Preparation, Crystallization and Mechanical Properties of Potassium Aluminosilicate Glass-ceramics

In this study,transparent K_(2)O-Al_(2)O_(3)-SiO_(2)(KAS)glass-ceramics with leucite as the main crystalline phase were prepared by melting-quench method and two-step heat treatment.The effects of SiO_(2)/Al_(2)O_(3) ratio and heat treatment on crystallization and mechanical properties were studied.The crystallization kinetics and X-Ray Diffraction(XRD)results showed that SiO_(2)/Al_(2)O_(3) ratio and heat treatment system had a direct impact on the crystallization behavior of potassium aluminosilicate glass-ceramics.When heat-treated at 680℃/2 h and 780℃/1 h,cracks generated on the surface of the sample with the addition of SiO_(2)/Al_(2)O_(3)=4.8(in mol)due to the huge difference in the coefficient of thermal expansion between glass matrix and surface.When the addition of SiO_(2)/Al_(2)O_(3)(in mol)was 4,the sample with leucite as the main crystalline phase showed an excellent fracture toughness(1.46 MPa·m^(0.5))after the heat treatment of 680℃/2 h and 780℃/5 h.And there was a phase transformation from kaliophilite to leucite.The crystalline phases of the sample heat-treated at 680℃/8 h and 780℃/1 h were leucite and kaliophilite,which resulted in the visible light transmittance of 63%and the fracture toughness of 0.91 MPa·m^(0.5).Furthermore,after the heat treatment of 680℃/2 h and 780℃/5 h,the main crystalline phase of the sample with SiO_(2)/Al_(2)O_(3)=3.2(in mol)was still kaliophilite.Because leucite only grows on the surface of the sample and is hard to grow inward,it is hard to achieve the bulk crystallization of leucite in the sample with SiO_(2)/Al_(2)O_(3)=3.2(in mol).

Glass-Ceramics with High Strength and High Transmittance Obtained by Multi-Factor Controlling

The presence of Li_(2)Si_(2)O_(5) and LiAlSi_(4)O_(10) could effectively improve the elastic modulus and transmittance of lithium disilicate(LD)glass-ceramics.Through synergistically modulation of the crystal content and grain size,we obtained high strength and high transmittance of LD glass-ceramics.The optimal sample had a high transmittance of 90.3%,the hardness was 7.72 GPa,the fracture toughness was 1.07 MPa·m^(1/2),and the elastic modulus was 103.1 GPa.

Isotropic sintering shrinkage of 3D glass-ceramic nanolattices:backbone preforming and mechanical enhancement

There is a perpetual pursuit for free-form glasses and ceramics featuring outstanding mechanical properties as well as chemical and thermal resistance.It is a promising idea to shape inorganic materials in three-dimensional(3D)forms to reduce their weight while maintaining high mechanical properties.A popular strategy for the preparation of 3D inorganic materials is to mold the organic–inorganic hybrid photoresists into 3D micro-and nano-structures and remove the organic components by subsequent sintering.However,due to the discrete arrangement of inorganic components in the organic-inorganic hybrid photoresists,it remains a huge challenge to attain isotropic shrinkage during sintering.Herein,we demonstrate the isotropic sintering shrinkage by forming the consecutive–Si–O–Si–O–Zr–O–inorganic backbone in photoresists and fabricating 3D glass–ceramic nanolattices with enhanced mechanical properties.The femtosecond(fs)laser is used in two-photon polymerization(TPP)to fabricate 3D green body structures.After subsequent sintering at 1000℃,high-quality 3D glass–ceramic microstructures can be obtained with perfectly intact and smooth morphology.In-suit compression experiments and finite-element simulations reveal that octahedral-truss(oct-truss)lattices possess remarkable adeptness in bearing stress concentration and maintain the structural integrity to resist rod bending,indicating that this structure is a candidate for preparing lightweight and high stiffness glass–ceramic nanolattices.3D printing of such glasses and ceramics has significant implications in a number of industrial applications,including metamaterials,microelectromechanical systems,photonic crystals,and damage-tolerant lightweight materials.

Properties of Ultra-low Thermal Expansion LAS Transparent Glass-ceramics Prepared by Spodumene

The glass-ceramics were prepared with the spodumene mineral as the main raw material,and the effects of ZrO_(2)replacing TiO_(2)on the samples were systematically investigated.The results show that the substitution of ZrO_(2)for TiO_(2)is not conductive to precipitate𝛽β-quartz solid solution phase,but can improve the transparency and flexural strength of glass-ceramics.And the glass-ceramic with the highest visible light transmittance(87%)and flexural strength(231.80 MPa)exhibits an ultra-low thermal expansion of-0.028×10^(-7)K^(-1)in the region of 30-700℃.

