氮化硅对刚玉质高炉喷补料抗渣性能的影响

以板状刚玉为原料,纯铝酸钙水泥和SiO2微粉为结合剂,制成刚玉质高炉喷补料的坩埚试样,然后在还原气氛中于1550℃3h进行抗高炉渣的侵蚀试验,研究了氮化硅加入量(分别为0、5%和10%)对刚玉质高炉喷补料的抗渣侵蚀性能的影响,通过对侵蚀试样的微观分析,得出了渣侵蚀机理。结果表明:刚玉喷补料中不加氮化硅时,渣很容易侵蚀喷补料,而加入5%和10%的氮化硅后,改善了喷补料的抗渣渗透性,大大提高了其抗渣能力;氮化硅在喷补料基质中呈网状结构,这也是提高喷补料抗渣侵蚀能力的主要原因。     

高炉用铝碳化硅质喷补料的研制

以电熔刚玉、碳化硅、蓝晶石、硅微粉、铝微粉和纯铝酸钙水泥等为原料,添加增粘剂、减水剂、抗氧化剂等,研究了铝微粉和蓝晶石的加入对高炉喷补料性能的影响;并通过SEM对高温烧成后的试样进行微观分析.结果表明:Al2O3微粉加入,提高了喷补料的粘塑性,这有利于提高喷补料施工时的附着率;其次,铝微粉的加入有利于硅微粉与Al2O3反应生成莫来石,提高了喷补料内部的结合强度,增强了喷补料的体积稳定性能和抗渣侵蚀能力.而蓝晶石的加入,作为晶核也促进了莫来石的形成,使材料的热震稳定性能和抗侵蚀能力进一步提高.     

SiC结合刚玉材料的抗高炉渣侵蚀性

采用电熔刚玉、Si粉和SiC粉为原料,用酚醛树脂做结合剂,混练成型后于1 450℃埋炭烧成,采用静态坩埚抗渣试验研究了烧后试样对碱度为1.1的高炉渣在1 500℃的抗渣侵蚀性。结果表明:Si与C、CO在高温下原位反应生成纤维状SiC,形成原位SiC结合刚玉材料,该材料具有良好的抗侵蚀性能,渣蚀厚度都在2.6mm以下,其中,加入8%(w)Si粉和5%(w)SiC粉的试样抗渣侵蚀性最好。通过对抗侵蚀后试样的侵蚀层、渗透层和未变层的相组成和显微结构的分析认为:(1)这种复合材料抗渣侵蚀性能良好的主要原因是熔渣难润湿的SiC自身抗渣侵蚀性较好,且原位生成的纤维状SiC穿插在刚玉骨架结构的空隙中,阻挡了熔渣的侵蚀和渗透;(2)熔渣侵蚀材料的过程是SiC先被氧化,然后其氧化产物SiO2与熔渣中的CaO和SiO2以及材料基质中的A l2O3反应生成钙长石低熔相。     

不同气相组成下高炉喷补料的抗CO侵蚀能力

研究了高炉用高铝喷补料在纯CO和混合气相95%CO 5%H2(以体积分数计,下同)两种气相组成条件下的抗CO侵蚀能力,并分析探讨了采用混合气相作为侵蚀介质检测耐火材料抗CO侵蚀能力的可行性。结果表明:添加H2促进了CO对喷补料的侵蚀;在两种气相条件下,侵蚀反应生成的沉积碳的结构是相同的,而试样的气孔率和质量随侵蚀时间的延长变化微弱,耐压强度降低明显;同一试样在95%CO 5%H2气相中反应24h与在纯CO中反应200h取得相似的结果。因此,可以用95%CO 5%H2代替纯CO进行耐火材料抗CO侵蚀能力检测,以缩短检测时间。     

SiC/SiAlON对原位SiC结合刚玉材料抗侵蚀性的影响

采用矾土基高铝刚玉为骨料,以电熔刚玉细粉、Si粉、SiC粉或SiAlON粉为基质料,用酚醛树脂为结合剂,试样于1450℃埋炭烧成后,制备了烧结良好的原位SiC结合刚玉复合材料;采用静态坩埚法研究了加入SiC或SiAlON对这种复合材料抗渣性的影响.结果表明:原位SiC结合刚玉材料具有良好的抗侵蚀性能,加入适量SiC或SiAlON后复合材料的抗侵蚀性进一步提高;原位SiC结合刚玉基材料抗侵蚀行为和机理为:熔渣侵蚀材料的过程是SiC和SiAlON等非氧化物先被氧化,然后其氧化产物SiO2和Al2O3与熔渣中的CaO和Al2O3以及材料基质中的Al2O3反应生成钙长石,材料被侵蚀;原位生成的SiC难被熔渣润湿,且填充在气孔中,堵塞了熔渣渗透的主要通道;加入SiC和SiAlON,材料中非氧化物的量明显增多,因此抗侵蚀性明显提高.     

