主因は単純な機
械的強度ではなく，摩耗により切削抵抗が増大した結果
であり，耐摩耗性の目安として使われる。The conditions of Tests 1, 2, and 3 are as follows. Note that Test 2 is shown in parentheses and Test 3 is shown in curly brackets. Also,
The life in Test 1 takes the time until loss as described below. In this case, the main cause of the defect is not a simple mechanical strength but a result of an increase in cutting resistance due to wear, which is used as a measure of wear resistance.
テスト１ （テスト２） ［テスト３］ 被削材； インコネル718 （FC20） ［FC23］ 切削速度（m/分）； 250 （600） ［150］ 切込み（mm）； １ （0.5） ［２］ 送り（mm/rev）； 0.25 （0.2） ［0.6］ 切削油； 水溶性油 （なし） ［なし］ 切削時間（秒）； 欠損まで （330） ［欠損まで］ 寿命判定； 秒 （mm） ［山数］ 被削材（図中の１）形状；第２図に示すように外径30
0mmφ，内径200mmφのドーナツ状（第３図に示すように
外径240mmφの棒状）［第４図に示すように外径240mm
φ，山幅15mmのリング状溝付き棒状］。Test 1 (Test 2) [Test 3] Work material; Inconel 718 (FC20) [FC23] Cutting speed (m / min); 250 (600) [150] Depth of cut (mm); 1 (0.5) [2] Feed (Mm / rev); 0.25 (0.2) [0.6] Cutting oil; water-soluble oil (none) [None] Cutting time (seconds); Until chipping (330) [Until chipping] Life judgment; seconds (mm) [Number of peaks] ] Workpiece (1 in the figure) shape; outer diameter 30 as shown in FIG.
Donut shape with 0mmφ and inner diameter 200mmφ (rod shape with outer diameter 240mmφ as shown in Fig. 3) [240mm outer diameter as shown in Fig. 4
φ, rod-shaped grooved rod with a peak width of 15mm].
尚，図中の３はホルダーを示す。テスト２の寿命判定
は側面側の摩耗によった。Incidentally, reference numeral 3 in the drawing denotes a holder. The life judgment in Test 2 was based on the wear on the side surface.
表１のNo.1〜８は第１の視点に関連し,No.9は第２の
視点に,No.10〜13は第３の視点と夫々関連する。No.9
は、No.3の試料を焼成後1500℃×4hrs熱処理して結晶化
させたものである。No.11〜13は,No.10の試料を，焼成
温度，焼成時間，及び焼成雰囲気（焼成位置，例えば匣
鉢上の位置，炉内の位置等）を変化させて作成した。Nos. 1 to 8 in Table 1 relate to the first viewpoint, No. 9 relates to the second viewpoint, and Nos. 10 to 13 relate to the third viewpoint. No.9
Is obtained by baking the sample of No. 3 and then heat-treating it at 1500 ° C. for 4 hours to crystallize it. Nos. 11 to 13 were prepared by changing the sintering temperature, sintering time, and sintering atmosphere (sintering position, for example, the position on the sagger, the position in the furnace, etc.) of the sample of No. 10.
