不同颗粒尺寸α-Al2O3粉体制备稳定浆料的研究

通过改变pH值和分散剂的浓度 ,对不同颗粒尺寸的αAl2 O3粉体制得浆料的稳定性、分散性以及流变特性进行研究。结果表明 :pH值和分散剂用量对αAl2 O3浆料的稳定性和分散性有显著影响。用不同颗粒尺寸的αAl2 O3粉体制备高稳定、高分散的陶瓷浆料 ,其最适pH值和最佳分散剂用量各不相同。αAl2 O3浆料的流变特性呈剪切稀化特点 ,悬浮浆料的粘度随固含量的增加而上升 ,而最佳分散剂用量不随浆料固含量的变化而改变     

不同颗粒尺寸α－A12O3粉体制备稳定浆料的研究

通过改变pH值和分散剂的浓度，对不同颗粒尺寸的α—A12O3粉体制得浆料的稳定性、分散性以及流变特性进行研究．结果表明。pH值和分散剂用量对α—A12O3浆料的稳定性和分散性有显著影响．用不同颗粒尺寸的α—A12O3粉体制备高稳定、高分散的陶瓷浆料，其量适pH值和量佳分散剂用量各不相同．α—A12O3浆料的流变特性呈剪切稀化特点，悬浮浆料的粘度随固含量的增加而上升，而最佳分散剂用量不随浆料固含量的变化而改变．     

加料顺序对锂电隔膜陶瓷涂层浆料稳定性的影响

锂离子电池隔膜的性能决定着电池的界面结构、内阻等,并影响着电池的容量、循环寿命,尤其电池的安全性能。为优化隔膜的热稳定性、抗锂枝晶穿刺等性能,通常在隔膜表面涂覆陶瓷涂层。本文重点研究了加料顺序对锂电隔膜陶瓷涂层浆料稳定的影响,考察了不同加料顺序制备的陶瓷浆料的粒径及涂覆浆料的隔膜的剥离强度随放置时间的变化情况,发现锂电陶瓷涂层浆料的加料顺序通过影响纳米Al2O3颗粒的分散效果来影响浆料的放置稳定性;依CMCNa、Al2O3、PVA、DLS的加料顺序所得的锂电陶瓷涂层浆料中,Al2O3颗粒在浆料中的分散效果最佳,浆料放置96h稳定性依然良好。     

氧化铝泡沫陶瓷浆料的研究

有机泡沫陶瓷浸渍工艺中,浆料性能对泡沫陶瓷的显微结构与力学性能具有重要影响.本文研究了球磨时间和浆料固相含量对氧化铝泡沫陶瓷浆料的稳定性、流变性和颗粒粒度分布的影响.实验结果表明,球磨时间4 h后,氧化铝浆料的沉降度降低,粘度适宜,氧化铝颗粒中位径较小,表明浆料稳定性提高,流变性改善,可保证浆料在泡沫中的有效浸渍.当固相含量在25%～35%之间时,浆料的性能较优.实验证明球磨时间及固相含量对浆料的性能有重要影响.     

直接发泡法制备孔特性可控的氧化铝泡沫陶瓷

综述了近10年氧化铝泡沫陶瓷方面的研究进展,包括表面活性剂稳定泡沫制备的开孔泡沫陶瓷和颗粒稳定泡沫制备的闭孔泡沫陶瓷。对于表面活性剂稳定泡沫,分别采用环氧树脂–多胺和自发凝固2种凝胶体系进行固化成型,制备开孔氧化铝泡沫陶瓷。对于颗粒稳定泡沫,在采用调节浆料pH值或加入分散剂制备陶瓷浆料的基础上,使用长链的表面活性剂对分散的陶瓷颗粒进行疏水修饰,直接发泡后具有自发固化特性,制备出闭孔氧化铝泡沫陶瓷。     

颗粒级配对发泡法-凝胶注模制备Al_2O_3多孔陶瓷性能的影响

为了降低Al2O3多孔陶瓷制备过程中的干燥后收缩和烧后收缩,提高成品率,将d50分别为25.1、9.4和1.1μm的粗、中、细Al2O3粉体按粗粉中粉细粉质量比分别为50 40 10、10 40 50和100%全细粉的级配方式制备Al2O3泡沫浆料,研究颗粒级配对浆料黏度、干燥生坯的线收缩、烧后试样的线收缩、烧后试样的热导率等性能的影响。结果表明:颗粒级配可以有效提高固含量,且颗粒级配后的发泡浆料在静置30 min后仍能保持稳定,颗粒级配可以明显降低生坯的干燥线收缩以及烧后线收缩,并能降低热导率,提高了发泡法-凝胶注模工艺制备氧化铝多孔陶瓷的成品率。     

注浆成形制备金尾矿基轻质瓷浆料性能的研究

本研究采用了注浆成形工艺制备金尾矿基轻质瓷制品,研究了其浆料性能。通过引入通过温轮胶、魔芋胶和羟丙基甲基纤维素等悬浮稳定剂来改善陶瓷浆料稳定性和流动性,使浆料达到注浆成形的要求。同时,还阐明了悬浮稳定剂对陶瓷浆料稳定性和流变特性的影响。     

