钢包壁工作衬用耐火材料

选择钢包内衬用耐火材料时,应主要考虑包衬的使用条件、对钢水纯净度的要求、钢包操作的安全性.以及最佳的单位产品的费用支出.在欧洲大多采用碳质、铝镁碳质及方镁石刚玉碳质耐火材料作钢包工作衬.在钢包及钢包炉中对钢水进行炉外精炼时,则推荐采用镁碳质耐火材料.     

冲击参数对兰新铁路混凝土结构冲蚀磨损的影响

兰新铁路第二双线(新疆段)穿越五大风区,风区地段,强风携带的沙粒对兰新铁路混凝土结构产生严重的冲蚀磨损,造成混凝土结构耐久性的降低.本文针对戈壁风沙流环境特点,采用气流挟沙喷射法,对混凝土结构材料进行冲蚀磨损试验,研究冲击参数(冲蚀速度、角度和时间)对混凝土冲蚀磨损的影响.实验结果表明,混凝土靶材在各冲蚀速度下,90°冲蚀时冲蚀率最高,而30°冲蚀时冲蚀率最低,与传统的脆性材料的冲蚀规律相一致.在不同攻角下,冲蚀速度越大,冲蚀率越高;在低角度冲蚀时,速度指数与传统的脆性材料的冲蚀模型预测值相一致,而在高角度冲蚀时,速度指数偏离了理论预测范围.随着冲蚀时间的延长,混凝土材料的冲蚀率逐渐降低,且冲蚀率开始下降迅速,而后逐渐变缓.     

碳化硅陶瓷的冲蚀磨损机理

采用自主研发的冲蚀磨损试验机,以碳素钢为参照,对碳化硅陶瓷进行冲蚀磨损实验.通过控制冲蚀角度、冲蚀时间和粒子冲蚀速度,测定碳化硅陶瓷的冲蚀磨损量,并借助于SEM对冲蚀磨损后试样的显微结构进行观察.实验结果表明:碳化硅陶瓷体积冲蚀率随角度增大而增大,在90°下达到最大;碳化硅陶瓷的冲蚀磨损机理为:在小角度下主要以切削磨损为主,在大角度下主要以脆性断裂为主.     

烟气轮机叶材高温冲蚀建模及分析

塑性金属的冲蚀磨损是磨粒微切削和变形疲劳磨损的共同作用。建立了一种新的基于微切削和变形磨损的可用于高温环境的冲蚀率模型,采用积分计算了磨粒微切削造成的靶材磨屑体积,依据局部化模型和低周疲劳推导出变形磨损的表达式,分析了冲角和温度对冲蚀磨损率的影响。结果表明:GH864发生最大冲蚀率的冲角在50°左右;GH864的冲蚀率在低冲角(30、50°)下随温度的升高而增加,550℃以后增加缓慢,高冲角(90°)下在常温至400℃间几乎不变,400℃以后大幅减小;温度的升高会增加切削磨损,但减小变形磨损,不同温度下流动应力、动态硬度和临界应变的变化对冲蚀特性影响很大。     

Q235钢基体3Y-TZP/LZAS微晶玻璃梯度涂层冲蚀磨损性能研究

采用涂搪法烧结制备了Q235钢基体3Y-TZP/LZAS微晶玻璃梯度涂层。利用自制的冲蚀磨损试验机,在15°、30°、45°、60°、75°和90°冲蚀角下,控制冲蚀时间,分别对不同层数梯度涂层进行冲蚀,测定体积冲蚀磨损率。通过SEM对冲蚀后的试样表面进行显微结构分析,研究不同冲蚀角度下梯度涂层的冲蚀磨损机制。结果表明:梯度涂层的体积冲蚀磨损率随冲蚀角度增大均呈现出先增大后减小的趋势,并在60°时达到最大值;梯度涂层的抗冲蚀性能随着层数的增加而增强;低角度下的冲蚀机制主要为切削、犁削效应引起的切削磨损,高角度下的冲蚀机制主要为捶击锻打效应引起的脆性断裂,60°冲蚀角下捶击锻打效应和切削、犁削效应都比较强,涂层磨损量最大。     

宝钢120t VOD钢包耐火材料的选择和使用

低碳和超低碳不锈钢在VOD钢包中的脱碳在真空条件下进行,且在钢渣碱度变化的条件下冶炼.由于处理时间长,始终处于高温条件下精炼,因此钢包工作层耐火材料的选择对VOD钢包的使用寿命及不锈钢的质量显得非常重要.     

