高性能陶瓷创新工艺--陶瓷胶态注射成型技术

成型工艺作为制备高性能陶瓷材料及部件的关键技术,介绍黄勇教授创新提出的把胶态成型和注射成型结合的“陶瓷胶态注射成型新工艺”。     

陶瓷材料新术语诠释(八)

二、成型方法新词汇胶态成型 Colloidal Forming Process 陶瓷的成型方法一般可归纳为干法和湿法两大类。湿法成型又可分为塑性成型和胶态成型两种,后者指的是高分散陶瓷悬浮体湿法成型中的一种方法。传统的胶     

陶瓷成型技术的新进展

提高成型技术是提高陶瓷产品可靠性的关键步骤。本文介绍了陶瓷胶态成型技术方面的最新发展情况，并对它们的应用情况做了简要的分析。     

陶瓷材料成型工艺研究新进展

陶瓷制造经历数千年历史，当前阻碍陶瓷材料进一步发展的关键之一是成型工艺技术没有突破。本文介绍了胶态成型，固体无模成型工艺及气态成型，对上述工艺的原理、工艺过程及特点进行比较，提出了陶瓷成型工艺的关键问题。并介绍了水基非塑性浆料的注射成型新工艺。     

东盟成为广东潮州陶瓷主要进出口市场

清华大学材料系黄勇教授课题组承担的九五期间863课题“低成本、高性能陶瓷胶态注射原位快速凝固成型新工艺的研究”（简称为“陶瓷胶态注射成型新工艺”）取得重大成果,使陶瓷的制造成本降低一半,可靠性提高一倍以上,使各种复杂形状陶瓷零部件的近净尺寸制造技术获得突破性的进展。制备的陶瓷材料与制品的性能达到;坯体密度均匀（密度分布差小于0．5％）、坯体强度高（抗弯强度在20～30MPa）、易于加工：烧结后产品性能优异;     

陶瓷材料成型工艺研究新进展

陶瓷制造经历数千年历史,当前阻碍陶瓷材料进一步发文介绍了胶态成型、固体无模成型工艺及气态成型,对上述工艺的原理、工艺过程及特点进行比较,提出了陶瓷成型工艺的关键问题.并介绍了水基非塑性浆料的注射成型新工艺.     

陶瓷直接凝固注模（DCC）成型

直接凝固注模式型（ＤＣＣ）是一种陶瓷净尺寸胶态成型方法，ＤＣＣ成型的坯体具有成型密度高，密度及组分分布均匀，不含或只含少量有机物等特点，本文了ＤＣＣ成型的原理、成型过程及特点。     

陶瓷胶态注射成型中压力的影响

陶瓷胶态注射成型是一种结合了凝胶注模成型和注射成型优点的新成型工艺。不同于凝胶注模成型中通过温度诱发反应,在胶态注射成型中是利用温度与压力共同作用引发陶瓷浆料固化。采用自行研制的凝胶点测试装置,研究了不同温度条件下压力对氧化铝浆料固化过程的影响,发现提高压力能促进浆料固化,不仅能缩短其聚合诱导期,而且能加速固化过程。此外,探讨了胶态成型的作用机制,为胶态注射成型的自动化设计提供了相关工艺参数。     

陶瓷基复合材料胶态成型工艺研究进展

重点介绍了几种主要陶瓷基复合材料胶态成型工艺,包括注浆成型、注射成型、凝胶注模成型、直接凝固注模成型、温度诱导絮凝成型、水解辅助固化成型、电泳浇注成型和溶胶-凝胶法成型.对上述工艺的原理、工艺过程及特点进行了比较,并提出了陶瓷成型工艺的关键问题.     

