石墨加入量对低碳镁碳砖性能的影响

通过检测含有2%～14%石墨镁碳砖1400℃的高温抗折强度、1500℃的热膨胀系数、1000℃×2 h煅烧后的抗氧化性,比较低碳镁碳砖与传统镁砖的性能差异,研究了石墨加入量对低碳镁碳砖性能的影响。结果表明:在有2%Al存在的情况下,低碳镁碳砖高温抗折强度与石墨加入量无关;石墨加入量为6%时,可保证低碳镁碳砖具有较优良的抗剥落性及抗氧化性。     

Mg and Al mixed effects on thermal properties in aluminosilicate glasses

By using the aerodynamic levitation and laser melting technique to well extend the glass-forming region into the Mg-rich and peraluminous regime, a series of magnesium aluminosilicate glasses were prepared to investigate the Mg and Al mixed effects on thermal properties, including glass transition temperature (T_g), crystallization behavior, and thermal stability. With the gradual substitution of Mg by Al, T_g exhibits two types of near-linear rises with different slopes in two compositional regions separated by r = 0.57, where r is equal to the molar ratio of [Al₂O₃]/([Al₂O₃] + [MgO]). Moreover, when it comes to other properties, that is, crystallization behavior and thermal stability, this critical point precisely appears at the same r = 0.57. Compared to the slower increase of T_g in Mg-rich region, the steeper rise of T_g in the peraluminous region is mainly ascribed to the step-by-step formation of oxygen triclusters driven by Pauling's second rule. Moreover, the occurrence of the critical point for T_g rise at r = 0.57 rather than the theoretical 0.5 can be seen as a proof of the role of Mg cations partly as a network former.     

水泥添加量对电解锰渣免烧砖性能的影响

控制骨料掺入量为20％,成型压力为2 MPa,混料含水率为25％的条件下,系统研究了水泥添加量对电解锰渣免烧砖性能的影响.结果表明:当水泥添加量为20％时,电解锰渣免烧砖7 d抗压、抗折强度分别为10.21 MPa和2.35 MPa,28 d抗压、抗折强度分别为13.76 MPa和2.74 MPa,体积密度为1.36 g/cm3,线收缩率为1.13％,吸水率为33.32％,饱和系数为1.47,有轻微泛霜现象产生,强度达到国家烧结普通砖的标准要求,其他性能满足国标一级品的要求.     

The formation and properties of Al/Mg scales on Al heat- exchange surfaces in desalination plant

Three types of scales containing Al and Mg have been shown to form during the corrosion of Al in seawater in the pH range 6.3–8.5. The type most frequently occurring has a structure similar to that of the natural mineral hydrotalcite. It can be formed from the Al(OH)₃ produced by the corrosion of Al and Mg²⁺ ions present above pH 6.3. The Al:Mg ratio in this compound increases with pH, resulting in a form of buffering action. In the presence of these scales anodic breakdown of the corrosion film takes place at a potential 100–200 mV more anodic than in their absence. The structures, mechanisms of formation, and effects of these scales in the operation of distillation plants with Al surfaces are discussed, as well as their effects on the operation and interpretation of laboratory corrosion tests.     

复合抗氧化剂对Al2O3-SiC-C砖性能的影响

以均化矾土、板状刚玉、碳化硅、石墨为主要原料,利用酚醛树脂作为结合剂,研究了复合抗氧化剂(硅粉、铝粉、碳化硼)的引入形式及加入量对Al2O3-SiC-C砖的性能影响.结果表明:添加复合抗氧化剂可提高Al2O3-SiC-C砖的高温抗折强度,随铝含量的增加,对提高高温抗折强度的提高越明显;抗氧化效果从强到弱依次为:添加碳化硼的复合抗氧化剂>复合铝硅抗氧化剂>金属铝>金属硅;在复合抗氧化剂中引入碳化硼能够有效的提高Al2O3-SiC-C砖的抗渣侵蚀性能及热震稳定性.     

谈高掺量高强度粉煤灰蒸压砖生产前景

目前 ,粉煤灰、煤矸石烧结砖存在的缺点是生产中的尾气含有大量二氧化硫和三氧化硫等有害物质 ,对大气污染严重 ,加上脱硫成本较高 ,处于微利的砖厂很难上马 ,即使是部分较现代化的砖厂能够上得起脱硫装置的也运行不起 !一套大断面隧道窑的脱硫塔运行成本非常高。本文对粉煤灰蒸压砖的生产前景进行简要分析 ,以期和各地区的朋友共同探讨。1　高掺量粉煤灰砖发展现状粉煤灰烧结砖　粉煤灰烧结砖经过近半个世纪的摸索 ,工艺逐渐成熟 ,核心设备还是欧洲的先进设备比较可靠。目前粉煤灰烧结砖还存在着三个不好解决的难题 :一是二次污染 ;二是粉…     

添加金属Mg对MgO-C砖耐蚀性的影响

为提高转炉内衬用MgO-C砖的耐用性，研究了含有Al的MgO-C砖中添加Mg的同时，再添加BN、B4C和硼酸粉作为第3成分的结果。研究结果发现，添加金属Mg后再添加含硼的第3成分，不仅可以抑制还原热处理后Mg的逸出，还可以提高MgO-C砖的耐蚀性，减少对耐热震性的不利影响。     

