添加剂对堇青石合成温度及热膨胀系数的影响

采用煤系高岭土、滑石、镁砂为原料合成堇青石,主要探讨了添加剂对合成堇青石的性能影响。通过X-Ray衍射(XRD)分析,用K值法求算合成堇青石矿物相含量,在保证矿物相含量的前提下,探讨添加剂对热膨胀系数的影响。研究结果表明:添加剂的使用均能降低合成堇青石的热膨胀系数,不加添加剂的热膨胀系数为2.04×10-6/℃(20～1100℃);加入碳酸钡热膨胀系数为α=1.84×10-6/℃(20～1100℃);加入碳酸锂热膨胀系数为α=1.86×10-6/℃(20～1100℃)。     

低热膨胀系数堇青石材料的合成研究

以高岭土、烧滑石和氧化镁为原料合成堇青石,研究了烧成温度、镁铝硅含量及高岭土种类对合成堇青石热膨胀系数的影响。实验结果表明:合成堇青石的最佳配方1#高岭土82.4 wt%、滑石9.3 wt%、氧化镁8.4 wt%,试样热膨胀系数为1.24×10-6℃-1。适当的提高烧成温度可得到热膨胀系数低的堇青石材料,但合成温度过高则会因为形成过多的玻璃相而使其热膨胀系数增大。过多或过少的引入Si O2、Al2O3、Mg O均会由于形成高热膨胀系数的晶相而导致所合成堇青石的热膨胀系数增大。     

合成堇青石研究

文章通过添加剂的加人来研究堇青石的合成，分析比较了几种添加剂对堇青石合成时晶相、矿物组成等方面的影响，结果表明添加剂的加人均提高了堇青石的含量，且加人量都有一最佳值。     

不同结构态的堇青石的合成

本文论述了堇青石的两种同质多相，即低温堇青石和高温堇青石的合成工艺。应用烧结法成功地合成了高纯度低温堇青石。讨论了添加剂对于堇青石合成的影响。     

α-堇青石矿渣微晶玻璃热处理工艺优化及氟的影响

研究以白云鄂博西尾矿、粉煤灰为主要原料,用1~7 wt%的MgF_2渐近取代原组分中的MgO,采用熔融工艺成功制备了α-堇青石基矿渣微晶玻璃。采用XRD、SEM及相关力学及电学测试手段研究核化温度、晶化温度等热处理工艺参数及氟含量变化的影响。研究结果表明在所研究条件下760℃和1050℃分别进行核化与晶化热处理最有利于α-堇青石的析出。此时,随着F~-含量的增加,α-堇青石相先增加后减少,同时由六方柱变为条针状。MgF_2取代量为3wt%时,所制备α-堇青石微晶玻璃表现出最佳综合性能:维氏硬度7.04 GPa,抗折强度113.5 MPa,平均热膨胀系数1.86×10~(-6)/℃,介电常数6.62,介电损耗~10~(-2)。其抗折强度与热膨胀系数已与工业堇青石相当。     

堇青石红外特性的研究

参考国内外资料，结合红外辐射产生的条件、发射率的基本概念综述了堇青石具有高红外发射率的机理，从合成原料、合成方法和添加剂的加入等方面分析了对堇青石红外发射率产生影响的因素。对堇青石红外陶瓷材料的发展方向进行了展望。     

生产加工过程对堇青石-莫来石复合材料的影响

本实验主要研究生产加工过程对堇青石-莫来石复合材料的影响。为此,本试验中使用两种不同的加工方法:第1种方法是通过带式浇铸法使堇青石和莫来石层进行原位合成堇青石-莫来石复合材料;第2种方法是通过预制的莫来石粉末以不同的百分含量(0～30%)加入到初始的堇青石粉末中获得所需的复合材料。试验结果表明:通过在堇青石泥浆中加入预先烧制的莫来石粉末所生产的复合材料比通过层压法加工混合所产生复合材料具有更好的致密性和机械强度。     

氧化铬对菱镁矿风化石制备堇青石材料的影响

本研究以辽南地区菱镁矿风化石、工业氧化铝、二氧化硅微粉为原料制备堇青石材料,研究分析氧化铬对制备堇青石材料中晶相、晶胞参数、晶相含量及显微结构的影响.用XRD和SEM表征各试样中的晶相和显微结构;用X' Pert Plus软件对晶相的晶胞参数和晶相含量进行分析.结果表明:以菱镁矿风化石为原料经过1350℃烧成可以制备出以堇青石为主晶相的堇青石材料.氧化铬与堇青石形成有限的固溶体,当氧化铬加入量为0.8％时,堇青石晶格常数及晶胞体积都最大;小于1.2％的氧化铬的加入会降低了系统中晶相的含量,当氧化铬加入量大于1.2％时,系统中晶相的含量随着氧化铬加入量的增加而逐渐增大.     