氧化铝陶瓷注凝成型的研究

本实验探究了氧化铝陶瓷注凝成型工艺,综合分析了分散剂和浆料的固相含量对氧化铝陶瓷浆料粘度的影响,实验证明:当分散剂的加入量为0.6%,浆料的固相含量为50%时,浆料适宜注浆,得到的陶瓷产品颗粒分布均匀,结构致密。     

莫来石泡沫陶瓷浆料性能研究

以自制莫来石(粒度为0.045~0.075 mm)、高岭土(粒度为0.045~0.088 mm)和磷酸为主要原料,采用有机泡沫浸渍法制备泡沫陶瓷过滤材料,研究了球磨时间和固相含量对泡沫陶瓷浆料粘度、稳定性、颗粒粒径等性能的影响,并对其机理进行分析。采用XRD、SEM、EDS等手段研究了泡沫陶瓷的性能、物相及显微形貌。结果表明:通过配制固相含量为60%~62%的浆料、球磨8h,可以制备出沉降度较低,粘度适宜,莫来石颗粒D_(50)较小,适合浸渍的优质浆料;将浆料均匀涂覆在有机泡沫基体上,在1450℃烧结2.5h可以得到抗压强度高达1.59MPa,抗热震性13次,开孔率86%的泡沫陶瓷产品。     

纳米碳化硅的表面改性和分散性研究

采用氢氟酸对原始纳米SiC颗粒进行表面改性,以制备稳定分散的纳米SiC浆料。借助XRD、比表面仪、FT-IR和扫描电子显微镜等对改性前后纳米SiC颗粒进行了表征,发现SiC颗粒表面的Si—O键消失,表明表面的SiO2薄层被去除了,颗粒之间无明显团聚现象。根据比表面积结果,确定改性时间为15 min最好。借助分光光度法,对不同分散剂和超声时间进行研究,确定乙醇为分散剂,超声时间为5 min时,纳米SiC浆料具有较强的分散稳定性。     

Dispersion and stability of SiC ceramic slurry for stereolithography

Stereolithography based additive manufacturing provides an effective method to fabricate complex-shaped SiC ceramic components. The dispersion and stability of the ceramic slurry are very important for stereolithography. In this study, the dispersion and stability of SiC ceramic slurries were investigated systematically. The effects of resin monomers, dispersants, particle size, solid loading and ball milling time on the dispersion, rheological behavior and stability of SiC ceramic slurries were studied in detail. Finally, an optimal SiC ceramic slurry for stereolithography based additive manufacturing was obtained, and complex-shaped SiC ceramic architectures were fabricated.     

Effects of particle size and color on photocuring performance of Si3N4 ceramic slurry by stereolithography

Due to high absorbance of UV light and low solid loading, the stereolithography-based additive manufacturing of gray-colored and dense Si₃N₄ ceramic is of significant difficulty and challenge. The effects of geometric properties of ceramic powders on the curing performance were investigated by studying the absorption difference of the Si₃N₄ ceramic particles with different colors and particle sizes and ultraviolet light. The results show that the transmission of ultraviolet light and curing performance of the darker Si₃N₄ ceramic slurry are much poor. Under the same particle size, the Si₃N₄ ceramic slurry using lighter particles presents the smaller scattering coefficient. The scattering coefficient (～202) of the gray powder with ～0.8 μm average particle size is the smallest. Under the same color, the larger the particle size, the smaller the scattering coefficient. The smallest scattering coefficient of the white powder with ～2.0 μm average particle size is ～110.     

Stabilization of tricalcium phosphate slurries against sedimentation for stereolithographic additive manufacturing and influence on the final mechanical properties

Ceramic parts manufactured by lithography‐based ceramic manufacturing (LCM) excel in resolution and surface quality. The material for LCM is a photosensitive ceramic particle‐filled slurry which needs to have homogeneous properties over time and during each processing step. The goal of this study was to use “mechanical” stabilization for a tricalcium phosphate‐filled slurry done by increasing slurry viscosity, solids loading, or inducing thixotropic behavior. The modified slurries were compared with a nonstable reference slurry. While all methods lead to increased storage stability, only the stabilized slurry with 0.5 wt% fumed silica is stable during the printing process.     

Metal cation complexes as dispersing agents for non-aqueous powder suspensions

Formulation of high solid load slurries is an important aspect in achieving dense, high quality ceramic green body shaping by additive manufacturing techniques. To this end, the understanding and control of interparticle interactions in non-aqueous organic slurry systems is imperative. With nanosized powders gaining increasing interest, particle stabilization by long-chain polymeric dispersants is undesirable due to the high exclusion volume associated and the subsequent decrease in the maximum solid load of the suspension. In this study, we focus on the stabilization mechanisms provided by metal cation complexes in methyl ethyl ketone and isopropanol-based spinel slurries. Special focus is given to chromium (III) 2-ethylhexanoate. Hemi-micelle formation at the powder surface in methyl ethyl ketone is suggested as a highly efficient stabilization mechanism. Complexes of metal dopant cations may open new pathways towards future advances in ceramic slurry formulation, especially in the field of additive manufacturing. Furthermore, the importance of solvation forces is discussed on the basis of the protic or aprotic character of the solvent used.     