Si3N4（サイアロンも含む）は使用目的に応じてその
配合組成等は決定される。従って同一条件下でこれらの
例を比較することは困難である。例えば，上記比較例に
おいて，比較的高強度の型（比較例C1），比較例Ni合金
に適した型（比較例C2），比較的鋳物に適した型（比較
例C3）を示しており，これら型を相互に比較することは
ほとんど意味がなく，各型内での比較が意味がある。従
って，表には，同一又は類似の原料配合組成間にて性能
を比較できるように配列し，その結果を述べると以下の
通りである。尚，比較例C1,C3の各々は，各試料No.1とN
o.6の各々を研削加工してその表面から約0.2mm以上削除
し，表面部を完全に除去して内部を表出させたものであ
る（Ｘ−線にて確認）。比較例C2は試料No.3の組成で表
面のSiがほとんど減少してない焼肌をもつものである。The composition and the like of Si 3 N 4 (including sialon) are determined according to the purpose of use. Therefore, it is difficult to compare these examples under the same conditions. For example, in the above comparative example, a relatively high-strength mold (Comparative Example C1), a mold suitable for a comparative Ni alloy (Comparative Example C2), and a mold relatively suitable for a casting (Comparative Example C3) are shown. It makes little sense to compare these types with each other, and it makes sense to compare within each type. Therefore, the tables are arranged so that the performance can be compared between the same or similar raw material composition, and the results are as follows. Note that each of Comparative Examples C1 and C3 is
Each of o.6 was ground to remove about 0.2 mm or more from its surface, and the surface was completely removed to expose the inside (confirmed by X-rays). Comparative Example C2 has the composition of Sample No. 3 and has a burnt surface with almost no decrease in Si on the surface.
なお，試料No.1,No.2は特別の表面結晶化処理を施さ
ず，表面部の粒界相は第３相（HfN）を除いてガラス相
が主体であった。Samples No. 1 and No. 2 were not subjected to special surface crystallization treatment, and the grain boundary phase on the surface was mainly a glass phase except for the third phase (HfN).
表面部のSi癌量を減らした各実施例を各比較例と比べ
ると（試料No.1と比較例C1,試料No.3と比較例C2,試料N
o.6〜No.8と比較例C3），いずれも耐摩耗性が向上して
いる。この場合，いずれも強度は若干低下するがほとん
ど変わらず，問題となる程度のものではない。更に，試
料No.6〜No.8及び比較例C3において,Si減少率と耐摩耗
性の関係を第１図に示すと，その減少率が大きくなるに
従って耐摩耗性が向上しており，その効果に優れる。When the examples in which the amount of Si cancer on the surface portion was reduced were compared with the comparative examples (Sample No. 1 and Comparative Example C1, Sample No. 3 and Comparative Example C2, Sample N
o.6 to No.8 and Comparative Example C3) all have improved wear resistance. In this case, in each case, the strength slightly decreases, but hardly changes, and is not a problematic degree. Fig. 1 shows the relationship between the Si reduction rate and the wear resistance of Samples Nos. 6 to 8 and Comparative Example C3. As the reduction rate increases, the wear resistance improves. Excellent effect.
また，これらにIV a,V a族遷移金属の化合物（HfN,W
C,TiN）を配合したもの（試料No.2,4,6）は配合しない
もの（試料No.1,3,5）と比べると，耐摩耗性は改善され
る。尚，この配合量があまり多いと，比較例C4のように
強度がかなり低下する場合があるので注意する必要があ
る。In addition, compounds of Group IVa and Va transition metals (HfN, W
C, TiN) (Sample Nos. 2, 4, and 6) has improved abrasion resistance compared to those not mixed (Samples Nos. 1, 3, and 5). It should be noted that if the amount is too large, the strength may be considerably reduced as in Comparative Example C4.
以上より，試料No.1〜No.8については，表面部の窒化
珪素及びサイアロン粒子減少率が30vol％以上であるの
で，いずれも強度を維持しつつ耐摩耗性が向上してお
り，表面部及び内部を構成する材料の特性を十分に発揮
できた。From the above, for samples No. 1 to No. 8, the reduction rate of silicon nitride and sialon particles on the surface was 30 vol% or more. In addition, the properties of the material constituting the inside were sufficiently exhibited.
試料No.9〜13は，表面の結晶化処理により表面部に種
々のSi3N4−Y2O3基結晶が認められテスト１での改善が
めざましく，テスト３でも満足な結果を示している。In Samples Nos. 9 to 13, various Si 3 N 4 —Y 2 O 3 base crystals were observed on the surface due to the surface crystallization treatment, and the improvement in Test 1 was remarkable. I have.
