水泥窑用MgO-MgAl2O4-ZrO2-La2O3复合耐火材料的研究

根据耐火材料和水泥熟料的反应机理,找到一种既可阻止窑皮中C2S相变,又不损害镁铝质耐火材料的高温性能的添加物,开发了一种基于MgO-MgAl2O4-ZrO2-La2O3体系的新型复合耐火材料。该材料具有优异的耐火性能、抗热震性能、挂窑皮性能、抗侵蚀性能和较高的机械强度,是一种替代镁铬砖的理想材料,适用于水泥窑烧成带。     

Cr2O3对矾土基喷涂料性能的影响

以铝矾土为主要原料,铝酸钙水泥、硅微粉为结合系统,分别研究了不同添加量的Cr2O3对矾土基喷涂料性能的影响。试样自然干燥24h脱模后,再经110℃烘干24h,分别于1000℃、1300℃和1500℃热处理3h。检测各温度热处理后试样的线变化率、体积密度、抗折强度、耐压强度以及试样的热膨胀系数、耐磨性能和抗热震性能。结果表明,在矾土基喷涂料中添加Cr2O3不利于提高材料的低温和中温强度,但利于提高材料的高温强度;在矾土基喷涂料中添加Cr2O3不能提高材料的耐磨性能;试样中添加Cr2O3后增大了试样的热膨胀系数。添加适量的Cr2O3可提高试样的抗热震性能;过量的添加Cr2O3会对试样的抗热震性产生负面的影响。     

水煤浆加压气化炉用Cr2O3-Al2O3-ZrO2砖的损毁模式

详细分析了陕西渭河煤化工集团有限责任公司的德士古(Texaco)水煤浆加压气化炉用Cr2O3-Al2O3-ZtO2砖的损毁模式及影响因素,并提出了降低耐火砖损毁的方法.认为块状剥落、烧蚀损伤、冲蚀损伤和机械损坏是造成耐火砖损毁的主要原因;提高耐火砖自身的抗侵蚀能力,改善炉衬砌筑结构和炉内工况气氛,控制适当的炉渣特性,以及采用正确的修理维护方法,是提高德士古水煤浆加压气化炉用Cr2O3-Al2O3-ZrO2砖使用寿命的主要途径.经过几年的反复试验和技术改进,特别是采用中钢集团洛阳耐火材料研究院生产的Cr2O3-Al2O3-ZrO2砖后,渭河煤化工集团有限责任公司的德士古水煤浆加压气化炉用Cr2O3-Al2O3-ZrO2砖的使用寿命已从原设计的8000 h提高到现在的23000 h.     

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.     

锆英石对铝铬锆砖抗侵蚀性能及六价铬形成的影响

铝铬锆砖因具有优异的抗渣侵蚀性能,被作为炉衬材料广泛应用于工作环境恶劣的危废焚烧炉。然而,铝铬锆砖在制备和服役过程中可能形成有毒的水溶性Cr(VI),相关研究工作却未见报道。本研究分别以单斜氧化锆和锆英石为氧化锆源制备了两种铝铬锆砖,研究了铝铬锆砖在四种不同组成危废焚烧炉渣中的侵蚀行为及熔渣侵蚀前后砖中Cr(VI)的含量。结果表明,锆英石高温下分解形成单斜氧化锆和无定形的二氧化硅,促进化学稳定性较好的(Al,Cr)₂O₃固溶体的形成,提高了铝铬锆砖的致密化程度,同时改善了铝铬锆砖的抗渣侵蚀性能。此外,生成的二氧化硅可以还原砖中Cr(VI)化合物,降低铝铬锆砖中的Cr(VI)含量。熔渣侵蚀后,铝铬锆砖渗透层中Cr(VI)含量与熔渣成分密切相关。在被高碱性氧化物含量的熔渣侵蚀后,铝铬锆砖渗透层中的Cr(VI)含量较高,但锆英石作为氧化锆源的铝铬锆砖在不同熔渣中侵蚀前后的原砖层和渗透层内的Cr(VI)含量均低于欧盟限制标准。     

