微晶玻璃应力测量与退火实验研究

应力大小是玻璃光学性能的重要指标之一。介绍了玻璃应力的分类、计算方法、测量方法和先进测试设备。退火是消除应力的有效手段。采用最高575℃的温度曲线对微晶玻璃块(40mm×50 mm×30 mm)进行退火实验,退火前后采用高精度数字应力仪进行应力测量。退火前实验件的应力分布不均匀,应力最小值0.85 nm/cm,最大值25.06 nm/cm;退火后实验件的应力分布均匀,应力最小值为0.75 nm/cm,最大值2.39 nm/cm。实验结果表明此退火能够明显减小微晶玻璃应力值并大幅提高应力分布均匀性。     

玻璃应力对玻璃强度的影响

介绍了玻璃的应力与玻璃强度之间的关系,并讨论了几种不同类型的应力对玻璃强度的影响。     

散射光弹性技术在化学钢化玻璃表面应力测量中的应用

在智能手机、平板电脑等电子产品领域,化学钢化超薄玻璃的需求不断增加,而玻璃是易碎材料,要提高或保持强度和抗破碎能力,必须正确认识应力分布。如何有效的测量化学钢化玻璃的表面压应力(CS)和压应力层厚度(DOL),是当下一个迫切需要解决的问题。散射光弹性法是利用通过玻璃内部应力的双折射来改变极化激光束的延迟,并且散射光的强度随着激光束的延迟的变化而改变,最后通过偏振光光路上因激光束的延迟而出现的光程差和偏振特性来计算表面压应力和压应力层厚度。对散射光弹性法测量化学钢化玻璃的表面应力的理论依据、测量技术等进行了介绍。     

浮法玻璃的应力与退火

玻璃的退火是浮法平板玻璃生产过程的一个重要环节。文章阐述了玻璃热应力产生和消除方法,指出在线应力检测是控制退火质量的较好途径。     

Measurement of Very Slow Crack Growth in Glass

The rate of very slow crack growth in glass is measured by inducing small, controllable changes in the direction of propagation of Hertzian cone cracks at known times. After completion of a growth sequence, the sample is sectioned to reveal the fracture surface. The stress intensity factor at each stage of crack growth is calculated by using finite-element modeling of the stresses near the crack tip. Data are presented for crack growth velocities as low as 10⁻¹⁴ m/s in soda–lime glass. These data provide strong evidence for the existence of a subcritical limit for crack growth in this material.     

光波导效应在化学钢化玻璃表面应力测量中的应用

随着国际市场对化学钢化玻璃的需求不断增加,目前化学钢化的超薄玻璃在电子、仪表、和智能化科技行业的应用领域广泛使用。化学钢化玻璃的表面压应力(CS)和压应力层厚度(DOL),是业界认可的最重要的性能指标,而如何准确的表征这些参数,是当下一个迫切需要解决的问题。化学钢化玻璃表面层中的光导效应是用于测量表面应力的有效途径,可以有效的测量化学钢化玻璃的CS和DOL,从而用于钢化玻璃生产中的质量和过程控制。本文对基于光波导效应的表面应力计的理论依据、测量技术和相关仪器进行了介绍。     

光学玻璃应力的自动测试

根据1/4波片法测量应力的特点,采用光电编码器控制检偏器的旋转.高分辨率且无自动增益功能的CCD,由计算机控制并采集光学玻璃干涉条纹图,采样点根据需要可多达512×512.介绍应力图分析软件的设计思路,编制软件对多幅干涉条纹图进行处理与计算,得到被测样品所有点的应力值,并绘制样品应力三维分布图.采用CYY-1应力仪进行实验,实验表明,应力双折射光程差测量精度达0.2nm/cm,重复性为0.1nm/cm,并实现全测试过程的自动化和智能化.     

