先进陶瓷快速无模成型技术的研究与进展

系统综述了先进陶瓷快速无模成型技术及其最新研究进展,其中主要包括熔融沉积成型技术、喷墨打印成型技术、三维打印成型技术、分层实体成型技术、激光选区烧结成型以及立体光刻成型技术。最后论述了陶瓷快速无模成型技术所具有的独特优势和当前研究工作中面临的问题和挑战。     

陶瓷凝胶注模成型技术及其应用研究

凝胶注模成型技术是一种近净尺寸陶瓷成型技术，它为解决陶瓷材料的加工成型问题提供了一条十分有效的工艺途径。介绍了陶瓷凝胶注模成型技术的基本原理和工艺过程，着重介绍了目前凝胶注模成型技术的应用研究。     

复杂形状氧化铝陶瓷的消失模快速成型法

将凝胶注模成型(gelcasting)和选区激光烧结(selective 1aser sintering，SLS)制模技术相结合，提出了基于消失模法的复杂形状A12O3陶瓷快速成型法。通过选取合适的激光烧结用聚合物复合粉体，用SLS技术快速分层制备高温可完全挥发的模具，然后利用凝胶注模成型技术原位固化成型后坯体强度高的特点，使陶瓷在烧结过程中能完好保存所设计形状而不被破坏，模具材料完全烧除后即得所需陶瓷部件。     

陶瓷凝胶注模成型技术及其应用研究

凝胶注模成型技术是一种近净尺寸陶瓷成型技术,它为解决陶瓷材料的加工成型问题提供了一条十分有效的的工艺途径。介绍了陶瓷凝胶注模成型技术的基本原理和工艺过程,着重介绍了目前凝胶注模成型技术的应用研究。     

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。     

高性能陶瓷原位凝固成型技术的研究进展

综述了高性能陶瓷原位凝固成型工艺的特点;重点介绍了近年来的四种陶瓷原位凝固成型方法,即注凝成型,直接凝固成型,温度诱导絮凝成型和胶态振动注模成型,并简要介绍了国内陶瓷原位凝固成型技术研究取得的新成果。     

塑料管材连续双向拉伸技术

介绍六种塑料管材连续双向拉伸技术，包括压缩空气成型、口模拉伸成型、风冷却成型、模头胀拉成型、高压水成型和真空／压空成型，并对其成型方法、加工装置及用各种成型方法所制备的管材性能作了简单介绍。用连续双向拉伸技术生产的塑料管材周向性能和轴向性能都有所提高，而且运用该技术还能够提高生产率、节约原材料、降低成本。     

先进陶瓷快速无模成型方法研究的进展

介绍了快速无模成型的发展历史和特点,重点介绍了激光选区烧结成型（Selective Laser Sintering,SLS)、三维打印成型（3Dimensional Printing,3DP)、熔融沉积成型（Fused Deposition of Ceramics,FDC)、分层制造成型（Laminated Object Manufacturing,LOM)、立体光刻成型9Stereilithography,SL)、喷墨打印成型（Ink-jet Printing,I-JP）、选区凝胶成型（Selective Gelation,SG)和激光选区气相沉积成型（Selective Area Laser Deposition,SALD)等8种先进陶瓷的成型方法,并分析了目前该技术产业化所面临的一些问题。     

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.     

陶瓷微注射成型技术的研究与进展

本文介绍了陶瓷微注射成型工艺过程的新特点和新技术;探讨了陶瓷微注射成型充模流动模拟所采用的理论模型及其应用研究现状;最终指出微注射成型技术研究应该着重于陶瓷微注射模拟新方法、微尺寸型腔内的流动机理、微型零件的质量控制方法、微注射成型工艺和设备研制上.     

Tailored graded pore structure in zirconia toughened alumina ceramics using double-side cooling freeze casting

Ceramics with graded and continuously aligned open pores were investigated using a double-side cooling freeze casting setup. The ceramic preforms with tailored lamellae spacing (wavelength), wall thickness and graded pore structure were used to infiltrate with a second phase for the fabrication of graded interpenetrating phase composites. The effects of solid content, temperature setting and gradient, cooling rate and the introduction of electrophoretic deposition (EPD) on the freezing velocity of the ceramic suspension were analysed. On the bottom of the ceramic specimen, a dense layer was formed and tailored with the use of EPD. The ceramic was characterised by a graded open pore structure with wavelengths up to 115 μm and interconnected microstructure. The effect of solid content on the degree of supercooling and the effect of temperature gradient on the average freezing velocity were investigated. The addition of EPD before freeze casting affected significantly the microstructure, the wavelength decreased and the wavelength gradient became smaller compared to simple freeze casting.     

水基料浆凝胶注模法制备氧化锆陶瓷刀具的研究

本文采用水基料浆凝胶注模法制备出了高质量的氧化锆陶瓷刀具。解决了高固相体积分数水基料浆的配制、注模、凝胶固化和脱模操作等一系列问题。研究结果表明,其尺寸精度和表面质量良好。证实了水基料浆凝胶注模法制备氧化锆陶瓷刀具是一种新的低成本制备技术,值得推广应用。     

Ice-mould freeze casting of porous ceramic components

Porous, hollow ceramic components were produced by freeze casting technique. For this purpose aqueous slurries with high solid contents were prepared which were stable against freezing down to at least −5 °C. Ice cores were made by coating steel components with freezing water which were subsequently dip-coated with the ceramic suspensions. After freeze drying which removes both, the ice core and the frozen suspension liquid, and sintering, ceramic components with a high amount of open porosity including steel parts could be achieved. As an example hydroxyapatite was used for showing the opportunities of the freeze casting technology among others for applications in the field of bone replacement. The influence of the solid content of the hydroxyapatite slurries on the ice crystal growth has been investigated by means of compact hydroxyapatite bodies which were prepared by freeze casting using ice moulds with cylindrical cavities.     

