热喷涂纳米陶瓷涂层的研究现状及进展

热喷涂技术是制备纳米结构陶瓷涂层最具前途的方法之一.本文简要介绍了热喷涂陶瓷涂层的性能、研究现状,并对热喷涂纳米陶瓷涂层面临的问题进行了讨论.     

纳米复相陶瓷的制备及性能研究进展综述

本文综述了纳米复相陶瓷的研究进展。介绍了纳米复相陶瓷的分类及制备技术,详细地阐述了纳米复相陶瓷的力学性能和微观结构,分析了提高其断裂强度、断裂韧性及抗蠕变性等性能的机理。     

纳米抗菌技术在陶瓷生产中的应用及发展前景

纳米与抗菌技术相互结合应用在陶瓷生产中，将极大地改善传统陶瓷的性能。笔者介绍了抗菌机理及其在国内、外陶瓷生产中的应用现状，探讨了纳米抗菌技术在陶瓷生产中存在的问题，并对其发展前景作了预测和展望。     

关注纳米陶瓷建筑材料的研发应用技术

陶瓷材料作为材料的三大支柱之一,在日常生活及工业生产中起着举足轻重的作用。随着纳米技术的广泛应用,纳米陶瓷随之产生,使陶瓷具有象金属一样的柔韧性和可加工性。针对神奇的纳米技术孕育着技术变革,分析了纳米陶瓷的性能特点,介绍了纳米技术在陶瓷领域的应用,研究了纳米陶瓷的制备,同时指出了高性能陶瓷与纳米陶瓷的发展趋势。     

纳米陶瓷的制造及其性能

本文综述了国内外纳米陶瓷研究动态,介绍了纳米粉末的特点、纳米陶瓷的制造方法、纳米陶瓷的结构特征及其相关性能.     

纳米复合陶瓷涂层研究现状

介绍了国内外纳米复合陶瓷涂层的性能以及各种喷涂技术制备纳米陶瓷涂层的研究现状。与传统涂层相比,纳米涂层在韧性,强度和耐磨等性能均有了很大的提高。分析了面临的主要问题,并提出了相应的解决办法。     

纳米陶瓷无压烧结研究进展

纳米陶瓷是由纳米晶粒构成的比传统陶瓷具有更加优良理化性能的陶瓷材料。如何在陶瓷致密化过程中有效控制晶粒长大,从而制备高致密度纳米陶瓷一直是陶瓷制备中的重点和难点。在纳米陶瓷的众多制备方法中,通过压力辅助烧结或快速加热烧结抑制晶粒生长的方法较为普遍,而无压方法烧结作为工艺最为简单和最具商业价值的方法,近年来也受到国内外的广泛关注。本文综述了无压烧结致密纳米陶瓷的研究现状和进展,从纳米粉体的制备、团聚消除、素坯成型、纳米陶瓷烧结等四个方面进行了讨论,评述了目前无压烧结技术所面临的困难并进行了展望,以期为无压烧结技术对高致密度纳米陶瓷的制备提供有益参考。     

纳米陶瓷结合剂cBN砂轮的研究进展

文章综合论述了纳米陶瓷结合剂的性能特点、增强增韧机理以及研究进展,并探讨了纳米陶瓷结合剂cBN砂轮制备过程中存在的问题及对策,指出纳米陶瓷结合剂不仅可以解决目前陶瓷结合剂低熔点与高强度之间的矛盾,而且对于拓宽cBN砂轮的应用范围、适应超高速磨削技术具有十分重要的意义。     

热喷涂纳米陶瓷涂层的应用

采用热喷涂技术制备纳米结构涂层是构筑纳米结构材料最具前途的方法之一,本文综述了热喷涂陶瓷涂层材料的性能、制备方法及应用方面的研究现状,并对热喷涂纳米陶瓷涂层面临的问题及研究的发展趋势进行了讨论。     

纳米复相陶瓷

纳米复相陶瓷以其优异的性能受到大家的关注，成为陶瓷研究领域的研究热点。本文在介绍纳米复相陶瓷分类、材料设计和制备的同时，着重阐述了纳米复相陶瓷中纳米颗粒对材料的显微结构和性能的影响。     