电厂粉煤灰合成低成本高性能复相陶瓷与耐火材料的研究

目前粉煤灰在综合利用的基础上,提出拟利用电厂粉煤灰合成具有高附加值Sialon复相陶瓷／耐火材料新思路。研究结果表明,通过酸洗工艺参数的控制,可实现粉煤灰中杂质铁的去除,有利于合成陶瓷体积密度的改善。采用胶态成型工艺与碳热还原氮化工艺,可实现低成本高性能环境友好材料的研制。     

The transformation mechanism from suspension to green body and the development of colloidal forming

Colloidal forming is a novel wet-processing way to prepare complex shaped ceramic parts with high reliability at low cost. In this article, the transformation mechanisms from suspension to green body and the development of colloidal forming are reviewed. The transformation from suspension to green body in colloidal forming is mainly dependent on the characteristics of suspension, and solidification is the key link in colloidal forming. Various colloidal forming methods are developed to produce ceramic parts, and these methods include slip casting, tape casting, direct coagulation casting, injection molding, gel-casting and so on. The study of defects during colloidal forming should be focused on the defects formation, inheritance and evolution during drying, de-binding and sintering processes. External free controllable technology of colloidal forming is an effective way to achieve ceramic fabrication industrialization, and stress-free colloidal forming is important for the future development of ceramic fabrication.     

Fabricating colloidal crystals and construction of ordered nanostructures

Colloidal crystals of polymeric or inorganic microspheres are of extensive interest due to their potential applications in such as sensing, optics, photonic bandgap and surface patterning. The article highlights a set of approaches developed in our group, which are efficient to prepare colloidal crystals with ordered voids, patterned colloidal crystals on non-planar surfaces, heterogeneous colloidal crystals of different building blocks, colloidal crystals composed of non-spherical polyhedrons, and colloidal crystals of non-close-packed colloidal microspheres in particular. The use of these colloidal crystals as templates for different microstructures range from nanoscale to micron-scale is also summarized.     

Towards true 3-dimensional BCC colloidal crystals with controlled lattice orientation

A fabrication method of colloidal crystals possessing the BCC crystal structure is described. BCC colloidal crystals with a thickness of up to seven colloidal layers were grown in the direction of the (100) crystal plane. Defect free colloidal crystals with a homogeneous surface coverage were obtained over a surface area of several square millimeters. Quality and thickness of grown colloidal crystals were controlled by a set of deposition parameters such as deposition voltage, deposition time, and concentration of colloidal particles in the colloidal suspension, colloid surface charge density and withdrawal speed of electrodes out of the suspension. Optimal deposition parameters leading to a controlled BCC colloidal crystal growth were established.     

Creation of Controlled Defects Inside Colloidal Crystal Arrays with a Focused Ion Beam

In this work the reliability of the focused-ion-beam (FIB) patterning on polystyrene (PS) colloidal crystals at different scales is determined. Ordered arrays of PS spheres (465 nm) are successfully modified by selectively removing a single sphere. The water-vapor assisted FIB milling is crucial to obtain this result. Furthermore, isolated PS spheres are FIB drilled with or without chemically enhanced milling aiming at the exploration of the limits of such a technique. These controlled defects created using the FIB-assisted techniques may be helpful in preparing mockups of photonic crystals, sensors or as colloidal masks for diverse lithographic processes.     

胶体石墨中石墨细颗粒的制备

胶体石墨是一种多相胶体，其中的分散相（石墨）需求达到一细度，这是制备胶体石墨的先决条件，不同用途的胶体石墨细颗粒的纯度，粒子形态，粒度分布等的要求有所不同，因此在利用机械方法制备石墨细颗粒的过程中，需综合考虑石墨的结构，性能，粉碎过程中的晶体结构变化及所选粉碎设备，粉碎方式，粉碎环境等因素。     

Effects of addition of colloidal silica particles on TEOS-based stone protection using n-octylamine as a catalyst

Protective agents based on tetraethoxysilane (TEOS) have been widely used for the protection of stone heritages. However, TEOS-based protective agents suffer from practical drawbacks, such as crack formation of the gel during the drying phase due to the developed capillary force, which is typical for TEOS-based protective agents. In this paper, we have prepared new TEOS-based protective agent containing flexible hydroxyl-terminated polydimethylsiloxane (PDMS-OH) and colloidal silica particles (167 nm) using n-octylamine as a catalyst in order to reduce capillary force development and increase hydrophobicity, and have characterized them for the application of stone protective agent. The extent of surface hydrophobization depends on concentration of colloidal silica particles and reaches a maximum value of 123° at 0.2% (w/v) of colloidal silica particles for the case of treated with the modified composition. The presence of n-octylamine is a key factor which promotes the increase of the gel pore size. The protective performances were also evaluated by its ability to resist acid corrosion. The results reveal that the protective effects are satisfying.     

