固结磨料研磨镁铝尖晶石的材料去除机理

研磨过程中机械去除作用与化学去除作用的有效分离是实现研磨过程可控调节及提高加工表面质量的前提.本文通过尖晶石在不同介质中的材料去除速率,对其在不同研磨液中化学与机械作用的材料去除率进行了分离和计算;采用微/纳压痕仪测量了不同研磨液作用下工件表面的显微硬度,依此分析了其软化层厚度.结果表明:研磨液对镁铝尖晶石工件具有一定的化学去除作用,研磨过程中材料去除以机械作用下的脆性去除为主;研磨液的化学作用主要体现在工件表面形成了一层软化层,其中乙二醇产生的软化层最厚,三乙醇胺最薄.     

抛光液酸碱性对固结磨料抛光硫化锌晶体的影响

硫化锌晶体是一种重要的红外光学材料,在红外成像、导弹制导、红外对抗等红外技术领域应用广泛.抛光液能够与工件及抛光垫发生化学反应从而影响工件表面质量和材料去除率.实验采用乙二胺、氢氧化钠、柠檬酸、盐酸分别配制不同的酸碱性抛光液,研究抛光液酸碱性对固结磨料抛光硫化锌晶体材料去除率、表面形貌和表面粗糙度的影响.实验结果表明:酸性抛光液抛光的材料去除率高于碱性抛光液;柠檬酸抛光液可同时获得优表面质量和高加工效率,抛光后的晶体表面粗糙度Sa值为4.22 nm,材料去除率为437 nm/min.     

固结磨料研磨蓝宝石衬底的工艺研究

为获得高材料去除率和优表面质量的蓝宝石衬底,采用固结磨料研磨蓝宝石衬底提高加工效率,研究研磨压强、工作台转速、三乙醇胺(TEA)浓度和研磨垫类型四个因素对材料去除率和表面粗糙度的影响,并综合优化获得高材料去除率和优表面质量的工艺参数.结果表明:有图案的研磨垫、研磨压强为100 kPa、工作台转速为120 r/min、三乙醇胺的浓度为5;为最优研磨工艺参数组合,固结磨料研磨蓝宝石的材料去除率为31.1 μm/min,表面粗糙度为0.309 μm.     

研磨方式对单晶蓝宝石亚表面损伤层深度的影响

研磨过程中产生的亚表面损伤层深度是影响单晶蓝宝石抛光质量的关键因素.本文开展了游离磨料和固结磨料两种研磨方式研磨单晶蓝宝石的实验研究,采用三维形貌仪观察了加工前后的工件表面质量,运用差动腐蚀法比较了研磨方式对研磨后工件亚表面损伤层深度的影响.结果表明,金刚石磨料粒径分别为W 50和W 14的游离磨料研磨加工蓝宝石晶片的亚表面损伤层深度分别为48.85 μm和7.02 μm,而相同粒径固结磨料加工的亚表面损伤层深度分别为5.47 μm和3.25 μm.固结磨料研磨后的工件表面粗糙度也优于相同粒径的游离磨料加工的工件.固结磨料研磨方式对于蓝宝石单晶表面研磨质量的改善和亚表面损伤层深度的降低具有显著的效果.     

磨粒尺寸对FAP研抛工件亚表面损伤层深度的影响

建模分析了固结磨料研抛过程中结构因素与工艺参数对磨粒切入工件深度的影响;采用BOE分步腐蚀法测量了不同磨料粒径FAP研抛后K9玻璃、熔石英玻璃亚表面损伤层深度;建立了亚表面损伤层深度与磨粒粒径之间的相关关系.结果表明:固结磨料研抛条件下,工件亚表面裂纹层深度与工件特性、研抛垫特性及磨粒尺寸相关;基于平均切深的亚表面损伤层模型与实验结果有较好的吻合度.为固结磨料研抛垫的设计与工艺参数的制订提供了理论依据.     