纳米介电陶瓷的晶粒尺寸效应及低温烧结技术

微电子技术对纳米陶瓷材料的需求催生了各种新型纳米陶瓷材料制备与烧结技术的开发与研究。结合纳米晶介电陶瓷的晶粒尺寸效应（即晶粒尺寸与陶瓷介电特性、烧结特性之间的依赖关系）,系统介绍了制备纳米晶介电陶瓷材料的低温烧结技术,包括液相烧结、两步烧结、水热压烧结和放电等离子体烧结,重点阐述了各种低温烧结技术的基本原理、使用设备、实验参数,比较了其优、缺点和应用领域,综述了近年来国内外相关领域的研究进展,并对这些技术目前存在的问题和今后的研究方向进行了分析和展望。     

Grain boundary region and local piezoelectric response of BiScO3–PbTiO3 nanoceramics prepared by combination of SPS and two-step sintering

Highly dense 0.37BiScO₃–0.63PbTiO₃ (BS–PT) nanoceramics with average grain sizes of 23, 33 and 70 nm were prepared by a combination of spark plasma sintering and two-step sintering methods. The microstructure, phase and piezoelectric behaviours of BS–PT nanoceramics were investigated. High-resolution transmission electron microscopy revealed that the samples had dense and thin grain boundaries. Experimental evidence demonstrated that the polarisations of the BS–PT nanoceramics were switchable and that their ferroelectricity was retained with grain sizes as fine as 23 nm. However, the local piezoelectric response showed a large fluctuation over different regions. Moreover, a significant difference between local and macro piezoelectric coefficients was observed. The properties of the grain boundary regions are the key factor to understanding the ferroelectric behaviours of BS–PT nanoceramics.     

纳米陶瓷的特性和烧结

本文介绍了纳米陶瓷新颖的性能和特殊的烧结方法,阐述了这些特殊烧结方法的烧结机理。同时也对纳米复相陶瓷的性能和制备方法进行了介绍,并对纳米陶瓷今后的研究进行了展望。     

Densification and Grain Growth of Al2O3 Nanoceramics During Pressureless Sintering

α - Al₂O₃ nanopowders with mean particle sizes of 10, 15, 48, and 80 nm synthesized by the doped α-Al₂O₃ seed polyacrylamide gel method were used to sinter bulk Al₂O₃ nanoceramics. The relative density of the Al₂O₃ nanoceramics increases with increasing compaction pressure on the green compacts and decreasing mean particle size of the starting α-Al₂O₃ nanopowders. The densification and fast grain growth of the Al₂O₃ nanoceramics occur in different temperature ranges. The Al₂O₃ nanoceramics with an average grain size of 70 nm and a relative density of 95% were obtained by a two-step sintering method. The densification and the suppression of the grain growth are achieved by exploiting the difference in kinetics between grain-boundary diffusion and grain-boundary migration. The densification was realized by the slower grain-boundary diffusion without promoting grain growth in second-step sintering.     

Liquid-phase assisted spark-plasma sintering of SiC nanoceramics and their nanocomposites with carbon nanotubes

The appropriate conditions for liquid-phase assisted spark-plasma sintering (SPS) were identified for the fabrication of both SiC nanoceramics and their nanocomposites with carbon nanotubes (CNTs). A parametric study of the nanoceramics and nanocomposites with a given type of CNTs showed that the SPS temperature (as measured by the radial optical pyrometer) optimizing their densification, nanograin size, and mechanical properties is 1700 °C (soaking for a few minutes), below which there is incomplete densification, and above which there is obvious grain growth with no benefit in hardness or toughness in the case of the nanoceramics, and prejudicial to both properties in the case of the nanocomposites due to the CNT degradation. It was also shown that the nanocomposites have smaller nanograins than their nanoceramic counterparts, and are softer but tougher. Extension to nanocomposites with different types of CNTs confirmed these trends, and showed that the CNT features do not condition the densification, microstructure or mechanical properties of these nanocomposites.     

