Tool Wear and Its Effect on Surface Roughness in Diamond Cutting of Glass Soda-lime

For the technology of diamond cutting of optical glass, the high tool wear rate is a main reason for hindering the practical application of this technology. Many researches on diamond tool wear in glass cutting rest on wear phenomenon describing simply without analyzing the genesis of wear phenomenon and interpreting the formation process of tool wear in mechanics. For in depth understanding of the tool wear and its effect on surface roughness in diamond cutting of glass, experiments of diamond turning with cutting distance increasing gradually are carried out on soda-lime glass. The wear morphology of rake face and flank face, the corresponding surface features of workpiece and the surface roughness, and the material compositions of flank wear area are detected. Experimental results indicate that the flank wear is predominant in diamond cutting glass and the flank wear land is characterized by micro-grooves, some smooth crater on the rake face is also seen. The surface roughness begins to increase rapidly, when the cutting mode changes from ductile to brittle for the aggravation of tool wear with the cutting distance over 150 m. The main mechanisms of inducing tool wear in diamond cutting of glass are diffusion, mechanical friction, thermo-chemical action and abrasive wear. The proposed research makes analysis and research from wear mechanism on the tool wear and its effect on surface roughness in diamond cutting of glass, and provides theoretical basis for minimizing the tool wear in diamond cutting brittle materials, such as optical glass.

Modeling and Evaluating of Surface Roughness Prediction in Micro-grinding on Soda-lime Glass Considering Tool Characterization

The current research of micro-grinding mainly focuses on the optimal processing technology for different materials. However, the material removal mechanism in micro-grinding is the base of achieving high quality processing surface. Therefore, a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography is proposed in this paper. The differences of material removal mechanism between convention grinding process and micro-grinding process are analyzed. Topography characterization has been done on micro-grinding tools which are fabricated by electroplating. Models of grain density generation and grain interval are built, and new predicting model of micro-grinding surface roughness is developed. In order to verify the precision and application effect of the surface roughness prediction model proposed, a micro-grinding orthogonally experiment on soda-lime glass is designed and conducted. A series of micro-machining surfaces which are 78 nm to 0.98 ~tm roughness of brittle material is achieved. It is found that experimental roughness results and the predicting roughness data have an evident coincidence, and the component variable of describing the size effects in predicting model is calculated to be 1.5x 107 by reverse method based on the experimental results. The proposed model builds a set of distribution to consider grains distribution densities in different protrusion heights. Finally, the characterization of micro-grinding tools which are used in the experiment has been done based on the distribution set. It is concluded that there is a significant coincidence between surface prediction data from the proposed model and measurements from experiment results. Therefore, the effectiveness of the model is demonstrated. This paper proposes a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography, which would provide significant research theory and experimental reference of material removal mechanism in micro-grinding of soda-lime glass.

Model of Diffusion of Sulfur in Soda-lime-silicate Glass:An Experimental and Comparative Study

The diffusion property of sulfur on the soda-lime-silicate float glass surface was studied by using secondary ion mass spectroscopy（SIMS）.According to the Fick＇s Second Law,two models of diffusion of sulfur on the glass surface were built.When the diffusion of sulfate（S^6＋） is considered uniquely,the concentration-depth profile of sulfur can not be fitted very well,especially on the top surfaces of the air side and tin side of float glass.So the diffusion of sulfide（S^2-） on the profile of sulfur can not be ignored.The concentration-depth profile of sulfur on both sides of glass can be fitted more exactly when both S^6＋ and S^2- are considerd.Based on the above-mentioned fitting results,it is concluded that the diffusion coefficents of S^6＋ and S^2- of tin side are larger than those of the air side.Moreover,the diffusion coefficents are related to the contacted medium.

金刚石切削Soda-lime玻璃中的刀具磨损及其对工件表面粗糙度的影响

金刚石切削加工光学玻璃时,工件表面粗糙度与刀具磨损直接相关,为研究切削距离递增下的金刚石刀具磨损及其对工件加工表面粗糙度的影响,进行了Soda-lime玻璃金刚石切削的刀具磨损试验,并对刀具磨损形貌、后刀面磨损带的材料成份、工件的表面形貌及粗糙度进行了检测.结果表明:切削距离递增下的金刚石刀具前刀面磨损表现为平滑且均匀的月牙洼磨损,后刀面磨损表现为磨损带逐渐增大,且磨损带内有沿切削方向的微沟槽产生;切削距离未达到150 m时,工件表面粗糙度Rq、Ra及Rmax值始终低于32、25及300 nm,切削距离超过150 m后,工件表面粗糙度显著增大.机械摩擦作用、热化学作用及磨料磨损作用为导致金刚石刀具磨损的主要原因.