游离碳化硅磨粒辅助的蓝宝石固结磨料研磨研究

采用两种铜粉添加量的FAP,探索游离碳化硅磨料含量对蓝宝石研磨材料去除率和工件表面粗糙度的影响.结果表明:使用相同的研磨液时,铜粉含量高的FAP材料去除率大,表面粗糙度Ra差别不明显;使用相同的研磨垫时,材料去除率随研磨液中碳化硅浓度的增加而增加,FAP的自修正特性随碳化硅浓度的提高而改善.     

磷含量对金刚石镀层形貌及其加工性能的影响

通过化学镀方法,在金刚石颗粒表面制备一层不同P含量的Ni-P合金层;利用SEM分析了镀层的微观形貌;并用其制备了固结磨料研磨垫,比较了不同P含量金刚石研磨垫在加工过程中的摩擦系数、声发射信号及研磨垫的耐磨性;探索了不同研磨垫的加工特性;并与电镀镍金刚石进行了对比.结果表明:金刚石镀层P含量能够明显改变金刚石的形貌;研磨过程中的摩擦系数、材料去除速率和工件表面粗糙度随着P含量的增加呈先增大后减小的趋势;中磷金刚石磨粒对工件的摩擦力和切入深度最大,研磨垫的磨粒保持性与自修整性平衡;电镀金刚石表面粗糙度及加工性能介于低磷与中磷之间.     

腐蚀法测量研磨蓝宝石亚表面损伤的实验研究

化学腐蚀法是一种简单有效的蓝宝石亚表面损伤深度检测方法.利用高温熔融KOH对蓝宝石工件的化学腐蚀作用,开展W40固结磨料研磨后蓝宝石工件的化学腐蚀实验,设计耐高温陶瓷夹具固定腐蚀液中工件位置,并用称重法测算腐蚀速率和腐蚀厚度,揭示亚表面损伤的形成机理.结果表明:采用陶瓷夹具固定工件可使腐蚀面积的均匀性大大提高,平均腐蚀速率提高9.21;左右.蓝宝石工件的腐蚀速率和腐蚀厚度逐渐减小,最后趋于稳定,其亚表面损伤深度约为8.41 μm.天平称重法可有效提高腐蚀速率和腐蚀厚度的测算精度,为蓝宝石亚表面损伤的有效测量提供帮助.     

磨料粒度对雾化施液CMP抛光速率的影响及机理研究

针对超声波雾化施液化学机械抛光过程中磨料的机械作用和化学特性从化学动力学及分子动力学两方面研究了抛光液磨料粒度对材料去除速率的影响和机理.采用不同粒度的磨料及组合进行了雾化施液CMP抛光实验.实验结果表明:磨料粒径在15 nm至30 nm范围内,粒度比较大的磨料能够传递更多的机械能,较小的磨料比较大的磨料具有更强的化学活性,对硅片表面材料的去除影响更为显著.向当前抛光液中加入5wt;的15 nmSiO2时,材料去除率增加至196.822 nm/min,而加入相同质量的30 nm SiO2时,材料去除率增加至191.828 nm/min.说明小尺寸的磨料在雾化施液CMP过程中不仅起着机械作用,还起着增强化学活性的作用.     

碲锌镉晶体高效低损伤CMP工艺研究

本文采用新型的自行研制的化学机械抛光液,对碲锌镉晶体进行了化学机械抛光方法的尝试性试验,并分析了在化学机械抛光(CMP)过程中抛光垫的硬度、磨料的种类、氧化剂、抛光液的pH值对表面质量和材料去除率的影响,提出适合软脆功能晶体碲锌镉的高效低损伤抛光工艺.结果表明,采用自行研制的带有硝酸的化学机械抛光液,在pH优化值为2.5时,15 min即可获得Ra为0.67 nm的超光滑无损伤表面,大大提高了加工效率和精度.     

