Showing papers on "Sialon published in 1985"

The effect of grinding on the flexural strength of a sialon ceramic

Abstract: The effect of selected grinding parameters on the flexural strength of a sialon ceramic was studied. Support compliance was found to have no significant effect, while depth of incursion and grinding direction did. Weibull statistics and analysis of variance techniques were used to detect these effects which are explained through flaw magnitude and direction.

Synthesis of β-Sialon from Si3N4 and Aluminum-Iso-Propoxide

Abstract: アルミニウムイソプロポキシド {Al(Oi-Pr)3} 溶液中にSi3N4粉末を懸濁させ, それを加水分解, 解膠後乾燥し, 空気中で900℃, 2時間仮焼してz=0.25, 0.5, 0.75, 1及び2のβ-サイアロン焼結体の原料粉末を得た. これらの原料粉末を1850℃, 300kg/cm2の圧力下で1時間ホットプレスし, 得られた焼結体の組成, 組織及び強度を調べた.z=0.5, 0.75, 1及び2でち密な焼結体が得られたが, z=0.25では相対密度88%の焼結体となった. 焼結体の組成はz=0.25及び0.5でβ-サイアロン+O', z=0.75でβ-サイアロン+O'+X, z=1及び2でβ-サイアロン+Xとなった. 焼結体の組織は, 約0.5-1μmのβ-サイアロン結晶粒からなり, α-Si3N4とα-Al2O3から得た焼結体で見られた組織の不均一はなかった. 焼結体は破壊に際し, いずれも表面の加工傷から破断した. 焼結体の強度はz=0.5で平均67kg/mm2 (最高72kg/mm2) となったが, z=2では平均14kg/mm2となった. これは, 加水分解時の水酸化アルミニウムの凝集による組織の顕著な不均一によるものであった.

Cutting Tool Life Comparisons

Abstract: Single point tool performance data are presented, concerning the use of tungsten carbide, alumina, sialon and cubic boron nitride cutting tools, when machining a variety of hardened and annealed ferrous workpiece materials. When cutting hardened die steel Rc 55-61, at speeds between 50–100m /min with a constant feed rate of 0.12mm/rev, two of the three sialons tested fared substantially better than either of the two CBN products used. In contrast, when turning a medium carbon steel and an annealed die steel, the sialon tools showed rapid flank and crater wear over a wide range of cutting speeds. On grey cast iron, grade 260, the alumina tool proved the most effective. In industrial tests using Syalon and BZN shank tools to machine automotive valve seats, the Syalon tools showed on average three times the level of BZN flank wear for a working component output of only 1½% of the BZN total.

Silicon nitride ceramics

Abstract: Sintered silicon nitride ceramics excellent in sliding properties have the a-phase silicon nitride and the β-phase silicon nitride admixed therein, and the proportion in which the a-phase silicon nitride is present in the sintered silicon nitride ceramics is controlled to be in the range of 5 to 15%. The sintered silicon nitride ceramics of this invention are suitable for heat-resistant parts such as heat-resistant bearings which are required to have high abrasion resistance.

Composition which is capable of being converted into an aluminium oxynitride refractory

Abstract: A refractory containing aluminum nitride oxide, comprising 3 parts by weight or more of aluminum nitride oxide, 0.5 to 60 parts by weight of carbon and/or carbonaceous compound, and the balance of other refractories has excellent corrosion resistance against molten pig iron, molten steel, molten slug, etc. and excellent heat impact resistance. In another embodiment, a refractory for sliding nozzle containing 10 to 98 wt % of aluminum nitride, and a nozzle of continuously casting steel containing 3 to 60 wt % of aluminum nitride oxide and 10 to 40 wt % of carbon and/or graphite are also disclosed. Both the refractory and the nozzle have prolonged service lives.

Preparation of Sialon Powder from Alkoxides

Abstract: ケイ酸エチルとアルミニウムイソプロポキシドの溶液の加水分解により得た微細なSiO2-Al2O3系共沈粉末とカーボンの混合物を窒素気流中で1430℃に加熱し, 還元・窒化反応を行うことによりサイアロン粉末を合成した. 種々の組成について検討したところSi/Al=1の組成において単相のサイアロン粉末が得られることが分った. 粉末は微細でその粒径は0.05-0.3μmであった. Si/Al=1の組成において, サイアロンの合成反応と得られたサイアロンの化学組成の関係を調べたところ, 合成中に酸素の窒素による置換のみでなく, SiOの飛散も起こることが確かめられた. このため粉末中のSi/Al比は時間とともに減少した。

Influence of the intergranular microstructure of substituted nitrides on high temperature strength

Abstract: The relationships between the intergranular structure of substituted silicon nitrides and their high temperature strength have been considered. It has been shown that four types of intergranular structure can be distinguished. These structures depend on the nature and amount of additives. Analytical electron microscopy (X-ray microanalysis, microdiffraction and electron-induced processes) enables a precise characterization of these structures. If an extended glassy phase always appears to be detrimental, it has been shown that a thin glassy film may improve the high temperature strength and the cutting life of sialon tools and may at least be a fair compromise to obtain dense and homogeneous hot-pressed silicon nitrides.