実施例2.（第4,第５の視点） 結晶質粒界相をメリライト相とし，この効果を調べ
た。試料はメリライト相の出来る組成及び焼成条件を検
討し，作成した。 Example 2 (Fourth and Fifth Aspects) This effect was examined using a crystalline grain boundary phase as a melilite phase. Samples were prepared by examining the composition and sintering conditions for the formation of the melilite phase.
原料粉末としてSi3N4夫々，実施例１と同じ粉末,Al2O
3粉末若しくはMgO粉末,AlN粉末,Y2O3粉末,ZrO2粉末,TiN
粉末を用い，さらに平均粒径5.1μｍのYb2O3粉末を，夫
々，表に示す配合サ組成に配合し，湿式ボールミルで48
時間混合した後，成形助剤を添加して乾燥した。As raw material powders, Si 3 N 4 respectively , the same powder as in Example 1, Al 2 O
3 powder or MgO powder, AlN powder, Y 2 O 3 powder, ZrO 2 powder, TiN
Using powder, Yb 2 O 3 powder having an average particle size of 5.1 μm was added to each of the components shown in the table, and was mixed with a wet ball mill.
After mixing for an hour, a molding aid was added and dried.
この粉末を用いて金型成形し,1650〜1750℃の種々の
温度，窒素圧0.7〜10気圧の種々雰囲気中で約２時間以
上焼成して，種々のメリライト含有量をもつ各焼結体を
製造し，その結果を表に示す。尚，試料No.27〜29の表
面部のSi3N4/サイアロン粒子減少率は100vol％である。
試料No.27の表面部の厚さは約３μｍである。試料No.28
の同厚さは約15μｍであり，その表面部のＸ線回折結果
を第８図に，その内部のＸ線回折結果を第９図に示し
た。表面部の厚さは，研削による表面削除及び微小領域
Ｘ線回折により測定した。表面部の［メリライト／窒化
珪素］含有量比（R1）は第８図に示すように， R1＝1/IS式で， メリライト含有量の［内部／表面部］比（R2）は，第
８図中Ｉと第９図中のI M2の比， 即ちR2＝I/I式で，算出した。Using this powder, molds are formed and fired at various temperatures of 1650-1750 ° C and various atmospheres of nitrogen pressure 0.7-10 atm for more than 2 hours to produce sintered bodies with various melilite contents. It was manufactured and the results are shown in the table. The reduction rate of the Si 3 N 4 / SiAlON particles on the surface of Sample Nos. 27 to 29 was 100 vol%.
The thickness of the surface of Sample No. 27 is about 3 μm. Sample No.28
Has the same thickness of about 15 μm. FIG. 8 shows the result of X-ray diffraction on the surface portion thereof, and FIG. 9 shows the result of X-ray diffraction inside thereof. The thickness of the surface portion was measured by surface removal by grinding and X-ray diffraction in a small area. The surface portion of the melilite / silicon nitride] content ratio (R 1), as shown in FIG. 8, in R 1 = 1 / I S wherein the melilite content [Internal / surface section] ratio (R 2) Was calculated by the ratio of I M2 in FIG. 8 to I M2 in FIG. 9, that is, R 2 = I / I.
この焼結体は,SNMN432（JISB4103）の寸法に仕上げ
た。但し，この仕上加工は，上下面のみ研削加工を行い
側面は焼肌のままとし，これをテストピース（チップ）
２とした。その寸法はプレス成形時に調整した（以上実
施例１と同様）。以下に示す２つの方法による評価を行
い，その結果を表２及び第５図〜第８図に示した。This sintered body was finished to the dimensions of SNMN432 (JISB4103). However, in this finishing process, only the upper and lower surfaces are ground and the side surfaces remain as burnt skin, and this is used as a test piece (chip).
And 2. The dimensions were adjusted during press molding (the same as in Example 1). Evaluation was performed by the following two methods, and the results are shown in Table 2 and FIGS. 5 to 8.