Nucleation and crystallization of tailing-based glass-ceramics by microwave heating

The effect of microwave radiation on the nucleation and crystallization of tailing-based glass-ceramics was investigated using a 2.45 GHz multimode microwave cavity. Tailing-based glass samples were prepared fi＇om Shandong gold tailings and Guyang iron tailings utilizing a conventional glass melting technique. For comparison, the tailing-based glass samples were crystallized using two different heat-treatment methods： conventional heating and hybrid microwave heating. The nucleation and crystallization temperatures were determined by performing a differential thermal analysis of the quenched tailing-based glass. The prepared glass-ceramic samples were further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermal expansion coefficient measurements, and scanning electron microscopy. The results demonstrated that hybrid microwave heating could be successfully used to crystallize the tailing-based glass, reduce the processing time, and decrease the crystallization temperature. Furthermore, the results indicated that the nucleation and crystallization mechanism of the hybrid microwave heating process slightly differs fi＇om that of the conventional heating process.

Study of the material removal mechanism of glass-ceramics based on consecutive incremental loading in ductile-regime grinding

Glass-ceramics have many excellent properties and are widely used in various fields. During the grinding process,the workpiece surface is typically subject to material removal by grit of incremental heights, which has rarely been the focus of research. As such, it is necessary to study the material removal mechanism of glass-ceramics under consecutive incremental loading, which more closely reflects the actual grinding process. In this paper,to analyze the plastic deformation and residual stress of lithium aluminosilicate(LAS) glass-ceramics, a finite element model is established based on the Drucker–Prager yield criterion for ductile regimes. A nano-scratch test was also conducted and the test results show that both the residual depth and residual stress increase with an increase in the number of increments, and that consecutive incremental loading promotes the plastic deformation of glass-ceramics and increases the residual stress of the material in the ductile-regime process. These findings provide guidance for achieving higher dimensional accuracy in the actual grinding of glass-ceramics parts.

基于改进BAS算法的断路器操动状态辨识方法

断路器操动状态辨识方法容易陷入局部最优,导致辨识结果不精准。为此,提出基于改进BAS算法的断路器操动状态辨识方法。利用改进BAS算法,随机搜索断路器操动状态,获取感知范围内的最优天牛位置,使用LMD分解断路器操动状态信号,采用步长因子控制天牛须搜索范围,获取特征向量;使用指标权重判断断路器操动状态异常情况。实验结果表明,该方法只有在铁芯卡涩状态下,功率谱极坐标与实际坐标不一致,存在30°的误差,其余均一致,说明使用该方法辨识结果精准。

Preparation and Characterization of Glass-Ceramic Basalt Fiber

Basalt fiber(BF)is widely applied in the construction industry to improve the mechanical properties of construction materials.Recent studies show that BF has the potential to further enhance its performance via a crystallization approach.In this work,the glass-ceramic basalt fibers(GCBFs)were prepared through nucleation and crystallization treatments according to the crystallization kinetics calculations.Results from XRD and SEM show that GCBFs have main crystalline phases of Diopside and Augite reach crystallinity of around 46%±10%.In particular,the GCBFs sample with the largest mean crystal size maintains the lowest tensile strength of~197 MPa(compared with the pristine BFs of~737 MPa).Moreover,the weight loss and ion dissolution of GCBFs were explored in seawater environments and it was investigated that,GCBFs have better anti-seawater corrosion than the pristine BFs and have the potential to apply in the marine industry.

智能建筑狭义BAS系统中的电气设备施工要点

在智能建筑狭义自动化系统中,为了解电气设备的相关施工要点,对其进行具体分析。根据电气设备选择的注意事项,为电气设备的选择提供参考,在熟练掌握建筑电气图纸后,再科学合理地制订电气安装计划。完成电气设备的准备工作后,才能进行电气设备的安装工作。参考安装过程的注意事项,具体分析配电箱安装技术、管路敷设技术等技术的施工要点,以此来促进电气设备更加高效、安全地运行,强化对设备安装的重视程度,让电气设备施工技术能够得到不断优化。

轨道交通BAS系统的智能化管理与运营模式探讨

轨道交通BAS系统是保证轨道交通安全、稳定运行的重要设备,随着现代科技的发展,智能化技术也逐渐应用到了轨道交通工程建设当中,BAS系统的智能化管理与运营模式是保证轨道交通运行安全的重要保障。本文就智能化管理与运营模式进行探讨,通过对轨道交通BAS系统功能进行分析,明确其智能化管理和运营模式,有效地实现BAS系统智能化管理和运营模式的创新发展,从而促进轨道交通工程的稳定发展。