Structural Change in Au^3＋-Doped BK7 Glass Irradiated by Femtosecond Laser

We report on structural change in an Au^3＋-doped BK7 glass irradiated by an infrared femtosecond laser at 800 nm. A grating structure is inscribed in the glass sample. The glass sample is then annealed at various temperatures. Structural change of the grating is observed by an optical microscope. Absorption spectra indicate that colour centres are induced after the laser irradiation, and they decrease with increasing annealing temperature. Au nanoparticles are precipitated at high temperatures （≥ 600℃）. The mechanisms of the phenomena are discussed.

Production of High-Purity Silica Sand from Ivorian Sedimentary Basin by Attrition without Acid Leaching Process for Windows Glass Making

To produce high-purity silica sand usable for glass making, the present study was carried out. The objective of this work was to increase the silicon dioxide (SiO2) content to at least 99% using a simple process without chemical input. The raw sand samples were taken from the Ivorian sedimentary basin, from Maféré and Assinie areas, Côte d’Ivoire. Wet sieving and attrition technique were used for the purification process. The results from the energy dispersive spectrometer (EDS) analyses of the raw and treated samples show a significant increase of silica content and a significant reduction of impurities. The silica content (SiO2) of the sand of Maféré increases from 98.73% ± 0.15% to 99.92% ± 0.05%. And the sand of Assinie increased from 98.82% ± 0.67% in the raw samples to 99.44% ± 0.27% after treatment. The rate of iron oxide and alumina is reduced in these sands. Moreover, the sand of Maféré contains 53.2% of grains of size lower than 500 microns and that of Assinie contains 29.30%. Regarding the chemical composition of these purified sands, they meet the standard BS2975s, the American Ceramic Society and the National Bureau of Standards for window glass making.

氧化锌对钠钙玻璃的抗菌性及工艺性能的影响

采用高温熔融法制备钠钙玻璃,研究不同量的氧化锌对钠钙玻璃抗菌性和工艺性能的影响。采用贴膜法分析玻璃的抗菌性,测试包括表面张力、高温黏度和熔化澄清的工艺性能。结果表明:当氧化锌引入的质量分数大于3%时,玻璃对大肠杆菌和金黄色葡萄球菌的抗菌性达到90%以上;氧化锌的引入降低了玻璃的表面张力和高温黏度,使高温玻璃熔体中气泡的排出速率增大,气泡数量减少,利于玻璃熔体澄清,适用于工艺生产。

锆刚玉砖在超白及普通钠钙硅玻璃液中侵蚀分析

通过在实验室分别模拟了超白玻璃液和普通钠钙硅玻璃液对AZS33砖的动态侵蚀试验,即在相同温度、相同冲刷#速度和相同侵蚀时间的工况下,对电熔AZS33砖侵蚀量进行对比,分析得出由于超白玻璃液中铁含量较低,玻璃液的导热性好,玻璃液黏度低,在相同工况下对锆刚玉砖侵蚀更为严重。

应用裂纹控制法的钠钙玻璃YAG激光切割技术

针对目前对玻璃切割质量越来越高的需求,应用裂纹控制法进行了连续YAG激光切割钠钙玻璃的试验,分析了激光功率、激光扫描速度、激光光斑大小对切割质量的影响规律,得到了YAG激光切割钠钙玻璃平板的最佳切割参数。同时利用光学显微镜照片研究了玻璃切口表面的质量,对比了激光切割与机械法切割得到的玻璃切口质量,结果表明:采用裂纹控制法的玻璃YAG激光切割技术可以得到很好的切口质量,应用于高质量玻璃的加工。文中还进行了多层玻璃、管状玻璃以及平板玻璃曲线轨迹的YAG激光切割试验,为YAG激光切割玻璃的进一步应用提供了技术基础。

