JPH0587441B2 - - Google Patents
Info
- Publication number
- JPH0587441B2 JPH0587441B2 JP63140454A JP14045488A JPH0587441B2 JP H0587441 B2 JPH0587441 B2 JP H0587441B2 JP 63140454 A JP63140454 A JP 63140454A JP 14045488 A JP14045488 A JP 14045488A JP H0587441 B2 JPH0587441 B2 JP H0587441B2
- Authority
- JP
- Japan
- Prior art keywords
- oxygen
- powder
- weight
- silicon nitride
- temperature
- 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
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 43
- 239000001301 oxygen Substances 0.000 claims description 43
- 229910052760 oxygen Inorganic materials 0.000 claims description 43
- 239000000843 powder Substances 0.000 claims description 41
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 23
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 23
- 238000000034 method Methods 0.000 description 18
- 238000005245 sintering Methods 0.000 description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 10
- 239000000203 mixture Substances 0.000 description 7
- 238000005452 bending Methods 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- 239000000377 silicon dioxide Substances 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000000280 densification Methods 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 238000005121 nitriding Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- RAABOESOVLLHRU-UHFFFAOYSA-N diazene Chemical compound N=N RAABOESOVLLHRU-UHFFFAOYSA-N 0.000 description 2
- 229910000071 diazene Inorganic materials 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 1
- VRZJGENLTNRAIG-UHFFFAOYSA-N 4-[4-(dimethylamino)phenyl]iminonaphthalen-1-one Chemical compound C1=CC(N(C)C)=CC=C1N=C1C2=CC=CC=C2C(=O)C=C1 VRZJGENLTNRAIG-UHFFFAOYSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 235000019270 ammonium chloride Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000011033 desalting Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000000877 morphologic effect Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000004482 other powder Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 1
- 238000005375 photometry Methods 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- -1 silicon halide Chemical class 0.000 description 1
- 239000005049 silicon tetrachloride Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910052905 tridymite Inorganic materials 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
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Ceramic Products (AREA)
Description
〔産業上の利用分野〕
本発明は、高温強度の大きな焼結体を製造する
ことができる易焼結性アルフア窒化ケイ素粉末に
関する。
窒化ケイ素は、高温構造材料としてガスタービ
ン部材、ノズル、軸受等に利用されている。
〔従来の技術〕
従来、窒化ケイ素粉末の製法としては、(1)金属
ケイ素直接窒化法(2)シリカ還元窒化法(3)ハロゲン
化ケイ素法が知られている。これらの方法でつく
られる粉末は、製造履歴が異なるためか、金属不
純物量や酸素量或いは粒径・比表面積が同程度で
あつても、粉末の焼結性や焼結後の焼結体の特性
例えば曲げ強度に大きな違いがある。
一般的には、(1)の方法で製造された粉末は易焼
結性であるが高温曲げ強度が低い、(2)の方法の粉
末は難焼結性であるが高温曲げ強度が高い、(3)の
方法の粉末は中間的な性能を示すといわれてい
る。
酸素量については、(1)の方法の粉末は粉砕工程
を経るため通常全酸素量が２重量％を越える場合
が多く、少なくても1.5重量％以上はある。(1)の
方法で不純物除去のため酸処理等の工程を通すと