镁铝及镁锌铝水滑石的合成与表征

采用共沉淀法合成镁铝及镁锌铝水滑石,并通过X射线衍射（XRD）、红外光谱（FT-IR）、扫描电镜（SEM）、热分析（TG/DTG）、粒度分析等手段对合成的水滑石进行表征,研究不同镁、铝、锌的投料比例对合成的水滑石结构及热性能等的影响。XRD表征结果表明,合成产物均具有水滑石特征峰。合成的镁铝水滑石随着镁铝比的增加其层板间距增大,层板上原子密度降低;合成的镁锌铝水滑石随着锌含量的提高层板间距减小,层板上原子密度降低。镁铝水滑石热分解过程有两个明显阶段,层间结晶水先脱除,随后是层间阴离子脱除及层板上部分羟基脱水;镁锌铝水滑石热分解过程只有一个明显的阶段,层板间阴离子在层板间结晶水脱除的同时也在脱除。     

Microwave dielectric properties and crystal structures of Mg0.7Al2.2O4 and Mg0.4Al2.4O4 ceramics with defect structures

Mg_0.7Al_2.2O₄ and Mg_0.4Al_2.4O₄ ceramics with cation vacancies were synthesized using the molten salt method, and the relationships between the microwave dielectric properties and crystal structures of these materials were investigated. The ²⁷Al NMR spectra of these ceramics indicate that the preferential occupation of tetrahedral sites by Al³⁺ cations was enhanced by the introduction of cation vacancies. The λ values of Mg_0.7Al_2.2O₄ and Mg_0.4Al_2.4O₄ ceramics fired at 1600°C, which correspond to the fraction of Al³⁺ cations in tetrahedral sites, were 0.37 and 0.60, respectively. Crystal structure refinements using the Rietveld method suggest that cation vacancies are preferentially located at octahedral sites in both ceramics. The ε_r and Q·f values of a Mg_0.7Al_2.2O₄ ceramic fired at 1600°C were 7.7 and 201 111 GHz, respectively, while those of a Mg_0.4Al_2.4O₄ ceramic fired at 1600°C were 7.5 and 232 301 GHz, respectively. These data demonstrate that the preferential occupation of tetrahedral sites by Al³⁺ cations following the introduction of cation vacancies enhances the Q·f value.     

镁铝物质的量之比对水滑石纳米材料及其催化性能的影响

采用尿素法制备不同镁铝比的水滑石,利用X射线衍射(XRD)、傅立叶红外光谱(FT-IR)、扫描电镜(SEM)、能谱仪(EDS)和低温N2吸附技术(BET)等对水滑石进行表征,探讨了镁铝物质的量之比对水滑石晶体结晶度的影响.以合成丙二醇甲醚的反应为探针,考察了不同镁铝比对水滑石氧化物催化性能的影响.结果表明,水滑石的结晶...     

防氧化剂TiN和Al对MgO-C砖性能的影响

以3~1mm、<1mm、<0.088mm的电熔镁砂和<0.15mm的鳞片石墨为原料,热固性酚醛树脂为结合剂,分别加入0.5%、1%、2%、4%的含碳TiN或2%的Al粉为防氧化剂,制备了镁碳砖试样,并与无防氧化剂的试样对比进行抗氧化性和抗渣侵蚀试验。结果表明:添加Al粉试样的抗氧化性能最好,TiN的次之,未加防氧化剂的最差;添加TiN试样的抗渣性能最好,无防氧化剂的次之,添加Al粉的最差。镁碳砖中引入适量TiN后明显提高抗渣侵蚀性能的原因是:TiN氧化生成TiO2时产生的体积膨胀堵塞气孔,阻止熔渣侵入;TiO2与渣中的CaO反应生成3CaO·2TiO2,提高渣的粘度。综合各项性能,TiN的最佳加入量为2%。     

高掺量粉煤灰烧结砖的研究与工业试验

采用掺灰量80%的混合料和传统粘土砖厂生产工艺,可以烧成干密度1136kg/m3、导热系数0.376W/m.k、抗压强度13.8MPa、吸水率23.6%、比强度0.012MPa的轻质、隔热、高强、低能耗、调温、调湿等多功能的粉煤灰砖;用于施工能显著提高施工效率,降低劳动强度,减少运输、吊装、机械动力消耗等费用。     

镁铝水滑石对PVC热稳定性能的影响

采用比色法、热失重法研究了镁铝水滑石、铅盐、有机锡、以及镁铝水滑石与铅盐、有机锡复配的复合稳定剂对PVC的稳定效果,考察了铅盐稳定体系和镁铝水滑石与有机锡复合稳定体系对PVC力学性能和流变性能的影响.结果表明镁铝水滑石分别与铅盐、有机锡进行复配均具有较好的协同效应且后者对PVC的稳定效果更好.其中,VC、镁铝水滑石和有机锡以100.5.5质量比复配的复合体系具有较好的力学与加工流变性能.     

