多种湿法成型技术可满足复杂形状陶瓷制品

为了满足制备复杂形状陶瓷制品的要求,人们开发和研制了多种湿法成型技术,如注浆成型、注射成型、流延成型、凝胶铸成型、直接凝固注模成型等。这些成型方法的一个显著特征是以水或有机溶剂为介质将陶瓷粉料分散其中,通过添加分散剂形成均Ｇ一稳定的悬浮体系,最后经不同的液体排出途径而使颗粒固化。这些成型方法以素坯密度高、气孔小且气孔尺寸分布窄等多种优越性在工业中得到广泛应用。湿法成型中很关键的一步是稳定浆料的制备。陶瓷粉体的性质如纯度、颗粒尺寸的大小及分布将通过粉体对添加剂的吸附来影响浆料性质。所选用的添加剂如表面…     

二元复合体系Y-TZP/α-Al2O3浆料的流变性研究

湿法成型方法在降低粉体团聚,改善素坯显微结构均匀性方面有着明显的优势。本工作研究了二元体系Ｙ－ＴＺＰ／α－Ａｌ２Ｏ３形成稳定浆料的流变性质,在制备了具有较高固体含量的浆料基础上进行了凝胶注模成型。结果表明,在ｐＨ值为９－１０的范围内可以制备出固体体积分数分别为５０％和４５％的以α－Ａｌ２Ｏ３为主或以Ｙ－ＴＺＰ为主的浆料。尽管每一种组分都对复合体系的流变性产生影响,但具有较低稳定程度的氧化锆起决定作     

一种高性能芳纶绝缘纸及其制备方法与应用

正本发明属于特种纸生产领域,具体公开了一种高性能芳纶绝缘纸及其制备方法与应用。所述制备方法包括以下步骤:将生物质黏胶纤维﹑芳纶沉析纤维﹑芳纶浆粕分别进行有效分散,然后按质量比均匀混合,之后向混合浆料溶液中加入耐高温电子功能助剂,再将浆料进行超低浓(0.08%)斜网湿法成型﹑脱水﹑烘干处理得到     

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。     

湿法制造热塑性片材的工艺技术研究Ⅲ.湿片成型工艺研究

本文研究了湿法制造热塑性片材工艺过程中的湿片成型工艺技术,包括“固－液相系”浆料的搅拌和流送方式;浆料的上网布浆,脱水制片及湿片从成型网向干燥网过渡传递等工艺技术和相关设备。     

硅溶胶分散氧化铝浆料的免脱气注凝成型工艺

基于气泡的稳定性理论,发展了一种免脱气注凝成型技术制备莫来石陶瓷素坯。利用pH约为9.5的硅溶胶对氧化铝颗粒的分散作用,制备了固相体积分数为50%,浆料粘度为953 mPa.s的符合莫来石计量组成的硅溶胶分散氧化铝浆料。采用NH4Cl作为电解质,直接利用硅溶胶凝胶化实现浆料的原位凝固成型。研究发现:由于在浆料中不引入任何表面活性物质,浆料脱气处理时间对成型素坯气孔率影响不大,浆料无须经过脱气处理,即可成型得到抗折强度达4.83 MPa、显微结构致密均匀的莫来石素坯。     

提拉浸渍用氧化铝陶瓷平板膜料浆的制备工艺研究

陶瓷平板膜具有过滤精度高、化学稳定性好、价格适宜、使用寿命长等优点,可有效解决当前有机类膜材料可靠性差、寿命短,运行成本高等问题,在膜法水处理领域,具有广阔的应用前景。但是国内在陶瓷平板膜的制备、应用等方面的研究较少,面向产业化、工程化方面的研究开发工作极为匮乏,导致陶瓷平板膜的品控较差。而料浆的性能是决定陶瓷膜最终成型质量的重要因素,但是国内对于此项工作的研究报道较少。本工作以高纯α-Al_2O_3和高纯硅溶胶为主要原料,研究了陶瓷膜规模化制备过程中浆料湿法球磨时间、分散剂种类及加入量、pH值对陶瓷膜料浆性能的影响作用。结果表明:分离膜浆料湿法球磨6h,选用聚丙烯酸钠为分散剂且外加量为3.5wt%,浆料pH值为9时,浆料分散性能、悬浮性能最优。     

水基凝胶注模制备高导热氮化硅陶瓷

获得低黏度的氮化硅陶瓷浆料,并利用水基凝胶注模成型工艺制备高导热氮化硅陶瓷。探究和讨论了MgO对氮化硅陶瓷的浆料流变性及热导率的影响。结果表明：MgO在浆料中造成颗粒团聚导致黏度上升,并随着MgO添加量的提高,浆料黏度对pH值越来越敏感;合理调节pH值和分散剂的添加量能获得低黏度的陶瓷浆料;利用水基凝胶注模成型工艺制备了热导率为83.7 W·m^–1·K^–1,抗弯强度为945 MPa,断裂韧性为8.4 MPa·m^1/2的氮化硅陶瓷,表明环保的水基成型工艺制备高导热氮化硅陶瓷是可行的。     

