稀土氧化物在氮化硅陶瓷中应用的研究进展

简要论述了稀土氧化物在氮化硅陶瓷材料中的应用研究概况,介绍了单一稀土氧化物以及复合掺杂稀土氧化物在氮化硅陶瓷材料中的应用进展,并比较了它们对氮化硅陶瓷材料性能的影响;最后对稀土氧化物在氮化硅陶瓷材料中的应用前景作了简单分析和展望.     

稀土氧化物在陶瓷材料中应用的研究现状及发展前景

综述了稀土氧化物在陶瓷材料中的研究现状和发展前景．并阐述了稀土氧化物在陶瓷中的作用机理。     

稀土氧化物在陶瓷工业中的应用

本文论述了稀土氧化物在陶瓷坯釉料，陶瓷颜料，陶瓷金水，工业陶瓷等方面的应用研究，初步探讨了稀土氧化物的作用机理，表明了稀土氧化物在陶瓷工业中有着广泛的作用并有着广阔的应用前景。     

微波烧结在陶瓷材料中的应用

微波烧结作为一种陶瓷材料烧结的新方法,近年来得到飞速发展。本文介绍了微波烧结的原理,阐述了微波烧结在陶瓷 材料中的应用,并分析了微波烧结存在的问题及其解决途径。     

稀土氧化物在搪玻璃釉中的应用

稀土氧化物在搪玻璃釉中的应用陆介平（北京化工设备厂１０００２２）稀土氧化物在搪瓷工业中除作为着色剂有所报导外，其余尚在研究中。本文选择了六个既有实用性又有代表性的稀土氧化物，作为搪玻璃釉的组分，研究它们对搪玻璃釉形成、物化性和搪烧工艺的影响，以探索稀...     

稀土氧化物在陶瓷涂层中的应用

综述了稀土氧化物在陶瓷涂层中的应用状况,论述了稀土氧化物对陶瓷涂层的力学性能、抗热震性能、耐磨性和耐蚀性的影响,认为稀土氧化物对陶瓷涂层的改性作用主要表现在细化晶粒、净化组织、产生固溶强化和弥散强化等方面.     

稀土氧化物对铁基烧结材料性能的影响

本文研究了添加稀土氧化物对铁基烧结材料的影响，探索了稀土氧化物加入后在烧结材料中的作用机理。     

添加稀土氧化物对白云石烧结和抗水化性能的影响

通过测定烧后试样的体积密度、显气孔率和抗水化性能，研究了稀土氧化物及稀土精矿对白云石烧结和抗水化性能的影响。结果表明：添加少量的氧化铈、混合稀土氧化物、氧化镧可以明显地促进白云石的烧结．提高白云石的抗水化性能。尤以添加氧化铈对提高白云石熟料抗水化性能的效果最为显著；添加少量的氧化铈，经１６００℃，３ｈ煅炼后可获得体积密度达３．２４ｇ／ｃｍ￣３的白云石熟料。该熟料在水蒸汽表压为０．３ＭＰａ，２ｈ条件下的粉化率为１９．１１％，比没有添加剂的白云石熟料的粉化率９４．４９％有大幅度的降低。     

添加稀土氧化物对合成MgO－CaO系熟料的烧结和抗水化性能的影响

研究了稀土氧化物对二步合成ＭｇＯ－ＣａＯ砂的体积密度、抗水化性和抗渣性能的影响。结果表明：加入少量稀土氧化物可明显地促进合成ＭｇＯ－ＣａＯ砂的烧结和增强其抗水化性，且对合成砂的抗渣性能无明显不良影响。     

Effect of rare earth additives on properties of silicon nitride ceramics

Abstract

Silicon nitride ceramics with rare earth (Re) compound (5 wt-%) and MgO (3 wt-%) additives were fabricated by spark plasma sintering and following heat treatment. The Re compounds included two groups: ReF₃ ((Re?=?La,Nd,Gd) and Re₂O₃ (Re?=?La,Nd,Gd). Specimens show the same tendency in the sintering shrinkage rate, relative density, grain size and bending strength with the increasing Re cation (Re³⁺) radius both in ReF₃ and Re₂O₃ added samples. However, as to aspect ratios and thermal conductivity, the change rules are completely opposite between the two groups of specimens.     

稀土氧化物对钛酸铝陶瓷显微结构和力学性能的影响

研究了添加稀土氧化物Y2O3和Y2O3+Nd2O3对钛酸铝陶瓷的烧结温度、力学性能和显微结构的影响.结果表明,添加1%的稀土氧化物可以降低钛酸铝陶瓷的烧结温度,改善其显微结构,提高其力学性能,尤其是添加1%的复合稀土氧化物(Y2O3+Nd2O3)后,钛酸铝陶瓷的抗折强度和断裂韧性是未添加的试样的1.96倍和1.82倍.其性能提高的主要原因是由于稀土元素的细晶强化、净化界面、固溶强化、自增韧补强等作用.     