地铁BAS系统设计与实现

地铁车站内有着照明设备、风机、风阀、水泵、冷水机组、传感器、屏蔽门等大量机电设备,为实现对其统一、安全以及高效化管理,做好地铁机电设备监控系统设计工作,必须构建完善的监控系统,科学配置系统硬件,优化控制系统,加强数据处理分析功能,做好监测信息管理工作。本文将简单介绍地铁车站机电设备监控系统(BAS)组成,并综合探讨地铁BAS系统设计方案。

长链非编码RNA CDKN2BAS在子宫内膜癌组织表达及其生物学功能研究

目的探讨长链非编码RNA CDKN2BAS(long non-coding RNA CDKN2BAS,LncRNA CDKN2BAS)在子宫内膜癌(endometrial cancer,EC)组织表达,以及沉默该基因对人EC细胞HEC-1B生物学功能的影响。方法收集2018年3月~2021年3月在黄石市中心医院接受手术治疗的107例EC患者资料,实时荧光定量聚合酶链反应(qRTPCR)检测癌组织和癌旁组织中LncRNA CDKN2BAS表达。培养HEC-1B细胞,分成siRNA组、si-NC组和C组,分别转染LncRNA CDKN2BAS抑制序列、对照序列和不作任何处理,并分别采用qRT-PCR,MTT实验和Transwell实验检测细胞中LncRNA CDKN2BAS表达及其对HEC-1B细胞增殖活性、迁移和侵袭力影响。结果EC组织中LncRNA CDKN2BAS表达量为2.73±0.25,高于癌旁组织中的1.00±0.13,差异具有统计学意义(t=63.903,P<0.001);LncRNA CDKN2BAS在FIGO分期Ⅲ~Ⅳ期(2.83±0.25)、组织学分级G3级(2.85±0.24)和出现淋巴结转移(2.84±0.26)的EC组织中的表达量较Ⅰ~Ⅱ期(2.67±0.23),G1~G2级(2.67±0.22)和未出现淋巴结转移(2.68±0.22)的EC组织明显升高(t=3.246,3.894,3.270,均P<0.05);siRNA组细胞中LncRNA CDKN2BAS表达量低于si-NC组和C组(0.30±0.12 vs 1.02±0.10,1.01±0.12),差异具有统计学意义(F=77.210,P<0.05);siRNA组细胞24,48,72和96h时A值低于si-NC组和C组,差异具有统计学意义(F=5.003~8.495,均P<0.05);siRNA组迁移细胞数和侵袭细胞数低于si-NC组和C组,差异具有统计学意义(F=21.956,22.407,均P<0.05)。结论EC组织中LncRNA CDKN2BAS表达量升高,沉默人EC细胞HEC-1B中LncRNA CDKN2BAS表达可抑制细胞增殖活性,减少细胞迁移和侵袭数量。

刍议轨道交通BAS关键技术

轨道交通现已进入全自动化运行阶段,在智慧地铁建设期间,可搭建BAS(地铁环境与设备监控系统),用于完善轨道交通运行体系。基于此,文章首先简单阐述了轨道交通BAS功能,接着结合北京某轨道交通工程展开实例分析,探究该线路构建BAS时所应用的技术思路。

Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.

Luminescence of Er^(3+) in Oxyfluoride Transparent Glass-Ceramics

Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics （TGCs） were obtained with the formation of β-PbF2：Er^3＋ nanocrystals in the glass matrix were confirmed by X-ray diffraction.Well-defined diffraction peaks were observed in the samples after heat-treatment. The average crystal diameter of these precipitated crystals from full-width at half-maximum （FWHM） of the diffraction peak was estimated to be between 8 and 13 nm. Optical absorption, photoluminescence, and upconversion luminescence were measured on as-prepared glass and glass-ceramics. Luminescence spectra in the TGC samples revealed well-resolved, sharp stark-splitting peaks, which indicates that a majority of Er^3＋ ions has been incorporated into the crystalline phase of the nanocrystals. The intensity of the visible and near infrared luminescence mostly increases in TSG compared to that in the as-prepared glass. In 1.53 μm absorption and emission bands, the maximum absorption peak is blue-shifted from 1531 to 1507 nm, whereas the maximum emission peak is redshifted from 1535 to 1543 nm in TGC, as compared with that in glass. The bandwidth at half-maximum （BWHM） of the emission band is significantly broader in TGC than in glass, which is beneficial to the erbium-doped fiber amplifier （EDFA）. Upconversion luminescence was measured using 800 nm near-infrared light excitation. Drastically increased upconversion 1 was observed from the TGC as compared to that from their corresponding as-prepared glasses. In addition to a strong green emission centered at 545 nm because of ^4S3/2→^4I15/2 transition and a weaker red emission centered at 662 nm because of ^4F9/2→^4I15/2 transition, generally seen from the Er^3＋ doped glasses, two violet emissions centered at 410 nm because of ^2H9/2→^4I15/2 transition and centered at 379 nm because of ^4G11/2→^4I15/2 transition were also observed from the was attributed to the decreased effective phonon energy and the increased energy transfer between the excited ions when Er^3＋ ions were incorporated into the precipitated β-PbF2 nanocrystals. The results indicated two attractive spectroscopic properties of the Er^3＋ doped TGC samples, compared to glass samples, namely a reduced multiphonon decay rate and a reduced inhomogeneous broadening. In addition, these oxyfluoride TGC materials were robust,easy and flexibile to process, and possible to be fabricated in the fiber form for device applications.

