氮化硅料浆的触变性

研究了分散剂加入量、球磨时间、料浆固含量、料浆pH值等因素对流动曲线上触变滞回环宽度大小的影响,据此分析探讨了各因素对料浆触变性的影响。     

注浆成形制备氮化硅陶瓷

研究了分散剂加入量、固含量、球磨时间、料浆pH值等因素对以氧化铝、氧化钇为烧结助剂的氮化硅料浆的粘度及注浆生坯密度的影响情况，并作了分析讨论。制备出生坯密度高达2．25g/cm^3的生坯。     

光固化ZrO2陶瓷料浆的流变性能研究

围绕陶瓷粉体在光敏树脂中的分散,研究了粉体性质、分散剂种类及其掺加量、固含量对光固化ZrO2陶瓷料浆流变性能的影响.结果表明:粉体性质对料浆的流变性能有着显著影响,比表面积小、球形度高的ZrO2陶瓷粉体更有利于配制低粘度、高固含量的料浆;料浆的流变性能以及稳定性主要受分散剂种类及其掺加量的控制,以相对粉体质量4％的X-...     

分散剂对刚玉-氮化硅浆体流变性能的影响

为优化刚玉-氮化硅透气砖用浇注料的性能,研究了刚玉水基浆体和氮化硅水基浆体的流变性能,并在此基础上研究了4种分散剂(分别为聚丙烯酸钠、高分子多元醇、木质素磺酸钙和六偏磷酸钠)对刚玉-氮化硅悬浮液流变性能的影响。结果表明:随着氮化硅悬浮液pH值的增大,其ζ电位的绝对值也增大,碱性条件有利于氮化硅悬浮液的稳定;当刚玉-氮化硅悬浮液的pH值=10时,其ζ电位的绝对值最大,悬浮液最稳定,分散性也最好;聚丙烯酸钠使刚玉-氮化硅悬浮液的ζ电位的绝对值明显增加,提高了悬浮液的稳定性,但其加入量不宜超过0.5%。将其结果应用在制备刚玉-氮化硅透气砖用浇注料上,使透气砖的性能得到了改善。     

水基纳米SiC复合料浆的流变性能和稳定性

引言 纳米复相碳化硅陶瓷是在多相复合碳化硅陶瓷基础上发展起来的-种新型碳化硅陶瓷材料,通过引人第二或第三纳米增强相来同时实现细晶结构、梯度残余应力场、裂纹桥联、自增韧等增强增韧机理,从而获得多强韧化机理协同强化碳化硅陶瓷,已成为碳化硅陶瓷的研究方向之一[1-4].其中,纳米增强相在碳化硅基体(包括料浆、复合粉体、陶瓷)中的分布是制备纳米复相碳化硅陶瓷的关键和前提之一[5].     

聚丙烯酸铵对氧化铝料浆分散行为的研究

研究了聚丙烯酸铵（PAANH4）的合成及其对氧化铝料浆稳定分散的机理。通过实验，优选出PAANH4的合成工艺；提出了沉降百分比、料浆粘度、zeta电势与聚丙烯酸铵加入量的关系，取得了比较满意的结果。     

高聚物对陶瓷料浆性能的影响机理

本文根据陶瓷料浆的三种稳定机制（静电稳定机制、空间位阻稳定机制、空缺稳定机制）,详细阐述了高分子聚合物对浆料的不同作用机理,同时,从对陶瓷原料粒子表面改性的角度出发,介绍几种陶瓷粉体表面改性技术用以制备出稳定、均匀及高固相含量的陶瓷料浆。     

Elevated-Temperature Mechanical Properties of Silicon Nitride/Boron Nitride Fibrous Monolithic Ceramics

A unique, all-ceramic material capable of nonbrittle fracture via crack deflection and delamination has been mechanically characterized from 25° through 1400°C. This material, fibrous monoliths, was comprised of unidirectionally aligned 250 μm diameter silicon nitride cells surrounded by 10 to 20 μm thick boron nitride cell boundaries. The average flexure strengths of fibrous monoliths were 510 and 290 MPa for specimens tested at room temperature and 1300°C, respectively. Crack deflection in the BN cell boundaries was observed at all temperatures. Characteristic flexural responses were observed at temperatures between 25° and 1400°C. Changes in the flexural response at different temperatures were attributed to changes in the physical properties of either the silicon nitride cells or boron nitride cell boundary.     

Mechanical Properties of Three-Layered Monolithic Silicon Nitride–Fibrous Silicon Nitride/Boron Nitride Monolith

A three-layered composite, composed of a strong outer layer (monolithic S₃N₄) and a tough inner layer (fibrous Si₃N₄/BN monolith), was fabricated by hot-pressing. For the inner layer, a Si₃N₄–polymer fiber made by extrusion was coated by dipping it into a 20 wt% BN-containing slurry. The three-layered composite exhibited excellent mechanical properties, including high strength, work of fracture, and crack resistance, because of the combination of a strong outer layer and a tough inner layer. In other words, the strong outer layer withheld the applied stress, while the tough inner layer promoted crack interactions through the weak BN cell boundaries. Also, the residual thermal stress on the surface due to the anisotropy in the coefficient of thermal expansion of BN affected a median/radial crack generation after indentation.     

