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。     

玻璃弯曲强度的裂纹影响

玻璃弯曲强度的裂纹影响宋显辉，潘素瑛（武汉工业大学４３００７０）ＴｈｅＥｆｆｅｃｔｏｆＣｒａｃｋｓｏｎＢｅｎｄｉｎｇＳｔｒｅｎｇｔｈｏｆＧｌａｓｓ￥ＳｏｎｇＸｉａｎｈｕｉ；ＰａｎＳｕｙｉｎｇ（ＣｅｎｔｒｅｆｏｒＭａｔｅｒｉａｌｓＲｅｓｅａｒｃｈ＆Ａｎ...     

Effect of Etched Depth on Glass Strength

Studies of fracture strength of abraded and as-received glass tubes as a function of etching depth showed that at depths less than the calculated initial flaw depth (∼50 μm) the strength increase was almost entirely due to reduction inflow depth from etching. This result is consistent with model 1 proposed by Proctor; it disagrees with his interpretation of his own results, no doubt because his study focused on etching depths of ≥100 μm.     

The Effect of Preparation Conditions on Tensile Strength of Soda-Lime-Silica Glass Rods

A study has been made of the relationship between conditions of specimen preparation and the tensile strength of small constricted soda-lime-silica glass rods. The preparation and testing techniques were basically the same as those used in a previous investigation' except that the drawing loads were systematically varied. It was found that different loads under which specimens were drawn resulted in significant changes in tensile strength values. The average strength values varied from 62,800 lb. per sq. in. to 88,400 lb. per sq. in., depending on the drawing loads used. Maximum strength values were obtained with the highest loads. The limits of error of the strength values did not change appreciably with different drawing conditions. Rubbing the specimens with the fingers reduced the strength by approximately 32%.     

Effect of Certain Organic Liquids on Strength of Glass

This investigation was undertaken to determine the effect of certain organic liquids on the strength of glass. Constricted glass rods 10 to 12 mils in diameter were broken under various organic liquids and the strength changes were noted and compared with breakage under water. In all cases except one (nitrobenzene), breaking strengths were higher under the organics than under water, ranging from increases of 36 to 19% for alcohols to values of 10 for heptane, benzene, and toluene. The value of 10 is equivalent to breakage in air. It is believed that the polar character of an organic liquid, its molecular bulk, and its solubility in water are significant factors in its effect on the strength of glass.     

酸处理对浮法玻璃抗折强度的影响

通过用一定浓度的硫酸、氢氟酸溶液对4 mm厚的浮法玻璃进行预处理,再采用离子交换的方法来制备钢化玻璃。然后通过测量玻璃试样的抗折强度,分析酸处理中不同因素对玻璃抗折强度的影响。实验发现氢氟酸的效果最好。     

端面摩擦对玻璃压缩强度的影响

为了研究端面摩擦对玻璃压缩强度的影响,采用铜箔和凡士林对压缩接触面进行减摩处理,使用MTS试验机对钠钙硅玻璃样品进行应变率为10^-4 s^-1的准静态压缩试验,利用高速摄影记录了试件的破坏过程,进一步分析了玻璃强度的统计分布规律。试验结果表明:玻璃样品的接触面只有凡士林时,在压缩过程中出现显著裂纹及部分表面碎片脱落;玻璃样品在接触面加入铜箔后再涂凡士林,整个压缩过程受力均匀,未出现显著裂纹或碎片脱落,呈现为理想的均匀压缩状态。端面摩擦力的降低导致玻璃压缩强度的显著降低,这主要是因为减小摩擦力使试样端部所承受的横向约束变弱,试样处于更加接近单轴应力的状态,一定程度上减少了围压引起的强化效应。     

Effect of Micromechanical Stress Cocentrations on Strength of Porous Glass

The effect of micromechanical stress concentrations around elastic discontinuities in a glass was investigated. Specimens of glass containing porosity of controlled size and volume fraction were fabricated by vacuum hot-pressing and strength was tested under uniaxial and biaxial stress conditions. Results were interpreted as a function of the relative sizes of Griffith flaws and the volume of material over which stress concentrations act. For the glass investigated, assuming an adequate flaw density, the strength was dependent on pore size and volume fraction as well as on the loading conditions. It is suggested that differences in uniaxial and biaxial strength are due to differences in stress concentration geometry.     

Effect of Silicone Quenching and Acid Polishing on the Strength of Glass

Soda-lime glass rods 5 mm in diameter were quenched in silicone oil and also in a saturated hydrocarbon oil of similar viscosity. The effect of etching, etching and quenching, and etching, quenching, and re-etching was examined in relation to the strength of the rods. Rods quenched in the silicone oil were no stronger than those quenched in the hydrocarbon oil. Etched rods had a strength of 300,000 psi. Quenching these high-strength rods reduced their strength to 110,000 psi. This decrease in strength may be explained in terms of the formation of crystalline and noncrystalline microflaws during the heating and cooling cycle. Re-etching, after quenching, resulted in rods with a maximum strength of 384,000 psi.     

Effect of Surface Energy on the Mechanical Strength of a High-Silica Glass

The mechanical strength of high-silica glass was measured in various organic liquids and in water. The extent of the surface-energy reduction of glass was also estimated from the swelling or the expansion of porous glass, immersed in liquids, by measuring the stress in the core of a partially leached glass. The stress, normalized to the value in water, showed a good correlation with the heat of immersion, which is a measure of the surface-energy reduction. Mechanical strength and the stress due to swelling showed a reasonable correlation, suggesting that the strength variation in various liquids is due to the surface-energy variation and the accompanying force which caused the swelling.     

