窑具材料显微结构与热震稳定性相关性研究

本文分析了影响窑具材料热震稳定性的重要参数,找出显微结构与这些因素的内在联系,表明通过调整显微结构可获得良好的材料性能。     

烧结的抗热震性赛隆材料

利用含有赛隆微米级细粉并加入CaO和Y2O3及Y2O3-Al2O3-MgO系共晶体制成了烧结试样。研究了材料的抗热震性、强度及热导率与加入剂种类和烧结条件的关系。     

耐酸材料抗热震性的研究

研究结果表明,降低线性热膨胀系数,可使耐酸材料的抗热震性提高到一定的程度——直至无定形相尚未被二氧化硅饱和为止;由氧化铁含量较高的粘土原料泥料生产的耐酸材料的抗热震性提高的原因是石英溶解过程得到强化;无定形相(玻璃相)饱和程度越高,制品的抗热震性就越高。     

氧化铝-锂霞石复合陶瓷在钢水中抗热震性研究

为了提高氧化铝陶瓷的抗热震性,将具有负膨胀系数的锂霞石加入到Al2O3中,通过无压烧结工艺,制备出了氧化铝-锂霞石复合抗热震陶瓷.结果表明,锂霞石加入量w(锂霞石)=20%,烧结温度为1500℃时,陶瓷样品能够承受钢水中1500℃温差(空冷)的热震破坏.采用SEM对陶瓷进行组织结构分析,发现在基体内部形成片状组织,这样的显微组织对提高陶瓷的抗热震性具有重要作用.     

陶瓷材料抗热震性的研究进展

阐明了陶瓷材料抗热震性研究的重要意义，系统总结了陶瓷材料抗热震的评价理论、热震断裂机制和设计高抗热震陶瓷材料的新近研究成果，并基于理论提出了改善陶瓷材料抗热震性的策略。即从控制显微结构出发，增加材料的韧性和热传导性、降低材料的弹性模量和线胀系数，为制作高抗热震陶瓷材料提供了可借鉴的工程技术途径。     

熔铸耐火材料抗盖板玻璃熔体侵蚀行为研究

本文以熔铸耐火材料为研究对象进行抗盖板玻璃熔体侵蚀试验,采用化学分析、岩相分析和电子显微镜能谱分析等测试分析方法,对比研究钠钙玻璃熔体、高铝玻璃熔体和锂铝玻璃熔体对熔铸耐火材料的侵蚀行为。结果表明,玻璃熔体中的碱金属离子向耐火材料中的玻璃相扩散,导致玻璃相黏度降低,同时耐火材料中刚玉相溶解,斜锆石分散,主体结构遭到破坏,并形成界面层。界面层内存在富铝含锆的玻璃相,由于高铝玻璃和锂铝玻璃氧化铝含量高,表面张力大,界面层内的玻璃相聚集在试样周围且扩散慢,从而阻止了侵蚀的发展。玻璃熔体的侵蚀速率为钠钙玻璃熔体＞高铝玻璃熔体＞锂铝玻璃熔体。     

纳米材料对紫砂陶器强度及抗热震性能的影响

以紫砂土为主要原料,加入纳米紫砂和纳米石英短纤,采用塑性成型并煅烧。通过XRD物相分析,采用急冷—强度法表征试样的抗热震性能,研究纳米材料添加量对紫砂陶器强度及抗热震性能的影响。结果表明:随着纳米材料的加入,紫砂陶器抗折强度与抗热震性能都有所提高。当纳米材料加入量为1.19%时,两者性能均达到最大,抗折强度达68.7 MPa,抗热震强度达26.0 MPa。     

Microstructure and Thermal Shock Resistance of Cr2O3 Ceramic Coatings Deposited by Supersonic Atmosphere Plasma Spraying

