水煤浆加压气化炉用高铬耐火材料的显微结构及损毁机理

采用扫描电镜和能谱分析方法 ,分析了水煤浆加压气化炉用高铬砖渣蚀前后的显微结构和相组成 ,探讨了主要损毁机理。结果表明 :煤熔渣与砖反应和渗透引起砖组成的改变 ,从而导致砖的结构剥落和强度弱化是砖损毁的主要原因 ;LIRR -HK90砖的显微结构呈网络状镶嵌结构 ,直接结合程度高 ,与渣反应可生成 (Mg ,Fe) (Al,Cr,Fe) 2 O4 复合尖晶石致密带 ,阻止了渣的进一步渗透 ,减缓渣蚀速度和结构剥落 ,其使用效果优于进口的同类产品     

玻璃窑用优质硅砖的相变及损毁机理

分析了残砖各段带的化学成分变化及相组成变化 ,指出硅砖的损毁机理是相变和蚀损。高纯致密的优质硅砖可以提高玻璃窑的使用效率和使用寿命     

气化炉用后高铬砖的渣蚀机理

采用扫描电镜和XRD等分析方法,对石油焦气化炉和水煤浆气化炉用后高铬砖及渣蚀试验砖的显微结构进行了观察与分析。根据高铬砖显微结构变化,研究了在不同气化炉内高铬砖受熔渣侵蚀损毁的机理。结果表明:石油焦气化炉用高铬砖中的Cr2O3与熔渣中的V2O5接触反应,在低温下形成液相而被熔蚀,是其蚀损的主要原因;水煤浆气化炉用高铬砖蚀损的主要原因是Cr2O3在熔渣里的溶解和ZrO2的熔蚀;LIRR-HK95砖由于成分和结构的优化,抗石油焦渣侵蚀性能好。     

使用后铝镁炭砖的显微结构分析

对宝钢电炉盛钢桶用铝镁炭砖使用后的显微组成和结构进行了分析 ,研究了用后铝镁炭砖的相组成和显微结构变化。结果表明 ,铝镁炭砖在使用过程中组成相的烧结反应产物产生的微膨胀使制品结构进一步致密 ,尤其是越靠近工作面 ,尖晶石晶粒尺寸越大 ,最终在工作面与蚀变铝酸钙一起形成致密层 ,有效地减缓和阻止了铁水和熔渣向砖内的侵蚀与渗透。     

Study on Microstructure and Slag Corrosion Mechanism of High Chrome Bricks for Gasifier

1 Introduction The gasifier like Texaco style is of important tech- nical equipment for ammonia synthesis and production of carbamide, carbinol and ethylene etc. Due to differ- ent energy resource structure, petroleum coke is adopt- ed as rawmaterial in A…     

Application Study onβ—Sialon—Al2O3 Brick in Iron Ladle

The microstructure and slag erosion fractal dimension of reaction interface of β-Sialon-Al2O3 brick used in 300 Mt iron ladle of Baosteel have been studied by SEM and XRD.The results indicated that β-Sialon-Al2O3 brick exhibited excellent slag resistance.The main wear mechanism of β-Sialon-Al2O3 brick is mainly from the spalling caused by thermal mechanical stress and attacked by slag secondly.     

AOD炉用白云石砖的使用试验

通过AOD炉用白云石残砖的化学分析和显微结构研究,分析了AOD炉用白云石砖衬炉龄不高的原因,并提出了改进措施。冶炼过程中炉渣碱度低,氧化末期温度高和氩气、氧气、氮气三种气体压力控制不好,形成湍流,加速了风眼区材料的剥落是炉龄不高的主要原因。     

Composition and microstructure of a periclase–composite spinel brick used in the burning zone of a cement rotary kiln

The composition and microstructure of a periclase–composite spinel brick used in the burning zone of a cement rotary kiln were investigated and compared to the original brick. The results indicate that cement clinker and alkali salts are two important agents that cause corrosion especially of the bonding phase of refractories in cement rotary kilns. When the molar ratio of alkalis to anions ((Na+K)/(Cl+2S)) is more than one, alkali salts accumulated in the pores, cracks and grain boundaries of the refractory but the severe corrosion of the bonding phase of the refractory did not occur in zones with lower temperatures. The interaction between the cement clinker and the refractory formed a liquid, which, together with alkali salts, improved sintering. The reaction between the cement clinker and the refractory formed a dense reaction layer. Cracks formed in the dense layer and extended through the boundary between the reaction and non-reaction (penetrated) layers by mechanical and thermal stress, which caused the spalling of the reaction and coating layer from the refractory. The recurrence of this process during service leads to degradation of the refractory.     