以稻壳为硅源和碳源制备多孔堇青石陶瓷的研究

稻壳是以C、O、H和Si为主要元素组成的一种农业废弃物。本文以稻壳为硅源和碳源合成了多孔堇青石陶瓷载体,讨论了多孔堇青石的最佳烧成温度、碳质组分含量对堇青石微观结构和性能的影响。实验结果表明:以稻壳中碳质成份为造孔剂,当其添加量为堇青石原料总量的8 wt%、烧成温度为1300℃时,可获得性能较好的多孔堇青石陶瓷。经测试,此样品的显气孔率为37.18%、抗折强度为19.48 MPa、热膨胀系数为3.1×10-6℃-1,可满足工业载体的要求。     

碳化硅/堇青石复相多孔陶瓷的制备及性能研究

采用碳化硅、烧高岭土、氢氧化铝、滑石为主要原料,石墨为造孔剂制备了碳化硅/堇青石复相多孔陶瓷.研究了烧结温度和烧结助剂二氧化铈对碳化硅/堇青石复相多孔陶瓷气孔率和强度的影响,并分别用XRD和SEM分析晶相组成和断面显微结构表明:制备出的SiC多孔陶瓷的主相是SiC,结合相是堇青石与方石英,多孔陶瓷具有相互连通的开孔结构;在1350℃烧结,并保温3h,当造孔剂含量为15％时,碳化硅/堇青石复合多孔陶瓷性能最佳,其气孔率31.80％,相应的弯曲强度为63.74 MPa.在1200℃下,添加不同含量的CeO2,对烧结样品的相组成有影响,能够降低生成堇青石的温度,在CeO2含量为3％的样品中,堇青石的峰最明显,但是过量的氧化铈会抑制了堇青石的生成;随着CeO2加入量的增加,其气孔率和弯曲强度也会随之变化,1200℃下,在CeO2加入量为4％时其弯曲强度最优.但随着CeO2的含量的增加,其气孔率逐渐下降.     

均相沉淀法制备不同晶形碳酸钡的研究

以八水氢氧化钡和尿素为原料,采用均相沉淀法制备了碳酸钡粉体。通过添加合适的晶形控制剂,合成了线状、针状和柱状等不同晶形的碳酸钡粉体,通过扫描电子显微镜(SEM)和X射线衍射仪(XRD)进行了表征,结果表明:当晶形控制剂用量为0. 3% (控制剂与氢氧化钡的质量比)左右时,合成的碳酸钡粉体分散性良好,粒度较小,形貌完整。同时对不同晶形碳酸钡的形成机理进行了初步的探讨。     

毒重石制氢氧化钡的热分解实验研究

毒重石的热分解率严重影响氢氧化钡的收率。研究了高温分解毒重石钡矿,经热水浸取制备氢氧化钡工艺条件,考察了温度、压力、粒径、添加剂和气氛对分解率的影响。结果表明,毒重石钡矿颗粒粒径较小时,有利于降低分解温度,粒径在150 μm以下时,理想分解温度为1 373.15 K;通过加入石墨等含碳添加剂能大幅提高碳酸钡分解率;通入氩气来改善炉膛的气氛,减小反应生成的一氧化碳、二氧化碳浓度对提高毒重石分解率效果不大,当通入氩气流量为0.5 m³/h时,分解率仅提高2.55%。在真空烧结炉中（绝对压力5 Pa）煅烧钡矿能大幅提高分解率和降低分解温度,最佳分解温度为1 273.15 K,钡转化率达82.3%。较低的分解压力和较少的二氧化碳气氛有利于毒重石热分解。     

Sintering Additives to Eliminate Interphases in Cordierite Ceramics

Effects of the sintering additives CeO₂ and K₂O on eliminating interphases of cristobalite and spinel were studied by means of XRD, SEM/energy-dispersive spectrometer, and TMA techniques to obtain high cordierite contents. Adding 4 wt% CeO₂ significantly stimulates the conversion of cristobalite to cordierite, depresses spinel formation and yields less glassy phase. It is helpful to prepare a ceramic with a high content of cordierite and a low thermal expansion coefficient when sintered at 1400°C for 3 h. Addition of 1–2 wt% K₂O results in a large amount of glassy phase and is less effective in eliminating the interphases.     

Properties of barium zirconate sintered from different barium and zirconium sources

In this study, barium zirconate powder was prepared by a solid-state reaction using different barium and zirconium sources. Thermal analysis and phase identification demonstrated that barium zirconate could be synthesized from barium hydroxide at a lower temperature than from barium carbonate. Copper oxide was used as a dopant to improve the sintering performance of the barium zirconate; sintered samples with 2 mol% copper oxide exhibited relatively superior comprehensive performance. The mechanical properties and thermal stability of barium zirconate were characterized; the internal composition structure of the samples prepared with basic zirconium carbonate was uneven, resulting in somewhat reduced performance. The samples maintained a high elastic modulus and strength before and after thermal shock. It was observed under an electron microscope that a liquid phase was generated inside the samples after thermal shock, and numerous barium zirconate whiskers were formed. The whiskers ensured that the sample could withstand greater thermal stress, thus exhibiting excellent thermal shock stability. This work demonstrates the promising potential of barium zirconate in the field of high-temperature materials.     