CsI-LiCl共晶材料的坩埚下降法生长与闪烁性能研究

本文采用坩埚下降法,在真空密封的石英坩埚中成功生长出CsI-LiCl与CsI-LiCl:Na共晶闪烁体。通过扫描电子显微镜(SEM)观察晶体微结构表明该共晶中LiCl相与CsI相存在周期性的层状排列,CsI相的厚度在5 μm左右。共晶样品的X射线激发发射谱显示在CsI-LiCl和CsI-LiCl:Na共晶样品存在缺陷发光,在CsI-LiCl样品中还观察到了纯CsI的自陷激子(STE)发光。CsI-LiCl样品在α粒子激发下的多道能谱中观察到明显的全能峰,这一结果证明CsI-LiCl共晶可用于热中子探测的潜力。     

First-principles coexistence simulations of supercooled liquid silicon

We perform first-principles coexistence simulations of the low-density and the high-density phases of supercooled liquid silicon and find a negative slope for the coexisting line in the temperature-pressure plane. Electron density maps and electron-localization function plots of the two phases of silicon show marked differences. The calculated differences suggest more localized electrons in the low-density liquid compared to the high-density liquid, coming from an increased population of covalent bonds, which further explain the calculated negative slope in the two phase coexistence regime. This is consistent with the presence of a pseudo-gap in low-density liquid silicon, absent in the high-density liquid which shows a metallic behavior.     

静电纺丝法制备CeO2微纳米纤维及其除氟性能

以聚丙烯腈(PAN)为载体,六水合硝酸铈[Ce(NO₃)₃·6H₂O]为原料,采用静电纺丝法制备了Ce(NO₃)₃/PAN纤维,在空气中热处理得到CeO₂微纳米纤维,通过XRD、BET和SEM对CeO₂微纳米纤维进行表征。采用静态吸附实验探讨了CeO₂微纳米纤维去除水溶液中氟离子的性能,考察了溶液pH值、初始氟离子浓度及共存阴离子等对吸附性能的影响。结果表明,pH=3时,CeO₂微纳米纤维对F^-的吸附性能最佳,CeO₂吸附量随着F^-浓度的增大呈上升趋势。CeO₂微纳米纤维对F^-的吸附等温线遵循Langmuir模型,二级动力学模型能很好地描述CeO₂微纳米纤维对F^-的吸附过程。CeO₂微纳米纤维的除氟性能优良,可为其实际应用提供理论参考。     

Crystal structures of thecis andtrans isomers of dithiahexahydro[3.3]metacyclophane

Structures of both thecis andtrans isomers of dithiahexahydro[3.3]metacyclophane, ?C₆H₄?CH₂SCH₂?C₆H₁₀?CH₂SCH₂?, have been determined, wherecis andtrans refer to the attachments to the cyclohexane ring. Thecis form crystallizes in the monoclinic space groupP2₁/c witha=8.4299(11)Å,b=21.772(2)Å,c=8.9724(13)Å, β=116.574(11)^o, andZ=4. Thetrans isomer packs into the monoclinic space groupP2₁ witha=8.159(16)Å,b=10.185(5)Å,c=9.558(2)Å, β=112.435(18)^o, andZ=2. The cyclohexane ring of thecis isomer is in the chair conformation, while the cyclohexane of thetrans isomer is found in a twisted boat conformation.     

CTAB与SDBS对碳酸锶粒子生长形态调控及机理研究

以表面活性剂CTAB和SDBS为化学添加剂,采用化学共沉淀法对碳酸锶晶体的生长形态进行调控,成功地制备出了实心的树枝状和花瓣为空心的花状碳酸锶粉体,并用X射线衍射(XRD)、扫描电子显微镜(SEM)和傅里叶变换红外光谱(FT-IR)等分析手段对样品进行了表征;最后重点对化学添加剂可能产生的影响机理进行了初步的探讨.结果表明,CTAB和SDBS在晶体生长的过程中能起到显著的影响作用,两者对粒子分散性能的作用效果相反,而且后者对晶体(013)和(213)晶面表面能降低的贡献明显大于前者.     