浮法超薄玻璃化学钢化及性能研究

本文研究高铝超薄浮法玻璃与浮法钠钙硅玻璃的化学钢化过程。用全自动化学钢化玻璃表面应力测试仪、万能试验机和数显显微维氏硬度计分别测试了样品的表面应力、应力层深度、抗折强度和显微硬度。结果表明:在一定的温度下,随着离子交换时间的增加,高铝超薄玻璃与浮法钠钙硅玻璃的表面应力、抗折强度、显微硬度均出现先增加再到减小的趋势,应力层深度则随着时间的增加而加深。在同样的离子交换制度下,高铝玻璃化学钢化后的力学性能优于钠钙硅玻璃。同时,以浮法工艺生产的玻璃锡面的表面应力小于非锡面的应力,应力层深度也相对小于非锡面的深度。

钠钙玻璃板激光热应力切割过程的有限元仿真

为了使脆性材料板的激光热应力切割得以完成并提高切割质量,提出了一种切割过程的仿真方法.利用有限元法分析玻璃板在激光扫描过程中的瞬态热传导,求得瞬态温度场.按热弹性平面应力理论分析热应力场,并采用最大切向应力准则和节点松弛法模拟板材的开裂.通过该仿真方法分析了钠钙玻璃板的切割过程,根据所导致的温度最高值和板材的开裂情况,研究了激光功率和激光扫描速度这两个关键参数对切割的影响,并给出了可完成连续切割的参数范围.仿真结果表明,该方法可以对激光功率和扫描速度等激光参数进行优化调节,从而改善切割的质量.

陶瓷材料压痕韧性的统计性质

采用直接压痕法测定了钠钙硅酸盐玻璃和一种ＴｉＣ 颗粒增强Ａｌ２Ｏ３复合材料的断裂韧性．研究表明，在同一压痕压制荷载下测得的同一种材料的压痕韧性呈现出较大离散性，可以采用Ｗｅｉｂｕｌｌ分布加以较好地描述．对两种材料的试验数据的对比分析指出，压痕韧性测试值的离散性反映了材料显微结构的不均匀性对材料局部裂纹扩展阻力的影响．基于这一分析，本文建议采用直接压痕法测定材料断裂韧性时，应尽可能增大试验量，从而对压痕韧性测试结果的统计性质作出完整描述．

一种钠钙硅酸盐玻璃的纳米压痕测试分析

采用纳米压痕测试技术对一种钠钙硅酸盐玻璃进行微观力学性能的测试分析.测得加载-卸载过程载荷与压入深度曲线,发现被测玻璃的最大压深、残余深度和弹性回复量随最大加载力的增加而增大,但其相对弹性回复率系数基本稳定,平均值为58.2%.通过电子显微镜观察了不同最大载荷下的压痕形貌,发现压痕区域出现了边界沉陷现象.当最大加载力为1 000 mN左右时,三棱锥工具头测试的压痕区域出现了较明显的微裂纹;采用四棱锥工具头时出现微裂纹的最大加载力要小于该值,且裂纹取向均与金刚石工具头的棱角取向一致.利用非线性有限元软件MSC.Marc对纳米压痕过程进行了仿真分析,得到载荷与压入深度的仿真曲线,该曲线与试验结果基本相符;分析了载荷作用下材料内部的应力分布.利用Oliver-Pharr模型得到不同压入深度下被测玻璃的接触刚度值,该值随压入深度的增加而增大.

钠钙玻璃上Mg_2Si薄膜的制备及其电学性质

采用磁控溅射技术和退火工艺在钠钙玻璃衬底上制备了Mg_2Si半导体薄膜,研究了Mg膜厚度对Mg_2Si薄膜结构及其电学性质的影响。在钠钙玻璃上分别溅射两组相同厚度(175nm)的P-Si和N-Si膜,然后在其上溅射不同厚度Mg膜(240nm、256nm、272nm、288nm、304nm),低真空退火4h制备一系列Mg_2Si半导体薄膜。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、霍尔效应测试仪对Mg_2Si薄膜的晶体结构、表面形貌、电学性质进行表征与分析。结果表明:采用磁控溅射技术在钠钙玻璃衬底上成功制备出以Mg_2Si(220)为主的Mg_2Si薄膜。随着沉积Mg膜厚度的增加,Mg_2Si衍射峰逐渐增强,薄膜表面更连续,电阻率逐渐减小,霍尔迁移率逐渐降低,载流子浓度逐渐增加。此外,Si膜导电类型和Mg膜厚度共同影响Mg_2Si薄膜的导电类型。溅射N-Si膜时,Mg_2Si薄膜的导电类型随着Mg膜厚度的增加由P型转化为N型;溅射P-Si膜时,Mg_2Si薄膜的导电类型为P型。可以控制制备的Mg_2Si半导体薄膜的导电类型,这对Mg_2Si薄膜的器件开发有着重要的指导意义。