为了研制一种新型连铸结晶器材料,采用高效能超音速等离子喷涂技术在纯铜基体上制备了 Cr2O3陶瓷涂层。使用 X 射线衍射、扫描电子显微镜、图形软件、彩色 3D 激光显微镜和显微硬度计对涂层进行了表征及分析,分别在 450 ℃和 600 ℃对涂层进行了热震试验。结果表明,涂层继承了起始粉末的物相,但是 Cr2O3的结晶度有所差异;陶瓷涂层表面为良好熔化区和部分熔融颗粒组成的双态组织,涂层断口形貌为典型的片层状组织,涂层截面可见均匀分布的富铬带。涂层孔隙率为 1.2%,表面粗糙度为 4.763 μm,Vickers 显微硬度为 1 628 MPa。试样在 450 ℃和 600 ℃分别经历了均值为 127.4 和 58.6 次热震循环后,其半球顶端出现大面积剥落,但圆柱主体部分完好,表明 Cr2O3陶瓷涂层具备良好的抗热疲劳性能,超音速等离子喷涂适合于结晶器铜板表面涂层的制备。     

凝胶注模堇青石-莫来石复相材料的制备及其抗热震性能

采用凝胶注模方法制备堇青石-莫来石复相材料,研究了聚乙烯醇对浆料稳定性、固化时间和表面氧阻聚的影响,分析了堇青石-莫来石复相材料的抗热震性能。结果表明,聚乙烯醇可提高粗颗粒悬浮体系的稳定性,增大浆料黏度,延长固化时间。聚乙烯醇还可以起到消除表面起皮、开裂的作用。通过控制浆料固相含量调节堇青石-莫来石复相材料的气孔分布,从而影响其热震稳定性。当浆料中堇青石-莫来石固相体积分数为41%～44%时,堇青石-莫来石复相材料的热震稳定性最好。     

Thermal Shock Resistance of Ladle Castables

High purity alumina-spinel( A-MA) and alumina-magnesia( A-M) castables are widely used in steel ladles due to their resistance against slag penetration and corrosion. With a calcium magnesium aluminate bond( CMA) excellent slag penetration resistance can be achieved which results in high wear resistance due to reduced structural spalling. This paper investigates the impact of matrix compositions and CMA-binder content of A-MA and A-M castables on thermal shock resistance( TSR). Standardized thermal shock tests have been applied with sample quenching from 950 ℃ down to room temperature. Results show that all castables are significantly damaged after 5 cycles despite their differences in microstructure. However,the mix with 12%CMA gave TSR that is at similar good level as the reference mix with 6% CAC( 70% alumina cement). While a similar strength level was achieved before and after the thermal cycling,the formulation with 12% CMA contains 0. 6% less total Ca O. The A-MA castables perform better on average than the A-M mixes with this test method. Within the group of A-M castables the mix with 18% CMA and 0. 5% SiO_2 gave superior TSR,similar good as castables of the A-MA group. The introduction of CMA in an A-M castable allows reduction of free Mg O and SiO_2-addition. The reduction of SiO_2 has been found beneficial for the TSR. This was also found during a thermal cycling trial at high temperature between 1 100 and 1 500 ℃. Here the A-M mix with18% CMA and 0. 5% SiO_2 performed better than the SiO_2-free A-MA castable.     

含碳耐火材料的抗热震性

由于抗热震性评估的综合过程所涉及的费用和时间，通常选用有良好导热性的含碳耐火材料。文中探讨了USIMINAS为确定浇注钢包用含碳耐火材料抗热震性所用的方法。所采用的检测方法涉及到根据裂纹开口位移和热震参数(R″″和Rst)测定断裂功。现已证实这种方法对选择和研究合适的显微结构借以延长耐火材料内衬寿命是有用的。     

莫来石-堇青石耐火材料的抗热震性

已经研究了在热震条件下，骨料尺寸对莫来石-堇青石样品强度减小的作用。被震样品的强度减小显示依赖于骨料的尺寸、被烧结样品的预震强度及堇青石的含量。热震后的残余强度在由细骨料制备的样品中有所增加，这是由于其较高的初始强度。这些样品含有较低量的堇青石，其结果是由于减小了骨料颗粒的尺寸而导致了堇青石分解的增加。     

Thermal Shock Resistance of Ceramic Foams

Thermal shock behavior of a variety of open-cell ceramic foams was evaluated using infrared heating and forced air cooling. The extent of damage after thermal shock was determined by a nondestructive, dynamic resonance technique. The damage in foams was found to be strongly dependent on cell size and weakly dependent on density. In zirconia-based foams, damage was found to increase with an increase in zirconia content. A thermal stress resistance parameter R '_f was derived to predict the effect of cell size and density on the damage incurred in foams. The experimental results were found to corroborate the predictions fairly well but a better approach was to compare the maximum applied thermal strains with the degree of damage.     

