硅粉粒度和含量对烧成Al2O3-ZrO2-C材料强度与结构的影响

选用4种不同粒度的硅粉,借助于压汞仪、扫描电子显微镜和能谱分析仪等测试手段,研究了硅粉粒度(粒度按A(d50=336.9μm)、B(d50=123.5μm)、C(d50=19.5μm)、D(d50=2.21μm)依次变小)和含量(分别为1%、3%、5%、7%)对埋炭烧成铝锆碳材料的耐压强度、孔径分布和显微结构的影响。结果表明:1)硅粉粒度和含量影响着材料的耐压强度,随着硅粉含量的增加,材料的耐压强度增大;硅粉粒度减小有利于提高强度,但硅粉粒度太细,强度反而大大降低;2)硅粉粒度和含量控制着材料的物相组成和显微结构,随着硅粉粒度减小,碳化硅晶须生成量增加,其长径比降低,逐渐形成良好网络结构,孔径分布范围也由宽变窄,气孔直径大大降低,但硅粉太细,晶须分布反而稀疏,小气孔的比孔容积也呈增加趋势;加入合适粒度和含量的硅粉还有利于氮化物在材料内部的形成。     

Al2O3-ZrO2-C质滑板材料的研究进展

从制备Al2 O3-ZrO2-C质滑板材料所用的氧化物、炭素、防氧化剂等原料对性能的影响方面,总结归纳了Al2 O3-ZrO2-C质滑板材料的研究进展,并对钙处理钢用滑板材料的未来研究方向进行了展望,期望为钙处理钢用滑板使用寿命的提高提供参考.     

超细炭素原料对Al2O3-ZrO2-C材料性能及微孔结构的影响

研究比较了粒度＜25 nm的炭黑A、粒度＜50 nm的炭黑B及粒度＜0.147 mm的鳞片石墨3种炭素原料对铝锆碳滑板材料的性能及微孔结构的影响,并采用扫描电镜观察材料中原位生成SiC晶须的显微结构变化.结果表明由于炭黑A和炭黑B的粒度细,它们在烧结过程中与硅粉更容易发生反应原位生成SiC晶须;SiC晶须发育良好,填充气孔,使试样中直径d＜1μm的微孔数量大大增加,同时提高了试样的强度.因此,添加炭黑A、炭黑B的试样的性能优于添加鳞片石墨的,而以添加炭黑A的最好.     

烧结刚玉锆莫来石材料的铝硅锆共析结构研究

通过对烧结刚王锆莫来石复合材料的高温缓冷试样及高温水淬冷试样的电子探针及能谱分析,发现其微观结构中存在纤维状、骨架状、线状、针柱状、细棒状等有定向规律分布的铝硅锆共析结构存在,其组成为ＺｒＯ２－ＳｉＯ２－Ａｌ２Ｏ３成份。     

烧结刚玉锆莫来石材料的铝硅锆共析结构研究

通过对烧结刚玉锆莫来石复合材料的高温缓冷试样及高温水淬冷试样的电子探针及能谱分析,发现其微观结构中存在纤维状、骨架状、线状、针柱太、细棒状等有定向规律分布的名硅锆共析结构慧其组成为ＺｒＯ２－ＳｉＯ２－Ａｌ２Ｏ３成份。     

SrO对刚玉锆莫来石材料的性能与结构影响研究

对氧化锶的加入量对刚玉锆莫来石材料的性能与结构的影响进行了分析，认为不超过3％的氧化锶对于稳定氧化锆的结构，改善性能有利。而氧化锆的作用，是以其共晶体的溶解改善基质的组成与侵蚀后渣的成分，以提高粘度来降低渣的渗透侵蚀。     

氮化硼对锆刚玉莫来石材料力学性能及显微结构的影响

研究了锆刚玉米莫来石－氮化硼复合材料的显微结构及力学性能，结果表明，在锆刚玉莫来基质引入氮化硼，降低材料的抗折强度，但可提高断裂韧性。这是氮化硼的微裂纹增韧作用所致。氮化硼的编织状结构可阻碍晶界的滑移，降低材料高温强度的衰减率。材料内生成的针状９Ａｌ２Ｏ３．２Ｂ２Ｏ３，在断裂过程生产拔出效应，有利于力学性能的提高。     