全酸素量は低減するが表面酸素量が0.2重量％未
満と小さくなつてしまう。一方、(2)の方法の粉末
でも、原料としてシリカ粉末を用いるためシリカ
の残留があり全酸素量は２重量％を越えるのが普
通である。更に(3)の方法の粉末においても、粉体
内部酸素量は通常1.3重量％である。
以上の粉末が現状入手可能なものである。当然
のことながら、粉末の焼結性及び焼結体特性には
粉体酸素量の影響があるのは勿論であるが、その
他に、比表面積、結晶性、粒子形状等様々の粉体
特性がからみあつており、前記各製法の粉末特性
が粉体特性にどのように関係しているかは殆んど
わかつていないのが現状である。
特開昭62−202807号公報には、窒化ケイ素粉末
中の内部酸素が1.5〜4.0重量％である粉末及びそ
の製法が記載されている。この発明は、金属ケイ
素原料を窒化する際、二酸化ケイ素を酸素源とし
て添加し、1550℃程度の低温で焼結可能な窒化ケ
イ素粉末を提案しているが、酸素量を増やすと焼
結体中の粒界相の比率が増加するので高温曲げ強
度の改善が充分望めず用途に制約を受けるという
問題があり、さらに改善の必要があつた。
〔発明が解決しようとする課題〕
以上の問題点を解決するために、本発明者らが
種々検討した結果、窒化ケイ素粉末のα分率、比
表面積及び酸素量特に表面酸素量と、内部酸素量
が特定範囲にある場合に著るしい高温強度の改善
が可能となることを見い出し本発明を完成した。
〔課題を解決するための手段〕
すなわち本発明は、α分率85％以上、比表面積
７m2／ｇ以上であり、表面酸素が0.3〜0.6重量％
で内部酸素が0.5〜1.1重量％であることを特徴と
する易焼結性アルフア窒化ケイ素粉末である。
以下、さらに詳しく説明すると、本発明におい
て、窒化ケイ素粉末のα分率を85％以上に限定し
たのは、それよりも少ないと焼結の際に生じるα
−β転移が低温から起きやすくなり、更には焼結
助剤が形成する粒界相への窒化ケイ素の溶解性が
変化して充分に成長したアスペクト比の高いβ柱
状晶を得ることが困難となり、それらの結果とし
て高温強度が低くなるためである。
比表面積を７m2／ｇ以上に限定したのは、それ
未満では焼結しにくく緻密化不足となるためであ
る。しかしながら20m2／ｇ以上の高比表面積にな
ると焼結性はよいが、予備成型がしにくい、焼結
収縮が大きい等の欠点が現われるようになる。
α分率85％以上、比表面積７m2／ｇ以上の条件
を備えていても、焼結性が悪く焼結体の特性が向
上しないことが非常に多い。これは、粉末中に含
まれる酸素特に表面と内部に存在する酸素、謂ゆ
る形態別酸素に強い影響を受けており、窒化ケイ
素粉末の表面酸素と内部酸素が多くても少なくて
もよくない。この点について、本発明者らは、酸
素含有量の異なる窒化ケイ素粉末を意図的に種種
合成し、その焼結性と焼結体特性を評価した結
果、表面酸素が0.3〜0.6重量％で内部酸素が0.5〜
1.1重量％の範囲にある窒化ケイ素粉末は焼結性
と焼結体の高温強度が著しくよくなることを見い
出したものである。
窒化ケイ素粉末の表面酸素は、用いる焼結助剤
酸化物、通常は酸化イツトリウム、酸化アルミニ
ウム等と反応し、結晶相や複合ガラス相である粒
界相を焼結過程の高温雰囲気下で形成するが、表
面酸素が0.3重量％未満ではガラス層の形成温度
が高くなり充分に緻密化しなくなる。一方、0.6
重量％を越えると粒界相の形成温度は低くなり緻
密化しやすくなるが内部固溶酸素との関係で全酸
素量が増えるとかえつてガラス層形成温度を上げ
てしまうことがある。即ち、窒化ケイ素粉末の内
部酸素を全くなくすることは困難であるのでこの
内部酸素とのバランスから表面酸素は0.6重量％
を越えない方が良く、それを越えると高温強度の
改善が認められない。
内部酸素は粉末の製造方法により種々の値をも
つており、第１表に示すように、通常は１重量％
以上である。本発明者らは、表面酸素との関係で
0.5〜1.1重量％が好ましいことを確認した。
内部に固溶した酸素は焼結助剤が形成する粒界
相中へ徐々に溶けこみ粒界相の組成を変化させ
る。組成が変化すると粒界相の融点や焼結下での
粘度更には粒界相への窒化ケイ素の溶解性が異な
つてくるため、焼結性及び焼結体の組織に影響を
及ぼし、これらの結果として焼結体の高温強度に
違いが現われる。即ち、内部酸素が1.1重量％を
越えると高温強度が低下し、一方、0.5重量％未
満ではβ柱状晶が異常成長することがあり緻密化
しにくくなる。
本発明における表面酸素量及び内部酸素量の分
析手法の一例を示せば次のとおりである。
まず粉末中の全酸素量(A)を、例えばLECO社製
Ｏ／Ｎ同時分析計（TC−136型）により測定す
る。次に粉末1gを秤量し、１：９弗化水素酸水
溶液50mlを加えた後20℃の恒温槽内で20分間マグ
ネチツクスターラー（300〜600rpm）を用いて攪
拌する。その後5C濾紙を用いて炉過し、濾液を
JISR−1603法により分析しSi量を求める。この
Si量に相当するSiO2量(B)を算出する。更に濾液
中のNH4 +量をインドフエノール青吸光光度法に
より求めてSi3N4量を算出し、このSi量に相当す
るSiO2量(C)を換算する。Ｂ−Ｃにより溶出SiO2
量(D)が求まり、その値より表面酸素量(x)は次式に
より算出される。また、内部酸素はＡ−Ｘにより
求められる。
Ｘ＝Ａ−（O2／SiO2）Ｄ＝Ａ−（32／60）Ｄ
この方法により分析された市販窒化ケイ素粉末
の酸素量を第１表に示す。
[Industrial Application Field] The present invention relates to an easily sinterable alpha silicon nitride powder that can produce a sintered body with high high-temperature strength. Silicon nitride is used as a high-temperature structural material in gas turbine components, nozzles, bearings, and the like. [Prior Art] Conventionally, as methods for producing silicon nitride powder, (1) metal silicon direct nitriding method, (2) silica reduction nitriding method, and (3) silicon halide method are known. Perhaps because the powders produced by these methods have different