Effect of Composition on Mechanical Properties of β-Sialon

Abstract: Si3N4, Al2O3, AlNを用いたβ-サイアロン試料調製方法に検討を加え, ホットプレス法で製造したz=1, 2, 3, 4組成のβ-サイアロンの強度特性を調べた.ボールミル混合時間は, 72時間のときが曲げ強度のばらつきが最も少なかった. アルミナの粒径は, 平均粒径が1μm以下程度なら, それ以下の粒径のものを用いても曲げ強度に著しい効果は認められなかった. 曲げ強度及びビッカース硬度は, z=1から4になるに従い各々約50kg/mm2から約38kg/mm2及び約2100kg/mm2から約1300kg/mm2へと低下した. ヤング率はz=1からz=3までは2.91×106kg/cm2から2.34×106kg/cm2へと下がったが, z=4では2.37×106kg/cm2とz=3よりわずかに高い値を示した. 破壊靱性値はz=1からz=3までは約3.6MN/m3/2から約2.4MN/m3/2と低くなったが, z=4はz=3とほぼ同じ値であった.

Production of sialon powder

Abstract: PURPOSE:To produce high-purity sialon powder having fine and uniform particle size, by adding a specific amount of carbon powder to a specific powdery mixture of silica and alumina, and calcining in nitrogen atmosphere. CONSTITUTION:A mixture of a silicon alkoxide (e.g. methyl silicate) and an aluminum alkoxide (e.g. aluminum ethoxide) at an atomic ratio (Si/Al) of about 0.5-2 is dissolved in isobutanol, etc., and added with about 3-4pts.wt. of water and a small amount of ammonia water per 1pt.wt. of the alkoxide. The obtained precipitate is heated at about 500-700 deg.C for about 1-5hr to obtain a powdery mixture of silica and alumina composed of 50-80mol% silica and 50-20mol% alumina. The above powdery mixture is mixed with 16-25wt% carbon powder (preferably carbon black), and the mixture is calcined at 1,350-1,550 deg.C in nitrogen atmosphere.

Effect of Silicon Activity on Liquid‐Phase Sintering of Nitrogen Ceramics

Abstract: Volatilization resulting from the thermal decomposition of Si3N4 causes the large weight loss and desintering phenomenon observed during pressureless sintering of Si3N4-5% MgO and sialon (z =2)-5% MgO. The addition of a few weight percent of Si to the powder suppresses this volatilazation and helps to achieve fully dense Si3N4 components.

Refractories of silicon carbide and related materials having a modified silicon nitride bonding phase

Abstract: A refractory that is highly resistant to sequential steam oxidation and molten alkali attack is formed by reaction nitriding a mixutre of granular silicon carbide (as defined in the specification), silicon metal and aluminum metal. The refractory is suitable as a blast furnace lining, and comprises a bonded silicon carbide material consisting essentially of granular silicon carbide and a bonding phase comprising Si3N4 modified by the presence of oxygen and aluminum to form a sialon, said material having a resistance to at least one of either (a) a molten K2C03 attack alone or (b) a steam oxidation followed by a molten K2C03 attack, which resistance in excess of that possessed by a similar material in which the Si3N4 bonding phase is not modified by the presence of oxygen and aluminum.

Production of ceramic-metal composite body

Abstract: PURPOSE:To produce a ceramic-metal composite body having excellent resistance to thermal impact by coating a metal having specific porosity around a ceramic core material and converging said metal to an oxide, nitride, carbide, silicide, boride, sulfide, etc. then subjecting the same to insert-casting into a metal. CONSTITUTION:A metal such as Al, Zr, Si, Cr, Ti, Mo, etc. is thermally sprayed by gaseous acetylene/oxygen onto the surface of a core material 1 made of ceramics such as alumina, zirconia, magnesia silicate, silicon nitride, titanium silicide, Sialon, etc. or the material 1 is enveloped by said metallic powder and is sintered to form a metallic layer having 5-85% porosity to about 0.5mm. thickness. Such porous metallic layer is chemically treated to form a metallic compd. layer 11 composed of one or >=2 kinds among the oxide, nitride, carbide, silicide, boride and sulfide of said metal. The core material is then put into a casting mold and a molten metal such as ''Inconel'' or the like is poured into the mold to form insert-casting layers 2, 3 having respectively about 5mm. wall thickness. The composite body which obviates cracking of the ceramic core material 1 by thermal impact is obtd.

