硅微粉对铝镁浇注料的性能影响

铝镁浇注料具有优良的高温强度、抗蠕变性、抗热震性和较高的使用温度,其抗碱性渣的能力较强,广泛应用于钢包包壁.硅微粉对铝镁浇注料性能影响较大,本文通过在铝镁浇注料中变化硅微粉含量,分析了硅微粉对铝镁浇注料性能的影响.研究结果表明:铝镁浇注料在1773 K及1373 K热处理条件下,随着硅微粉含量的增加,试样体积密度及耐压抗折强度呈现先增大后减小趋势,显气孔率呈现先减小后增大趋势;加入5％硅微粉的试样线膨胀系数比4％试样的大,1773 K热处理的线膨胀系数比1373 K热处理试样的大,在低于873 K情况下铝镁浇注料导热系数随硅微粉含量增加而增加.综合考虑铝镁浇注料在钢包使用过程中各方面的性能要求,在现有颗粒级配工艺下,硅微粉含量较为合适的配比值为3％～4％.     

微粉对抗铝浇注料性能的影响

本文主要讨论了硅微粉及α-Al2O3微粉对抗铝浇注料施工性能、成型性能及强度的影响.结果表明:(1)基质中单独引入硅微粉时,随着硅微粉加入量的增加,抗铝浇注料的用水量减少,施工性能得到改善;随着硅微粉含量增加,试样的体积密度逐渐上升,烘干及烧后高温烧后强度升高,烧后线变化逐渐下降;(2)基质中引入硅微粉和α-Al2 O3的复合粉,随着二者比例的增加,抗铝浇注料的性能不断得到改善;本试验中,当基质中硅微粉占4％,α-Al2O3占1％,此时加水量、成型性能、强度、线变化率最优.     

养护温度对铝酸钙水泥结合刚玉质浇注料中温性能的影响

为了研究养护温度对铝酸钙水泥结合刚玉质浇注料中温性能的影响,将制得的浇注料分别在5、10、25、40和50℃养护,110℃烘24 h后分别于800和1 100℃热处理,检测其显气孔率、常温抗折强度和常温耐压强度,并分析了相同条件处理的基质试样的物相组成以及养护温度对浇注料中温强度影响的原因。结果表明:随养护温度的升高,铝酸钙水泥水化程度增加,促进水化产物均匀分布,使水化产物分解后与Al_2O_3反应原位生成CA、CA_2的量增加,因而增强了浇注料的中温强度。     

硅微粉对ρ-Al2O3结合莫来石浇注料的影响

以各种粒度烧结莫来石做骨料,以棕刚玉细粉和氧化铝微粉为基质,以ρ-Al2O3微粉为结合剂,制备了莫来石浇注料,研究了不同硅微粉加入量对浇注料性能的影响,并借助XRD、SEM等对其物相和显微结构进行检测.结果表明:随着硅微粉量的增大,浇注料强度呈现先升高后降低的变化规律,高温抗折强度在硅微粉加入量为6％时达到极值.主要原因在于:硅微粉加入适量能形成液相促进烧结,并在基质中形成较多莫来石,提高了高温强度;硅微粉加入过多时,产生过烧结,在试样中产生大量液相并形成较多裂纹,又使得高温抗折强度降低.     

MgO-SiO2-H2O凝胶结合MgO浇注料的水化行为

虽然高性能耐火浇注料在先进炼钢中扮演着重要角色,然而镁质浇注料却没有被广泛使用. 其中一个首要的问题是MgO水化过程中水镁石的生成会导致体积膨胀和随之而来的开裂,通常被称为"熟化". 为了克服这些问题,开发了一种基于MgO-SiO2-H2 O结合的无水泥MgO浇注料的新特色产品( SioxX-Mag). 本文进行了系统的工作以弄清MgO水化和制备出无裂纹MgO浇注. 将SioxX-Mag和硅微粉配合,可以抑制水镁石生成产生的裂纹,也可以研制出干燥后无裂纹的大型预制块. 用XRD技术对干燥过程中水化后取自大型预制块内部的试样进行了研究. 结果表明,对于MgO浇注料,硅微粉是一种有效的抗水化添加剂. 当硅微粉为8%时,MgO的水化被抑制,也观察不到水镁石相,而且能制备出无裂纹的大型MgO浇注料预制块. 当硅微粉较少时(如6%) ,干燥过程中会生成水镁石,而且预制块中可以观察到裂纹.     