高钛金属化球团熔分用电炉炉衬材质探讨

针对攀钢高钛金属化球团熔分用电炉的工况条件,选择炭砖及七种含碳耐火材料作为研究对象,借助热力学计算和动态抗渣试验探讨应用这些材料的可行性.结果表明,在不考虑氧化的前提下镁质或铝质耐火材料中引入高含量C和SiC组分有利于提高其抗熔分渣侵蚀能力;综合考虑认为,引入高SiC含量的镁碳化硅碳材料或铝碳化硅碳材料是高钛金属化球团熔分用电炉炉衬的最佳候选.     

引入SiC提高中间包镁质挡渣墙高温使用性能

通过对引入SiC的镁质挡渣墙理化指标检测和用后残砖分析,认为引入SiC能够很好地改善镁质中间包挡渣墙高温体积稳定性和抗侵蚀性,减少挡渣墙使用中出现的断裂和侵蚀问题,提高镁质挡渣墙在高温钢水中的使用性能。     

电站锅炉用SiC质耐火材料抗渣性的研究

以SiC粉和Al2O3粉为主要原料,分别添加5%(质量分数,下同)的ZrO2粉或锆英石粉和5%、10%的Cr2O3粉以及4%的羧甲基纤维素(CMC),按照配料组成配料后,以成型压力为20 MPa制成40 mm×40 mm×30 mm的试样.试样经120℃干燥8 h后,置于硅钼棒炉中.于1 420 ℃保温5 h烧成后,分别采用经900℃保温2 h处理后的粉煤灰在1 400和1 450 ℃下进行抗侵蚀试验.结果表明:SiC质材料随着温度的升高,抵抗灰渣侵蚀能力不断下降,在1 400 ℃时的抗渣性明显优于1 450 ℃时的;在SiC质材料中分别加入5%的ZrO2或锆英石,前者的抗渣性能强于后者;含Cr2O3为10%的SiC质材料比含5%Cr2O3的具有更好的抗渣性.     

MgO-SiC-C材料的抗渣性能研究

以电熔镁砂、碳化硅、鳞片石墨(w(C)>97%)、铝粉(≤0.088mm,w(Al)>98%)和硅粉(≤0.088mm,w(Si)>98%)为主要原料,按w(电熔镁砂)=81%,w(SiC)=10%,w(鳞片石墨)=4%,w(铝粉 硅粉)=5%的组成配料,以酚醛树脂为结合剂,压制成125mm×25mm×25mm的MgO-SiC-C试样,在220℃干燥24h后采用感应炉法进行了抗转炉终渣试验,并对抗渣试验后试样进行了XRD、SEM和EDAX分析。结果发现熔渣对MgO-SiC-C试样的侵蚀和渗透并不显著,试样的侵蚀速率为0.25~0.3mm·h-1;抗渣试验后试样原质层主要组成为MgO、SiC和MgO·Al2O3;在与熔渣接触后,SiC被氧化成SiO2,由此导致在试样和熔渣间形成一高粘度的液相反应层,有效地减轻了试样受熔渣渗透和侵蚀的程度,提高了试样的抗渣能力。     

高炉喷补料在不同气相条件下的抗CO侵蚀性能研究

对同一高炉喷补料在纯CO和95%CO 5%H2混合气相中进行了抗CO侵蚀对比试验,并初步分析了侵蚀机理。结果表明,添加5%的氢气促进了CO对喷补料的侵蚀;在两种气相条件下,经X射线衍射分析因侵蚀反应生成的沉积碳的结构是相同的,而试样的气孔率随侵蚀时间的延长变化微弱,耐压强度显著降低。     

A basic gunning material interfaces study

Corrosion mechanisms of various basic gunning materials were investigated using crucible tests. The low corrosion resistance of olivine-containing materials was shown to be related to melted phases formation which occurs, at the gunning material/slag interface, at high temperature. MgO-rich materials are more resistant to basic slag attack. Moreover, increasing the refractory material CaO content by means of dolomite addition rises the slag penetration resistance and lowers the bulk modification resulting from slag interaction. In these materials, the corrosion mechanism involves a slag reaction with the starting binder, (NaPO₃)_n, and dolomite initially contained in the gunning material. A dolomite-containing material was projected on slag-covered MgO-C bricks, using a laboratory test equipment. Investigations carried out at the gunned material/slag/bricks interface show that the suitable silicophosphate bond still forms, at interface, despite slag interaction.     

Al_2O_3－SiC－C质浇注料抗热震性和抗渣铁侵蚀性的研究

对新研制的Ａｌ２Ｏ３－ＳｉＣ－Ｃ质浇注料和现用出铁沟料的抗热震性和抗渣铁侵蚀性进行了研究、结果表明，该材料具有较高的抗渣铁侵蚀能力和较好的抗热震稳定性。调节Ｓｉ与Ｃ的比例可生成高强度、耐渣蚀的纤维状ＳｉＣ。     

冲天炉炉缸用Al2O3-SiC-C质捣打料的研制

研究了酚醛树脂对冲天炉炉缸用Al2O3-SiC-C质捣打料保存期和施工性能的影响,分析了SiC加入量对材料抗氧化性和抗侵蚀性的影响及作用机理.结果表明加入6%的热塑性酚醛树脂作为结合剂,加入3%的热固性酚醛树脂作为硬化剂时,可使材料同时具有良好的施工性能、烘烤强度和满意的保存期;SiC在高温下发生的氧化-还原反应的最终产物SiO2增加了材料表层的粘度,堵塞了材料表面的气孔,这是SiC能够提高材料抗氧化性和抗侵蚀性的主要原因.     