Effect of Fe_2O_3 on the crystallization behavior of glass-ceramics produced from naturally cooled yellow phosphorus furnace slag

CaO–Al_2O_3–SiO_2(CAS) glass-ceramics were prepared via a melting method using naturally cooled yellow phosphorus furnace slag as the main raw material.The effects of the addition of Fe_2O_3 on the crystallization behavior and properties of the prepared glass-ceramics were studied by differential thermal analysis,X-ray diffraction,and scanning electron microscopy.The crystallization activation energy was calculated using the modified Johnson–Mehl–Avrami equation.The results show that the intrinsic nucleating agent in the yellow phosphorus furnace slag could effectively promote the crystallization of CAS.The crystallization activation energy first increased and then decreased with increasing amount of added Fe_2O_3.At 4wt% of added Fe_2O_3,the crystallization activation energy reached a maximum of 676.374 k J×mol-1.The type of the main crystalline phase did not change with the amount of added Fe_2O_3.The primary and secondary crystalline phases were identified as wollastonite(CaSiO_3) and hedenbergite(Ca Fe(Si_2O_6)),respectively.

Preparation,crystallization,and wetting of ZnO-Al_2O_3-B_2O_3-SiO_2 glass-ceramics for sealing to Kovar

A novel type of ZnO-Al2O3-B2O3-SiO2 glass-ceramics sealing to Kovar in electronic packaging was developed, whose thermal expansion coefficient and electrical resistance are 5.2× 10^-6/℃ and over 1×10^13 Ω·cm, respectively. The major crystalline phases in the glass-ceramic seals were ZnAl2O4, ZnB2O4, and NaSiAl2O4. The dielectric resistance of the glass-ceramic could be remarkably enhanced through the control of alkali metal ions into crystal lattices. It was found that crystallization happened first on the surface of the sample, leaving the amorphous phase in the inner, which made the glass suitable for sealing. The glass-ceramic showed better wetting on the Kovar surface, and sealing atmosphere and temperature had great effect on the wetting angle. Strong interracial bonding was obtained, which was mainly attributed to the interracial reaction between SiO2 and FeO or Fe3O4.

Effect of Water Washing Pre-treatment on the Properties of Glass-ceramics from Incinerator Fly Ash Using Electronic Arc Furnace

Production of glass-ceramics by sintering the molten slag obtained from electric arc furnace treatment of fly ash was investigated. The effect of washing pretreatment prior to melting the fly ash on the microstructure and properties of the glass-ceramics was examined. The results show that washing pretreatment of fly ash can decrease alkali metal chloride and increase network former in fly ash, which results in the increase of peak crystallization temperature of parent glass and strengthening of properties of bending strength and chemical stability of the glass-ceramics. The optimal heat treatment temperature for parent glass of washed fly ash is 1 173 K, at which the crystalline phase of glass-ceramics is composed of gelignite （Ca2A12SiO7） and akermanite （Ca2MgSi207）. Glass-ceramics produced at optimal heat treatment temperature are excellent in term of the physical and chemical properties and leaching characteristics, indicating attractive potential as substitute of nature materials.

Effect of sintering temperature on the microstructure and properties of foamed glass-ceramics prepared from high-titanium blast furnace slag and waste glass

Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature(900–1060℃) on the microstructure and properties of foamed glass-ceramics was studied. The results show that the crystal shape changed from grainy to rod-shaped and finally turned to multiple shapes as the sintering temperature was increased from 900 to 1060℃. With increasing sintering temperature, the average pore size of the foamed glass-ceramics increased and subsequently decreased. By contrast, the compressive strength and the bulk density decreased and subsequently increased. An excessively high temperature, however, induced the coalescence of pores and decreased the compressive strength. The optimal properties, including the highest compressive strength(16.64 MPa) among the investigated samples and a relatively low bulk density(0.83 g/cm^3), were attained in the case of the foamed glass-ceramics sintered at 1000℃.