Thermal cycling behavior of EB-PVD rare earth oxides co-doping ZrO2-based thermal barrier coatings

Novel ceramic topcoat of Gd₂O₃–Yb₂O₃–Y₂O₃ co-stabilized ZrO₂ (GYbYSZ) thermal barrier coatings were fabricated via EB-PVD technique. The phase structural stability, phase constituent, chemical composition, morphology and cyclic oxidation of the thermal barrier coatings (TBCs) were systematically studied. Based on the XRD results, the GYbYSZ ceramics has not undergone phase transformation upon long-term annealing at 1373 K and 1523 K. Although the chemical content of the GYbYSZ ceramic coat deviates from the stoichiometric value, the coating is mostly composed of cubic phase, which is accord with the XRD pattern of the original ingot. A pyramidal-like morphology appears in the microtexture of the column tips and the measured diameters of the pyramids are about 2.5~4 μm. After thermal cycling, the surface of the coating presents a multi-layer structure, which is followed by layer-by-layer spallation. The failure zone of the ceramic coats is possible to occur the interior of the thermally grown oxide (TGO) layer, or within the top ceramic coat at the interface of bond coat/TGO layers. The degradation of GYbYSZ TBCs is primarily attributed to the accumulation and relaxation of residual stress, propagation of vertical through microcracks, the growth rumpling of TGO layer, the ridges of grain boundary and the abnormal oxidation of bond coat.     

Effect of rare earth oxides on the microstructure and properties of mullite/hBN composites

Mullite/hBN composites were fabricated with different rare earth oxides additives (ReO: Er₂O₃, CeO₂, La₂O₃, Lu₂O₃) by pressureless sintering at 1600 °C for 4 h. The impacts of ReO on the phase composition, microstructure, mechanical, dielectric and tribological properties of the composites were investigated. XRD results showed that all the ReO additives were beneficial to the formation of mullite phase. With the decrease in the ionic radius of the ReO, the mullite grains of the composite were refined while their mechanical properties were increased. The sample sintered with Lu₂O₃ showed the smallest grain size and the most excellent mechanical properties, e.g., its relative density, flexure strength, fracture toughness and hardness reached 93.7%, 222 MPa, 3.2 MPa m^1/2 and 6.02 GPa, respectively. Due to the different porosity and phase composition of the composites, the sample sintered with La₂O₃ had the lowest dielectric constant while the sample sintered with Er₂O₃ exhibited the lowest dielectric loss. Attributing to the highest hardness and fracture toughness, the sample sintered with Lu₂O₃ showed the best tribological properties.     

Effect of rare earth oxides addition on the mechanical properties and coloration of silicon nitride ceramics

The aim of this study was to evaluate the mechanical properties and coloration of silicon nitride ceramics in the presence of RE₂O₃ (RE = Nd, Eu or Dy). Dense Si₃N₄ ceramics were prepared by gas pressure sintering at 1800 °C for 2 h. XRD analysis confirmed the complete transformation of α-Si₃N4 to β-Si₃N₄. The fracture toughness and flexure strengths were 11.93 ± 0.56 MPa·m^1/2, 667 ± 40.98 MPa with the addition of Eu₂O₃ (SE). Base on the SEM image, the pull-out, bridging and deflection of large grains were observed and contributed to the increase in mechanical properties. The chromaticity of sintered bodies was measured using a spectrophotometer. The color difference of the ceramics is due to the formation of different color developing compounds according to the EDS. Results showed that high-toughness and colorful Si₃N₄ ceramics can be prepared using YAG:Ce³⁺ as sintering additive and RE₂O₃ as the colorant.     

Role of different rare earth oxides on the reaction sintering of magnesium aluminate spinel

Role of three rare earth oxides, viz., La₂O₃, CeO₂ and Yb₂O₃ on reaction sintering of magnesium aluminate spinel having molar ratio of MgO:Al₂O₃?=?1:2 from its solid oxide precursors was investigated in static and dynamic heating conditions. Effect of these additives (3?wt%) on densification behavior, phase assemblage and microstructure development were studied in the temperatures of 1500–1700?°C. Yb₂O₃ enhanced the sintering of spinel, while La₂O₃ and CeO₂ negatively impacted the sintering of magnesium aluminate spinel which can be discerned from the shrinkage curve of TMA as well as from static firing regime. This is ascribed to the formation of secondary phases in La₂O₃ and CeO₂ containing samples which have different crystalline structures to that of spinel. This anisotropy due to different crystallinity hindered the pore shrinkage and pore removal and thereby retarded the densification. Whereas, the cubic structure of the secondary phase formed in Yb₂O₃ containing sample which is isotropic with the crystalline orientation of the parental spinel phase assisted the densification.     

Preparation and characterization of branched polyesteramide/mix rare earth oxides composites

Branched polyester amide containing various amount of mix rare earth oxides (RE₂O₃) were synthesized by in-situ solution condensation of AB₂ monomer synthesized based on the reaction between maleic anhydride and diethanolamine (DEA). The effect of AB₂ monomer self-polycondensation on the RE₂O₃ surface and the properties of synthesized composites were investigated by using Fourier-transform infrared spectra (FT-IR), ultraviolet–visible absorption spectra (UV–vis), X-ray photoelectron spectroscopy, scanning electron microscopy, thermogravimetric analysis and viscosity determination. AB₂ monomer can envelop RE₂O₃ particles as an organic matrix (HBPEA′) by self-polycondensation under the proposed condition. Ionization of surface of RE₂O₃ aggregates can result in the rare earth ionic (RE³⁺) and the resulting RE³⁺ might coordinate with the organic matrix. Thermal stability of branched polyesteramide can be significantly improved in presence of 5 wt% RE₂O₃, possibly due to the coordination reaction between RE₂O₃ and the active group of the organic matrix.