含硅微粉的低水泥镁铝尖晶石浇注料的流变行为和性能

研究了低水泥镁铝尖晶石浇注料的流变行为,并分析了硅微粉对浇注料力学和物理性能的作用和影响,同时还研究了它的抗渣渗透性。结果显示,在110℃和1500℃时,体积密度随着硅微粉含量增加而增大。硅微粉的粒度分布和颗粒形状及其含量影响了浇注料的流变行为和性能。     

刚玉莫来石复相陶瓷热震及蠕变性能的影响因素分析

采用正交设计方法研究了硅微粉、氧化铝微粉及烧成温度对刚玉莫来石复相陶瓷热震稳定性及蠕变性能的影响机制。结果表明:烧结温度对复相陶瓷热震稳定性及蠕变性的影响最大,氧化铝微粉次之,硅微粉最小。高温抗折强度损失率在烧成温度为1650℃时最低,随氧化铝的含量增加而减小,并随硅微粉含量增加而增大。蠕变率随烧成温度的提高而减少,氧化铝质量分数为7%时最低,并随硅微粉含量增加而增大。通过调节硅微粉、氧化铝微粉及烧结温度,可控制颗粒与基质、莫来石的结合状态,气孔及残留α-Al2O3,从而改善材料的抗热震性及蠕变性。     

硅微粉pH值对高铝质低水泥浇注料性能的影响

研究了硅微粉pH值、草酸和柠檬酸对高铝质低水泥浇注料的流动性、硬化时间和常温力学性能的影响.结果表明,硅微粉pH值在5.5～8.5之间,高铝质低水泥浇注料可以获得良好的流动性;随着硅微粉pH值的增大,浇注料的硬化时间缩短;当硅微粉呈弱碱性时,浇注料强度最好.草酸和柠檬酸的加入对浇注料的流动性影响不显著,但会明显延长硬化时间,减弱流动值的衰减,延长可施工时间,其中柠檬酸的效果比草酸显著;酸性物质的加入降低了浇注料110℃的强度,而1 100℃的强度则有所提高.     

水泥窑用耐碱浇注料的性能研究

本研究中以建筑陶瓷为主要原料制备耐碱浇注料,重点研究了铝酸钙水泥和硅微粉对耐碱浇注料性能的影响,并对试样的显微结构进行了分析。试验结果表明:铝酸钙水泥加入量的增加有助于110℃,24 h处理后常温强度的提高,而在10100℃,3 h处理条件下,铝酸钙水泥加入量的增加会提高基质中生成的液相,加入量在一定范围内使强度出现先增加后降低的趋势,同时也导致了线变化率的增加,在试验条件下铝酸钙水泥的合适加入量在7%~8%左右;耐碱浇注料中加入活性较高的硅微粉能够提高试样的强度和致密度,其加入量增加也会导致试样线变化率的增加,综合分析硅微粉的加入量以5%~6%为宜;经1100℃,3h处理后的试样中骨料和基质结合牢固,基质中存在莫来石化和低共熔物生成的双重反应。     

高纯二氧化硅微粉含量对Al2O3-SiC-C铁沟渣线浇注料性能的影响

以棕刚玉颗粒(15～8 mm,8～5 mm,5～3 mm,3～1 mm),板状烧结刚玉(1～0 mm),碳化硅(3～1 mm,≤1 mm,≤0.063 mm)、白刚玉粉,活性氧化铝微粉和高纯二氧化硅微粉以及单质硅粉和球状沥青等为主要原料,制备了出铁沟渣线用Al2 O3-SiC-C质浇注料,并研究了高纯硅微粉含量对其流动性及高温使用性能的影响.结果表明:随高纯硅微粉含量的增加,浇注料的初始流动性基本呈增加趋势,且其流动值的保持时间延长.随高纯硅微粉含量的增加,浇注料的热态抗折强度呈增加趋势,且抗侵蚀性也会增强.     