气固两相流作用下工程玻璃的冲蚀性能及损伤机理研究

根据内蒙古中西部地区风沙环境特征,采用气流挟沙喷射法,通过模拟风沙环境侵蚀实验系统,对比分析冲蚀力学参数对不同特性工程玻璃冲蚀率的影响规律,并结合扫描电镜(SEM)分析其损伤机理.结果表明:钢化玻璃的冲蚀率随冲蚀角度的增加而增大,在90°时达到最大值,表现出脆性材料的特征;有机玻璃的冲蚀率随冲蚀角度增加先增大后减小,在45°处达到最大值,90°时为最小值,表现出半塑性材料的特征.两种玻璃的冲蚀率随沙流量的增加,先迅速减小后趋于平缓;随速度的增加而增加.在高角度冲蚀时,钢化玻璃和有机玻璃冲蚀率和冲蚀速度回归曲线的速度指数较接近,分别为3.94和3.66,均偏离了理论预测的范围.钢化玻璃高角度冲蚀损伤严重,其表面冲蚀损伤机理是与塑性区相关的残余应力,在冲击部位产生横向裂纹,裂纹不断扩展在材料表面交叉引起材料流失;有机玻璃低角度冲蚀磨损严重,其损伤机制主要是微切削作用,损伤程度由材料的硬度控制.     

赛隆结合刚玉滑板的性能及使用

赛隆材料在高温下具有良好的化学稳定性和机械性能,热膨胀系数小,抗热震性、抗侵蚀性和抗氧化能力强,是耐火材料、密封圈、轴承、阀体的理想材料,在切削刀具方面也得到广泛的应用。目前,赛隆结合的碳化硅制品正在用于各种窑炉内衬和高温元件上,尤其是用于高炉炉腹和炉身下部之间的内衬,显示出更大的优越性。赛隆结合的刚玉材料也已用于高炉陶瓷杯和钢包透气砖,但赛隆结合刚玉滑板的使用还没有详细报道。本文主要介绍了赛隆结合刚玉滑板的生产     

Al粉加入量对凝胶粉结合铝镁不烧砖力学性能的影响

以各种粒径的棕刚玉、白刚玉(<0.047 mm)、镁砂细粉和α-Al2O3为主要原料,铝凝胶粉为结合剂,研究了铝粉加入量对精炼钢包铝镁不烧砖线变化率、抗折强度、耐压强度、显气孔率、体积密度和高温抗折强度的影响,并借助XRD和SEM研究了不烧砖的物相组成和显微结构.结果表明:随着铝粉量的增加,借助于塑性相成型,不烧砖烘干后的显气孔率减小、体积密度增大,抗折、耐压强度增大;在热处理过程中,铝粉一方面促进烧结,另一方面由于铝粉被氧化导致体积膨胀,并占主导地位,使得不烧砖显气孔率增大,体积密度减小,强度先增大后减小.高温抗折强度随铝粉加入量的增加而增大.     

改性环氧树脂固体颗粒冲蚀磨损试验研究

采用气流挟沙喷射法对改性环氧树脂材料进行固体颗粒冲蚀磨损试验,考查冲蚀速度和角度对其冲蚀磨损的影响,并探讨了其冲蚀磨损机理,对比了相同冲蚀条件下几种材料冲蚀率的大小。实验结果表明,改性环氧树脂材料冲蚀率与冲蚀速度近似呈线性关系;在不同的冲蚀速度下,改性环氧树脂材料的冲蚀率在45°冲蚀时最大,表现出半塑性材料的冲蚀特征;在相同的冲蚀条件下,改性环氧树脂材料冲蚀率是对比材料(如M30砂浆、水泥石等)冲蚀率的1/16~1/4,适合用作强风沙流环境下混凝土桥梁墩身的防护材料;冲蚀形貌扫描电子显微镜照片表明,冲蚀能量的法向分量使材料表面产生裂纹和破碎,而其切向分量使材料表面产生切削。     

300t精炼钢包温度场和应力场的有限元分析

在目前所用材质体系和砌筑结构的基础上,对精炼过程中的300 t精炼钢包剪切应力场、温度场和热应力场以及膨胀缝的最大接触应力进行了有限元研究.结果表明:在LF精炼过程中,渣线处的内衬砖最容易受冲刷和热应力的作用而损毁,需在保证良好抗渣性能的同时采用热膨胀系数低、抗冲刷性好的耐火内衬砖;膨胀缝的最大接触应力与膨胀缝的大小呈线性反比关系,以保持在0.8～1.8 mm之间为宜.     

Formation of ferrospinel layer at the corroded interface between Al2O3-spinel refractory and molten steel in RH refining ladle

Refining ladle is generally the last inclusion-removal vessel before the continuous casting of steel, so, it has a vital effect on the final steel quality. In this work, degradation process of a cement-free Al₂O₃-MgAl₂O₄ refractory in contact with molten steel/slag in the metal bath area of a Ruhrstahl Heraeus (RH) refining ladle was investigated. A reaction product layer with the formation of ferrospinel (hercynite) and Fe-rich phases was observed, suggesting that the interactions/reactions between the refractory lining and the molten steel should also be considered to have a better understanding of overall degradation mechanism of the refractory served under the RH refining conditions. The two types of alumina grains in the refractory, sintered and fused alumina, were attacked in an active way and a passive way, respectively. The effect of the crack generation and steel infiltration on degradation of the refractory was also discussed in detail, based on the microstructural characterizations.     