粗铜对镁铬砖的侵蚀

以贵溪冶炼厂PS卧式转炉 (15 0t)风口区使用后的残砖为样品 ,用化学分析、物理性能检验、EDAX和SEM等手段进行了分析研究。结果表明 :粗铜对镁铬耐火材料的侵蚀主要表现为渗透 ;粗铜渗透的主要途径为开口气孔 ,也有少量的粗铜沿晶界渗透     

玄武岩熔液对耐火材料的侵蚀

为深入了解玄武岩高温熔体对耐火材料的侵蚀行为,参照ASTM C621—1984(2001)分别对致密氧化铬砖、致密锆英石砖和熔铸锆刚玉砖(AZS-33)进行了1 500℃72 h的玄武岩熔液侵蚀试验,并对侵蚀后试样进行了显微结构对比分析。侵蚀试验结果表明,致密氧化铬砖的抗熔融玄武岩侵蚀性最好,其次是致密锆英石砖,最差的是熔铸AZS-33砖,其在液面线处出现严重剥落现象。显微结构分析表明:致密氧化铬砖结构均匀,与玄武岩熔液反应性小,同时与玄武岩渣中的成分形成尖晶石致密层阻止了渣的进一步渗透;致密锆英石砖表面与玄武岩熔液反应产生很薄的脱锆层和玻璃相,并且其致密均匀的结构也阻止了渣的进一步渗透;熔铸锆刚玉砖的显气孔率虽然很低,对玄武岩熔液有较好的抗渗透性,但其液相量较多,因此抗侵蚀性相对较差。     

Analysis of Spent High Chrome Brick in Slagging Gasifier

Wear of the spent high chrome brick in slagging gasifier was studied.The result shows that erosion and spalling are the main wear mechanism of high chrome brick and the CaO content of coal slag is crucial to wear of high chrome brick.     

Use of dense magnesite-chrome brick in roof of rocking open-hearth furnace

Conclusion The use of dense magnesite-chrome brick for the basic roof of rocking open-hearth furnaces processing high-phosphorous pig irons increase the wear resistance of the roofs by 7–17%, which makes it possible to intensify the operation of the furnaces.The nature of the wear and tear in the dense magnesite-chrome brick in the roof of a rocking furnace does not differ from that of normal magnesite-chrome brick and shows up as the splitting of the working zone.The slighter wear and tear in dense magnesite-chrome brick is due to reduction in the rate of formation of zones on account of retarded migration of the melts into the brick.To increase the wear-resistance of magnesite-chrome roof refractories, they have to be pressed at a greater specific pressure and at optimum grain composition.     

MECHANISM OF STRUCTURE FORMATION IN SELF-PROPAGATING THERMITE REACTIONS: THE CASE OF ALUMINA AS DILUENT

The mechanism of structure formation of the global reaction Fe₂O₃ + 2Al → 2Fe + Al₂O₃ under self-propagating high-temperature synthesis (SHS) conditions in the presence of alumina as diluent is investigated. The reactants in powder form are converted into products by passing through four transformation zones with different structure and composition. Some of the early stages of this reaction are explained on the basis of the mechanism proposed by Korchagin and Podergin (1979). Final products seem to be then formed as a consequence of a crystallization process from a melt. These findings may contribute to improve the manufacturing of wear and corrosion resistant SHS coatings.     

磷酸复杂系统液固相反应动力学(Ⅰ) 分形介质中的扩散与反应机理

采用随机过程理论导出了液相在固体颗粒分形介质中的扩散方程 ,得到了分形扩散系数与自由空间扩散系数的关系式 .同时研究了以磷酸与具有丰富内孔隙的磷矿颗粒为代表的液固两相反应的机理和动力学模型 .发现已反应完毕的区段与尚未反应的区段之间的反应界面不是一个面 ,而是一个过渡区段 ,这一反应区段将逐步向颗粒中心移动 .根据固相物质的分形结构与反应机理 ,导出了描述这一过程的理论模型 .     