水煤浆气化炉用Cr2O3-ZrO2-Al2O3砖的蚀变过程

利用扫描电镜及能谱仪对水煤浆气化炉用进口铬锆铝砖的蚀变过程进行了显微观察与分析.结果表明此砖在水煤浆气化炉环境条件下的侵蚀主要由熔渣中的SiO2、CaO和P2O5引起;Cr2O3对这种渣蚀表现出很强的化学惰性,溶蚀很小,其使用过程中的主要变化是高温蒸发和在砖内蚀变液相作用下的溶蚀、溶析;而氧化锆蚀变生成的系列产物不仅在蚀变初期有利于保持砖结构致密,并且对蚀变后期基质连续网络结构的形成和保持也起了重要的作用.     

铝锆炭滑板中锆莫来石分解的显微结构研究

本文从显微结构角度研究了宝钢３００ｔ钢包铝锆炭滑板使用后锆莫来石分解的情况。锆莫来石分解后氧化锆游离出来并形成（ＺｒＯ２·Ａｌ２Ｏ３）Ｃ聚集体,锆莫来石分解导致滑板结构疏松、熔损加快,因此滑板中不加入锆莫来石而加入氧化锆或锆刚玉有利于提高使用寿命     

铝粉、硅粉加入比例对Al_2O_3-ZrO_2-C材料力学性能的影响

在A l2O3-ZrO2-C材料中加入总质量分数为5%的铝粉和硅粉,改变试样中铝粉和硅粉的质量比(分别为0:1、1:4、2:3和4:1),经配料、混练、成型、烘干后,在埋炭(煤焦炭)气氛中分别于800、1 000、1 300和1 400℃保温3 h煅烧,然后对烧后试样进行三点弯曲试验,并测定烧后试样的平均孔径,分析烧后试样的显微结构。结果表明:铝粉、硅粉的加入比例显著影响A l2O3-ZrO2-C材料的力学性能:经800和1 000℃煅烧后,试样的抗折强度、弹性模量和韧性均随铝粉加入量的增加而增大,而经1 300和1 400℃煅烧后,试样的抗折强度、弹性模量和韧性均随铝粉加入量的增加而减小;试样的平均孔径呈现出与力学性能相反的变化规律。上述这些变化规律是铝液的促烧结作用与高温下生成SiC、A lN晶须的强韧化作用和填隙作用以及生成A lN过多导致的结构疏松作用共同作用的结果。     

Effects of Particle Size and Content of Silicon Powder on Strength and Microstructure of Coked Al2O3-ZrO2-C Refractories

Effects of particle size (A: d50=336.9μm, B: d50=123.5μm, C: d50=19.5μm, D: d50=2.21μm) and content (1wt%, 3wt%, 5wt%, 7wt%) of silicon powder on cold crushing strength (CCS), pore size distribution and microstructure of Al2O3-ZrO2-C refractories coked at high temperature had been investigated by means of mercury porosimeter, SEM, EDS, etc. The results indicated that particle size and content of silicon powder affected the cold crushing strength of coked specimens. It increased with the addition of silicon powder and its finer particle size. However, it decreased greatly when using too fine silicon powder. The particle size and content of silicon powder also impacted the phase evolution and microstructure of coked specimens, much more β-SiC whiskers constituted network structure and well distributed in specimens with reduction of their slenderness ratios when finer silicon powder was added, corresponding to that, the specimens' pore size distribution range became narrower with smaller pore diameter, but β-SiC whiskers were distributed sparsely and the specific pore volume of small pores increased when much finer powder was added. It was worthly mentioned that some nitride could form in specimens with addition of appropriate particle size and content of silicon powder.     

