金属颗粒增韧氧化铝陶瓷研究现状

概述了金属颗粒增韧氧化铝陶瓷的研究进展,对氧化铝/金属复合材料的研究现状、增韧机理及制备方法进行了介绍,并对氧化铝/金属复合材料的主要发展方向进行了分析预测。     

耐火喷补料的形成工艺

炼钢、炼铜、炼铝和玻璃等行业对耐火材料使用条件要求比较苛刻 ,氧化铝质耐火材料由于具有良好的抗热震性 ,因而得到广泛的应用。利用陶瓷焊接喷补技术对氧化铝质耐火材料表面进行修补 ,可进一步提高耐火材料的使用寿命。陶瓷焊接喷补技术所用的混合物包括含氧化铝的耐火材料、金属易燃物和添加剂。含氧化铝的耐火材料从矾土 (Al2 O3·2H2 O)、莫来石 (3Al2 O3·2SiO2 )、烧结氧化铝 (Al2 O3)和镁铝尖晶石中选取 ;金属易燃物在混合物中的含量至少占 5% ,易燃物可以是金属铝、镁、锆、铬中的一种或几种 ,但金属铝至少占 3 0 % ;添加剂从…     

氧化铝基金属复合材料界面结构研究进展及问题

氧化铝-金属界面结构是氧化铝-金属系复合材料中极其重要的理论和现实问题.由于氧化铝陶瓷-金属界面结构的复杂性,界面结构问题,特别是界面结构与性能的关系一直得不到很好的解决,因而受到材料科学家和化学家们的极大关注.本文从界面结合及增韧机理、界面结构理论模型、界面原子结构及化学三方面概述了氧化铝-金属复合材料界面结构研究进展,指出了目前存在的主要问题,并提出了氧化铝-金属复合材料技术今后发展的方向.     

耐磨工程和切削钢用氧化锆增韧氧化铝

叙述了用溶液蒸发分解来合成Y2O3基部分稳定氧化锆,以及用湿化学沉淀法获得α-Al2O3和用粉末冶金工艺制造氧化锆增韧氧化铝陶瓷的方法。对用氧化锆增韧氧化铝烧成的制品用作切削工具嵌刃和在其它耐磨工程性能方面进行了特性分析。在实验中切削钢时观察到应力引起的氧化锆增韧氧化铝陶瓷的韧性变化,调查了月牙洼和侧面磨损对切削钢的影响。硬度和断裂韧性与提高切削性能(钢切削效率)和其它耐磨工程的使用都有关联。     

氧化铝陶瓷增韧技术及机理

介绍了氧化铝陶瓷增韧技术及其机理(包括相变增韧、晶须和纤维增韧、颗粒弥散增韧、微结构设计增韧、纳米技术增韧、耦合协同增韧),探讨了氧化铝陶瓷材料增韧技术的研究现状和今后的发展方向。     

氧化铝陶瓷增韧研究进展

介绍了氧化铝陶瓷增韧技术及其机理,包括相变增韧、晶须和纤维增韧、颗粒弥散增韧、微结构设计增韧、纳米技术增韧、耦合协同增韧;探讨了氧化铝陶瓷材料增韧技术的研究现状和今后的发展方向。     

Al2O3陶瓷材料的增韧

氧化铝陶瓷因脆性而限制了其广泛应用。本文对目前氧化铝瓷的增韧方法及主要机理进行了评述，主要有层状复合增韧、纳米复合增韧、纤维（晶须）增韧、自增韧等。其中复合增韧是主要手段。而且纳米技术和微观结构设计将是今后氧化铝提高韧性的发展方向。     

金属复合Al2O3基耐火材料的研究进展

介绍了金属复合Al2O3基耐火材料的研究进展,重点介绍了金属加入物对Al2O3基耐火材料性能的影响。加入金属可提高材料的常温和高温强度、断裂韧性、抗热震性和抗侵蚀性等,从而提高了材料的使用寿命。材料性能优化的原因是加入的金属反应生成了碳化物、氮化物和SiAlON(或AlON),以及少量金属熔融后的助烧结作用。     

塑性相结合刚玉复合材料的力学性能

在刚玉－碳化硅耐火材料中添加硅粉,利用硅粉所具有的金属塑性特征,使得制品具有了塑性成型的性质,而且提高了制品的致密化程度和断裂韧性,并达到了坯体增韧的效果。     

赤泥外排泥浆泵陶瓷缸套的应用

根据对活塞式泥浆泵缸套的失效分析,采用一种新型的增韧氧化铝陶瓷材料作为缸套的内衬套,并与金属缸套进行同机台运行比较。结果表明,其耐磨性能明显优于金属缸套,使用寿命也成倍增加。     