镁铝水滑石的制备及其改性

充分利用正交试验方法对镁铝水滑石的制备和微波改进工艺进行探讨,并主要针对使用过程中改性温度、时间以及钛酸酯的使用量等相关因素对镁铝水滑石活化指数的影响进行分析,通过实验发现当改性温度为75℃,改性的时间设置为30min,且钛酸酯的使用量为5%的状况下是镁铝水滑石的更佳改性条件。与此同时发现,镁铝水滑石能够进一步提升PVC的热稳定性,有效提升其加工性能,并能发挥出明显的阻燃消烟作用,通过改性后镁铝水滑石的性能得到进一步优化。     

Effect of Zircon Addition on Properties of Low Carbon Al2O3-C Refractories

Using tabular alumina as aggregate,tabular alumina fines, reactive alumina ultra-fines, aluminum powders,silicon powders,carbon black,flake graphite,B4C and zircon fines as matrix,low carbon Al2O3- C refractories were prepared. Influences of zircon powders additions( 0,3%,5% and 7%,in mass,the same hereinafter) on properties,phase composition and microstructure were investigated. The results show that the ZrO2- nitride can be in-situ formed through carbothermal reduction and nitridation in Al2O3- C refractories.With the increase of zircon powder,the oxidation resistance of the Al2O3- C refractories improves obviously,the oxidized layer thickness decreases from 7. 94 mm without zircon to 2. 71 mm with 5% zircon. HMOR at 1 400 ℃of the Al2O3- C refractories reaches the maximum 14. 9MPa when zircon addition is 5%. With the increase of zircon powder,the apparent porosity and bulk density change a little,CMOR and CCS increase.     

Al、Mg添加剂对方镁石-尖晶石-碳砖性能的影响

采用烧结镁铝尖晶石、电熔镁砂和鳞片石墨为主要原料 ,研究了方镁石 -尖晶石 -碳砖中添加的金属Al、Mg和不同Mg/Al比对其碳化后残存膨胀率、热膨胀率和N2 中 15 0 0℃ ,1.5h处理后的失重率的影响。结果表明 :添加适量Al、Mg组分及控制适当的Mg/Al质量比可明显提高其性能     

添加Al粉对直接法合成甲基氯硅烷的影响及其机理研究

针对直接合成法合成甲基氯硅烷单体,系统考察了添加微量Al粉对该反应的影响及其作用机理.分别在4%和10%铜浓度下,通过在线色谱分析的方法研究了添加Al粉对反应速率和M2选择性的影响.实验结果表明,添加Al粉可以很大程度上增加反应速率,缩短反应诱导期,但是Al粉的添加量超过一定量后会急剧降低反应选择性.建议工业中添加Al粉的量不应超过0.25%.通过SEM观察反应触体,发现添加铝粉可以改变触体反应活性中心的形貌,推测Al粉的作用主要是去除Si颗粒表面的氧化层,形成更多的缺陷,有利于催化剂与Si颗粒更好地结合.通过XRD对触体进行分析,发现添加Al粉后形成了更多的活性组分η相,从而加速了反应的进行.     

Zr4+掺杂对Mg/Al水滑石磷吸附行为的影响

采用共沉淀法制备了系列不同Zr4+含量的Mg/Al/Zr三元类水滑石材料，研究了其对废水中磷酸根离子的吸附性能。采用XRD、DRIFTS、氮气吸脱附实验等手段对材料的结构及织构性质进行了表征，并研究了溶液初始pH以及竞争阴离子对磷吸附量的影响。结果表明：掺杂Zr4+能提高类水滑石层板正电荷密度以及增大层间距，有利于磷酸根阴离子的吸附；Mg/Al/Zr类水滑石对磷的吸附过程符合准二级动力学模型，吸附等温线符合Langmuir模型，当n(Zr4+)/(Al3++Zr4+)为0.3时，理论饱和吸附量最大，达到76.6 mg/g，比Mg/Al水滑石高出28.7%；酸性环境有利于磷酸根的吸附，而二价阴离子的竞争吸附作用会显著降低磷吸附效果。Mg/Al/Zr类水滑石对磷的吸附机理为静电吸引和阴离子交换协同作用。     

储氢材料85Mg10C4Ni1Al的制备及性能研究

在Mg粉中添加微晶碳及少量Ni和Al,用机械力化学法氢气反应球磨制备储氢材料.球磨2～3 h即可使Mg完成氢化,Ni和Al的添加可提高储氢密度,降低初始放氢温度和放氢高峰温度,加快放氢速度.储氢材料85Mgl0CANilAl的粒度约为100～300 nm,其储氢密度达6.0%,初始放氢温度仅220℃,与传统Mg基储氢材料相比其储氢性能有较大改善.     

Effect of Pt Particle Size and Phosphorous Addition on Furfural Hydrogenation Over Pt/Al2O3

Catalysis Letters - Pt/Al2O3 catalysts with different Pt particle sizes and after phosphorous deposition were studied for liquid phase catalysed furfural hydrogenation. The activity and selectivity...