含炭耐火材料用硼化物添加剂

综述了近几年国外研究含炭耐火材料防氧化而采用的一些含硼添加剂，介绍了这些添加剂的特性及其防止碳氧化的基本原理。     

几种钢包用含碳耐火材料对IF钢增碳的比较

通过感应炉试验分析了钢包渣线用3种碳含量不同的镁碳砖(C的质量分数分别为8.3%、15.5%和17.9%),钢包底用蜡石-碳化硅砖(C的质量分数为3.71%)以及实验室开发的MgO-Al2O3-SiC质钢包渣线浇注料(C的质量分数为4.07%)对IF钢增碳的影响,并对其增碳的机理进行了初步分析讨论。试验结果表明:渣线镁碳砖的碳含量越高,对IF钢造成的增碳量越大;包底蜡石-碳化硅砖对IF钢水的增碳量达到渣线镁碳砖的7.73倍;MgO-Al2O3-SiC质浇注料也对IF钢产生明显的增碳效果,不宜用作冶炼超低碳钢的钢包渣线材料。     

直流电弧炉用导电耐火材料

本文报道了MgO-C、MgO-CaO-C、MgO-CaO-Fe系材料的超高温稳定性.试验和分析结果表明上述系列材料超高温稳定性由好到坏的次序为MgO-CaO-Fe、MgO-CaO-C、无金属添加物的MgO-C材料和含金属添加物的MgO-C材料.研制的导电Mgo-C质捣打料在钢针型直流电弧炉上应用,热补料在钢针型、钢片型直流电弧炉底电极进行冷、热修补,使用效果良好.     

A508-3钢液对钢包用含碳耐火材料的侵蚀机理

采用感应炉浸渍实验法模拟钢包现场使用情况,借助X-射线衍射仪(XRD)、扫描电子显微镜(SEM)和热重分析设备(TGA)等分析手段,研究了含碳耐火材料的相组成、高温失重特性以及被钢液侵蚀后的显微组织。结果表明,在20～1 300℃加热阶段,MgO-C试样一直在减重,减重共计1.142 7mg,占试样总质量的16.93%,而Al2O3-MgO-C试样减重较少,减重共计0.441 4mg,占试样总质量的6.45%。加热温度在1 070～1 170℃,Al2O3-MgO-C试样少量增重。钢液对MgO-C和Al2O3-MgO-C耐火材料的侵蚀机理基本相同,均沿主相晶界侵入,晶界处有许多小孔洞,且晶界和晶内分布有许多小铁珠。     

导电耐火材料及其常温电阻率测试仪的研制

简要介绍了直流电弧炉用导电耐火材料的理化性能及导电机理 ,根据其导电特性研制了导电耐火材料用常温电阻率测试仪 ,介绍了电阻率测试仪的结构及特点     

Corrosion of carbon steel in compacted bentonite and its effect on neptunium diffusion under reducing condition

The corrosion of carbon steel and its effect on neptunium diffusion were studied by corrosion tests of carbon steel and neptunium diffusion tests under conditions designed with consideration of constituents of a repository for High-level Radioactive Waste disposal. The major constituents of the conditions were carbon steel, corrosion products pre-formed under aerobic conditions, compacted bentonite, reductant and a low-oxygen glove box. The corrosion tests were performed in the presence of water-saturated compacted bentonite. The neptunium diffusion tests were performed with and without carbon steel. The carbon steel and the bentonite were observed by taking photographs and analyzed by X-ray diffraction. The color of the corroded surface of the carbon steel changed from red/orange/black under aerobic conditions to a dark-green under reducing conditions. Portions of the bentonite changed their original color, pale-gray, to a brownish color after the test. Gas-induced cracks were also observed in some bentonite specimens. These changes were discussed combining thermodynamic predictions under the present experimental conditions. The results revealed that anaerobic corrosion of carbon steel occurred in the bentonite. The corrosion processes were also discussed. The corrosion rate of carbon steel was estimated to be 0.1 μm/year from iron profiles in the bentonite. This value was much lower than the conservative setting value 20 μm/year in the current performance assessment. The significant restriction in corrosion could be attributed to the presence of bentonite and corrosion products. Oxidation states of neptunium in the bentonite were investigated by thenoyltrifluoroacetone in xylene extraction technique. It was found that tetravalent neptunium accounted for 99% of the total neptunium in the presence of carbon steel and only 63% without. The results revealed that anaerobic corrosion of carbon steel could maintain strong reducing conditions to keep most tetravalent neptunium from being oxidized to pentavalent neptunium, thus effectively restraining migration of neptunium in the bentonite. The apparent diffusions were estimated to be in the order of 10⁻¹⁵–10⁻¹⁴ m²/s for tetravalent neptunium and 10⁻¹³–10⁻¹² m²/s for the pentavalent. No significant effect of the corrosion products on neptunium sorption was found through comparing the apparent diffusion coefficients obtained in the diffusion with and without carbon steel. Corrosion of carbon steel under conditions relevant to the repository is essential for further studies, providing a confident and defensible value of corrosion rate for repository design. The effects of corrosion on radionuclide migration, especially redox-sensitive radionuclides in the buffer, should be considered for a reliable safety assessment of geological disposal.     

