Calcium Phosphate Glass-Ceramic Crown Prepared by Lost-Wax Technique

A calcium phosphate glass-ceramic crown for dentistry was developed. The glass is cast into the shape of the crown by the lost-wax technique and subsequently heat-treated to convert it into the glass-ceramic, which exhibits excellent mechanical strength. The fine structure of the glass-ceramic is similar to that of the enamel of a natural tooth, and its hardness is near that of enamel.     

烧结法制备Y-TZP/微晶玻璃复合材料的研究

用烧结法制备了Y-TZP，微晶玻璃复合材料，结合DTA分析制定了热处理制度，研究了烧结温度和Y-TZP的加入对复合材料力学性能的影响。     

烧结法制备粉煤灰微晶泡沫玻璃

利用粉煤灰通过烧结法制备了微晶泡沫玻璃。研究表明,选用碳酸钙作为发泡剂,最佳用量为5%。通过正交实验确定了最佳热处理条件:发泡温度1025℃、升温速率14℃/min、发泡时间30min。通过XRD和SEM研究了微晶泡沫玻璃的析出晶相和显微结构。主晶相为钙长石CaAl2Si2O8,次晶相为普通辉石Ca(Mg,Fe,Al)(Si,Al)2O6。所制得微晶泡沫玻璃综合性能优于泡沫玻璃和粘土砖。     

室内环境污染及其控制

文章分析了室内空气污染物的种类、来源、污染状况等,并阐述了其对人体健康的危害。当前室内空气污染状况相当严重,对人体健康的危害亦十分明显,应引起重视。在污染控制策略上,应先从污染源加以控制,同时保证室内环境有很好的通风能力,在此基础上积极开发和应用新的污染控制技术。     

Preparation of Zirconia-Toughened Bioactive Glass-Ceramic Composite by Sinter–Hot Isostatic Pressing

High-strength bioactive ceramics, MgO-CaO-SiO₂-P₂O₅ glass-ceramic composites toughened by zirconia, were prepared by sinter-hot isostatic pressing (sinter-HIPing) to achieve easier mass production and higher reliability. Raw materials for preparing a dense presintered body were investigated to obtain almost complete densification by sinter-HIPing. It was found that the densification of a presintered body was influenced by residual glassy phases in the crystallized glass particles. By using a controlled crystallized glass powder and a zirconia powder as raw materials, a presintered body with a relative density higher than 94% was prepared, and then it was densified to near its theoretical density by sinter-HIPing. This bioceramic exhibited an extremely high bending strength of 400 to 1000 MPa and fracture toughness of 3 to 5 MPa.m^1/2 for 30 to 80 vol% of zirconia.     

大气污染的环境监测及治理

近些年,雾霾天气使我国大气污染受到非常严重的污染,对大气污染进行监测以及进行有效治理对我国具有非常重要的影响,主要对我国大气污染的主要特点及监测现状进行有效分析,并提出解决办法。     

CBZS/AlN玻璃-陶瓷的低温烧结及性能研究

以CaO-B2O3-ZnO-SiO2(CBZS)玻璃粉以及AlN粉体为原料,采用常压烧结法制备了CBZS/AlN玻璃-陶瓷,研究了不同CBZS玻璃含量对复合材料烧结性能、热学性能、介电性能以及力学性能的影响规律.结果表明:CBZS玻璃含量的增加,能有效促进CBZS/AlN玻璃-陶瓷的致密化,可在700～775℃烧结获得致密结构的CBZS/AlN玻璃-陶瓷复合材料;但当CBZS玻璃的含量超过65％后,对玻璃-陶瓷烧结性能的促进作用开始减弱,并恶化了复合材料的热导率与弯曲强度,同时增加其介电损耗.当CBZS玻璃含量为65wt％时,在750℃烧结可获得致密结构的玻璃-陶瓷复合材料,其体积密度为2.87 g·cm-3,热导率为5.31 W/(m·K),介电常数为7.45,介电损耗为0.86×10-3,抗弯强度为209.04Mpa.     

Sintering and Hot Pressing of Uranium Tetrafluoride

The basic sintering and hot-pressing conditions have been established for UF₄. Either sintering of cold compacted material in argon or direct hot pressing in graphite dies can be used satisfactorily to obtain high-bulk-density compacts. Vacuum sintering is ruled out because of the volatility of the UF₄. The occurrence of black localized areas in both sintered and hot-pressed material is attributed to the internal distortion of fluorine atoms into lattice voids resulting in the formation of strained areas.     