整体式催化剂制备过程中料浆流动特性测定及其对催化剂机械性能的影响

利用浇注压制成型制备了SO_2氧化反应的整体式催化剂,研究了成型过程中不同处理方法和不同的配方对浇注料浆流动性质的影响规律,测定了催化剂料浆在不同处理条件下的塑限、液限、流动度等参数,讨论了浆料流动性质与成型后的催化剂机械强度之间的关系。结果表明通过对催化剂硅藻土载体的酸洗处理、调节催化剂活性组分浆料pH值、对浆料进行捏合处理、适当添加润滑剂等措施,可以有效提高浆料的流动性、降低浆料在相同流动性情况下的含水量,利用该浆料浇注压制成型的催化剂裂纹少、机械强度高。     

欧罗巴绒感聚氨酯合成革的生产方法

日前,安徽安利合成革股份有限公司公开了去年发明的一种欧罗巴绒感聚氨酯合成革的生产方法,步骤如下：首先制备湿法合成革半成品;然后将离型纸花纹转移后的聚氨酯浆料层热接于印花后的湿法合成革半成品表面,聚氨酯浆料中各原料组分重量份比为：     

Aqueous tape casting process for hydroxyapatite

The condition for the preparation of stable hydroxyapaptite (HA) slurries by aqueous tape casting was identified. To acquire stable low-viscosity slurries, the influences of dispersant, binder and plasticizer on the rheological properties were investigated. The slurries of submicron sized HA behaved as near Newtonian up to a solid loading of 56.1 vol%. Films of HA had very good qualities, such as homogeneity, surface quality, and so on. Results indicated that slurries at selected conditions met the needs of tape casting process.     

Fabrication of stable Al2O3 slurries and dense green bodies using soft-energy milling process

Wet-jet milling and planetary homogenizing processes as soft-energy milling methods were employed as a novel method to prepare stable Al₂O₃ slurries. The viscosity of slurries prepared from the soft-energy milling was constant and stable for long time, as compared to ball-milled slurries. Though Al₂O₃ particles surface after ball milling yielded more hydroxyl groups, Al₂O₃ particles surface after the soft-energy milling was similar state to raw particles surface. Relative density of the green bodies prepared from the wet-milled slurries was about 67% and was independent on the slurry solid content. On the other hand, the relative density of the green bodies prepared from the ball-milled slurries increased with increasing solid content. Linear shrinkage of the sintered bodies prepared from the soft-energy milled slurries was independent of the slurry solid content, whereas that of the sintered bodies prepared from the ball-milled slurries increased with decreasing solid content.     

How Does the Preparation of Rye Porridge Affect Molecular Weight Distribution of Extractable Dietary Fibers?

Extractable dietary fiber (DF) plays an important role in nutrition. This study on porridge making with whole grain rye investigated the effect of rest time of flour slurries at room temperature before cooking and amount of flour and salt in the recipe on the content of DF components and molecular weight distribution of extractable fructan, mixed linkage (1→3)(1→4)-β-d-glucan (β-glucan) and arabinoxylan (AX) in the porridge. The content of total DF was increased (from about 20% to 23% of dry matter) during porridge making due to formation of insoluble resistant starch. A small but significant increase in the extractability of β-glucan (P = 0.016) and AX (P = 0.002) due to rest time was also noted. The molecular weight of extractable fructan and AX remained stable during porridge making. However, incubation of the rye flour slurries at increased temperature resulted in a significant decrease in extractable AX molecular weight. The molecular weight of extractable β-glucan decreased greatly during a rest time before cooking, most likely by the action of endogenous enzymes. The amount of salt and flour used in the recipe had small but significant effects on the molecular weight of β-glucan. These results show that whole grain rye porridge made without a rest time before cooking contains extractable DF components maintaining high molecular weights. High molecular weight is most likely of nutritional importance.     

PVDF黏结剂含量对锂离子电池正极 浆料流变性能的影响研究

制备了3种具有不同聚偏四氟乙烯（PVDF）黏结剂含量的锂离子电池正极浆料,并对它们的流变性能做了测试和比较。结果表明,随着PVDF黏结剂含量的提高,浆料的黏度变大,流动性变差。触变性测试结果还表明,只有当加入适量的PVDF时,浆料中的颗粒之间才能形成稳定均匀的浆料,过多或者过少都会导致颗粒间的团聚产生。     

Wet jet milling of Al2O3 slurries

A wet jet milling process was employed as a novel method to prepare ceramic slurries. The wet jet milling pulverized raw materials to primary particle size within a short time. The wet jet-milled slurries showed very low viscosity, as comparing to ball-milled slurries. Moreover, the viscosity of wet jet-milled slurries was stable for long times, whereas that of ball-milled slurries increased rapidly with increase in the time. Al₂O₃ particles after wet jet milling kept initial surface conditions, though Al₂O₃ particles after ball milling yielded more OH groups on the surface. The relative density of the green bodies prepared from the wet jet-milled slurries was about 65% or more without depending on the solid content of slurry. On the other hand, the relative density of the green bodies fabricated by the ball-milled slurries increased with the slurry solid content, and it reached more than 60% at 50 vol% of solid content.     