聚丙烯酰胺母液胶状杂质组分分析及成因研究

聚丙烯酰胺(PAM)作为驱油剂在油田的三次采油中发挥了重要作用。PAM的性质改变会影响原油采收率。PAM在配制站滤袋内产生胶状杂质,本实验对胶状杂质取样并进行分析,结果表明,胶状杂质中有大量的细菌(硫酸还原菌,铁细菌,腐生菌)、无机离子和有机物质。这些物质的存在对设备产生腐蚀,并对注入的聚丙烯酰胺产生了凝聚作用,影响驱油效果。     

破伤风抗体胶体金检测试剂盒的研制

目的 研制破伤风抗体胶体金检测试剂盒。方法 应用胶体金免疫斑点法研制破伤风抗体胶体金检测试剂盒,并对破伤风类毒素免疫的豚鼠及人血清的破伤风抗体水平进行测定。结果 该试剂盒所测定的结果与小鼠体内法的相关性好(r>0.95,P=0.25),远优于目前使用的间接血凝法(r<0.10);且该试剂盒的灵敏度较小鼠法高1倍,特异性强,无交叉反应,精密准确。结论 可用于临床检测患者创伤后的血清破伤风抗体水平。     

Synthesis of colloidal polyoxazoline/silica hybrids prepared in an aqueous solution

New colloidal polymer hybrids with polyoxazolines such as poly(2-methyl-2-oxazoline) (PMeOZO) and poly(2-ethyl-2-oxazoline) (PEtOZO) were obtained in an aqueous solution as a sol-gel solvent. The polyoxazoline segment was incorporated into the siliceous particle and formed strong hydrogen bonds with silanol moieties, judging from TGA and FT-IR studies. Colloidal polymer hybrids exhibited no glass transition temperature of the polyoxazoline and showed excellent thermal stability and solvent-resistant property. Porous silica obtained by charring the colloidal polymer hybrids at 600 °C exhibited the peak at 3.5 Å. These results strongly indicate the homogeneous molecular scale dispersion of polyoxazoline in the colloidal silica gel matrix.     

Transformation of amorphous silica colloids to nanosized MEL zeolite

Si-MEL molecular sieve is prepared from aged colloidal precursor solutions under hydrothermal treatment (HT) at 90 °C. In situ dynamic light scattering (DLS) investigations of the precursor solutions and the crystalline Si-MEL sols are performed with the original concentrations. Sub-colloidal particles with a mean radius of about 1 nm and colloidal aggregates with a radius of 10 nm are detected in the precursor colloidal solutions after 5 h aging at room temperature. Consumption of the sub-colloidal particles with time and an increase of the colloidal fraction of 10 nm particles after 48 h aging is observed. After heating of the aged precursor solution at 90 °C for 30 h, three particle populations of 1, 10, and 100 nm radius are formed. Complete transformation from amorphous to crystalline colloidal particles is observed after 68 h extended HT of the aged precursor solution. The mean hydrodynamic radius of the crystalline Si-MEL particles is about 100 nm based on the DLS measurements. The size of the MEL crystals was also confirmed with SEM. Additional time-dependent ²⁹Si NMR measurements of the aged precursor colloidal solutions prior to further crystal growth show that the amount of Q⁰ species (δ=−71.2) decreases, while signals of high intensity in the range between δ=−88.6 and −98.9 indicating the formation of Q³₆ and Q³₈ silicon species appear. IR data reveal that with aging of the precursor colloidal solutions at room temperature, an increased ordering of the silica species similar to those found in the final MEL product is observed.