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.     

高炉出铁沟喷补料实验室研制

以一级矾土熟料和碳化硅为主要原料 ,配以适量的碳质材料、复合添加剂等 ,研制出适用于中小型高炉出铁沟的快速修补用喷补料。试验结果表明 ,该料具有附着率高、粘接强度大、耐侵蚀、耐冲刷、热震稳定性好等特点     

Effect of carbon black on corrosion resistance of Al2O3–SiC–C castables to SiO2–MgO slag

Metallurgical solid waste recycling is the shape of things to come in green development of Chinese iron and steel industry. Utilization of ironworks slag for producing mineral wool at high temperature is an important approach. However, refractory lining is seriously corroded by the SiO₂–MgO based slag at 1600 °C during the production process. Different production steps need different atmospheres, the changeable service atmospheres (air and reducing atmosphere) put forward high requirements for slag resistance. The Al₂O₃–SiC–C castables containing carbon black are usually used in iron runner, which faces high-temperature service condition of 1450 °C–1500 °C. Nevertheless, the function of carbon black in the Al₂O₃–SiC–C castables at 1600 °C is till essentially unknown. In the current study, the carbon black was introduced to tabular alumina based Al₂O₃–SiC–C castables to improve corrosion resistance to SiO₂–MgO based slag at 1600 °C. The result showed that 0.4 wt% carbon black was suitable for the castables, which the slag resistance of castables was significantly improved. The carbon black had contributed to block slag by wettability resistance. By comparison with the castables without carbon black, the corrosion index and penetration index had been reduced by 20.2% and 28.0%, respectively, under air atmosphere. And there were little corrosion or penetration under reducing atmosphere for castables with 0.4 wt% carbon black. For the mechanical properties, the Al₂O₃–SiC–C castables with 0.4 wt% carbon black could serve production process although the carbon black impaired the physical properties.     

Rheological and Adhesive Behavior of Gunning Mix for Blast Furnace Repair

The aim of this experimental work was to investigate the theological and adhesive performance of gunning mix suspensions.The results of rheological tests indicate that:the rheological curve of gunning mix bonded by high-alumina cement(HACG) is Bingham type;the rheological curve of low cement gunning mix(LCG) bonded by microsilica is characterized by pseudo-plasticity fluid with yielding stress;and the rheological property of low-cement gunning mix bonded by microsilica is proved to be better than that of gunning mix bonded by cement.Meanwhile as indicated by the adhesive teste;the better the rheological properties of gunning mix suspension,the better the repair effect would be.     

Preparation of SiC coated graphite flake with much improved performance via a molten salt shielded method

Oxide-based castables have been used in high-temperature furnace linings, especially for steel and iron processing, however, the poor thermal shock resistance and corrosion resistance limited the further enhancement of their service life. Carbon possesses excellent performances including low wettability to slag, low thermal expansion coefficient, which can greatly improve thermal shock resistance and slag resistance of oxide-based castables. However, it has poor water-wettability and oxidation resistance, which limited its application in the castables. Many efforts have been attempted to improve water-wettability of graphite flake used for carbon-containing castables, but it is still a huge challenge. In this work, a facile method for fabricating silicon carbide (SiC) coated graphite flakes has been firstly proposed by using graphite flake and silicon powder as the precursors via a molten salt shielded synthesis technique in air atmosphere, KCl was chosen to be a salt encapsulation providing a liquid reaction medium and a shield against oxidation of air. Effects of firing temperature, holding time, and molar ratio of Si and graphite flake on the formation of SiC coatings were investigated. The results show that the as-prepared SiC coated graphite powders were loose and non-agglomerated, and the coatings with ∼5 μm in thickness were crack-free and firmly grown on the surface of graphite flake, composed of SiC nanosized particles. Compared to uncoated graphite flake, the SiC coated graphite possessed significantly improved water-wettability, dispersibility, and oxidation resistance, making it to be a prime carbon form for fabricating carbon-containing castables.     

机械飞轮基体电泳沉积SiC涂层的研究

使用电泳技术在机械飞轮用30CrMo钢表面制备了SiC涂层,并研究了SiC的质量浓度对SiC涂层的厚度、表面形貌、硬度及耐蚀性的影响。结果表明:增加SiC的质量浓度有利于提高SiC涂层的厚度、硬度及耐蚀性。当SiC的质量浓度为35 g/L时,团聚作用和界面效应使得SiC涂层的厚度明显减小,表面裂纹增多,导致SiC涂层的硬度及耐蚀性大大降低。在SiC的质量浓度为30 g/L的条件下电泳沉积的SiC涂层具有最佳的硬度和耐蚀性。