Ceramics containing alpha-sialon

Abstract: Alpha-sialon-containing ceramics having the following composition (presented as nitrides or oxides): Si3N4: 82.0-97.4 wt %, A$(1,3)$N: 1.6-12.5 wt %, Y2O3: 1.0-7.5 wt %, MgO: x wt %, CaO: Y wt %, Li2O: z wt % (where 0<=x, y, z<=5, 0.05<=x + y + z<=5) and substantially comprising a complex crystalline phase of alpha-sialon and beta-silicon nitride, excellent in mechanical properties, can be produced with a high density according to an atmospheric pressure sintering process.

Secondary Ion Mass Spectroscopy of Ceramics

Abstract: Application of SIMS to ceramics is a complicated but rewarding technique for characterization. The variable composition, hardness and insulating nature of these materials render spectra interpretation complex. Basic data reduction procedures from graphical data collection are presented along with spectra from SIMS applied to a glass frit, magnesium sialon, silicon and PTCR barium titanate.

High-strength ceramics containing alpha-sialon

Abstract: High-strength ceramics containing alpha-sialon substantially comprising an alpha-sialon composition represented by the formula: Yx(Si, Al)12(O, N)16, where 0

Production of novel carbon-containing composition and novel sialon

Abstract: PURPOSE:To produce the titled composition having high uniformity and fine particle size of the constituent particles, by charging a decomposable Si compound together with a decomposable Al compound and a C compound into hot gas containing steam, and decomposing the components. CONSTITUTION:A decomposable Si compound of formula I (n is 1-4; X is H, halogen, alkyl, aryl or alkoxy) is charged together with a decomposable Al compound of formula II and a C compound (e.g. toluene) into steam-containing hot gas, and decomposed at >=700 deg.C to produce a mixed aerosol containing the aerosol of Si oxide, Al oxide and elemental carbon. The objective carbon- containing composition can be produced by the solid-gas separation of the mixed aerosol. The composition is calcined at 1,350-1,650 deg.C in a gaseous atmosphere of a nitrogen-containing compound for about 2hr, and if necessary, heated at 500-1,000 deg.C in the presence of oxygen to remove the admixed carbon. The novel sialon can be produced by this process.

Contact interaction between materials based on silicon nitride and sianols with Al, Si, and Ni

Abstract: This paper presents some results from a study of the interaction between materials based on Si/sub 3/N/sub 4/ and sialons of various purities and melts of Al, Si, and Ni. The specimens were obtained by sintering and hot-pressing methods and their residual porosity was 10-16%. The general data on the wetting of materials of technical purity obtained from waste products and natural silica-containing raw materials are presented.

Sintering of synthesized sialon powders.

Abstract: 合成したサイアロン粉末の焼結性を化学組成の近いSi3N4-Al2O3-AlN系混合物と比較した. ホットプレス下で1750℃まで昇温した結果, 合成サイアロンの方が50°-100℃低温でち密化することが分った. 1730℃で1時間常圧焼結すると合成サイアロンは到達密度は混合物系より低いが, 理論値の98%以上に達し, かつより均一な微構造であった. 破壊靱性値はほぼ同じであるが, 硬度は合成粉末から得た焼結体の方が高かった.

Process for producing silicon aluminum oxynitride

Abstract: A process for producing a refractory material comprising essentially beta'-SiAION wherein initial reactants comprising Al2O3 and Si02 are nitrided for sufficient times and temperatures to convert at least a portion of the initial reactants to at least a portion of effective reactants and the effective reactants are then further heated to produce an essentially beta'-SiAlON refractory material.

Wear behaviour of sintered β'-sialon ceramic under sliding contact conditions

Abstract: On etudie l'usure par frottement non lubrifie de couples homogenes de sialon-β' frittes avec des ajouts de Y 2 O 3

Process for producing corrosion resistant silicon nitride bodies containing La 203

Abstract: A process is disclosed for producing corrosion resistant silicon nitride bodies from compositions of pure silicon nitride, lanthanum oxide with and without aluminium oxide by hot pressing.