六方氮化硼复合氧化铝耐火材料的性能研究

以粒度为3~1和≤1 mm的板状刚玉为骨料,板状刚玉细粉、α-Al2O3微粉和Si粉为细粉,分别添加质量分数为3%的六方氮化硼、3%和10%的鳞片石墨制备了Al2O3-BN和低碳、高碳Al2O3-C三种试样,并对比了其常温物理性能、高温强度、抗氧化性、抗热震性和抗渣侵蚀性。结果表明:1)Al2O3-BN耐火材料的常温、高温物理性能与低碳铝碳材料相差不大,并优于传统高碳铝碳材料;2)Al2O3-BN耐火材料具有比碳复合耐火材料更好的抗热震性和抗氧化性,抗渣性与低碳铝碳材料的相当;3)考虑到材料的整体性能,六方氮化硼可以替代石墨作为原料,用于制备综合性能优异的氧化铝质复合耐火材料。     

MgAlON对碳结合制品性能的影响

采用合成MgAlON部分或全部取代铝碳砖和铝镁碳砖中的基质部分 ,并测试其对材料密度、强度、抗氧化性和抗渣性能的影响。结果表明 :在铝碳和铝镁碳耐火制品中加入MgAlON后 ,体积密度上升 ,耐压强度提高 ,抗氧化性能改善 ,抗渣性能略有降低但仍保持较好水平     

活性炭对苯酚废水的处理

在静态条件下,研究了活性炭对苯酚废水的处理．比较了不同条件下活性炭对苯酚废水的处理效果,确定了处理废水的振荡时间、活性炭用量、废水pH值、温度、废水中苯酚浓度对处理结果的影响。实验结果表明,活性炭在振荡时间3．5h、用量4．0g、温度30℃、pH值为3．6左右的条件下,对100 mL质量浓度为50mg/L的苯酚废水的吸附效果最好。进行了活性炭处理不同浓度废水的比较实验,结果表明,活性炭处理各种浓度苯酚废水的去除率都很高,适用于对出水要求较高的水处理工艺。     

Al2O3-C耐火材料对超低碳钢的增碳作用

在空气中利用中频感应炉加热,研究了以Si为抗氧化剂的Al2O3-C耐火材料对超低碳钢的增碳作用.利用高频燃烧红外吸收法测定钢样中的碳含量,并对用后耐火材料进行了SEM和EDS分析.研究结果表明钢熔化后,炭的直接溶解机制造成钢水中碳含量迅速增加;随着保温时间的增加,"渗透-溶解"机制对钢水增碳占主导作用;同时,耐火材料与钢水接触部位生成反应脱炭层,反应脱炭层隔离了钢水与耐火材料的直接接触,进而减缓并停止耐火材料对钢水的增碳作用;空气中的氧通过渣向钢水中传递,氧和钢水中的碳发生反应对钢水产生脱炭作用,同时,碳氧平衡决定了在钢水的碳含量很低时,脱炭反应接近于平衡状态,钢水中的碳含量趋于平衡.     

拉伸蠕变仪改造与应用研究

根据聚合物拉伸蠕变原理和光电原理,设计并制造了光电拉伸蠕变仪。该仪器实验精度、准确性较高,仪器误差和人为误差较小;可测试在标准和非标准条件下聚合物的拉伸蠕变性能。试验结果表明,蠕变与湿度成正比,本体黏度与湿度成反比。     

Al2O3-SiO2系低蠕变耐火材料的研究现状和进展

对典型蠕变曲线的特征,蠕变理论以及影响耐火材料蠕变变形的因素等作了综述.根据Al2O3-SiO2系耐火材料蠕变性能研究的现状和进展,分析指出,在Al2O3-SiO2系耐火材料中,高铝(Al2O3≥70%)低蠕变制品的生产技术目前是比较成热的,而对于低铝(Al2O3≤50%)低蠕变制品的研制和生产,还需要采取一定的技术措施.     

电熔耐火材料的超声检测技术应用研究

本文主要包括超声穿透法对缩孔和裂纹的检测、结构均匀性检测和采用平测法对电熔耐火材料残余厚度和开口裂纹深度的检测。试验结果表明采用(T'-V')法能判断电熔砖缩孔的形状、大小和位置;完整波形数目是确定裂纹扩展面积的有效参量;采用平测法能检测电熔耐火材料的残余厚度和开口裂纹深度,检测精度在7％以内。     