氮化硅陶瓷在现代制造业中的应用

本文论述了氮化硅结构陶瓷材料的性能,着重介绍了此种材料在国内外制造业中的应用现状,也讨论了氮化硅陶瓷的缺陷及研究方向。     

氮化硅流延膜的制备

流延成型是一种制备高质量陶瓷基片的成型方法.氮化硅是一种高热导率的材料,有望在电子基片领域获得应用.本文利用流延成型制备了具有较好柔韧性和一定强度的氮化硅流延素坯膜.研究了无水乙醇、无水乙醇/丁酮作为溶剂时对浆料粘度的影响.通过优化流延浆料添加剂的各种配比,得出了适合氮化硅粉体(SN-E10)流延的最佳配方.     

蛭石基流延浆料的流变性能研究

以改性膨胀蛭石和滑石填料为原料,蓖麻油为分散剂,聚乙烯醇缩丁醛(PVB)为粘结剂,邻苯二甲酸二丁酯(DBP)为增塑剂,采用球磨法制备蛭石基流延浆料.考察浆料固含量和各组分添加量对浆料流变性能的影响,得出了合适的浆料配方为:固含量质量分数为50％、蓖麻油用量为粉体质量的2％、PVB用量为粉体质量的6％、DBP用量为R=0...     

Si3N4及其复合材料强韧化研究进展

简述了氮化硅陶瓷的结构、性能和制备工艺，并分别通过自增韧补强、纤维／晶须强韧化、层状结构强韧化、相变强韧化以及颗粒弥散强韧化等方法对氮化硅陶瓷的强韧化研究进行了分类叙述。     

Tribological Properties of Unidirectionally Aligned Silicon Nitride

A silicon nitride ceramic with unidirectionally aligned β-Si₃N₄ elongated grains (UA-SN) was fabricated by sintering the extruded Si₃N₄ green body with a small amount of rodlike β-Si₃N₄ seed. The effect of anisotropy in microstructure on tribological properties was investigated, compared with a fine-grained Si₃N₄ without seed. Block-on-ring tests without lubricant were conducted at sliding speeds of 0.15 and 1.5 m/s, with a normal load of 5 N and a sliding distance of 75 m, using the UA-SN and Si₃N₄ without seeds as block specimens and commercially supplied Si₃N₄ as ring specimens. For UA-SN, tribological properties were evaluated in three directions with respect to the grain alignment: the plane normal to the grain alignment, and in the direction parallel to or perpendicular to the grain alignment in the side plane. For both sliding speeds, the plane normal to the grain alignment exhibited the highest wear resistance, and the worn surface of this plane was quite smooth, in contrast to the other specimens whose surfaces were irregular owing to grain dropping. It is considered that the high wear resistance achieved in this plane is attributable to the inhibition of crack propagation along the sliding surface by the stacked elongated grains normal to the sliding surface.     

Effect of Acid Cleaning and Calcination on Rheological Properties of Concentrated Aqueous Suspensions of Silicon Nitride Powder

The powder characteristics of two types of Si₃N₄ (referred to as FD1 and FD2), as well as the rheological properties of their aqueous suspensions, were studied in this paper. There are distinctive differences in size distribution, soluble counterions, and surface groups. Highly concentrated aqueous slurries could not be prepared from these two as-received powders. Acid cleaning and calcination improved the solids loading of their aqueous slurries, but the improvement varied with the powder. For the as-received FD1 powder, poor dispersibility was caused by high-valence counterions, which can be eliminated through acid-cleaning. However, for the as-received FD2 powder, it was the surface group of amine structures and carbon-hydrogen bonding that limited the dispersibility. The calcination of FD2 can remove the amine structure and carbon-hydrogen bonding and improve the slurry's rheological properties almost perfectly. For acid-cleaned and calcined FD1, and calcined FD2, the solids loading of their aqueous suspensions reached 50 vol% with a viscosity below 300 mPa·s.     

Silicon Nitride and Related Materials

Silicon nitride has been researched intensively, largely in response to the challenge to develop internal combustion engines with hot-zone components made entirely from ceramics. The ceramic engine programs have had only partial success, but this research effort has succeeded in generating a degree of understanding of silicon nitride and of its processing and properties, which in many respects is more advanced than of more widely used technical ceramics. This review examines from the historical standpoint the development of silicon nitride and of its processing into a range of high-grade ceramic materials. The development of understanding of microstructure–property relationships in the silicon nitride materials is also surveyed. Because silicon nitride has close relationships with the SiAlON group of materials, it is impossible to discuss the one without some reference to the other, and a brief mention of the development of the SiAlONs is included for completeness.     

生物质复合材料浆料流变特性及管道输料条件研究

利用数字黏度测量仪对生物质复合材料的浆料阶流变特性进行研究,采用SEM分析浆料中纤维空间结构,最后研究了管道输送料的温度。实验结果表明:浆料中纤维搭接呈网状结构,其黏度随时间先增大后减小,最终趋于稳定。剪切速率和剪切应力之间能够利用卡森模型进行良好的拟合。随浆料温度升高,浆料黏度减小;在温度介于55~85 ℃的,充分搅拌900 s后,浆料黏度较小且稳定,最适合管道输料。