テスト4,5の各条件は以下の通りである。尚，テスト
５は括弧内に召した。また，テスト４における寿命は摩
耗量（mm）で，テスト５の寿命は欠損までの山数をとっ
ている。The conditions of tests 4 and 5 are as follows. Test 5 was called in parentheses. The life in test 4 is the amount of wear (mm), and the life in test 5 is the number of peaks up to loss.
テスト４ （テスト５） 被削材； FC20 （FC23） 切削速度（m/分）； 600 （150） 仕込み（mm）； 0.5 （２） 送り（mm/rev）； 0.2 （0.6） 切削油； なし なし 切削時間（秒）； 330 （欠損まで） 寿命判定； mm （山数） 被削材（図中の１）形状；第３図に示すように外径24
0mmφの棒状（第４図に示すように外径240mmφ，山幅15
mmのリング状溝付き棒状）。Test 4 (Test 5) Work material; FC20 (FC23) Cutting speed (m / min); 600 (150) Preparation (mm); 0.5 (2) Feed (mm / rev); 0.2 (0.6) Cutting oil; None None Cutting time (seconds); 330 (until chipping) Life judgment; mm (number of peaks) Workpiece (1 in the figure) Shape; outer diameter 24 as shown in Fig. 3
0mmφ rod shape (outer diameter 240mmφ, peak width 15 as shown in Fig. 4)
mm rod-shaped rod with groove).
Si3N4及び／又はサイアロンは使用目的に応じてその
配合組成等は決定される。従って同一条件下でこれらの
例を比較することは困難である。即ち目的により組成成
分比が異なる系列を相互に比較することはほとんど意味
がなく，各同系列内での比較が意味がある。従って，表
２には，同一又は類似の原料配合組成間にて性能を比較
できるように配列し，その結果を述べると以下の通りで
ある。尚，比較例C21,C24は0.5mm以上表面を研削して，
表面部を完全に除去して内部を表出させたものであり，
表２中＊を付した。The composition of Si 3 N 4 and / or Sialon is determined depending on the purpose of use. Therefore, it is difficult to compare these examples under the same conditions. That is, it is almost meaningless to compare the series having different composition component ratios with each other depending on the purpose, and it is meaningful to make a comparison within each same series. Therefore, Table 2 shows the arrangement of the same or similar raw material composition so that the performance can be compared, and the results are as follows. In Comparative Examples C21 and C24, the surface was ground by 0.5 mm or more.
The surface is completely removed and the inside is exposed.
In Table 2, * was added.
比較例C21と比べて試料No.21,22は，比較例C22〜24と
比べて試料No.27〜30は，いずれも摩耗量が少なく耐摩
耗性が向上しており，また破損までの山数も同様又はそ
れ以上であり耐欠損性も維持されている。試料No.23,24
並びに試料No.25,26も耐摩耗性に優れている。第６図及
び第７図に，試料No.27〜30,比較例C22,C23について摩
耗量等の試験結果を示した。Samples Nos. 21 and 22 compared to Comparative Example C21 and Samples Nos. 27 to 30 each had a smaller amount of wear and improved wear resistance than Comparative Examples C22 to C24. The number is the same or more, and the fracture resistance is maintained. Sample No.23,24
Samples Nos. 25 and 26 also have excellent wear resistance. FIG. 6 and FIG. 7 show the test results such as the amount of wear for Sample Nos. 27 to 30, and Comparative Examples C22 and C23.
第６図に示すように，メリライトの［内部／表面部］
比が0.5未満の各試料では，それ以上の比較例と比べて
摩耗量が少ない。更に，試料No.21,22と比較例C21,試料
No.23とNo.24,試料No.25とNo.26の比較でも，その比の
小さい前者の摩耗量が少ない。従って，その比が小さい
即ち表面部のメリライト量が内部よりも，より多いとき
には耐摩耗性に優れることを示している。As shown in Fig. 6, [inside / surface] of melilite
Each sample having a ratio of less than 0.5 has a smaller amount of wear than the comparative examples having higher ratios. In addition, Sample Nos. 21 and 22 and Comparative Example C21, Sample
Also in the comparison between No. 23 and No. 24 and Sample No. 25 and No. 26, the former with a smaller ratio has less wear. Therefore, when the ratio is small, that is, when the amount of melilite on the surface is larger than that on the inside, it indicates that the wear resistance is excellent.
