Strength and Fatigue of Fluoride Glass Optical Fibers

Strength and fatigue characteristics of fluoride glass optical fibers, used as a new infrared transmission medium, were examined. A correlation parameter between mirror size and tensile strength of 0.826 MPa.m¹² was obtained, and a fatigue parameter of 16.2 was determined from a dynamic fatigue test at 20°C and 60% rh .     

Mechanical Properties of Phosphate Glass Optical Fibers

In this work, step-index 40/125 μm diameter optical fibers produced from two slightly different lithium phosphate glasses were subjected to mechanical characterization. Tensile tests were carried out on fibers with gage length from 10 to 150 mm, allowing for the determination of the failure stress (ranging from ≈200 to 400 MPa) and the elastic modulus (60 GPa). Some tests were also performed with the fiber “immersed” in water; an important subcritical crack growth effect was pointed out, and a fatigue susceptibility parameter (n) equal to 11.4 was determined. The analysis of fracture mirror allows an estimated fracture toughness equal to 0.5 MPa m^0.5.     

Predicted Static Fatigue Behavior of Specially Coated Optical Glass Fibers

Long-term static fatigue behavior of optical glass fibers is controlled by their strength, fatigue resistance, and zerostress aging behavior. The effectiveness of four special coatings in preventing the long-term static fatigue deterioration of optical glass fibers was evaluated by determining the dynamic fatigue behavior and the effects of zero-stress aging on strength of the four specially coated optical glass fibers in water from 25° to 85°C. The results clearly show that the strength, fatigue resistance, and aging behavior varied significantly between these specially coated fibers. By analysis of these experimental results in terms of fracture mechanics principles, the predicted static fatigue behaviors of the four fibers were compared. Ideally the optimum fiber is one that exhibits a high strength, low strength variability, high fatigue resistance, and high aging resistance. Each of these specially coated fibers had a deficiency in at least one of these properties.     

碲卤系红外玻璃光纤的制备及性质

研究了碲卤系中远红外玻璃光纤的制备及性质,提出了制备碲卤系玻璃预制棒的一个改进的方法,用该方法制备出了高透光率的中远红外玻璃,拉制出了在１０．６μｍ附近光损耗约为１０ｄＢ／ｍｒ Ｔｅ３Ｓｅ４Ｉ３玻璃光纤,并测试了这种玻璃纤维的最小抗弯曲率半径。     

Strength of Proof-Tested Optical Fibers

Minimum strengths of proof-tested optical fibers were investigated on the basis of the fracture mechanics concept. To confirm truncation of the minimum strength by the proof test, tensile tests were performed for long proofed fibers over a total length of 150 km. The results confirm that the proof test is useful in guaranteeing the minimum strength.     

Fluoride Glass Fibers with Improved Mechanical Strength

The practical strength of ZrF₄-based optical fibers reported to date is still significantly lower than that of state-of-the-art silica fibers. Longer length fluoride fibers with improved strength were, however, achieved after the preforms were polished to a mirrorlike finish prior to etching in acidic ZrOCl₂ solution. Strength in the range of 430 to 820 MPa (62 to 119 ksi) was observed using the bend technique.     

Static Fatigue of Optical Fibers in Bending

A two-point bending technique for making static fatigue measurements on optical fibers is described which allows large quantities of data to be rapidly and conveniently gathered. Statistical analysis is used to compare the times to failure of the method with those of the commonly used mandrel and tensile methods. Direct experimental comparison of the two-point bend and tensile methods shows that while the times to failure are generally longer for two-point bend than tension, the essential fatigue behavior is identical for the two methods.     