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-100分散剂制备的陶瓷料浆的流变性及稳定性更佳;固含量与粘度之间的关系满足Krieger-Dougherty模型。本文对分散剂的作用机理进行了分析探讨,为光固化ZrO₂陶瓷料浆高精度固化成型提供了试验基础。     

Effects of powder characteristics,solid loading and dispersant on bubble content in aqueous alumina slurries

Bubbles occurring in ceramic slurries usually result in formation of abnormal pores in the subsequently consolidated green samples, thus deteriorating the properties of the final ceramic product. In this work, bubble content and its stability in aqueous alumina slurries were investigated with applying vacuum deairing. The experimental results show that the powder characteristics and solid loading greatly affected the bubble stability in the slurries and thus determined the bubble content. The bubble content was obviously increased with increasing solid loading, as well as using powders of high specific surface area in both as-prepared and deaired slurries. The stabilization mechanism of air bubbles in the slurries is attributable to the enhanced hindrance effect on bubble uprising caused by dense particle arrangement in slurry bulk, and the increased strength of bubble films at the slurry surface.     

Thermal-shock stable Al2O3 crucible for superalloy smelting through slip casting with particle gradation

Crucible is a key vessel in superalloy smelting, and high-performance crucible is quite important to the development of superalloy. Pointed at the easy cracking and poor thermal-shock stability of Al₂O₃ crucibles for superalloy smelting, particle gradation was managed in slip casting of Al₂O₃ crucibles. The ceramic slurry in good dispersion was prepared by optimizing particle gradation, with solid content of 86 wt% and viscosity of lower than 0.5 Pa s. For the crucible with optimized particle gradation, the density was 2.37 g/cm³, the linear shrinkage was less than 2%, the porosity was 18.72%, the bending strength was close to 22 MPa and the thermal expansivity was 2.77 × 10^?6/°C. Strength retention rate was raised to evaluate the thermal shock stability of crucibles, which was up to 73.5% after five-time thermal shock, well meeting the requirements of crucibles for superalloy smelting, and the superior thermal-shock stability was attributed to the uniform network microstructure and low thermal expansivity. The optimal particle gradation in experiments was explained in terms of Dinger-Funk model. This work provides a reference for preparing high-performance Al₂O₃ crucibles for superalloy smelting with low thermal expansivity as well as excellent thermal-shock stability.     

Development of alumina primary coat for single crystal investment casting ceramic mould

Abstract

The use of an alumina primary coat to eliminate the interaction between aluminium in NiAl single crystal alloy and silica in the ceramic investment casting mould has been examined in this study. The properties of the alumina slurry were characterised and the main factors controlling stability identified. It was found that the pH of the slurry must be carefully controlled to avoid polycondensation reactions. The most stable slurry was produced using filler with lower mean particle size and alkalinity. Alumina primary coat produced with low filler loading does not survive completely during wax removal. The surface condition can be improved by increasing the plate weight, which corresponds to a higher filler loading in the slurry. Moulds with a consistent alumina primary coat exhibit slightly higher green and sintered strength than moulds with the standard zircon-silica primary coat.     

Effect of particle size distribution of petroleum coke on the properties of petroleum coke-oil slurry

The effect of particle size distribution of petroleum coke on the properties of petroleum coke-oil slurry (PCOS) from four Chinese petroleum coke samples, such as apparent viscosity, rheological behavior, static stability, were systematically investigated. The size and morphology of petroleum coke particle with different grinding time and the corresponding stabilizing mechanisms were analyzed by SEM and zeta potential measurements. Experiments proved the petroleum coke grinding time of 60 min is suitable for the particle distribution and stability of PCOS. Besides, the effect of the sample type and loading of petroleum coke on the properties of PCOS was studied. The factors governing the apparent viscosity and stability of slurries have been discussed. The experimental results showed that the properties of PCOS could be effectively improved, and a suitable PCOS with low viscosity and good stability could be prepared through controlling the particle size distribution and petroleum coke loading.     

Influence of behaviour of alumina slurry on quality of alumina powder prepared by jet wheel impact atomization

Alumina slurries prepared in pilot plant scale have been characterized in terms of slurry rheology and stability and processed in a spray drier based on jet wheel impactor for atomization. Spheroidal alumina granules have been produced and their density, particle size and flowability behaviour are determined. Microstructure of the spheroidal granules has been observed under SEM and results are reported. The powders find application in plasma spray coatings, production of dense ceramic parts, components and tiles.