微波烧结制备Ti3SiC2-金刚石复合材料的显微形貌及界面反应机理

采用Ti3SiC2粉体和金刚石粉体为原料,通过微波烧结制备Ti3SiC2结合剂金刚石复合材料,研究金刚石的含量和粒度对该复合材料的物相组成与显微形貌的影响.结果表明,通过高温微波烧结Ti3SiC2结合剂金刚石复合材料,金刚石表面会形成不同的涂层,从而与基体结合剂结合良好.金刚石的粒度和含量对复合材料中基体组成和金刚石的表面涂层状态有显著影响.烧结过程中,金刚石会不同程度的影响Ti3SiC2的分解.Ti3SiC2分解后生成Si与TiC.当金刚石含量相同(10％)、粒度较粗(30/40)时,金刚石表面会形成钛硅相与SiC涂层组织;基体的主相为Ti3SiC2、钛硅相与SiC.当金刚石粒度较细(W20)时,金刚石表面的C元素充分地与Si反应生成SiC涂层,基体主相变成TiC和Ti3SiC2.当金刚石粒度适中(120/140目与170/200目)时,基体的主相为Ti3SiC2.选取金刚石粒度为170/200目、金刚石含量较低时(5％与10％),基体的组成为Ti3SiC2与少量的SiC.金刚石含量较高时(20％与30％),基体的组成为Ti3SiC2与少量的TiC和SiC.各试样中金刚石表面都会形成钛硅相与SiC涂层组织.     

R-Curve Behavior and Thermal Shock Resistance of Ceramics

The influence of R -curve behavior of ceramics on the strength degradation associated with thermal shock is explored. Of particular significance for this interdependence is the observed nonlinear stress-strain behavior of materials that exhibit minimal strength degradation under severe thermal shock conditions. These two features, R -curve behavior and nonlinear behavior, are incorporated into a fracture mechanics analysis to provide a framework with which to understand severe thermal shock of ceramics. This analysis enables the estimation of the crack growth due to thermal shocking and also the anticipated strength degradation. The influence of specimen size is also addressed, and it is shown that greater strength degradation is anticipated with increasing specimen size. Experimental results for an alumina-zirconia composite material are presented to support the simple analysis.     

Reliability of Brittle Materials in Thermal Shock

The fracture-of alumina disks subjected to thermal shock is predicted from Weibull parameters derived from isothermal three-point-bend tests. Both the shear-insensitive Batdorf model and the principle of independent action model are used to compare results from three-point-benr1 and isothermal biaxial strength tests to results from thermal fracture tests. It is found that the shear-insensitive Batdorf model gives good agreement between mechanical tests and fracture of the thermally shocked disks.     

CZP陶瓷的烧结特性与抗热冲击性能

采用固相合成法制备CaZr4（PO4）6（calcium zirconium phosphate,CZP）陶瓷粉体。研究添加剂对CZP陶瓷烧结特性和热膨胀系数的影响以及CZP陶瓷的抗热冲击性能。通过X射线衍射分析、扫描电镜分析、热膨胀法和Archimedes排水法分别表征CZP陶瓷的晶体结构、微观形貌、热膨胀系数和体积...     

红柱石砖的抗热震性

通过实验对比了烧成和不烧红柱石砖的矿物成分、超声波速度及显微结构,发现了红柱石莫来石化形成的复合显微结构使得红柱石烧成砖有良好的抗热震性,在热循环中其性能的均一性和重复再现性与不烧砖相比有明显优势。