manufacturing histories, even if the amount of metal impurities, oxygen content, particle size, and specific surface area are similar, the sinterability of the powder and the sintered body after sintering are different. There are large differences in properties such as bending strength. Generally, the powder produced by method (1) is easily sinterable but has low high temperature bending strength, and the powder produced by method (2) is difficult to sinter but has high high temperature bending strength. The powder obtained by method (3) is said to exhibit intermediate performance. As for the amount of oxygen, since the powder produced by method (1) undergoes a pulverization process, the total oxygen amount usually exceeds 2% by weight, and is at least 1.5% by weight. If the material is subjected to a process such as acid treatment to remove impurities in method (1), the total oxygen content will be reduced, but the surface oxygen content will be as small as less than 0.2% by weight. On the other hand, since silica powder is used as a raw material in the powder produced by method (2), silica remains and the total oxygen content usually exceeds 2% by weight. Furthermore, even in the powder obtained by method (3), the amount of oxygen inside the powder is usually 1.3% by weight. The above powders are currently available. Of course, the sinterability of the powder and the properties of the sintered body are affected by the amount of oxygen in the powder, but there are also various other powder properties such as specific surface area, crystallinity, and particle shape. Currently, there is little understanding of how the powder properties of each of the above-mentioned manufacturing methods are related to the powder properties. JP-A-62-202807 describes a silicon nitride powder containing 1.5 to 4.0% by weight of internal oxygen and a method for producing the same. This invention proposes a silicon nitride powder that can be sintered at a low temperature of about 1550°C by adding silicon dioxide as an oxygen source when nitriding a metallic silicon raw material. Since the proportion of the grain boundary phase increases, there is a problem in that the high temperature bending strength cannot be sufficiently improved and the applications are restricted, and further improvements are needed. [Problems to be Solved by the Invention] In order to solve the above problems, the present inventors conducted various studies and found that the α fraction, specific surface area, and oxygen content of silicon nitride powder, especially the surface oxygen content, and the internal oxygen The present invention was completed by discovering that when the amount is within a specific range, it is possible to significantly improve high temperature strength. [Means for Solving the Problems] That is, the present invention has an α fraction of 85% or more, a specific surface area of 7 m 2 /g or more, and a surface oxygen content of 0.3 to 0.6% by weight.