また，第７図に示すように，表面部のメリライト量が
多いもの程摩耗量が少なく，耐摩耗性に優れることを示
している。このことは，他の系列である試料No.21,22と
比較例C21,試料No.23とNo.24,試料No.25とNo.26の比較
でも，その比の大きな前者の摩耗量が少ないことからも
証明される。尚，第７図に示すように,R1が大きくな
り、R2に関しては第６図に示したように、内部の粒界相
にメリライト含有量が多くなる（例えば試料No.27,28）
と，切削山数が少なくなり，耐欠損性が低下する。Further, as shown in FIG. 7, the larger the amount of melilite on the surface, the smaller the amount of wear, indicating that the wear resistance is excellent. This means that the other series, Samples Nos. 21 and 22, and Comparative Example C21, Samples No. 23 and No. 24, and Samples No. 25 and No. 26 also show the former with the larger ratio. It is proved from the small number. In addition, as shown in FIG. 7, R 1 increases, and as for R 2 , as shown in FIG. 6, the content of melilite in the internal grain boundary phase increases (for example, sample Nos. 27 and 28).
As a result, the number of cutting peaks decreases and the fracture resistance decreases.
また，比較例C25の市販サイアロン工具は特に摩耗量
が多く，比較例C26の市販コーティング窒化珪素工具は
著しく欠損しやすい。In addition, the commercial sialon tool of Comparative Example C25 has a particularly large amount of wear, and the commercial coated silicon nitride tool of Comparative Example C26 is extremely prone to chipping.
以上より，試料No.21〜30については，表面部の［メ
リライト／窒化珪素］比が0.37〜4.5であり，かつメリ
ライトの［内部／表面部］比が0.02〜0.31であるので，
いずれも耐欠損性を維持しつつ耐摩耗性が向上してお
り，表面部及び内部を構成する材料の特性を十分に発揮
できた。Si3N4−サイアロン粒子減少率は，内部より表
面部に粒界相が多いこと（１）を示すが,R2とは必ずし
も相関があるとはいえない。表面部においては，内部よ
り結晶化し易いこと（２）が認められる。従ってR2は，
（１）と（２）の相乗効果により定まると考えられる。From the above, for sample Nos. 21 to 30, the [melilite / silicon nitride] ratio of the surface portion was 0.37 to 4.5 and the [internal / surface portion] ratio of melilite was 0.02 to 0.31.
In each case, the abrasion resistance was improved while maintaining the fracture resistance, and the properties of the material constituting the surface and the interior were sufficiently exhibited. The reduction rate of Si 3 N 4 -Sialon particles indicates that there are more grain boundary phases on the surface than on the inside (1), but it cannot be said that there is always a correlation with R 2 . At the surface, it is recognized that crystallization is easier than at the inside (2). Therefore R 2 is
It is considered that it is determined by the synergistic effect of (1) and (2).
本第４及び第５の視点の窒化珪素基焼結体は，その表
面部のメリライト含有量が内部と比べて多いので，表面
部の耐摩耗性に優れるという性質と内部の高靭性等とい
う本質的特性が十分に発揮される。Since the silicon nitride-based sintered bodies of the fourth and fifth aspects have a higher melilite content on the surface than on the inside, they have excellent properties such as excellent wear resistance on the surface and high toughness inside. Characteristic is fully exhibited.
本第５視点の窒化珪素基焼結体は，更に表面部のメリ
ライト含有量が窒化珪素に比べて多いので，耐摩耗性が
確実に保証される。Since the silicon nitride-based sintered body of the fifth aspect further has a higher melilite content in the surface portion than silicon nitride, wear resistance is reliably ensured.