Triethyl ammonium salt of O,O′-bis(p-tolyl)dithiophosphate, [Et3NH]+[(4-MeC6H4O)2PS2]−

Triethyl ammonium Salt of O,O′-bis(p-tolyl)dithiophosphate and O,O′-bis(m-tolyl)dithiophosphate have been obtained by reaction of p- and m-cresol, respectively with P₂S₅ in toluene and have been characterized by elemental analysis, IR, ¹H and ³¹P NMR spectroscopy. The molecular structure of O,O′-bis(p-tolyl)dithiophosphate has been determined. Crystal data: [Et₃NH]⁺[(4-MeC₆H₄O)₂PS₂]⁻: Monoclinic, P2₁/c, a=15.2441(9) ?, b=10.415(2) ?, c=3.9726(9) ?, β=91.709(7)°, V=2217.5(1) ?⁻³, Z=4.Supplementary materials Additional material available from the Cambridge Crystallographic Data Centre (CCDC no. 600927 for [Et₃NH]⁺[(4-MeC₆H₄O)₂PS₂]⁻ comprises the final atomic coordinates for all atoms, thermal parameters, and a complete listing of bond distances and angles. Copies of this information may be obtained free of charge on application to The Director, 12 Union Road, Cambridge CB2 2EZ, UK (fax: +44-1223-336033; email: deposit@ccdc.cam.ac.uk or www:http://www.ccdc.cam.ac.uk).     

Crystal structure of Zn4Na(OH)6SO4Cl·6H2O

The structure of Zn₄Na(OH)₆SO₄Cl·6H₂O, a secondary mineral from Hettstedt, Germany, was determined by single-crystal X-ray diffraction. The crystals are hexagonal,a=8.413(8),c=13.095(24) Å, space group $P\bar 3$ , Z=2. The structure was refined to R=0.0554 and R_w=0.0903 for 970 reflections with I≥3σ(I). The structure can be described as zinc hydroxide layers perpendicular toc, from which sulfates and chlorides extend. The layers are held together by a system of hydrogen bonds involving hexaaquo Na⁺ ions which occupy the interlayer space.     

Synthesis and Crystal Structure of 5-[2-(6-bromonaphthalenyloxymethyl)]-3-(4-morpholinomethyl)-1,3,4-oxadiazole-2(3<Emphasis Type="Italic">H</Emphasis>)-thione

Abstract  The title compound, C₁₈H₁₈BrN₃O₃S, a derivative of 1,3,4-oxadiazole, crystallizes in the triclinic space group P-1 with unit cell parameters a = 6.8731(3), b = 8.9994(4), c = 15.7099(6) ?, α = 92.779(3)°, β = 130.575(3)°, γ = 107.868(4)°, Z = 2. The dihedral angle between the mean planes of the planar naphthyl and morpholine (chair) rings with the planar oxadiazol ring is 50.1(8) and 76.8(6)°, respectively. The planar naphthyl ring is twisted 52.2(5)° with the mean plane of the morpholine ring. A group of four intermolecular close contacts are observed between a bromine atom and hydrogen atoms from the closely packed naphthyl, morpholine and oxy–methyl groups in the unit cell. These molecular interactions in concert with an additional series of π–π stacking interactions that occur between the center of gravity of the two 6-membered rings of the naphthalene group influence the twist angles of each of these three groups. A MOPAC AM1 calculation of the conformation energy of the crystal structure [226.0128(9) kcal] compared to that of the minimum energy structure after geometry optimization [29.9744(1) kcal] reveals a significantly reduced value. The twist angles of the three groups above also change after the AM1 calculation giving support to the influence of both intermolecular C–H···Br short-range interactions and Cg π–π stacking interactions on these angles which therefore play a role in stabilizing crystal packing. Graphical Abstract  Crystal structure of 5-{[(6-bromonaphthalen-2-yl)oxy]methyl}-3-(morpholin-4-ylmethyl)-1,3,4-oxadiazole-2(3H)-thione, C₁₈H₁₈BrN₃O₃S, is reported and its geometric and packing parameters described and compared to a MOPAC computational calculation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Crystal structure of irisolidone from the flowers of Pueraia lobata

Irisolidone (5,7-dihydroxy-6,4′-dimethoxyisoflavone) was isolated from the flowers of Pueraia lobata and its crystal structure was examined by X-ray single crystal diffraction. The crystal structure of irisolidone is monoclinic, space group P2₁/c with a = 15.491(9) ?, b = 7.895(4) ?, c = 13.321(7) ?, β = 110.546(9)° and Z = 4. Hydrogen bonding and aromatic π–π stacking assemble the title compound into a three-dimensional networking structure.