铝锆碳质长水口损毁机制的研究

采用SEM、EDS对使用后的铝锆碳质长水口内壁及渣线部位材料的蚀损过程进行了分析研究.结果 表明:1)铝锆碳质长水口内壁蚀损过程为碳首先被氧化和溶解形成脱碳层,之后钢水中的夹杂物FeO与脱碳层中的Al2O3反应形成铁铝尖晶石,随着FeO继续附着,在脱碳层表面形成FeO富集区并生成低熔点相,致使脱碳层在高速钢水的冲刷下逐渐蚀损;2)长水口渣线部位蚀损首先为碳向钢液中溶解,之后为中间包渣侵蚀材料中的氧化物,两个过程交替进行,从而导致了长水口渣线部位材料的蚀损;3)适当降低长水口制品中的碳含量,可以减少铝锆碳质长水口内壁以及渣线部位材料中碳的氧化及溶解所导致的材料结构的破坏,可望延长长水口的使用寿命.     

Effect of particle size distribution of raw powders on pore size distribution and bending strength of Al2O3 microfiltration membrane supports

To lower the sintering temperature of Al₂O₃ microfiltration membrane support, Al₂O₃ powders with particle size distribution of tri-modal are chosen. The results show that the function of fine Al₂O₃ grains depends on their agglomeration state: if fine Al₂O₃ grains distribute discretely, the bending strength of the support increases along with a slight increase in porosity; however, the aggregated fine grains are harmful to both bending strength and pore size distribution of the support. The bridging of medium Al₂O₃ grains between coarse grains contributes to increase the bending strength, but has less effect on porosity. The addition of medium (and/or fine) Al₂O₃ powder has less effect on the pore size distribution of the support if only coarse Al₂O₃ grain forms the support's framework, which suggests a new way to prepare the support with both high bending strength and high porosity at low temperature.     

铝锆碳质转炉挡渣闸阀开发与应用

主要研究了膨胀石墨含量对低碳铝碳耐火材料的显微结构,力学性能和抗热震性的影响;在此基础上选择合适含量的膨胀石墨引入铝锆碳质转炉挡渣闸阀中,考察了转炉挡渣闸阀的现场服役行为.结果表明:膨胀石墨引入铝碳耐火材料中有助于促进碳化硅晶须的生长;正是由于碳化硅晶须以及膨胀石墨自身的强韧化作用,铝碳耐火材料热震后的残余强度由空白样的4.87 MPa提高至9.31 MPa,残余强度保持率由38%提高至54%.工业试验结果显示引入0.5wt%膨胀石墨的铝锆碳质转炉挡渣闸阀的平均使用寿命较传统滑板提高0.77次.     

临界粒度对Al2O3-C耐火材料可靠性的影响

选择临界粒度分别为1、0.8、0.6和0.5 mm的亚白刚玉颗粒为骨料,骨料与细粉的质量比为4 6,以酚醛树脂为结合剂进行配料。混好的物料于60℃干燥15 h,以120 MPa压力等静压成型为25 mm×25 mm×150mm的样条,然后直接在氮气保护气氛下于950℃5 h热处理。采用三参数Weibull分布,研究了临界粒度对Al2O3-C质耐火材料可靠性的影响。结果表明:减小骨料的临界粒度,Al2O3-C材料的Weibull模数m值逐渐增大,材料可靠性增加。分析认为制备过程对Al2O3-C材料的可靠性有较大影响,减小临界粒度,使坯料粒度分布集中,流动性变好,从而有利于Al2O3-C材料可靠性的提高。     

AlN对Al2O3-C材料性能的影响

采用碳热还原法制备的AlN复合粉(主成分是AlN和Al2O3)部分取代Al2O3-C材料中的Al2O3微粉,研究了AlN复合粉加入量(分别为0、15%和25%)对Al2O3-C材料性能的影响。结果表明:(1)试样的显气孔率随AlN复合粉取代量的增加而增大,体积密度、常温抗折强度随AlN复合粉取代量的增加而减小;(2)AlN复合粉的引入能显著提高Al2O3-C材料的高温抗折强度;(3)添加AlN复合粉的试样经熔钢侵蚀后,在材料表面形成较连续的致密层,有利于提高材料的抗熔钢侵蚀性和冲刷性。     