It is an easily sinterable alpha silicon nitride powder characterized by an internal oxygen content of 0.5 to 1.1% by weight. To explain in more detail below, in the present invention, the reason why the α fraction of the silicon nitride powder is limited to 85% or more is that if it is less than that, α will occur during sintering.
-β transition tends to occur at low temperatures, and furthermore, the solubility of silicon nitride in the grain boundary phase formed by the sintering aid changes, making it difficult to obtain sufficiently grown β columnar crystals with a high aspect ratio. This is because the high temperature strength becomes low as a result. The reason why the specific surface area is limited to 7 m 2 /g or more is because if it is less than that, sintering will be difficult and densification will be insufficient. However, when the specific surface area is 20 m 2 /g or more, although the sinterability is good, disadvantages such as difficulty in preforming and large sintering shrinkage appear. Even if the α fraction is 85% or more and the specific surface area is 7 m 2 /g or more, the sinterability is poor and the properties of the sintered body are not improved in many cases. This is strongly influenced by the oxygen contained in the powder, particularly the oxygen present on the surface and inside, so-called morphological oxygen, and it does not matter whether the surface oxygen and internal oxygen of the silicon nitride powder is large or small. Regarding this point, the present inventors intentionally synthesized silicon nitride powders with different oxygen contents and evaluated their sinterability and sintered body properties. Oxygen is 0.5~
It has been found that silicon nitride powder in the range of 1.1% by weight significantly improves sinterability and high-temperature strength of the sintered body. The surface oxygen of silicon nitride powder reacts with the sintering aid oxide used, usually yttrium oxide, aluminum oxide, etc., and forms a grain boundary phase, which is a crystalline phase or a composite glass phase, in the high-temperature atmosphere of the sintering process. However, if the surface oxygen content is less than 0.3% by weight, the formation temperature of the glass layer will be too high and it will not be sufficiently densified. On the other hand, 0.6
If it exceeds % by weight, the temperature at which the grain boundary phase is formed becomes low and densification becomes easy, but if the total amount of oxygen increases in relation to the internal solid solution oxygen, the temperature at which the glass layer is formed may be increased. In other words, it is difficult to completely eliminate the internal oxygen of silicon nitride powder, so the surface oxygen is 0.6% by weight due to the balance with this internal oxygen.
It is better not to exceed this value, otherwise no improvement in high-temperature strength will be observed. Internal oxygen has various values depending on the powder manufacturing method, and as shown in Table 1, it is usually 1% by weight.
That's all. In relation to surface oxygen, we
It was confirmed that 0.5 to 1.1% by weight is preferable. The solid dissolved oxygen inside gradually dissolves into the grain boundary phase formed by the sintering aid and changes the composition of the grain boundary phase. If the composition changes, the melting point of the grain boundary phase, the viscosity during sintering, and the solubility of silicon nitride in the grain boundary phase will change, which will affect the sinterability and the structure of the sintered body. As a result, differences appear in the high-temperature strength of the sintered bodies. That is, if the internal oxygen content exceeds 1.1% by weight, the high-temperature strength decreases, while if it is less than 0.5% by weight, abnormal growth of β columnar crystals may occur, making densification difficult. An example of a method for analyzing surface oxygen content and internal oxygen content in the present invention is as follows. First, the total amount of oxygen (A) in the powder is measured using, for example, an O/N simultaneous analyzer (Model TC-136) manufactured by LECO. Next, 1 g of powder is weighed, 50 ml of a 1:9 aqueous hydrofluoric acid solution is added thereto, and the mixture is stirred using a magnetic stirrer (300 to 600 rpm) in a constant temperature bath at 20°C for 20 minutes. After that, filter the filtrate using 5C filter paper.