钢化玻璃应力斑的成因分析及控制

分析了钢化玻璃产生应力斑的原理，论述了钢化玻璃生产过程中导致应力斑产生的工艺原因，介绍了影响应力斑视觉效果观察入射角、玻璃厚度等非玻璃本身因素。     

Stress Corrosion Cracking of Bioactive Glass Composites

Bioactive glass was reinforced with 20 vol% Ag particles and 20 vol% SiC whiskers. Fatigue parameters and lifetime data for the two composites were determined via the stressing rate dependence of the bend strength in a bio-simulating buffered solution (pH of 7.4). A lifetime of 10 yr was estimated for the SiC-reinforced composites under bend stresses of 34 MPa and for Ag composites under 23 MPa. Stresses for similar survival of pure bioactive glass are 17 MPa.     

液晶玻璃基板应力分析与对策

光电产业对液晶基板玻璃的要求向超薄化、高清晰、全面屏发展,对液晶玻璃基板的品质需求也日益提高。由于玻璃基板行业竞争日益强烈,对生产企业来说,提升玻璃基板品质尤为关键。为降低TFT-LCD液晶玻璃生产过程中因退火温度不均、厚薄差异大、形状不稳、环境压差波动及切割晃动造成成型品质应力的波动,从溢流下拉法生产原理、应力分类、应力影响因素及对策方法展开深入研究,并通过实践加以论证,为TFT-LCD液晶玻璃生产中应力分析与对策提供正确思路,同时提升高效对策,促进行业健康稳定发展。     

浮法玻璃在线应力检测及相关退火概念

退火一直是浮法工艺中较难把握的环节之一.究其原因,与工艺人员对退火及应力的一些基本概念的理解有很大关系.本文首先对浮法玻璃在线应力检测作一综合性介绍,然后对有关退火的几个基本概念进行说明.     

钢衬玻璃管道系统的应力分析问题

介绍一种基于钢衬玻璃管道实验数据的工程处理方法，利用这种方法，可以将钢衬玻璃管道的应力分析问题转化为普通金属管道的应力分析问题，从而可以应用CAESAR－Ⅱ程序对复杂的钢衬玻璃管道系统进行详细的应力分析。     

Sintering of Spherical Glass Powder under a Uniaxial Stress

The sintering of spherical borosilicate glass powder (particle size 5 to 10 μm) under a uniaxial stress was studied at 800°C. The experiments allowed the measurement of the kinetics of densification and creep, the viscosities for creep and bulk deformation, and the sintering stress which was found to increase with density. The data show excellent qualitative agreement with Scherer's theory of viscous sintering. In addition, the quantitative comparison between theory and experiment shows good agreement; the measured viscosity of the bulk glass was ∽1×10⁹ P (∽1×10⁸ Pa·s) compared to ∽3×10⁹ P (∽3 Pa·s) obtained by fitting the data with Scherer's theory.     

浮法玻璃熔窑内玻璃液温度的测量

玻璃熔窑内的温度对产品质量起决定性的作用,合适的温度制度有利于玻璃质量的提高,能最大限度地节约燃料并延长熔窑寿命.熔窑空间温度容易测量和控制,熔窑内玻璃液的温度却很难实现实时检测,对于玻璃生产,玻璃液温度比熔窑空间温度更为重要.通过对熔窑内玻璃液温度的测量,探索熔窑内玻璃液在不同区域的温度特性.     

钢化真空玻璃球形支撑的玻璃压痕应力场理论及分析

针对钢化真空玻璃球形支撑物对玻璃压痕的应力场分布问题,采用接触力学,对Hertzian压痕方程进行了修正,推导了三维应力场方程,同时,对完全发展的锥形裂纹的应力强度因子进行了数值求解。结果表明,在球体与玻璃接触区域内,所有的主应力都是压应力,主应力σ₁导致了裂纹的萌生,而主应力σ₂形成了环形裂纹。与玻璃表面正交的最小主应力从接触边缘向外偏离,形成的近似平行的曲线即为锥形裂纹的形状,而最大拉应力总是垂直于这些曲线。因此,在最大主拉应力的作用下,球体加载后裂纹遵循最小主应力的轨迹。裂纹尖端的应力强度因子决定了断裂韧性,随着裂纹的扩展,应力强度因子减小,在离表面一定距离后,应力强度因子达到临界值,裂纹停止。不同压痕载荷下的归一化应力强度因子是一组具有相似形状的曲线。     