PMMA/纳米三氧化二镧复合材料的制备及性能

制备了聚2–甲基–2–丙烯酸甲酯(PMMA)/纳米三氧化二镧(La_2O_3)系列复合材料,对复合材料浇注体板材进行了力学性能、腐蚀性及吸湿率测试。结果表明,表面经PMMA接枝处理后的纳米La_2O_3质量分数为0.3%时,浇铸体复合材料板材的力学性能最佳,冲击强度比纯PMMA板材提高了154.7%,弯曲强度提高了52.0%;当纳米La_2O_3含量为0.5%时,浇铸体板材的耐酸、碱腐蚀性及吸湿性得到明显改善;在实验含量范围内,随着纳米La_2O_3含量的增加,浇铸体板材的邵氏硬度线性上升。得到了性能优异的复合材料浇铸体板材,并总结了浇铸体板材性能得以综合提升的原因。     

化学镀Ni-P-Cr2O3和Ni-P-SiO2复合镀层的研究

本文对化学镀镍及化学镀镍磷基质中SiO2与Cr2O3的共沉积进行了研究.微粒在不断生长的膜层中共沉积引起了新的化学复合镀层的出现,这些复合镀层许多都具有优异的耐磨及耐蚀性能.通过选取镀层合金/复合微粒/金属基体的组分可改进镀层,获得所需的性能,以满足特别的需求.在对这些复合镀层的应用需求正在迫近与增长的同时,其市场正在迅速扩张.本文开发出了一种合适的复合化学镀镍液,并通过维氏硬度法对化学复合镀镍层进行了表征.采用动电位极化及交流阻抗法测定了镀层的Taber耐磨性能及耐蚀性能.采用SEM及XRD对复合镀层的表面形貌进行了分析.     

Cr2O3-ZrO2材料的烧结及抗热震性研究

应用复合覆盖剂方法研究了Cr2O3-ZrO2材料在还原性气氛下的烧结和抗热震性.结果发现Cr2O3-ZrO2材料的烧结完全取决于Cr2O3的烧结;Cr2O3和ZrO2构成复合材料之后,可使其抗热震性明显提高.     

Al2O3陶瓷与金属材料连接的研究进展

Al2O3陶瓷具有优良的高温强度、耐磨和抗腐蚀等性能而被广泛关注,而金属材料具有良好的塑性、导热和导电等性能。Al2O3陶瓷与金属材料的连接是获得这些良好性能的关键技术之一。综述了Al2O3陶瓷与金属材料连接的一般方法和连接技术,同时指出其发展趋势。     

Slag Resistance of Magnesite-chrome Brick Impregnated with Chrome-bearing Sols

Cr2O3 has eminent slag corrosion resistance.So,the magnesite-chrome brick is thought as an important refractory material used in RH refining furnace in the process of steel-making around the world.After chromebearing sots being prepared by sol-gel method,single sol (Cr(OH)3)and mixed sol(Mg(OH)2-Cr(OH)3)were impregnated into magnesite-chrome bricks by vacuum impregnation.The corrosion resistance of the impregnated bricks to silicon steel slag was studied by porosimetric analysis and fiactal dimension calculation.The results showed that the corrosion resistance of impregnated magnesite-chrome brick was better than that of the unimpregnated brick and the brick impregnated by MgSO4 solution,and the one which has surface-treated by Mg(OH)2-Cr(OH)3 sol was the best,mainly because of lower apparent porosity,smaller pores diameter and their smoother inner suoface.     

ZrO2(f)-NiFe2O4惰性阳极在冰晶石熔盐中的腐蚀行为

以NiO和Fe2O3为原料,采用固相烧结法合成了NiFe2O4尖晶石,通过添加ZrO2纤维[ZrO2(f)]制备了ZrO2(f)-NiFe2O4惰性阳极材料. 采用失重法测量了阳极试样在冰晶石熔盐中的静态热腐蚀率和电解腐蚀率,并对腐蚀机理进行了探讨. 结果表明,ZrO2(f)添加量由0增加至4%(w)时,阳极试样的气孔率从4.9%上升到5.8%,导致其静态热腐蚀率由3.8 mg/(cm2×h)增大到4.3 mg/(cm2×h);在电场作用下,氧化物在冰晶石熔盐中的溶解反应受到抑制,含3%(w) ZrO2(f)阳极试样的电解腐蚀率为2.2 mg/(cm2×h),远小于其静态腐蚀率,腐蚀均为物理化学溶解过程;高温下ZrO2(f)在冰晶石熔盐中稳定性良好,可作为铝电解NiFe2O4基惰性阳极的强韧化材料.     