Solid particle impact erosion of alumina-based refractories at elevated temperatures

Solid particle erosion tests have been conducted on three different alumina-based refractories at elevated temperatures up to 1400 °C, using sharp SiC particles between 325 and 830 μm in diameter. The impact speed is 50 m/s and the impact angle is varied between 30° and 90°. The objective of this study is to ascertain the effects of temperature and impact angle on the erosion resistance of alumina refractories. The experimental results reveal that the alumina-based refractories, in general, exhibit increasing erosion resistance with increasing temperature and decreasing impact angle, with the minimum erosion rate at 1200 °C and 30° impact angle. Chrome corundum refractory brick is the most resistant to vertical erosion, due to its highest alumina content, and associated hardness and density, as well as strongly bonded aggregate and binder phase. The primary material removal mechanisms are fracture and chipping of binder phase and aggregate, as well as aggregate pull-out.     

Corrosion mechanism of lightweight microporous alumina-based refractory by molten steel

Lightweight refractory linings for industrial furnaces have become important subjects of development in high-temperature industries. The reaction mechanism between a lightweight microporous alumina-based refractory material and molten steel was investigated in this study. The main mechanism of refractory damage was structural spalling, caused by steel penetrating the pores. The many micropores in lightweight microporous alumina have high specific surface area and reactivity, inducing the formation of FeO–Fe₂O₃–Al₂O₃ phases. This impeded the further penetration of molten steel and the direct dissolution of refractory oxides, promoting greater resistance to molten steel than that shown by common tabular alumina-based refractories, in which Fe does not react and steel penetration through the pores cannot be retarded.     

Conventional and microwave-assisted sintering of ZnO-containing CAC-bonded alumina-based refractory castables

Recent studies have pointed out that ZnO can induce early spinel formation in alumina-based refractories, giving rise to gahnite (ZnAl₂O₄). Besides that, the high microwave absorption of zincite enables the likelihood of applying this sintering technique to compositions comprising this oxide. In this work, microwave and conventional sintering were applied to ZnO-containing alumina-based refractory castables. Microwave-processed samples displayed higher densification, enhanced mechanical properties at RT, a faster sintering schedule, and 70%-lower energy consumption compared to the conventionally produced counterparts, which could be attributed to the higher heating rates and enhanced ion diffusion induced by the electromagnetic-assisted sintering. Moreover, thermodynamic and experimental analyses indicated that the oxidation of SiC used as microwave susceptors induced zinc volatilization, resulting in small (∼ 40 µm) pores in a densified refractory matrix. Although not necessarily detrimental to the castables’ properties, this volatilization was reduced by controlling the atmosphere of the microwave cavity during sintering.     

Thermal shock damage evaluation of refractory castables via hot elastic modulus measurements

When refractory castables are submitted to continuous thermal changes, crack nucleation and/or propagation can take place resulting in a loss of mechanical strength and overall degradation of such materials. This work evaluates the thermal shock damage cycling of high-alumina and mullite refractory castables designed for petrochemical application. Hot elastic modulus analyses were carried out after 0, 2, 4, 6, 8 and 10 thermal cycles (ΔT=800 °C) in order to investigate the microcracking evolution due to the temperature changes. Additionally, apparent porosity, hot modulus of rupture, erosion and work of fracture measurements were also performed. According to the attained results, it was detected at which temperature range the stiffening or embrittlement took place in the mullite-based refractory (M-SA) microstructure. Nevertheless, the damage induced by the thermal shock tests was not permanent, as further increase of the elastic modulus results was observed for all evaluated samples after annealing. On the other hand, the alumina-based composition containing a sintering additive (TA-SA) presented enhanced mechanical strength, high thermal stability and E values. Simulations indicated that refractories with high E values (∼140 GPa, such as those attained for alumina-based castable) showed a reduced amount of stored elastic strain energy even under severe thermal stresses, which seems to be a key aspect for the engineered design of thermal shock resistance materials.     