高强度高模量玻璃纤维开发状况

从玻璃纤维本身物化性能的角度,结合其专利情况对目前市场上出现的各种高强度高模量玻璃纤维进行了较全面的汇录。高强度高模量玻璃纤维以其高强度、高模量、高耐热性、高耐腐蚀性等优异性能,广泛应用于航天、航空、兵器、舰船、化工等对复合材料性能要求更苛刻的领域。详细对比分析了高强度高模量玻璃纤维的化学组成、机械性能和作业情况。     

Correlation of Strength of Glass with Fracture Flaws of Measured Size

The purpose of this study was to develop a method of producing a single small crack on a glass surface which would become the initiating flaw in the fracture process. Techniques for measuring dimensions of this flaw also formed an essential part of the study. The cracks were formed by pressing a wedge-shaped tungsten carbide point against the glass. Measurements were made from visible patterns found on the fracture surface after the glass was broken. Strict adherence to carefully worked out procedures was found to be essential for obtaining satisfactory cleaved cracks. Based on fracture caused by a semicircular crack 0.002 in. deep, the 1-second breaking stresses of five different glasses were as follows: lead-alkali glass 6800, soda-lime glass 9000, 96% silica glass 11,500, low-expansion borosilicate glass 12,000, and aluminosilicate glass 13,800 lb. per sq. in. These values are believed to correlate with the intrinsic strengths of the glasses. This method should have definite advantages in the investigation of fracture phenomena in glasses and in other brittle materials, specifically the effects of composition on strength and the causes of stress fatigue     

Strength Measurement of Optical Fibers by Bending

A bending technique for the strength measurement of glass fibers is described and an analysis is presented which determines the effective tested length as a function of the statistical parameters which describe the fracture properties of the fiber. The analysis is used to compare strength data determined in both tension and bending for various representative fibers. It is found that the tensile strength cannot be predicted from the strength in bending and vice versa because the tested lengths differ by at least 3 orders of magnitude. Thus, while bending does not replace tension as a measurement technique, it does provide additional valuable information about the flaw size distribution.     

中红外碲酸盐玻璃及光纤研究进展

近/中红外激光和超连续光源在红外光电对抗、生物医疗、遥测感知和激光探测及测距(LIDAR)等领域具有十分重要的应用价值。近年来,基于软玻璃光纤来产生和传输高亮度近/中红外(特别是2～5μm)激光方面的研究取得了显著进展。在中红外软玻璃基质中,具有相对较低声子能的碲酸盐玻璃对于设计近红外和中红外激光器和放大器、高功率中红外激光传输和传感应用无源光纤具有特别的吸引力。本文重点总结了低损耗碲酸盐玻璃的关键制备技术,并综述了碲酸盐玻璃及光纤在稀土掺杂中红外发光方面的研究进展,最后对碲酸盐玻璃及光纤应用存在的问题和发展趋势进行了总结和展望。     

Relation Between Multiregion Crack Growth and Dynamic Fatigue of Glass Using Indentation Flaws

The influence of transport-limited kinetic crack growth on the fatigue properties of soda-lime glass was examined. Dynamic fatigue data were taken on specimens with controlled indentation flaws and were compared with the predicted response from measured crack velocity characteristics. Heptane was used as the operational test environment because of its pronounced crack velocity plateau; control tests in water served to establish a baseline reference for comparing the results. Frac-tographic observations using a stress wave marker technique showed a complex growth history for flaws broken in heptane compared to that for flaws broken in water. The magnitude of the predicted region II influence is too small to be detected in the dynamic fatigue results, even allowing for the relatively high degree of data reproducibility. The implications of this conclusion for lifetime predictions are discussed.     

含镝玻璃的制备及性能研究

以Dy2O3、Li2CO3和H3BO3为原料,制得满足医学使用要求的DyLB系统玻璃微球.通过测定该系统的密度、显微硬度、结构以及生物特性,结果显示:DyLB玻璃的密度随Dy2O3替代B2O3而逐渐增大;当Li2O质量分数为10%,显微硬度随Dy2O3含量的增加先升高后降低;DyLB玻璃微球具有良好的生物相容性.     