AI2O3溶胶的体积分数对Zn-Ni-AI2O3复合镀层性能的影响

向Zn-Ni合金镀液中加入AI2O3溶胶,获得了Zn-Ni-AI2O3复合镀层。研究了A12O3溶胶的体积分数对镀层的相结构、表面形貌、横截面形貌、显微硬度、耐磨性及耐蚀性的影响。结果表明:当A12O3溶胶的体积分数低于6 mL/L时,不会对镀层的相结构产生影响。但当A12O3溶胶的体积分数较高时,会改变镀层的相结构,并影响镀层的致密性。当AI2O3溶胶的体积分数为6 mL/L时,镀层的耐磨性和耐蚀性均最佳。     

Electrochemical corrosion behavior of chromium-phosphorus coatings electrodeposited from trivalent chromium baths

Chromium-phosphorus (Cr-P) coatings are electrodeposited from trivalent Cr (Cr(III)) baths containing hypophosphite. The electrochemical corrosion behavior of Cr-P coatings, traditional Cr coatings deposited in hexavalent Cr (Cr(VI)) baths, and chromium-carbon (Cr-C) coatings deposited in Cr(III) baths containing formate are studied by measuring potentiodynamic polarization curves in a 10 wt% HCl solution. The composition and morphology of the coating surface layers are investigated by X-ray photoelectron spectrometry (XPS) and scanning electron microscopy (SEM), respectively. The results of electrochemical tests show that Cr-P coatings exhibit better corrosion resistance than traditional Cr and Cr-C coatings, which is characterized by a lower critical current density, lower passive current density, and lager passive potential range. XPS and SEM analyses confirm that the excellent corrosion resistance of Cr-P coatings is attributed to the formation of a phosphide passive film, which has high stability and self-repairing ability, and can act as a “buffer” to reject the penetration of chloride ions.     

Cr2O3-Al2O3-ZrO2高铬制品

介绍了Cr2O3-Al2O3-ZrO2制品的组成及各组成的作用、烧成气氛、制品的显微结构特征和性能指标.着重论述了影响制品性能的烧成工艺和以电熔、烧结两种Cr2O3颗粒生产的Cr2O3-Al2O3-ZrO2制品的显微结构差异,表明在还原气氛下烧成的Cr2O3-Al2O3-ZrO2制品性能优良,而采用电熔Cr2O3料生产的Cr2O3-Al2O3-ZrO2制品性能优于使用烧结Cr2O3料生产的.     

复合电沉积Ni-W-P-CeO_2-Al_2O_3镀层耐蚀性能的研究

采用复合脉冲电沉积法制备Ni-W-P-CeO2-Al2O3复合镀层,研究了该镀层耐蚀性能。实验结果表明：镀层的耐蚀性随着制备温度的升高而明显得到提高,同时随着电流密度的增大,镀层的腐蚀速率降低,耐蚀性能得到提高,升高到一定的程度后,耐蚀性反而降低。随着电沉积时间的延长,镀层的耐蚀性能明显提高,但时间延长到一定程度后,耐蚀性变化不明显。经热处理后,Ni-W-P-CeO2-Al2O3复合镀层耐蚀性均有所提高。     

达克罗技术的绿色特点及代镉镀层的研究

首先简介了达克罗技术涂层结构、发展及应用情况,然后从工艺过程少污染、涂层高性能长寿命和低六价铬溶出量三个方面阐述了达克罗技术的绿色特点,涂层高性能主要指优异的耐蚀性和无氢脆的特性,最后综述了以达克罗涂层取代镀镉层的对比性研究工作。     