［発明の効果］ 本発明の各視点に共通して，表面部が内部と強固に一
体に形成されると共に，内部の有する高靭性と表面部の
有する高い表面耐摩耗性を兼ね備えた窒化珪素基焼結体
が得られる。即ち，本焼結体では，従来のように両性質
の中間的特性を示すものではない。従って，本焼結体で
は，その表面改質により，内部の本質的特性を低下させ
ることなく耐摩耗性を向上させることができる。また，
表面部と内部は一体のため，両者間の接合強度が高く剥
離することもない。その結果，本発明の窒化珪素基焼結
体は，特に鉄系の難切削性の被削材の切削にも適する，
耐摩耗性・耐衝撃性の高い切削工具等の，耐摩耗性・耐
衝撃性材料として極めて有用である。耐熱性・耐熱衝撃
性にも優れることはもちろんである。 [Effects of the Invention] A silicon nitride base having a surface part formed integrally with the inside and having both high toughness inside and high surface wear resistance possessed by the surface part, which is common to all aspects of the present invention. A sintered body is obtained. That is, the sintered body does not show an intermediate property between the two properties as in the conventional case. Therefore, in this sintered body, the wear resistance can be improved without deteriorating the internal essential characteristics by the surface modification. Also,
Since the surface and the inside are integral, the bonding strength between them is high and there is no peeling. As a result, the silicon nitride based sintered body of the present invention is particularly suitable for cutting hard-to-cut work materials of iron type.
It is extremely useful as a wear-resistant and impact-resistant material for cutting tools with high wear resistance and impact resistance. Of course, it has excellent heat resistance and thermal shock resistance.
第１図は表面部のSi3N4・サイアロン粒子減少率と耐摩
耗性の関係を示すグラフ， 第２図はテスト１に用いた被削材形状等を示す説明断面
図， 第３図はテスト２に用いた被削材形状等を示す説明断面
図， 第４図はテスト３に用い被削材形状等を示す一部断面図
である。 第５図は,Si3N4相と焼結雰囲気の分圧との間の関係を示
す公知の図表である。 第６図はメリライト含有量の［表面部／内部］比（R2）
と耐摩耗性の関係を示すグラフ， 第７図は表面部の［メリライト／窒化珪素］含有量比
（R1）と耐摩耗性等の関係を示すグラフ， 第８図は試料28の焼結体の表面部のＸ線回折結果を示す
グラフ， 第９図は試料28の焼結体の内部のＸ線回折結果を示すグ
ラフ， 第10図は表面部（ａ）及び内部（ｂ）の組織の模式図で
ある。 第11図は1600〜1750℃におけるホットプレス試料により
求められた公知のSiO2−Si3N4−Y2O3三元状態図であ
る。FIG. 1 is a graph showing the relationship between the reduction rate of Si 3 N 4 and sialon particles on the surface and wear resistance, FIG. 2 is an explanatory cross-sectional view showing the shape of the work material used in Test 1, and FIG. FIG. 4 is an explanatory cross-sectional view showing the shape of the work material used in Test 2, and FIG. 4 is a partial cross-sectional view showing the shape of the work material used in Test 3. FIG. 5 is a known chart showing the relationship between the Si 3 N 4 phase and the partial pressure of the sintering atmosphere. Figure 6 shows the [surface / internal] ratio of the melilite content (R 2 ).