Analyze according to JISR-1603 method to determine Si content. this
Calculate the amount of SiO 2 (B) corresponding to the amount of Si. Further, the amount of NH 4 + in the filtrate is determined by indophenol blue absorption photometry to calculate the amount of Si 3 N 4 , and the amount of SiO 2 (C) corresponding to this amount of Si is converted. SiO 2 eluted by B-C
The amount (D) is determined, and from that value, the surface oxygen amount (x) is calculated by the following formula. Also, internal oxygen is determined by A-X. X=A-( O2 / SiO2 )D=A-(32/60)D Table 1 shows the oxygen content of commercially available silicon nitride powder analyzed by this method.
以下、実施例と比較例をあげてさらに具体的に
説明する。
実施例１〜12及び比較例１〜８
四塩化ケイ素とアンモニアをモル比１：６で、
200℃以下の温度で反応させシリコンジイミドと
塩化アンモニウムからなる中間体を合成した。
しかる後、種粉として、α分率が異なる比表面
積18m2／ｇの窒化ケイ素を添加量を変えて添加し
窒化ケイ素製ルツボ内にて窒素ガス流通下500℃
に保持し脱塩アンモニウム処理を行なつた。
この後、1500℃以上の温度に昇温しシリコンジ
イミドを分解して窒化ケイ素粉末とするが、その
際、種粉の種類（α分率）及び生成窒化ケイ素
100重量部に対する種の添加量（重量部）及び分
解時の雰囲気中の酸素分圧を変化させてα分率、
比表面積及び酸素量の異なる粉末を製造した。
特に表面酸素を多くする場合は生成窒化ケイ素
粉末を空気中で更に温度1000℃で２時間熱処理を
した（比較例８）。第２表に粉末特性を示す。
第２表の各種特性をもつ窒化ケイ素粉末100重
量部に焼結助剤として、Y2O3：Al2O3の重量比が
５：２である混合物を７重量部添加混合し3t／cm2
の圧力でラバープレス成形した後温度1800℃で４
時間焼結した。得られた焼結体ＡのJISR−1601
に従う1200℃における３点曲げ強度の測定結果を
第３表に示す。
また、焼結助剤として、MgO：Al2O3：Y2O3
の重量比が２：１：３である混合物を６重量部添
加し焼結条件を温度1600℃で４時間としたこと以
外は同様にして焼結した。得られた焼結体Ｂの曲
げ強度の測定結果を同じく第３表に示す。
Hereinafter, a more specific explanation will be given with reference to Examples and Comparative Examples. Examples 1 to 12 and Comparative Examples 1 to 8 Silicon tetrachloride and ammonia at a molar ratio of 1:6,
An intermediate consisting of silicon diimide and ammonium chloride was synthesized by reacting at a temperature below 200℃. Thereafter, varying amounts of silicon nitride with a specific surface area of 18 m 2 /g with different α fractions were added as seed powder, and the mixture was heated at 500°C under nitrogen gas flow in a silicon nitride crucible.
The sample was kept at a temperature of 100 mL and subjected to desalting ammonium treatment. After this, the temperature is raised to 1500℃ or higher to decompose the silicon diimide and make silicon nitride powder. At that time, the type of seed powder (α fraction)
α fraction,
Powders with different specific surface areas and oxygen contents were produced. In particular, when increasing surface oxygen, the produced silicon nitride powder was further heat treated in air at a temperature of 1000° C. for 2 hours (Comparative Example 8). Table 2 shows the powder properties. 7 parts by weight of a mixture with a weight ratio of Y 2 O 3 :Al 2 O 3 of 5:2 was added as a sintering aid to 100 parts by weight of silicon nitride powder having the various properties shown in Table 2, and the mixture was mixed at 3t/cm. 2
After rubber press molding at a pressure of 4, at a temperature of 1800℃
Sintered for hours. JISR-1601 of the obtained sintered body A
Table 3 shows the measurement results of three-point bending strength at 1200°C according to the following. In addition, as a sintering aid, MgO:Al 2 O 3 : Y 2 O 3
Sintering was carried out in the same manner except that 6 parts by weight of a mixture having a weight ratio of 2:1:3 was added and the sintering conditions were changed to a temperature of 1600° C. for 4 hours. The measurement results of the bending strength of the obtained sintered body B are also shown in Table 3.