Transparent hydroxyapatite ceramics with nanograin structure prepared by high pressure spark plasma sintering at the minimized sintering temperature

A hydrothermally processed bulky powder composed of loosely aggregated nano-sized rods was consolidated by spark plasma sintering. The use of a high pressure cell allows the application of pressure up to 500 MPa. It was found that applying of high pressure is beneficial for widening up the kinetic window for attaining dense HAp nanoceramics. The high transparency of HAp nanoceramics obtained in this study is ascribed to the high density and homogeneous nano-grained structure achieved besides the unique intrinsic optical properties of the HAp crystal itself, i.e. its low refractive index and very small birefringence. Achieving full densification at the minimized sintering temperature allows for the first time the preparation of transparent HAp nanoceramics with stoichiometric composition, i.e. avoiding the loss of structural water that commonly takes place during the conventional ways of sintering.     

Residual strain and effects of lattice compression in thermobaric-synthesized optical nanoceramics MgAl2O4:Mn

Optically transparent Mg_1?xMn_xAl₂O₄ (x = 0.005; 0.00005) nanoceramics were obtained by thermobaric synthesis. Varying the parameters of thermobaric synthesis leads to a controlled modification of crystallographic parameters, such as the lattice constant, the region of coherent scattering, and residual strain. It is shown that as a result of thermobaric pressing, intrinsic and impurity structural defects are formed, the concentration of which depends on the P-T parameters. Two stages of thermobaric synthesis were found, differing by both crystallographic and optical parameters. In optically transparent nanoceramics, a correlation between the residual strain and a scattering coefficient associated with localization of impurity manganese ions in anti-site positions of spinel was found. Thermobaric synthesis of optical nanoceramics can be used as a method of compressing nanosized objects in an optical spinel matrix while maintaining such objects in a metastable state.     

Data flow modeling, data mining and QSAR in high-throughput discovery of functional nanomaterials

Metal oxide nanoparticles are promising materials in applications for fuel cells, gas sensors and fine chemical catalysis. Their functionality depends excessively on composition, structure as well as synthesis and processing conditions. Continuous hydrothermal flow synthesis (CHFS) reactors are an effective technology to make nanoceramics. In order to increase sample throughput of CHFS, a manual high-throughput continuous hydrothermal (HiTCH) flow synthesis process capable of formulating scores of samples per day was developed. More recently, a fully automated nanoceramics synthesis platform called RAMSI (rapid automated synthesis instrument) based on the HiTCH synthesis technology was developed. When large numbers of nanoceramics are made and formulated into appropriate libraries, automated analytical instruments can be used to allow collection of a large amount of useful data. This paper describes the information flow management system of RAMSI (as well as CHFS) and the data mining system for supporting discovery, QSAR (quantitative structure-activity relationship) modeling and DoE (design of experiments). Case studies demonstrating the use of the high-throughput data mining system are presented. These include clustering of Raman spectra, interpretation of X-ray diffraction (XRD) measurements, and QSAR model building linking XRD data and photocatalytic properties. A genetic algorithm method for DoE is also presented that can guide the experiments to search optimal XRD patterns.     

Development of Nanocrystalline Wear-Resistant Y-TZP Ceramics

The present contribution reports some interesting and new results obtained while developing yttria-stabilized tetragonal zirconia (Y-TZP) using spark plasma sintering (SPS). The experimental results clearly showed that ZrO₂-nanoceramics with high hardness(∼14.5 GPa) can be processed at a lower sintering temperature of 1200°C in a short time (5 min). Another important result is that the newly developed Y-TZP nanoceramics, compared with the conventional sintered TZP, exhibit better fretting wear resistance against bearing steel. The intergranular fracture and the grain pullout were observed as the major wear mechanisms of the zirconia nanoceramics.     

Preparation of Transparent 3Y‐TZP Nanoceramics with No Low‐Temperature Degradation

The progresses of the relative density, average grain size (GS), and maximum pore size entering into the final sintering stage are investigated in 3 mol% yttria‐stabilized tetragonal zirconia polycrystals (3Y‐TZP) compacts in the range of 87%~99% theoretical density. It is found that during conventional pressureless sintering, the pores in the compact enlarged dramatically, which appears to be the major obstacle for preparing fully dense nanoceramics. Transparent 3Y‐TZP nanoceramics with an average GS of 87 nm were prepared by exploiting microstructural refinement on nanoscale. The yields a maximal optical transmittance of 67% and shows no noticeable low‐temperature degradation after 100 h aging at 134°C under a hydrothermal pressure of two bars.