Corrosion Resistance of Fused Cr_2O_3-Al_2O_3 Grains with Different Compositions

Six kinds of Cr2O3 Al2O3 fused grains ( the mass percent of Cr2O3 was 15% ,40% ,50% ,60% ,85% and 99% ,respectively) were prepared using chrome green and Al2O3 powder as starting materials by electrofusion,named as CR15,CR40,CR50,CR60,CR85, and CR99,respectively. The corrosion resistance of the six kinds of Cr2O3 Al2O3 fused grains ( 4 1 mm) was studied using rotary slag corrosion method. The results show that: ( 1) the corrosion resistance of the fused grains increases with the Cr2O3 content and the grain size increasing; ( 2) the grains of CR99 and CR85 with higher Cr2O3 content are corroded at the slag surface layer,because FeO and Al2O3 in the slag corrode the grains; FeO reacts with Cr2O3 in the aggregates forming ( Fe,Cr) 3O4 spinel firstly,and the spinel reacts with other phases forming composite spinel; when FeO is fully consumed,Al2O3 penetrated into the grains reacts with Cr2O3 forming Al2O3 Cr2O3 solid solution on the grains surface; ( 3) for CR60,the corrosion exists both in the slag surface layer and in the penetration layer; in the penetration layer,CaO and SiO2 react with Al2O3 in Al2O3 Cr2O3 solid solution forming anorthite, gehlenite, and glass phase; the grains of CR50,CR40 and CR15 have the same corrosion mechanism with CR60 in the penetration layer.     

Investigation of a transparent chromate (III) passive film on electroless Ni–P coating by XPS and electrochemical methods

A transparent passive film on electroless nickel phosphorus coating (ENPC) was obtained in a chromate (Cr³⁺) bath. An ENPC sample passivated in a Cr⁶⁺-containing bath was used for comparison. The corrosion properties were tested by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). SEM, XPS, and EDX were employed to analyze the chemical composition and surface morphology of the films. SEM results indicate that the passive film is too thin to be observed by SEM. The potentiodynamic polarization tests show that the corrosion currents of the two passivated samples are only about 1/25 of the un-passivated coating. The XPS analysis illustrate that the Cr⁶⁺-treated film comprises Cr, Ni and O, while the Cr³⁺-treated film is made up of Cr, C, O, Ni, P and N. High-resolution XPS analysis show that, both in Cr⁶⁺-treated and Cr³⁺-treated films, element Cr is only in the form of trivalent compounds, no hexavalent chromium existing. By XPSpeak analyzing, trivalent chromium compounds on the two treated surfaces were fitted as Cr(OH)₃ and Cr₂O₃. However, for the Cr³⁺ and Cr⁶⁺ passivation routes, the Cr(OH)₃ and Cr₂O₃ contents in passive films are widely divergent.     

TiN改性Al2O3纳米复相陶瓷的研究进展

Al2O3陶瓷具有高硬度、耐高温、耐腐蚀和耐磨损等优点．是应用最广泛的陶瓷之一．但脆性大．难以加工．严重限制了它的应用范围。主要介绍了TiN改性Al2O3纳米陶瓷的研究进展．与SiC、ZrO2改性Al2O3纳米陶瓷相比,TiN—Al2O3纳米复相陶瓷不仅力学性能优异,而且具有导电能力,可用于电火花加工．扩大了Al2O3陶瓷的应用范围。最后对Al2O3纳米复相陶瓷的发展前景作了展望。     

有色金属火法冶炼用耐火材料及其发展动向

根据近些年来有色重金属与轻金属火法冶炼工艺技术的发展,从有色重金属与轻金属火法冶炼条件的特点分析与阐述了所用耐火材料发展的动向,着重介绍了有色金属冶炼炉如:闪速炉、澳斯麦特炉、艾萨炉、诺兰达炉、转炉、连续炼铜炉、氧气底吹熔池直接炼铅炉(QSL炉)、铅锌密闭鼓风炉(ISP炉)、粗锌精馏炉、锌浸出渣挥发回转窑、碱石灰法回转窑、焙烧炉、铝电解槽、铝熔化炉以及硅热还原法制原镁等窑炉关键部位所用的耐火材料。另外,为了给上述冶炼炉的关键部位选择合适的耐火材料,还对一些耐火材料组元的抗FeO-SiO2渣侵蚀,抗炉渣与锍的渗透以及在炉衬工作面形成保护层等方面进行了分析与论述。此外,化学热力学计算与现场试验结果表明,含碳耐火材料不适宜用在重有色金属冶炼炉。还介绍了不同品种的镁铬耐火材料与碳化硅质耐火材料以及Al2O3-Cr2O3-尖晶石材料,并对含Cr2O3耐火材料存在的问题与解决途径做了分析与建议。