7 is a graph showing the relationship between the [Mellilite / silicon nitride] content ratio (R 1 ) on the surface and the wear resistance, etc. FIG. 8 is a graph showing the sintering of sample 28. FIG. 9 is a graph showing the result of X-ray diffraction of the surface of the body, FIG. 9 is a graph showing the result of X-ray diffraction inside the sintered body of Sample 28, and FIG. 10 is the structure of the surface (a) and the inside (b). FIG. FIG. 11 is a known ternary phase diagram of a known SiO 2 —Si 3 N 4 —Y 2 O 3 obtained by a hot press sample at 1600 to 1750 ° C.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭63−89641（ＪＰ，Ａ) 特許2719942（ＪＰ，Ｂ２) ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-89641 (JP, A) Patent 2719942 (JP, B2)
Claims (13)
り、内部は窒化珪素、サイアロンの一種以上を主体と
し、 表面部において粒界相の一部又はすべてが結晶化してい
ること、 表面部は内部にくらべ窒化珪素及びサイアロン結晶粒子
が30vol％以上少ないこと、 を特徴とする窒化珪素基焼結体。An inner surface is formed of one or more of silicon nitride and sialon, and a part or all of a grain boundary phase is crystallized on the surface portion. A silicon nitride-based sintered body, characterized in that, in the part, silicon nitride and sialon crystal grains are smaller by 30 vol% or more than inside.
増大していることを特徴とする請求項第１項記載の窒化
珪素基焼結体。2. The silicon nitride-based sintered body according to claim 1, wherein the ratio of the grain boundary phase is higher at the surface than at the inside.
り、内部は窒化珪素、サイアロンの一種以上を主体と
し、 表面部において粒界相の一部又はすべてが結晶化してい
ること、 表面部において内部よりも粒界相の比率が増大している
こと、 を特徴とする窒化珪素基焼結体。3. The method according to claim 1, further comprising a surface portion integrally formed with the inside, wherein the inside is mainly composed of one or more of silicon nitride and sialon, and a part or all of a grain boundary phase is crystallized on the surface portion. Wherein the ratio of the grain boundary phase in the portion is higher than that in the inside.
化合物の、表面部に対する内部の含有量比がＸ線ピーク
強度比法にて0.5未満であることを特徴とする請求項第
１項〜第３項記載の窒化珪素基焼結体。4. The method according to claim 1, wherein the content ratio of the crystalline compound forming part or all of the grain boundary phase to the inner portion relative to the surface portion is less than 0.5 by the X-ray peak intensity ratio method. Item 4. The silicon nitride-based sintered body according to item 1 to item 3.
化合物は、表面部において窒化珪素及びサイアロン結晶
粒子の含有量に比し最高Ｘ線強度比法にて0.3以上含有
されていることを特徴とする請求項第１〜４項の一に記
載の窒化珪素基焼結体。5. The crystalline compound forming part or all of the grain boundary phase is contained in the surface portion by 0.3 or more by the maximum X-ray intensity ratio method based on the content of silicon nitride and sialon crystal grains. The silicon nitride-based sintered body according to claim 1, wherein:
相、Ｊ相、Ｋ相、Ｈ相、Ａ相、又はこれらの混合相であ
ることを特徴とする請求項第１〜５項の一に記載の窒化
珪素基焼結体。6. The method according to claim 1, wherein the crystalline grain boundary phase at the surface portion is a melilite phase, a J phase, a K phase, an H phase, an A phase, or a mixed phase thereof. The silicon nitride-based sintered body according to the above.
のメリライトの含有量の比が、Ｘ線ピーク強度比法にて
0.5未満であることを特徴とする請求項第６項記載の窒
化珪素基焼結体。7. The ratio of the content of melilite inside to the content of melilite on the surface is determined by the X-ray peak intensity ratio method.
The silicon nitride-based sintered body according to claim 6, wherein the value is less than 0.5.
の含有量に対するメリライトの含有量の比が、最高Ｘ線
強度比法にて0.3以上である請求項第６又は７項記載の
窒化珪素基焼結体。8. The silicon nitride-based firing according to claim 6, wherein the ratio of the content of melilite to the content of silicon nitride and sialon at the surface is 0.3 or more by the maximum X-ray intensity ratio method. Union.