大气污染的环境监测及治理措施分析

在近几年,我国国民经济发展迅猛,各类交通工具的数量也大大增加,大气污染问题越来越严重,这会在一定程度上影响人们的身体健康和生活质量,同时人们的环保意识也逐渐增强,这都促进了大气污染环境监测的发展,加强大气污染治疗,为人类可持续发展提供更好的生活生存环境。本文主要是对目前在大气污染环境监测中存在的问题、有效治理大气污染的措施两个方面做出了详细的分析和研究。     

大气污染的成因分析及治理措施

随着近年来我国经济的飞速发展,各种工业工厂的崛起,汽车数量的不断增长,以及各种废气的排放,导致我国的大气污染问题越来越严重。虽然我国近几年来已经开始高度重视环境问题,但是日积月累的大量污染问题还是无法很快得到改善,这些污染给我们的正常生活和生存条件带来了巨大的影响。因此,我们必须高度重视大气污染问题,并不断进行改善和提出治理措施。     

大气污染治理政策给防腐涂料行业带来的机遇和挑战

简要介绍了我国大气污染状况和有关大气污染治理的政策及相关研究工作,汇总了国内外关于VOC排放限值的规范标准,并描述了当前VOC治理技术和涂料系统VOC排放现状。     

微晶玻璃板基础成分对烧结及析晶性能的影响

本文研究了碱金属及碱土金属以及氧化锌等对CaO—Al_2O_3—SiO_2—R_2O—ZnO微晶玻璃板烧结和析晶性能的影响及作用,以及烧结及析晶的规律。确定了烧结、析晶温度以及摊平温度。     

Viscous Sintering and Mechanical Properties of 3Y-TZP-Reinforced LAS Glass-Ceramic Composites

The densification of lithium aluminosilicate glass-ceramic composites strongly depended on dispersed 3-mol%-Y₂O₃-tetragonal-ZrO₂-polycrystal (3Y-TZP) content, rather than the crystallization of a parent glass phase. Because of the reaction between 3Y-TZP and the glass phase, tetragonal-ZrO₂ transformed to monoclinic-ZrO₂ with twinned structure because of the dissolution of Y₂O₃, and ZrSiO₄ formed. Composites containing >50 wt% 3Y-TZP were characterized by fully densified microstructures and decreased tetragonal-to-monoclinic transformation. Fracture toughness increased by almost a factor of 3, which was attributed mainly to stress-induced phase transformation of tetragonal-ZrO₂ particles.     

Photoluminescence Properties of Nanocrystalline ZnO Ceramics Prepared by Pressureless Sintering and Spark Plasma Sintering

Nanocrystalline ZnO ceramics with grain sizes of ∼100 nm were prepared by pressureless sintering at 800°C for 2 h and spark plasma sintering (SPS) at 550°C for 2 min, respectively. Excellent green emission properties were obtained in the ZnO ceramic prepared by the SPS process and in the pressureless-sintered ZnO ceramic prepared at 1000°C for 2 h, which are attributed to the vacuum ambience of the SPS process and the sublimeness of the interstitial Zn at >900°C in air, respectively.     

控制大气污染化工技术的研究进展

综述了控制大气污染化工技术中关于硫氧化物（SOx）、氮氧化物（NOx）、挥发性有机化合物（VOC）的相关控制技术和化学原理;重点评述了烟气脱硫技术、固定源氮氧化物控制技术、脱硫脱硝一体化技术、机动车尾气净化技术、挥发性有机物的污染控制等。介绍了最新研究成果,展望了控制大气污染化工技术的发展方向。     

等离子体技术在大气污染控制中的应用

随着工业技术的发展,生产过程中所排放的废气蛩及种类有不断上升的趋势,而传统的物理-化学处理方法越来越难满足处理的需要。等离子体技术具有费用低、处理彻底、无二次污染等优点,具有良好的发展前景。     

生物过滤技术在大气污染控制中的应用

随着现代社会经济快速发展,社会环境污染程度也越来越严重,特别是大气污染,对人们日常生活及身体健康造成严重不良影响及危害。在当前环境保护及环境治理不断深入开展的大形势下,大气污染控制已经成为十分重要的一项社会任务。在当前大气污染控制过程中,为能够保证得到更加理想的效果,可对生物过滤技术进行应用。本文主要就生物过滤技术在大气污染控制中的应用进行分析。     

Evolution of Macropores in a Glass-Ceramic Under Microwave and Conventional Sintering

Densification and microstructural evolution of a CaO-ZrO₂-SiO₂ glass powder were studied during heating in order to produce a glass-ceramic material. Microwave (2.45 GHz) and conventional heating were used for different soaking times and temperatures. Macropores, as visible from the last stage of glass sintering, were monitored as a function of temperature by SEM microscopy and image elaboration. The porosity as a results of micropores has proved to be negligible. Other important densification parameters, such as initial powder size distribution and green pellet density, which would have affected macropores evolution were kept constant. Microwave prepared samples have been compared to conventionally treated ones. The effect of microwaves was to speed up the sintering process, but did not affect the crystallization evolution of glass-ceramic materials differently when compared to the conventional sintering.     

微晶玻璃烧结过程中晶化和致密化的关系

以钢渣和粉煤灰为主要原料,采用烧结工艺,制得以透辉石为主晶相的微晶玻璃;通过热分析、X射线衍射、收缩率、扫描电镜等分析方法,详细说明了在烧结过程中晶化和致密化的关系;试验结果表明晶化主要发生在烧结的前期,后期以致密化为主,晶化会影响烧结体的致密化。