Microstructural changes and evolutions of elastic properties versus temperature of alumina and alumina–magnesia refractory castables

This paper deals with the evolutions of thermo-mechanical properties of castable refractories versus temperature. The measured properties are mainly Young's modulus evaluated by a high temperature ultrasonic technique and thermal expansion followed by dilatometry. Materials are alumina-based low cement castables with a fraction of alumina eventually substituted by spinel or magnesia. The granularity of the different used raw materials is chosen by using a packing model, in order to reduce the final porosity in the hydrated state. The interpretation of results is carried out by considering the materials as composites, constituted of aggregates (size > 100 μm) into a matrix where most of chemical and phase transformations occur. By using two-phase analytical models, it is shown that the evolutions of thermo-elastic properties of castables can be qualitatively predicted from measurements performed in a matrix-equivalent simplified material. Moreover, considering the elastic properties after heat treatment, the castable with magnesia is comparable to the castable processed with synthetic spinel.     

MgO-CaO-ZrO2耐火材料的性能、制备与应用

系统地介绍了MgO-CaO-ZrO2耐火材料的性能特点、应用领域、制备与使用情况.指出,利用高纯原料制备MgO-CaO-ZrO2耐火材料已取得成功,而利用天然原料低成本地制备MgO-CaO-ZrO2耐火材料将成为今后研究的主要课题;同时指出,MgO-CaO-ZrO2耐火材料的剥落现象是影响其使用寿命的主要原因,还有待于进一步研究改进.     

耐火材料力学—热物理性能的评述

本文简述了对耐火材料机械性能及热震稳定性的已有知识及有关研究的进展。讨论了耐火材料化学成份，相组成，微观及宏观组织对其弹性常数、力学强度、断裂及热震参数等物理化学性能的影响；探讨了耐火材料现有测试评价技术中的问题和未来研究的方向。     

The physical and mechanical properties of alumina-based ultralow cement castable refractories

In this study, the effects of the type of alumina on the physical, chemical and mechanical properties of the ultralow cement castable (ULCC) refractories were investigated. Brown fused alumina, tabular alumina and rotary bauxite-based ULCC refractories were prepared by mixing each type of alumina with silicon carbide, carbon, cement, metallic silicon and microsilica. The density, porosity and cold crushing strength (CCS) of the refractory castables were measured after drying at 110 °C for 24 h and firing at 1450 °C for 5 h. The slag penetration resistance of the refractory castables was determined using slag corrosion tests. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffractometry (XRD) were used to characterize the castables. It was found that all three refractory castables had strong slag penetration resistance and that the tabular alumina-based refractory castable had the largest specific cold crushing strength with an acceptable percent of porosity among the refractory castables.     

低碳MgO-C耐火材料结构和性能优化的研究进展

MgO-C耐火材料作为钢铁冶炼用关键基础材料,被广泛用作转炉衬砖、电弧炉炉壁和钢包渣线用砖。寻求制备高性能低碳MgO-C耐火材料的新方法对耐火材料及冶金行业的发展至关重要,本文从纳米碳源的引入、骨料表面的改性和镁基骨料的引入、酚醛树脂的改性、抗氧化剂的引入及陶瓷相的原位形成角度出发,综述了改善低碳MgO-C耐火材料结构和性能的研究进展,以期为进一步推动低碳MgO-C耐火材料的发展提供参考,并对MgO-C耐火材料未来的研究方向进行了展望。     

Determination of mechanical properties and thermal treatment behavior of alumina-based refractories

Two different types of alumina-based refractories have been investigated. Chamotte and bauxite were the raw materials, being molded using a system of aluminate cement and water or a phenol–formaldehyde resin, as binder. Different raw material's grain size, water content, molding pressure, and firing temperature were selected for the preparation of the specimens. The mechanical strength of all specimens was determined using compressive tests, where parameters with physical meaning, such as maximum stress, maximum strain, elasticity parameter, and viscoelastic parameter were obtained after modeling the collected stress–strain data. In addition, water quenching test was performed for both samples, in order to present their thermal stability and mechanical wear after certain cycles.Process conditions as well as the raw materials’ characteristics were correlated with the compressive properties. More specifically, maximum stress seemed to increase when increasing all parameters except grain size both for bauxite and chamotte samples. The increment of bonding phase, grain size, and molding pressure caused an increment in maximum strain for both types of refractories. However, the higher the firing temperature was the higher the maximum strain of bauxite appeared, while the maximum strain of chamotte samples was decreased. Modulus of elasticity seemed to increase with bonding phase content and firing temperature and decreased with grain size for both types of refractories. For bauxite samples higher molding pressure caused a decrement in elasticity parameter while for chamotte in caused an increment. As far as the quenching tests are concerned chamotte samples seemed to be more tolerant to thermal shock. After data acquisition, the change presented in elasticity parameter (E) was also modeled with the number of cycles. Both bauxite and chamotte samples showed a decrement in maximum stress after thermal treatment, while elasticity parameter seemed to have a more severe decrement for bauxite samples.