Effect of the Position of the Float-Side on the Bending Strength of Sheet Glass

It is established that the lateral bending strength of sheet glass produced by the float method depends on the position of its float-side with respect to the load applied. If the side contacting tin (the float-side) in bending is in the tension zone, the strength of the glass on the average decreases by 40% compared to its strength when the float-side is in the compression zone. This phenomenon has to be taken into account in designing light-transmitting structures and three-layer glass. __________ Translated from Steklo i Keramika, No. 5, p. 11, May, 2005.     

Effect of Stress and Temperature During Forming on Strength of Glass

The effect of mechanical stress during the drawing process on the strength obtained was determined for large-diameter fibers of soda-lime-silica glass. Fibers were formed by down-drawing cane at a constant rate, using loads of from 100 to 8000 gm. Tensile strength was determined by transverse loading on annealed specimens. The results showed that the variation of temperature and load during forming increased the strength of the drawn fiber as much as 62%. The tendency toward increased strength persisted, but to a lesser extent, after the surface of the fibers was abraded.     

激光内雕工艺对玻璃强度和钢化性能的影响

激光加工是一种高效环保的材料加工方法,激光内雕玻璃因具有经久耐磨、图案精美的特点,得到越来越广泛的应用.采用波长为532 nm的激光对玻璃进行内雕加工,测试分析了激光加工后玻璃内部的断口形貌、抗弯曲强度和抗冲击强度,研究了激光能量、点间距和层间距等激光加工参数对玻璃强度及后续物理钢化性能的影响.研究结果表明,当玻璃的厚度为5 mm时,在激光加工点间距设置为0.13 mm、层间距设置为0.80 mm、激光能量设置为6.5 V的条件下,玻璃的性能较好、且适合后续的物理钢化加工.     

Effect of Gamma Radiation on the Strength of Plate Glass of Varying Arsenic Content

Samples of plate glass containing a small amount of arsenic oxide as well as arsenic-free samples were subjected to gamma radiation from a cobalt-60 source after which modulus of rupture measurements were made. The arsenic-containing glass showed a significant increase in strength upon irradiation while the arsenic-free glass became weaker.     

废弃玻璃粉对活性粉末混凝土强度的影响

研究了玻璃粉作为矿物掺合料替代部分水泥配制活性粉末混凝土(RPC)的可行性.研究了玻璃粉掺量、细度以及养护温度对RPC强度的影响;采用数理统计分析方法进行数值处理,求得玻璃粉掺量、细度以及不同养护温度与RPC强度间的多元线性回归方程,分析三个因素的影响规律.试验结果表明:玻璃粉可作为掺合料加入RPC中并提高其强度;当玻璃粉掺量为10％、研磨1h、养护温度为80℃时试件的抗压强度最佳.     

Effect of Loading Rate and Surface Conditions on the Flexural Strength of Borosilicate Glass

This study evaluates the loading rate and surface condition dependence of the flexural strength of a borosilicate glass. The glass specimens are subjected to three different surface treatments before four-point bending tests to study the effect of surface flaws. Quasistatic (Material Test System 810) and dynamic (Kolsky bar) experiments are performed at loading rates ranging from 0.7 to 4 × 10⁶ MPa/s. The results show that the flexural strength of the borosilicate glass has a strong dependence on the loading rate. A chemically etched surface produces an enhanced flexural strength by about an order of magnitude. Scanning electron microscopy images on fracture surfaces indicate that the failure is governed by different types of flaws under different surface treatment conditions. Edge failure is also identified for samples possessing high flexural strength.     

Indentation Strength of Glass

The tensile strength of plate and sheet glasses was investigated by means of indentation experiments with small spherical indenters. In agreement with earlier experiments by Powell and Preston, tensile strengths were observed about 10 to 100 times higher than those found in tensile or bending tests, the highest values being about one-half the greatest strength of thin fibers or freshly drawn rods. It did not seem that any further reduction of the diameter of the indenting sphere below 1 mm. would lead to a significant increase of the highest strength values. The highest values of the indentation strength of freshly cleaved surfaces were not above those of ordinary surfaces, although the average was considerably higher. This indicates that, unless the use of the Hertz stress distribution involves a significant inaccuracy, the upper limit of about 300,000 lb. per sq. in. of the tensile stress may represent the order of magnitude of the tensile strength of bulk glass in the absence of surface defects. This value is within a factor of two to five of the probable molecular tensile cohesion of a glass of maximum homogeneity. Fracture stress histograms and maximum endured stress histograms are given for a variety of flat glasses.     

Effect of Contact Residual Stress Relaxation on Fracture Strength of Indented Soda-Lime Glass

The strength of Vickers-indented soda-lime glass measured in air at room temperature steadily increases with time after indentation, whereas optical retardation steadily decreases in the same interval. Annealing after indentation causes further strength increase and retardation decrease. The results are consistent with Marshall and Lawn's treatment of the slow crack growth of indentation flaws driven by the combined influence of residual contact stress and applied stress. Post-indentation strengthening of indentation flaws can be explained without recourse to flaw blunting.