Effects of WC particles on microstructure and mechanical properties of 316L steel obtained by laser melting deposition

Stainless steel has many excellent characteristics such as high strength, weldability, corrosion resistance, easy processing and surface gloss. It has been widely applied in many industrial and architectural decoration aspects such as aerospace, chemical, and automotive. However, 316L material manufactured by Laser melting deposition has poor wear resistance and tensile strength. In this paper, WC particles are used as a strengthening phase to make up for these deficiencies of 316L. In order to comprehensively evaluate the effect of WC particles on the mechanical properties of 316L formed by laser melting deposition, 316L samples with different proportions of WC particles and different fabricating directions were prepared. The microstructure of samples was observed, and the phase composition, Vickers hardness, friction and wear properties, tensile properties were analyzed. The mechanism of the influence of WC particles on the structure and the mechanism of friction, wear and tensile fracture were studied. The results show that most of the WC particles are evenly distributed in the coating. The microhardness and wear resistance of the 316L/WC composite coating have been significantly improved with the increase in the proportion of WC. The tensile strength and elongation are the best when the WC mass fraction is 6%.     

LIQUID AND SOLID PHASE REACTION KINETICS OF PHOSPHORIC ACID COMPLEX SYSTEM(Ⅰ) DIFFUSION AND REACTION MECHANISM IN FRACTAL MEDIA

采用随机过程理论导出了液相在固体颗粒分形介质中的扩散方程 ,得到了分形扩散系数与自由空间扩散系数的关系式 .同时研究了以磷酸与具有丰富内孔隙的磷矿颗粒为代表的液固两相反应的机理和动力学模型 .发现已反应完毕的区段与尚未反应的区段之间的反应界面不是一个面 ,而是一个过渡区段 ,这一反应区段将逐步向颗粒中心移动 .根据固相物质的分形结构与反应机理 ,导出了描述这一过程的理论模型 .     

大型干法水泥回转窑过渡带用镁铝尖晶石砖的损毁机理

对5000t.d-1的大型干法水泥回转窑过渡带用后镁铝尖晶石砖(LMLJ-80)分别进行了外观观察及物理性能、XRD、SEM和EDAX等分析,探讨了其损毁机理。研究结果表明:水泥熟料对镁铝尖晶石砖的侵蚀不是其损毁的主要原因,而碱盐的沉积和热震综合作用下的结构剥落和热剥落是过渡带用镁铝尖晶石砖损毁的主要形式。因此,提高镁铝尖晶石砖的韧性和抗剥落性是提高炉衬寿命的重要措施之一。     

炼镍转炉溅渣护炉过程中溅渣层形成机理

对炼镍转炉溅渣护炉期间镁铬残砖溅渣层的化学成分、熔化温度、粘度、物相结构及形成机理进行了研究. 结果表明,溅渣初始砖衬表面形成了以铁氧化物为主的过渡层;炉渣进一步挂结,形成由铁镁橄榄石和磁铁矿构成的粘渣层,其中MgO含量上升至11.01%,半球点温度达1424℃;溅渣后下一炉冶炼过程中,过渡层中铁氧化物通过扩散与镁铬砖作用形成以高铁尖晶石和镁铁固溶体为主的反应层,其中Fe2O3含量由1.33%增至18.43%,半球点温度升高至1598℃. 砖衬单炉损耗率降低近一半,炉龄大幅提高.     

三元硼化物陶瓷涂层的制备及其力学性能研究

笔者采用的是在Q235钢基体表面用固相反应法制备三元硼化物陶瓷涂层,因为固相反应法制备陶瓷消耗的能源少、污染小、工艺简单,相对传统的制备工艺所需成本较低,所以研究固相反应型三元硼化物陶瓷涂层有很高的科学价值和实用价值。笔者采用Fe-B、Mo、Fe、Al、Cr为陶瓷骨料,使用无机粘结剂磷酸二氢铝作为陶瓷涂层的粘结剂来制备三元硼化物陶瓷涂层,对这种制备陶瓷涂层的工艺做基础性的研究。研究主要有:陶瓷涂层配比研究,陶瓷骨料配比,陶瓷骨料与磷酸二氢铝粘结剂最佳配比;固相反应法制备三元硼化物陶瓷涂层工艺:Q235钢基体表面预处理,固化温度,固化工艺等;涂层结构与性能研究:对涂层的致密性、显微组织、相组成、涂层与基体的结合强度、涂层抗热震性能、涂层的耐磨性进行了研究。     

提高焦炉硅砖质量的途径

用X射线衍射仪、偏光显微镜及扫描电子显微镜对焦炉硅砖进行了分析研究。结果表明：原料和矿化剂不同，其显微结构及制品的残余石英和鳞石英的含量不同，而这些差异与制品的物理性能有直接关系，因此要提高焦炉硅砖的物理性能就必须严格控制相组成和微观结构。建议焦炉硅砖的标准中列入残余石英的允许含量及鳞石英的最低含量。