ZrO2-C质耐火材料中碳对氧化锆的稳定作用

分别以粒度均<0.045 mm的氧化钙部分稳定氧化锆、氧化镁部分稳定氧化锆和氧化钇部分稳定氧化锆为原料,酚醛树脂作为结合剂和碳源,按部分稳定氧化锆与酚醛树脂质量比为9 1配料,研究了在埋焦炭条件下于1 600℃渗碳处理后3种部分稳定氧化锆的相组成变化,以及保护渣对渗碳处理后氧化锆稳定性的影响。结果表明:1)高温下树脂碳对氧化锆存在渗碳过程,并对氧化锆有稳定作用,促进了部分稳定氧化锆中单斜相向四方相的转化;但也发现渗碳过程对部分稳定氧化锆中的氧化钙和氧化镁稳定剂存在还原作用并引起其挥发。2)由于渗碳处理过程中部分氧化钙和氧化镁稳定剂被还原挥发,高温下空气气氛中部分稳定氧化锆随着氧化锆晶格中碳的氧化而迅速失稳;而在埋炭条件下部分稳定氧化锆晶格中碳的存在减缓了部分稳定氧化锆的失稳过程。     

Al2O3-C耐火材料抗氧化性研究进展

综述了Al2O3-C耐火材料抗氧化方法的研究进展,介绍了浸渍氧化抑制剂法、添加抗氧化剂法、表面涂层法等抗氧化方法及其各自的抗氧化机制,并提出了改进Al2O3-C 材料抗氧化性能的研究方向.     

Changes in the properties of aluminosilicate refractories under prolonged reducing conditions

Conclusions Studies of corundum and aluminosilicate refractories of dense and granular structures in an atmosphere of hydrogen and dissociated ammonia at 1200, 1500, and 1700°C in periods of 175 and 50 h showed that the resistance of the products increases with an increase in the alumina concentration and density. The maximum resistance is exhibited by corundum products. In the aluminosilicate refractories there is some additional sintering of the material with the separation of mullite and glass. Simultaneously on the surface of the specimens we detected deeper mineralogical changes, accompanied by the decomposition of the mullite, with the formation of corundum, silicon monoxide, and glass.The changes in the phase composition are accompanied by a change in the structure, and an increase in the creep. Considering that a reduction in the temperature of 100°C causes a reduction in the creep by approximately a half [26], it can be recommended that corundum refractories should be used (under a load of 2 kg/cm²) in a reducing atmosphere at temperatures of up to 1550–1600°C, sillimanite up to 1450–1500°C, kaolin and chamotte (high-grog) up to 1300°C, with a reduction in the load and an increase in the density, the temperature of application for the products examined, especially corundum, can be increased.Translated from Ogneupory, No.5, pp.26–32, May, 1972.     

Creep behaviour of steel bonded joints under hygrothermal conditions

The aim of this research is to study the influence of moisture absorption at low moisture contents on the creep behaviour of an epoxy adhesive in steel bonded joints. Single lap joints were manufactured using high strength steel adherends and a two-component epoxy adhesive. The single lap joints were tested at load levels corresponding to average lap shear stresses of ± 5%, 15%, 30% and 45% of the dry lap shear strength in both 40 °C air and 40 °C distilled water. Specimens were not pre-aged to be able to analyse the coupled effect of moisture and loading. The test results show that an increase in the load level resulted in an increase in the instantaneous strain and in the creep strain rate. The creep strain of single lap joints loaded in water was generally larger than for the ones loaded in air. For joints loaded in water the creep behaviour was found to be dependent on the moisture concentration in the adhesive. At low moisture percentages creep was suppressed, resulting in a lower instantaneous strain. At higher moisture percentages creep was promoted, resulting in a larger strain rate. The suppression of creep at low moisture percentages is attributed to water molecules bonding to the epoxy macromolecules, resulting in a reduction in molecular mobility and a smaller creep strain. At higher moisture percentages the plasticizing effect of the water dominates, resulting in a larger creep strain. The Maxwell three-element solid model and Kelvin-Voigt three-element solid model were used to simulate the creep behaviour of the single lap joints loaded in air and water. The models gave good representations of the creep response across the different load levels in both water and air, they were however unable to give a correct representation of the instantaneous strain of the single lap joints loaded in water. This is attributed to the models being unable to account for the present short-term relaxation process that is dependent on the moisture concentration.     

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。     

胶接接头在静态负载条件下的蠕变和松弛行为

Modern high performance adhesives are designed to offer an optimized balance of elasticity,toughness and plastic deformation capacity for the individual fields of application in e.g. the building and construction or transportation and vehicle industry. The long-term life prediction for adhesive joints based on laboratory tests requiring only days,weeks,or months is still a demanding challenge. Testing in practice is carried out with the intention of accelerating time dependent aging effects that may occur in a bonded joint during its service time. Initial strength values of bonded joints,such as shear or peel properties can often be obtained from the adhesive manufacturers or retrieved from literature. They are useful to compare different adhesives and to demonstrate the effect of parameters such as bond line thickness,overlap length or curing conditions,and,in some cases,the surface state. On the other hand only few data are available describing the mechanical long-term properties of adhesives related to creep and relaxation under static load conditions. Due to the nature of the polymer network of organic adhesives their viscoelastic-plastic deformation behavior is strongly time-and temperature dependent. The objective of this paper is to illustrate effective methods for investigating and predicting the creep and relaxation properties of adhesively bonded joints in the long-term region and for creating basic data for the design and engineering with adhesives.