Cladding Glass Development for Semiconductor Core Optical Fibers

Glass-clad optical fibers comprising a crystalline semiconductor core have garnered considerable recent attention for their potential utility as novel waveguides for applications in nonlinear optics, sensing, power delivery, and biomedicine. To date, cladding compositions have relied on commercially-available expedients and have not been tailored for the specific semiconductor core nor the application. In this work, more-optimum silicate and nonoxide glass compositions are developed for unary (Si, Ge), binary (InSb, GaAs), and ternary (GaAlSb) semiconductor cores based on two main design criteria: (1) matching the thermal expansion coefficient between semiconductor core and glass cladding and (2) matching the viscosity-temperature dependences such that the cladding glass draws into fiber at a temperature slightly above the melting point of the semiconductor. While this latter requirement is critical to the molten core fabrication method, which offers a practical approach to long fiber lengths at acceptable manufacturing speeds (>m/s), these compositions are more broadly applicable to other semiconductor fiber processing methods. Preliminary experimental results on silicon core optical fiber are provided and show a marked diminution in oxygen content relative to analogous fibers drawn using a pure silica cladding.     

Acoustic Location of Fracture Origin in Optical Glass Fibers

During strength measurements on plastic-coated optical glass fibers, the positions of fracture origins were determined by an acoustic technique. For samples other than those in which fracture was initiated at or very near the fixed ends, Weibull plots of the strength data exhibited a single-mode distribution with low variability (m=20 to 25, corresponding to a coefficient of variation of 6.6 to 10.6%).     

Relation of Microindentation Hardness to Glass Composition

Microindentation hardness measurements on Na₂O-CaO-SiO₂ and Na₂O-Al₂O₃-SiO₂ glasses showed that Knoop hardness numbers are linearly related to oxide compositions expressed in mole fraction. Evaluations of the data indicate that these linear relations are unique for each of the primary crystallization phase fields of the glasses studied.     

远红外Ge-Te-Se硫系玻璃与光纤(英文)

采用传统的熔融–淬冷法制备了系列GexTe65Se(35–x)(x=20,22,23,24;摩尔分数,x%)Te基硫系玻璃。利用X射线衍射、差示扫描量热分析、分光光度计、红外光谱仪等设备研究了玻璃的性能。这些玻璃具有良好的热稳定性和红外透过性能。组分为Ge23Te65Se12,Ge24Te65Se11的玻璃的差示扫描量热曲线中没有出现析晶峰,表明玻璃具有良好的抗析晶性能。组分为Ge24Te65Se11的玻璃的转变温度Tg最高,达到了188℃。这些玻璃样品的红外透过范围都很宽,从近红外的1.8μm到远红外的18μm。通过在玻璃的制备工艺中引入蒸馏提纯工艺可以有效减弱杂质吸收峰对玻璃红外透过性能的影响。最后,选用Ge23Te65Se12玻璃作为包层,Ge24Te65Se11玻璃作为纤芯,采用棒管法完成了具有纤芯包层结构的Ge-Te-Se红外光纤的拉制。     

SiO2-Al2O3-MgO系高强玻璃纤维耐酸性能研究

采用高温熔融法制备了SiO2-Al2O3-MgO系统的S级高强玻璃纤维,研究了不同玻璃组分对玻璃耐酸性能的影响,利用扫描电镜(SEM)、红外光谱(IR)和核磁共振(NMR)等手段分析了酸侵蚀前后纤维的表面形貌和微观结构,进而分析了S级高强玻璃纤维在酸腐蚀环境下的破坏机理.结果表明:S高强玻璃的结构主要由硅氧四面体[SiO4]和铝氧四面体[AlO4]等构成,随着酸蚀的进行,玻璃网络结构被破坏,Si-O-Si断裂形成Si-OH键并形成凝胶附着在纤维表面;而铝氧多面体中Al-O键断裂,Al3+逐渐从玻璃结构中被置换出来,导致玻璃网络中Al3+浓度大大降低;高强系列玻璃的耐酸性能与玻璃表面的化学组成以及玻璃内部的微观结构关系密切.致密的玻璃网络结构有利于抑制H+对玻璃结构破坏,抑制阳离子与H+的置换作用;此外引入离子场强高的Ti4+,由于"积聚"作用而使玻璃结构致密,提高玻璃纤维的耐酸性.