抗氧化耐磨蚀复合SiC材料的研究及应用

研究试验了稀土氧化物，A、B添加物及硅线石的加入量对碳化硅－硅线石复合材料性能的影响。结果表明：引入适量的稀土氧化物能改善材料的抗氧化性及抗侵蚀性，氧化速度比粘土结合SiC降低十余倍；采用A、B添加剂能提高材料的基质密度、抗折强度及耐磨性能，基质强度可达100MPa以上；适量的硅线石使材料的抗热震性明显提高。用该材料做的分离器叶片，满足了循环流化床锅炉内恶劣环境中长期使用的要求。     

Preparation and characterization of cordierite glass–ceramics for bonding solar thermal transmission pipelines

TiO₂ was employed to develop cordierite glass–ceramics for thermal transmission pipeline binders by a melt-quenching method. The effects of TiO₂ on the phase composition, microstructure, and physical properties of glass–ceramics were studied. In addition, the thermal shock resistance of the glass–ceramics based binder was investigated. The results showed the formation of α cordierite could be increased by adding 1.0 wt% TiO₂, thereby improving bending strength and decreasing the coefficient of thermal expansion. However, a 3-5 wt% TiO₂ additive resulted in massive generation of µ cordierite, which exhibited a negative effect on the above performances. After crystallization at 1000°C for 2 h, sample B1 (1 wt% TiO₂ additional) displayed the best overall properties. It was demonstrated that cordierite glass–ceramics were satisfactory materials as heat transmission pipeline binders when the C2 binder (40 wt% frit, 60 wt% as-prepared sample B1) was applied, which had a good thermal shock resistance.     

某白钨多金属矿浮选尾矿中萤石提取技术研究

为了缓解萤石资源严峻形势,提高低品位难选萤石矿以及共（伴）生型萤石矿的综合利用水平,结合矿石性质分析基础上,进行了系列条件试验研究、部分流程开路试验研究以及全流程闭路试验研究,研究结果表明：在一次粗选二次扫选,粗精矿再磨后进行五次精选,中矿顺序返回的原则流程条件下,以油酸为捕收剂、水玻璃和腐植酸钠为组合抑制剂、碳酸钠为pH调整剂,可实现该白钨多金属矿尾矿中萤石二次资源的有效回收利用;当捕收剂油酸用量450 g／t,组合抑制剂2．8 kg／t,碳酸钠1 kg／t时,在给矿CaF2品位16．41％的条件下,获得了CaF2品位为87．92％、CaF2回收率为53．53％的萤石精矿。     

堇青石的红外辐射特性

堇青石是一种硅酸盐矿物，因其具有优良的红外辐射特性、较高的热稳定性和化学稳定性等优点而成为一种重要的红外辐射材料。分析了改善堇青石材料红外性能的几个主要途径：适当减小原料的粒度、合理选择堇青石合成方法、在堇青石基质中添加适量过渡金属氧化物、选取适宜的堇青石烧结温度等。介绍了堇青石在红外辐射导电陶瓷、红外泡沫陶瓷、高温红外辐射涂料和常温红外辐射涂料中的应用，展示了堇青石作为红外材料的发展前景。     

NOx storage on barium-containing three-way catalyst in the presence of CO2

NO_x trapping capability of NO_x storage–reduction commercial catalysts (4–9 wt% Ba-containing three-way catalysts) was compared to that of bulk barium carbonate and alumina-supported barium carbonate from Rhodia (9 wt% Ba). These samples were characterized by infrared spectroscopy, X-ray diffraction, HRTEM and EDX. It was shown that bulk barium carbonate was partially converted to barium nitrate in flowing NO/O₂ mixture without CO₂. Thermodynamic calculation showed that bulk barium nitrate could not form in the presence of CO₂-containing gas exhausts. Using HRTEM and EDX, it was evidenced that barium was engaged as either large barium carbonate crystals or highly dispersed barium species on the alumina support. NO_x storage experiments using gas mixtures containing or not O₂ or CO₂, confirmed firstly that NO was stored on barium trap only via NO₂ and secondly that NO₂ and CO₂ are competing for the same barium trapping sites. The fact that no significant amount of stored NO_x could be evidenced in the bulk barium carbonate, suggested that over the catalytic surface, the well dispersed barium phase can play an important role in the NO_x trapping properties of these catalysts.     

贵金属催化燃烧催化剂的研究

VOCs大多具有毒性,并伴有刺激性的恶臭,直接排放会威胁人类健康,并对环境造成严重污染。目前,催化燃烧技术是工艺较为成熟,同时也是应用较为广泛的VOCs的净化方法。实际过程使用的催化燃烧催化剂多为具有规整结构的蜂窝状催化剂,活性组分通常为Pt、Pd、Ru等贵金属。从整体式催化剂的角度出发,制备了Al_2O_3和TiO_2两种涂层的整体式催化剂用于催化燃烧消除苯的实验,未添加铈锆粉时的活性顺序:Pt/Al_2O_3/堇青石Pt/TiO_2/堇青石;添加铈锆粉后的活性顺序:Pt/CZ-Al_2O_3/堇青石Pt/CZ-TiO_2/堇青石,同时铈锆粉的添加还可以提高催化剂的热稳定性。