Stress Development during Constrained Sintering of Alumina/Glass/Alumina Sandwich Structure

Stress development during the constrained sintering of a sandwich structure of alumina/glass/alumina has been studied. Stress distribution in the glass layer was calculated using a finite element method. The shear stress exhibited a maximum at the edge of the alumina/glass interface. The in-plane tensile stress, formed during constrained sintering, decreased from the interface of the alumina/glass to the middle of the glass in the z -direction, but increased from the edge to the center of glass in the x − y direction. This in-plane tensile stress reduces the driving force of densification, resulting in a larger x − y shrinkage and higher densification in the middle of the glass.     

Extended Charles–Hillig Theory for Stress Corrosion Cracking of Glass

The work originally performed by Charles and Hillig (C&H) on the chemical stress corrosion cracking of glass is based on the chemical reaction rate theory and restricts the analysis to only the kinetic change at the exact location of the crack tip. As a result, crack sharpening/blunting is predicted when the applied stress lies above/below the static fatigue limit. The present paper extends the investigation within the same physical framework to the geometric change of the entire cavity surface, particularly in the vicinity of the cavity apex region. It has been found that a physical-property-dependent parameter ( m ) exists which exerts a strong influence on the crack-tip morphology. In the case of m = m _th, where m _th is a threshold m which assumes a value of ∼ 45 for an elliptical cavity having a minor to major axes ratio of 0.01, the current predictions reduce to the C&H results. In general, however, m ≠ m _th, and the single-valued fatigue limit degenerates into a range of applied stresses under which either enhanced blunting ( m > m _th) or necking ( m < m _th) is predicted to take place. Evaluation of m for soda–lime glass reveals that m > 45, suggesting that enhanced blunting takes place at the crack tip when external loads are applied at a moderate level for a typical crack having an initial major to minor axes ratio > 100 in a soda–lime glass specimen.     

浮法玻璃应力检测系统及其应用

简述了ZYL6型浮法玻璃应力监测系统的原理及测量方法,将测量出的综合应力及温度信号经过处理,通过软件编制,将玻璃的永久应力、暂时应力相区分,绘制相应的曲线,根据应力曲线对退火窑温度参数调整,从而有效地指导玻璃的退火操作,提高玻璃的成品率。     

风冷钢化玻璃应力分布特征及不均匀度评价

钢化玻璃表面应力分布的不均匀性对其钢化品质、安全性都产生重要影响,但风冷钢化玻璃应力分布不均匀是无法消除的,因此需对钢化玻璃应力分布不均匀性给予一定的客观评价.本文基于不同刚化程度玻璃表面应力的测试结果,分析了其应力分布特征,并采用标准偏差对其应力分布不均匀度进行评价,研究结果表明:钢化玻璃表面应力分布总体上是边部应力较大,中间应力偏小,但任一钢化玻璃表面应力分布形态各异,无规律可循.钢化玻璃表面应力分布不均匀度基本在0～0.05范围内,建议采用标准偏差衡量的钢化玻璃表面应力不均匀度应不大于0.05为佳.     

钢化玻璃表面应力测量结果不确定度的评定和分析

钢化玻璃属于安全玻璃.钢化玻璃其实是一种预应力玻璃,为提高玻璃的强度,通常使用化学或物理的方法,在玻璃表面形成压应力,玻璃承受外力时首先抵消表层应力,从而提高了承载能力,增强玻璃自身抗风压,耐冷热冲击及抗冲击能力等.故钢化玻璃的表面应力是表征玻璃钢化程度及钢化玻璃质量优劣的一个重要指标.所以能否准确地对表面应力进行测量,并对其测量不确定度进行科学的评估是评价钢化玻璃质量好坏的关键.本文采用GB/T 18144-2000标准规定的方法对钢化玻璃进行了表面应力测量,根据JJF 1059.1-2012《测量不确定度评定与表示》评定和分析了测量结果的不确定度,为同类结果不确定度提供了评定的参考依据.