M- S-H formation in MgO-SiO2slurries via wet milling for magnesia based castables

It is believed that the formation of hydration phase, MgO-SiO₂-H₂O (M-S-H), contributes to good workability and reliable comprehensive properties for magnesia based castables. In order to stimulate the formation of M-S-H in magnesia based castables and understand the minimum introduction of microslica amount, wet milling process was used to promote the dissolution of MgO and SiO₂ in this work. The slurry containing different content of microsilica with wet milling technology and the castables with/without wet milling slurry were prepared. The effects of microsilica content on the formation of hydration phases were analyzed by XRD, FT-IR and TG/DSC and the properties of magnesia based castables were evaluated by explosion resistance, CMOR, HMOR and so on. The results showed that the formation of M-S-H was accelerated because of the dissolution of Mg²⁺ and HSiO₃^? in wet milling process. Higher amount of M-S-H led to a tight bonding in the early stage, and a denser structure after firing at high temperature due to the limited formation of brucite and in-situ formation of evenly distributed forsterite phase. In addition, much higher HMOR were obtained when less microsilica was added, attributing to the suppressed formation of low-melting-point liquid. Therefore, 2–3 wt% microsilica addition was recommended in this process.     

Rheological behavior as influenced by plasticizers and hydration kinetics

In the calcium aluminates cement - Portland cement - calcium sulfate based self leveling underlayments, the influence of raw materials on the properties such as rheology and hydration kinetics was considered. It was confirmed that calcium aluminates cement system formulation is suitable in cases where a short open time is required, and Portland cement system formulation is suitable in cases where a long open time is required with the result of flowability or rheology. And, in order to thin the viscosity of slurry, it turned out that the application of MF 2651F as a plasticizer and tartaric acid as a retarder were effective. Moreover, MF 2651F seldom delayed the hydration reaction compared with other plasticizers. The flow value and the yield stress showed correlation, without being dependent on the difference in formulation or a water powder ratio. This was considered to be because for the yield stress to relate to the fragility of the aggregation structure of slurry.     

不同二氧化硅微粉对矾土基低水泥浇注料性能的影响

研究了4种理化性能不同的二氧化硅微粉对矾土基低水泥浇注料流动性、抗热震性和高温抗折强度的影响。结果表明:加入纯度高,杂质含量少,颗粒分布均匀、集中,表面光滑,自身流动性好的二氧化硅微粉,则浇注料的流动性好,抗热震性好,高温抗折强度高;加入碳和碱金属含量高,颗粒粒度偏粗,表面粗糙,自身分散性差的二氧化硅微粉,则浇注料流动性差,抗热震性差,高温抗折强度低。     

Hydration mechanism and sintering characteristics of hydratable alumina with microsilica addition

Hydratable alumina is potential for the application in refractory industry as one of Ca-free binders, but it is greatly limited because of the excess hydration of rho-alumina (ρ-Al₂O₃). In this study, hydration mechanism and sintering characteristics of hydratable alumina with different microsilica addition are researched, via the rheological, hydration, and morphological characteristics of ρ-Al₂O₃–SiO₂–H₂O system during aging are analyzed using various techniques. Boehmite (AlOOH) initially appears and increases in content after 1 h aging at the setting temperature of 30 °C and relative humidity of 80%. As the addition of microsilica increases from 0 wt% to 8 wt%, the SiO₂ coating combines with the boehmite gel and efficiently suppresses the hydration reaction, resulting in decrease of relative hydrated densities from 5.42% to 4.27% and increase of zeta potential from −10.1 mV to −21.3 mV. Further, the thus-formed SiO₂-AlOOH gels cover the surface of hydratable alumina particles, connect with each other, and get distributed homogeneously around hydratable alumina particles to harden, thus inhibiting the further hydration. This is reflected by the high-temperature X-ray diffraction and the final sintering microstructures. Overall, these results indicate that the 6 wt% addition of microsilica makes hydratable alumina promising for application as a kind of controlled binders.     