Alumina-spinel castable for steel ladles: An overview

Alumina-spinel castable has excellent refractory properties, including high volume and thermal stability, good hot strength, and excellent resistance against corrosion, erosion, and thermal spalling. Excellent refractory properties have made it a preferred lining for steel ladles, reducing the erosion and corrosion of molten metal and slag and improving the ladle life and efficiency for decades. These castables are also significant for the replacement of chrome-bearing refractories that cause several health hazards. The current review paper covers preformed and in situ spinel containing alumina castables. It focuses on the importance of these castables in the sidewall and bottom portion of the steel ladle in detail, the effect of spinel and MgO content, and the factors affecting castable properties. The review also covers the final properties of castable and the application areas of alumina-spinel castable in steel ladle, purging plugs, and RH-degasser.     

250 t钢包底吹氩卷渣和钢液裸露的模拟

针对某钢厂250 t钢包底吹氩气过程进行水模型实验和数值模拟,考察了吹气量和渣层厚度对卷渣行为和吹气量、渣层厚度及透气砖透气性能对钢液裸露面的影响,分析了卷渣形成机理. 结果表明,吹气量对卷渣形成具有决定性作用,吹气量控制在0.96 m3/h(对应实际流量69 m3/h)以下可避免卷渣;随着吹气量的增加,钢液裸露面积逐渐增大,当吹气量达到0.70 m3/h时,钢液裸露面积百分比约达14%,继续增大吹气量,其增加幅度变缓;随着渣层厚度的增加,临界卷渣吹气量和钢液裸露面积逐渐减小,以37 mm(对应实际渣厚150 mm)厚渣层覆盖,可有效防止钢液二次氧化;透气砖堵塞对钢液裸露面积影响较大,顶部钢液形成两不同大小的裸露亮圈,并加重对包壁耐材的冲刷与侵蚀,降低钢的洁净度. 工艺优化后,钢包水口结瘤率降低至0.1%以下,且可降低生产成本.     

MECHANISM OF EROSION OF NOZZLES IN OPEN-HEARTH LADLES*

A detailed report is presented of experiments made with removable nozzle extensions to determine the relative amount of erosion when various types of steel are teemed through (1) regular fire-clay nozzles fired to different temperatures and (2) nozzles of the more refractory types. The mechanism of erosion is discussed. The data indicate the limitation of refractory materials having a P.C.E. of 28 or higher for use in nozzles or as open-hearth ladle brick.     

LF精炼钢包用铝尖晶石浇注料的研制与应用

通过调整富铝尖晶石及镁砂的粒度组成和添加量,优化浇注料的基质组成,使研制的富铝尖晶石浇注料具有优良的抗渣侵蚀性和抗剥落性。该浇注料在首钢第三炼钢厂９０ｔ ＬＦ炉包壁使用,取得了较好的使用效果。     

MgO-Al2O3-C材料服役状态下MgO致密层的形成机理

一种SiC含量为6.0％的MgO-Al2O3-C(MAC)材料被用于精炼钢包包壁部位,表现出优异的抗侵蚀性能,对用后MAC材料的物相组成和显微结构进行分析.结果显示,在MAC材料侵蚀界面形成MgO致密层,提高了MAC材料的抗侵蚀性能.MAC材料内的SiC,一方面与MgO反应形成更多的Mg(g);另一方面,SiC氧化后形成的部分SiO2进入侵蚀层熔渣使熔渣碱度下降,粘度大幅上升,不但提高了MgO在熔渣中的形成速率,而且同时降低了MgO的溶解速率,促进MgO再结晶和MgO致密层的形成.     

精炼条件对狭缝式透气砖使用效果的影响

对狭缝式透气砖在大型精炼钢包中的损毁原因进行了分析,热应力和强大的冲刷磨损作用是两个主要因素.对狭缝式透气砖使用中影响其透气性能的各种因素加以分析后认为,除了透气砖本身狭缝的尺寸、钢水温度、钢水种类外,操作过程和使用中受保护的程度也是影响透气性能的重要因素.     

Ladle service under the conditions of vacuum-oxygen decarburization

The Izhstal plant has created a technology for treating corrosion-resistant steel by the method of VOD in a 30-ton ladle. The lining of the ladle is made of periclase-chromite refractories produced by the Magnezit Works JSC. The effect of the process parameters and lining patterns on the endurance of the ladle was studied in development of the process. The main factors determining the wear of the functional layer of the lining are the density of its joints, the composition of the slag of the refining period, the intensity of the mixing, and the thermal regime of the ladle between the heats. The pattern of the lining has been improved by reinforcing the slag line. The mixing regimes and the composition of the killing mixture have been improved where the consumption of lime and the proportion of aluminum to silicon are concerned. These measures have increased the endurance of the ladles by a factor of 2.2 and that of the refractory roofs by a factor of 2.5. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 5, pp. 41–43, May, 2000.     

Progress and Developing Trend of Purging Plugs for Refining Ladle

Damage reasons of purging plugs for refining ladle and research progress on thermal shock resistance of corundum- spinel purging plugs were summarized. Research achievements and application results of nonoxides bonded corundum purging plugs for refining ladle were briefly reviewed. The further research and developing trend of purging plugs was proposed.