Influence of sewage sludge on the slurryability of coal-water slurry

In this study, the maximum solids loading, stability and rheological properties of coal-sludge slurries were investigated and compared with those of coal-water slurries. The maximum solids content of coal-sludge slurry was much lower than that of coal-water slurry because of the ∼82% water in sewage sludge. NaOH addition as a pre-treatment of sewage sludge improved the maximum solids content to 61% and 60% for dispersants A₁ and A₂, respectively, for a sludge-coal mass ratio of 22.1:100. Compared to coal-water slurries, the stability of coal-sludge slurries was better, with no solid deposition after 96 h. Coal particles and sewage sludge formed a stable medium and settlement of large coal particles was prevented. All the coal-sludge slurries exhibited pseudo-plastic behavior; this type of fluid is shear-thinning and is easy to transport.     

Dispersion and rheological properties of concentrated kaolin suspensions with polycarboxylate copolymers bearing comb-like side chains

Comb-like polycarboxylate copolymers (PCs) were synthesized and first used as the dispersants for kaolin suspensions. The apparent viscosity, adsorption behavior, zeta potential, rheological behavior, and TEM images of concentrated kaolin slurries deflocculated with these copolymers were systematically investigated. Sodium acrylate homopolymer (SA) was selected as a reference in order to contribute to the knowledge of how the electrostatic interaction and molecular structure of these copolymers influenced the dispersion, adsorption, and rheological properties of colloidal kaolin suspensions. The results showed that the dispersion of kaolin slurries mainly depended on the synergistic effects of electrostatic interaction and steric hindrance for APEG type comb-like copolymers. PC₂ bearing proper carboxylic groups and side chains produced stable dispersion and fluidity in concentrated kaolin slurries. Based on the electrostatic and steric effect of comb-like copolymers, the kaolin slurries displayed a shear thickening behavior, and the Herschel–Bulkley model well described their rheological behaviors.     

Droplet ignition of coal–water slurries prepared from typical coal- and oil-processing wastes

The requirements for stable ignition (and subsequent combustion) of fuel suspensions prepared from typical coal- and oil-processing wastes are studied experimentally. Attention focuses on the differences between the ignition characteristics of coal–water slurries (containing petrochemicals) obtained on the basis of filter cakes containing T, K, SS, Zh, D, and G coal. To eliminate the influence of the droplet holder (traditionally, thermocouple junctions, ceramic rods, or metal wire) on the ignition characteristics of the fuel droplet, the experiments employ a special model combustion chamber and a device for introducing a single drop of suspension. The ignition time and the minimum temperature of stable ignition of a droplet of coal–water slurries suspended in an oxidant flux are established. The influence of the following factors on the initiation of fuel combustion is determined: the oxidant temperature, the droplet size, the size of the coal dust, and the properties and concentrations of the components. The compositions of the coal–water slurries corresponding to optimal ignition (minimum inertia) are identified.     

Fabrication and Crack Deflection in Ceramic Laminates with Porous Interlayers

A simple and general method for making ceramic laminates with porous crack-deflecting interlayers is demonstrated. Both the strong laminae and the porous interlayers are made by tape casting suitable slurries using the same ceramic powders. Porosity is introduced into the interlayer by adding starch particles to the slurry. The effects of the starch on the burn-out and sintering behavior of the laminates has been fully described. The influence of resulting porosity on the ability of an interlayer to deflect a growing crack and to remain stable on prolonged heating has also been investigated. For the pore morphologies studied here, it is the volume fraction of pores that controls whether crack deflection takes place. Using existing mechanics solutions, a simple theoretical criterion for this volume fraction of porosity is given and is consistent with all the experimental observations.     

Fabrication of Aluminum Oxynitride (γ‐AlON) Transparent Ceramics with Modified Gelcasting

Transparent aluminum oxynitride (AlON) ceramics have been prepared through aqueous gelcasting forming technique starting from the raw materials of single phase AlON powders. The powder was specially treated for anti‐hydrolysis in ethanol before the shaping technique. The surface‐treated AlON powders could then be dispersed in an aqueous‐organic solution to prepare stable slurries containing 35 vol% solids loading. The obtained stable slurries were subsequently casted, calcined, and pressureless sintered at 1950°C for 8 h in nitrogen atmosphere. High transparent AlON ceramics with an average grain size of 112 μm and the in‐line transmittance of 81% at wavelength 1100 nm have been obtained.