【表】【table】
【表】【table】
本発明の窒化ケイ素粉末は、焼結性に優れ得ら
れた焼結体の高温曲げ強度は600MPa以上にする
ことも可能である。これは、焼結体のβ柱状晶の
発生とその成長を調節し組織を制御した結果によ
るものである。
The silicon nitride powder of the present invention has excellent sinterability, and the resulting sintered body can have a high-temperature bending strength of 600 MPa or more. This is due to the control of the structure by regulating the generation and growth of β-columnar crystals in the sintered body.
Claims (1)
り、表面酸素が0.3〜0.6重量％で内部酸素が0.5〜
1.1重量％であることを特徴とする易焼結性アル
フア窒化ケイ素粉末。1 α fraction is 85% or more, specific surface area is 7 m 2 /g or more, surface oxygen is 0.3 to 0.6% by weight, and internal oxygen is 0.5 to 0.5% by weight.
Easily sinterable alpha silicon nitride powder characterized by a content of 1.1% by weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63140454A JPH01313308A (en) | 1988-06-09 | 1988-06-09 | Easily sinterable alpha silicon nitride powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63140454A JPH01313308A (en) | 1988-06-09 | 1988-06-09 | Easily sinterable alpha silicon nitride powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01313308A JPH01313308A (en) | 1989-12-18 |
| JPH0587441B2 true JPH0587441B2 (en) | 1993-12-16 |
Family
ID=15268991
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63140454A Granted JPH01313308A (en) | 1988-06-09 | 1988-06-09 | Easily sinterable alpha silicon nitride powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01313308A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3829504A1 (en) * | 1988-08-31 | 1990-03-01 | Bayer Ag | SILICON NITRIDE POWDER WITH IMPROVED SURFACE PROPERTIES AND METHOD FOR THE PRODUCTION THEREOF |
| DE3829502A1 (en) * | 1988-08-31 | 1990-03-01 | Bayer Ag | SILICON NITRIDE POWDER WITH LOW ISOELECTRIC POINT AND METHOD FOR THE PRODUCTION THEREOF |
| DE69309515T2 (en) * | 1992-01-24 | 1997-11-06 | Sumitomo Electric Industries | Silicon nitride powder and process for its production |
| JP2731333B2 (en) * | 1993-03-23 | 1998-03-25 | 日本碍子株式会社 | Silicon nitride sintered body, method of manufacturing the same, silicon nitride powder and method of manufacturing the same |
| GB9306802D0 (en) * | 1993-04-01 | 1993-05-26 | Tioxide Specialties Ltd | Process for the production of silicon nitride |
| JP2907366B2 (en) * | 1993-05-18 | 1999-06-21 | 宇部興産株式会社 | Method for producing crystalline silicon nitride powder |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5388011A (en) * | 1977-01-13 | 1978-08-03 | Tokyo Shibaura Electric Co | Pulverized ceramic material and method of its manufacture |
| JPS6060909A (en) * | 1983-09-13 | 1985-04-08 | Mitsubishi Metal Corp | Manufacture of silicon nitride powder |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6456369A (en) * | 1987-08-26 | 1989-03-03 | Ngk Spark Plug Co | Production of silicon nitride sitered body of high toughness |
-
1988
- 1988-06-09 JP JP63140454A patent/JPH01313308A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5388011A (en) * | 1977-01-13 | 1978-08-03 | Tokyo Shibaura Electric Co | Pulverized ceramic material and method of its manufacture |
| JPS6060909A (en) * | 1983-09-13 | 1985-04-08 | Mitsubishi Metal Corp | Manufacture of silicon nitride powder |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01313308A (en) | 1989-12-18 |
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