冲击载荷作用下脆性材料的失效波实验研究

为研究玻璃、陶瓷等脆性材料在冲击加载条件下的失效波问题,在一维应变条件下,采用VISAR测量了不同冲击载荷作用下A95氧化铝陶瓷和soda lime玻璃试件背面的粒子速度时间历程。结果显示:采用相同的实验方法,soda lime玻璃试件背面粒子速度时间曲线出现了表征失效波现象的再压缩信号,与文献[1,4,8-12,17-21]结果一致,而氧化铝陶瓷试件无此现象出现。这表明陶瓷与玻璃虽同为脆性材料,但是其破坏机制不尽相同,需要进一步开展研究。

氟云母加入量对可加工氟闪石玻璃陶瓷反应析晶的影响

用X射线衍射、扫描电镜研究了不同加入量氟云母晶体的钠钙玻璃粉末在烧结过程中的反应析晶。结果表明:氟云母加入量小于20%(质量分数,下同)时,反应析晶形成透辉石;加入40%时形成氟闪石;加入60%时氟闪石和氟云母共存;加入80%时大部分氟云母未反应,只有少量氟闪石形成。提出氟云母向透辉石和氟闪石转变的晶体学模型来解释上述结果。烧结过程中,玻璃中的Na2O和CaO通过扩散进入氟云母晶体,导致硅氧四面体平面网断裂,转变成链状结构。反应析晶的最终产物与进入氟云母晶体中的氧含量有关,决定于最终晶体中O和Si的摩尔比。

陶瓷材料应力腐蚀特性的测试与分析

建立了玻璃与陶瓷材料应力腐蚀(SCC)特性的有效测试方法,对Al_2O_3陶瓷和普通钠钙玻璃两种材料在水、甲醇和甲酰胺三种介质中的SCC特性进行了试验研究。结果表明,Al_2O_3陶瓷在上述三种介质中的da/dt-K_1曲线均存在平台区,而钠钙玻璃在上述介质中均不存在平台区。Al_2O_3陶瓷和钠钙玻璃在三种介质中的SCC敏感性大小依次为:蒸馏水>甲醇>甲酰胺。理论分析认为,SCC敏感性与介质未共享电子轨道的非对称性及给H^+质子键的活性有关。文中还对两种材料是否出现平台区的差异从理论上进行了探讨。

等离子体显示屏用基板玻璃的研究现状

从等离子体平板显示技术和等离子体显示屏(PDP)对前后基板玻璃的要求出发,介绍了传统钠钙硅玻璃及PD200和Cs25等几种新型玻璃的组成、性能特点和应用中存在的问题与不足。指出了开发一种性能优异、成本低廉且适合于大规模工业化生产的PDP专用基板玻璃的制备技术和产品对我国国民经济建设和国防军建设的重要意义。

钠钙硅酸盐玻璃和铅玻璃的离子溅射抛光

采用 2 0keV的离子注入机对钠钙硅酸盐玻璃和中铅玻璃进行离子溅射抛光。玻璃样品在N+ 离子剂量为 1× 10 14 ions/cm2 、1× 10 17ions/cm2 ,束流强度 15 0 μA/cm2 于室温下抛光。

彩色平板等离子体显示器(PDP)用基板玻璃

本文分析了普通钠钙玻璃不能作为大面积彩色ＰＤＰ基板玻璃的原因，指出大面积ＰＤＰ最终应用的基板玻璃必将是与现已开发应用的、与彩色ＰＤＰ相关材料匹配的，但其应变点温度高于彩色ＰＤＰ制造过程中最高热处理温度的玻璃，同时提出了一种在ＰＤＰ制造过程中减小普通钠钙玻璃热变形的方法。最后从浮法玻璃的制造方法和特点出发，指出彩色ＰＤＰ制造工艺中，应特别区分浮法玻璃的正反面。