SiO_2微粉对Al_2O_3-ZrO_2-C材料力学性能的影响

在复合引入不同比例A l粉、Si粉(A l粉、Si粉的组合分别为2%(w)A l+3%(w)Si,3%(w)A l+2%(w)Si,4%(w)A l+1%(w)Si)的A l2O3-ZrO2-C材料中进一步外加质量分数分别为0、1%、2%的SiO2微粉,经配料、混练、成型、烘干后,在埋炭(煤焦炭)气氛中分别于800、1 000、1 200、1 300和1 400℃保温3 h煅烧,然后对烧后试样进行三点弯曲试验,并测定烧后试样的平均孔径,分析烧后试样的显微结构。结果表明:1)对于含不同比例A l粉和Si粉的A l2O3-ZrO2-C材料,SiO2微粉的引入使其经1 200℃或更高温度煅烧后的抗折强度、弹性模量和韧性提高,平均孔径减小;2)显微结构分析发现,含有SiO2微粉的试样中,A lN和(或)SiC晶须发育良好并且分布均匀,孔径细小,从而优化了材料力学性能。     

添加Si_3N_4对Al_2O_3-ZrO_2-C滑板性能的影响

通过在Al2O3-ZrO2-C滑板材料中引入Si3N4细粉(≤0.043 mm),研究了Si3N4加入量(质量分数分别为2%、4%、6%、8%)对滑板材料性能的影响,并对比研究了1 300℃6 h氮化烧成和1 450℃6 h埋炭烧成后试样的性能。结果表明:在不同烧成条件下,Si3N4的加入均改善了材料的性能,随着Si3N4加入量的增加,材料的显气孔率逐渐下降,体积密度、常温强度、高温抗折强度逐渐增大;Si3N4的加入,一定程度上改善了材料的抗氧化性;埋炭烧成滑板性能优于氮化烧成滑板,因为埋炭烧成过程中部分Si3N4反应生成了O’-SiAlON相。     

Improving the microstructural and mechanical properties of in-situ zirconia-mullite composites by optimizing the simultaneous effect of mechanical activation and additives

The current study aims to investigate the microstructural properties, diametral tensile strength, Weibull modulus, and surface roughness (Ra) of the zirconia-mullite composites. The simultaneous effect of duration of the mechanical activation (MA) process of starting materials, as well as TiO₂ and ZnO additions on the mentioned properties, were studied. X-ray diffraction analysis showed that mullite was the main crystalline phase in 6–24 h mechanically activated-TiO₂ containing samples which were subsequently heat treated at 1450 °C. Prolonging the duration of the MA process to 72 h led to the crystallization of the tetragonal zirconia as one of the main crystalline phase in the mentioned samples. As the heat treatment temperature increased to 1550 °C, the dependence of the type of the crystalline phases on the milling time eliminated and mullite became the main crystalline phase in 6–72 h MA processed samples. The transformation of starting materials to mullite and t-zirconia was not progressed effectively in ZnO containing samples which were heat treated at 1450 °C. However, by increasing the temperature of the heat treatment process to 1550 °C, both mullite and zirconia were efficiently crystallized in 6–72 h MA processed ZnO containing ones. Scanning electron microscopy results revealed that prolonging the duration of the milling process of the additive containing mixtures from 6 to 72 h could eliminate the acicular morphology of the mullite phase. 72 h mechanically activated ZnO containing sample which was later heat-treated at 1550 °C had the highest noticeable diametral tensile strength of 270 ± 15 MPa. The Weibull modulus of composite samples increased from 10.07 to 12.37 and 20.95 by the addition of TiO₂ and ZnO to the starting mixture, respectively. Finally, it was found that prolonging the milling time increased the Weibull modulus remarkably and decreased the Ra values as a result of the homogeneity development in the composite samples.