陶瓷材料流延成型研究现状

简要概括了陶瓷坯体流延成型的工艺过程,比较了水基流延成型与传统流延成型技术相比的优点和不足之处,着重介绍了陶瓷材料新型流延成型工艺的研究现状,并指出了陶瓷坯体水基流延成型工艺的发展方向。     

Fractions design of irregular particles in suspensions for the fabrication of multiscale ceramic components by gelcasting

A new approach for the preparation of suspensions with a high solid loading and low viscosity by using irregular particles was proposed. These suspensions were prepared for the fabrication of multiscale ceramic components by gelcasting. Based on the Funk-Dinger function and fractal theory, the closest packing theory was applied to optimize the volume fractions of different particles. The maximum solid loading of slurries prepared for gelcasting was 62 vol%, and the viscosity at a shear rate of 100 s^?1 was only 0.29 Pa s. By as-prepared suspensions, a decimeter-scale ceramic part with submillimeter features was fabricated successfully by gelcasting, which verify the feasibility of the proposed method.     

Effect of Dispersants on the Rheological Properties and Slip Casting of Concentrated Alumina Slurry

Slip casting is one of the most common forming techniques used in the fabrication of ceramics. To obtain successful casting results, one need first to fully deagglomerate the ceramic powders and get concentrated slurries with good rheological properties. In this work, the rheological properties of concentrated alumina slurries were studied as functions of solid contents and quantities of two different dispersants, i.e., sodium pyrophosphate and diammonium hydrogen citrate. It was found that these properties could be satisfactorily related to the maximum packing fractions which were determined from sedimentation experiments. Our results also indicated that an optimum deflocculation process can always lead to optimal casting and sintering results.     

流延法制备陶瓷薄片的研究进展

流延成型是一种目前使用较广泛,能够获得高质量、超薄型陶瓷薄片的成型方法.本文论述了流延成型时有机物(包括溶剂、分散剂、粘结剂、增塑剂等)的选择原则、浆料的制备以及流延工艺过程,并对影响流延膜厚度和流延膜质量的因素进行了分析讨论,同时提出了改进流延膜质量的措施.     

Ceramic domes fabricated by a combination of tape casting and vacuum forming

Tape casting is a low cost fabrication process for flat ceramic sheet and this paper demonstrates how it can be combined with vacuum forming to make α-alumina domes of 250-300 μm sintered thickness. The suspension formulation makes use of systems of double plasticizers and double solvents in a poly(methyl methacrylate) binder to provide plastic ceramic films by tape casting from which preforms for vacuum forming were cut. In order to retain the shape of vacuum formed domes during debinding and sintering, an initial low temperature anneal is needed. The study indicates that the ratio of plasticizers to binder and the particle size are two dominant parameters in influencing the elongational flow. The whole process provides a novel method to make thin ceramic domes.     

Additive manufacturing of Al2O3 ceramic core with applicable microstructure and mechanical properties via digital light processing of high solid loading slurry

Ceramic cores are essential intermediate mediums in casting superalloy hollow turbine blades. The developing of additive manufacturing (AM) technology provides a new approach for the preparation of ceramic cores with complex structure. In this study, alumina oxide (Al₂O₃) ceramic cores with fine complex geometric shapes were fabricated by digital light processing (DLP) in high resolution. The maximum solid content of 70 vol% of ceramic slurry was adopted in the printing process, which is important for the regulation of deformations and mechanical properties. The effects of the printing parameters, including exposure intensity, printing layer thickness and sintering temperature on the microstructures and mechanical properties of printed samples were investigated. The decrease of residual stress and similar shrinkage in X, Y, and Z directions could be obtained by adjusting the printing parameters, which are crucial to prepare complex ceramic cores with high quality. Besides, the flexure strength and open porosity of ceramic cores reached 34.84 MPa and 26.94%, respectively, which were supposed to meet the requirement of ceramic cores for the fabrication of superalloy blades.     

Additive manufacturing of low-shrinkage alumina cores for single-crystal nickel-based superalloy turbine blade casting

We prepare bimodal particle size photo-curable ceramic pastes with high solid loadings (up to 65 vol %) and fabricate porous alumina ceramic cores with complex shapes via ceramic stereolithography (Cer-SLA) 3D printing technique. The sintering temperature is carefully selected, ranging from 1500 °C to 1650 °C, and a high holding time (>4 h) is applied to guarantee that the materials can withstand the subsequent high temperature (>1500 °C) casting process for single-crystal nickel-based superalloy hollow turbine blades. Herein, the originally spherical fine particles are found to become platelet-like after sintering, and the forming mechanism is discussed in detail. In addition, we explore the influence of platelet-like particles, coarse particles and sintering process on the microstructural evolution of alumina particles, and reveal the relationship between microstructure and properties of ceramic cores. These results illustrate that the proposed materials for SLA 3D printing exhibit a great potential in the fabrication of complex-shaped alumina ceramic cores for high-precision investment casting, e.g., manufacturing single-crystal nickel-based superalloy hollow turbine blades for an advanced aircraft engine.