氧化锆喷雾造粒料浆的制备

为了制备出流动性和稳定性好的喷雾造粒料浆,研究了分散剂三聚磷酸钠、六偏磷酸钠、聚丙烯酸铵和PEG2000对氧化锆喷雾造粒料浆流变特性的影响,认为聚丙烯酸铵对于氧化锆料浆具有较好的分散效果。在此基础上采用正交试验设计,以料浆的平均黏度和沉降度为评价指标,对料浆固含量、结合剂PVA和分散剂聚丙烯酸铵加入比例进行了优选,选用料浆固含量(w)为85%、结合剂PVA加入量(w)为8%、分散剂聚丙烯酸铵加入量(w)为0.5%,制备了综合性能较好的氧化锆料浆,利用此料浆获得了较好的喷雾造粒效果。     

纳米SiO2对氧化镁激发矿渣材料性能的影响试验研究

为改善MgO-激发矿渣材料(MASM)力学性能,利用纳米SiO₂(NS)促进MASM的强度发展,研究了不同NS掺量对MASM凝结时间、抗压强度、水化历程、水化产物和微观形貌的影响,分析并揭示了NS的作用机理。研究结果表明:随着NS掺量的增大,MASM凝结时间逐渐缩短,流动度逐渐减小;NS掺量越大,矿渣水化越快,主要水化峰出现越早,峰值越高。NS不仅促进了MgO的反应和C-(A)-S-H的形成,还提高了MASM的结构密实性。掺入1%~2%(质量分数)的NS,可将MASM的抗压强度分别提高7.12%~33.37%(3 d)、12.44%~26.29%(7 d)、12.49%~31.09%(28 d)。     

碱激发碳酸盐-矿渣复合灌浆材料的工作性能

在碱激发碳酸盐-矿渣复合灌浆材料试验研究中引入浆液Marsh时间与Mini扩展度试验方法,以表征浆液的表观粘度和屈服应力,并结合传统的凝胶时间试验方法,综合研究了不同配方浆液的工作性能.结果表明:硅酸钠溶液浓度和矿渣掺量对浆液工作性能的影响相似,其值增大,浆液凝胶时间缩短,Marsh时间延长,扩展度减小,即浆液的表观粘度和屈服应力随之增大,并且发现其将随时间而进一步显著增大,说明浆液保持良好流动性的时间缩短.硅酸钠溶液模数或缓凝剂掺量增加时,浆液凝胶时间延长,且保持良好流动性的时间增加,但其起始表观粘度和屈服应力变化不大.     

聚合铝改性再生胶凝材料力学性质与微结构

采用800℃脱水净浆模拟废弃混凝土中的胶质组分,与矿渣粉复合制成再生胶凝材料,以聚合氯化铝为添加剂,采用抗压强度测试、XRD分析、TG-DSC分析、扫描电镜等方法研究了再生胶凝材料的水化产物微结构和砂浆力学性能,对再生胶凝材料的水化过程及聚合氯化铝的作用机理进行了分析研究.结果表明掺加2%聚合氯化铝后,生成新的水化产物Friedel盐,胶凝材料水化产物数量增加,水泥浆与砂的粘结界面密实程度提高.     

Improvement in nano-pattern replication of injection molding by polyamide/dendrimer blend

In general, lower viscosity of materials leads to desirable nano-pattern replication characteristics in injection molding processes. However, such materials do not meet the properties required for manufacturable products owing to their poor mechanical properties. In this study, we blended a small amount of dendrimer with high-viscosity polyamide 6 to lower viscosity and enhance flowability of the polymer blend while maintaining desirable mechanical properties. It was observed that the flowability of the polyamide 6/dendrimer blend increased significantly with an increase in dendrimer content without affecting the mechanical properties of high-viscosity polyamide 6. To investigate the nano-pattern replication characteristics of the blend, injection molding process and the mold of metal stamp were used to manufacture a nano-pattern specimen. Blending more than 0.6 wt% of dendrimer with high-viscosity polyamide 6 significantly improved its nano-pattern replication characteristics and flowability.     

SiO_2微粉结合镁质浇注料的基质组成与抗渣性能

借助XRD、SEM和相图分析对SiO2 微粉结合镁质浇注料的基质组成与抗渣性能的关系进行了研究。结果表明 :随着SiO2 微粉加入量的增加 ,镁质浇注料的抗渣渗透性提高 ,因为生成的液相中SiO2 增多 ,粘度提高 ;当SiO2 微粉加入量为3%时 ,可得到较理想的基质 ,此时试样的显气孔率较低 ,组成合理 ,抗侵蚀指数最小 ;SiO2 微粉加入量过小 ,耐火材料中液相出现的温度较低 ;SiO2 微粉加入量过大 ,则在渣蚀后的耐火材料中生成过多的液相及低熔点化合物