リライトから成る、請求項第６〜８項の一記載の窒化珪
素基焼結体。9. The silicon nitride-based sintered body according to claim 6, wherein the crystalline grain boundary phase at the surface portion is substantially made of melilite.
化度が高いことを特徴とする請求項第１〜９項の一に記
載の窒化珪素基焼結体。10. The silicon nitride based sintered body according to claim 1, wherein the crystallinity of the grain boundary phase is higher at the surface than at the inside.
る窒化珪素基焼結体において、表面部のメリライトの含
有量に対する内部のメリライトの含有量の比が、Ｘ線ピ
ーク強度比法にて0.5未満であることを特徴とする表面
改質窒化珪素基焼結体。11. A silicon nitride-based sintered body comprising a surface portion and an interior formed integrally, wherein the ratio of the content of internal melilite to the content of melilite on the surface portion is determined by an X-ray peak intensity ratio method. Surface-modified silicon nitride-based sintered body, characterized in that it is less than 0.5.
り、内部は窒化珪素、サイアロンの一種以上を主体と
し、 表面部において粒界相がガラス相であること、 表面部は内部にくらべ窒化珪素及びサイアロン結晶粒子
が30vol％以上少ないこと、 を特徴とする窒化珪素基焼結体。12. An inner surface comprising an integrally formed surface portion and an interior, wherein the interior is mainly composed of at least one of silicon nitride and sialon, and a grain boundary phase is a glass phase at the surface portion. A silicon nitride-based sintered body, characterized in that silicon nitride and sialon crystal particles are reduced by 30 vol% or more.
り、内部は窒化珪素、サイアロンの一種以上を主体と
し、 表面部において粒界相がガラス相であること、 表面部において内部よりも粒界相の比率が増大している
こと、 を特徴とする窒化珪素基焼結体。13. A surface part formed integrally with an interior, wherein the interior is mainly composed of at least one of silicon nitride and sialon, and the grain boundary phase is a glass phase at the surface, and the interior is more than the interior at the surface. A silicon nitride-based sintered body, characterized in that the ratio of the grain boundary phase is increased.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00364190A JP3266200B2 (en) | 1989-01-12 | 1990-01-12 | Silicon nitride based sintered body |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1-5791 | 1989-01-12 | ||
| JP579189 | 1989-01-12 | ||
| JP00364190A JP3266200B2 (en) | 1989-01-12 | 1990-01-12 | Silicon nitride based sintered body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02275763A JPH02275763A (en) | 1990-11-09 |
| JP3266200B2 true JP3266200B2 (en) | 2002-03-18 |
Family
ID=26337271
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP00364190A Expired - Fee Related JP3266200B2 (en) | 1989-01-12 | 1990-01-12 | Silicon nitride based sintered body |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3266200B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2402098A1 (en) | 2004-12-22 | 2012-01-04 | NGK Spark Plug Co., Ltd. | Sialon insert, cutting tool equipped therewith, and manufacturing method thereof |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4716855B2 (en) * | 2005-11-08 | 2011-07-06 | 日本特殊陶業株式会社 | Sialon cutting tool and tool equipped therewith |
| JP2007230788A (en) * | 2006-02-27 | 2007-09-13 | Kyocera Corp | Silicon nitride sintered compact |
| JP5289054B2 (en) | 2006-09-20 | 2013-09-11 | 三井化学株式会社 | Polyolefin composition |
| WO2008114752A1 (en) | 2007-03-22 | 2008-09-25 | Ngk Spark Plug Co., Ltd. | Insert and cutting tool |
| WO2021124690A1 (en) * | 2019-12-20 | 2021-06-24 | 日本特殊陶業株式会社 | Cutting tool |
-
1990
- 1990-01-12 JP JP00364190A patent/JP3266200B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2402098A1 (en) | 2004-12-22 | 2012-01-04 | NGK Spark Plug Co., Ltd. | Sialon insert, cutting tool equipped therewith, and manufacturing method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02275763A (en) | 1990-11-09 |
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