超声喷雾共沉淀法制备纳米铕掺杂钇铝石榴石荧光粉

以NH4HCO3与NH3·H2O的混合溶液为沉淀剂,用超声喷雾共沉淀法获得Eu:YAG粉末先驱体,经一定温度煅烧后得到纳米铕掺杂钇铝石榴石(Eu:YAG)荧光粉。用荧光光谱仪、X射线衍射仪、扫描电子显微镜对粉体的结构、物相组成、颗粒形貌进行了研究。详细地研究了不同铕掺杂浓度粉体的发射光谱和激发光谱特性。结果表明:采用超声喷雾技术能获得大小为50～70nm、颗粒度均匀的Eu:YAG纳米颗粒,与溶胶-凝胶等方法制备的颗粒大小与均匀性相比,显示出一定的优势。同时研究还表明,烧结温度对Eu:YAG荧光粉的析晶有重要影响,随着烧结温度的升高,衍射峰逐渐变窄,衍射强度增大,有利于促进YAG相的生成。因此利用超声喷雾共沉淀法制备红色Eu:YAG荧光粉体是一种有效的途径。     

钕离子掺杂钇铝石榴石(Nd3+:Y3Al5O12)透明陶瓷研究进展

回顾了新一代激光工作物质Nd3 :Y3Al5O12透明陶瓷的发展历史,并与激光晶体进行了比较介绍了其技术优势,同时简述了Nd3 :Y3Al5O12透明陶瓷的2种常用工艺。     

硒化锌晶体精细雾化抛光液及去除机理研究

目的配制适合硒化锌雾化施液化学机械抛光的最优抛光液。方法选取氧化铝磨粒、pH调节剂四甲基氢氧化铵、氧化剂过氧化氢、表面活性剂聚乙烯吡咯烷酮为主要活性成分,以材料去除速率和表面粗糙度为评价指标,通过正交试验对硒化锌晶体进行精细雾化抛光,分析材料去除机理,并与传统抛光对比。结果氧化铝质量分数为9%、pH值为11、过氧化氢含量为3.5%、聚乙烯吡咯烷酮含量为0.75%时,材料去除率较高,为923.67 nm/min,同时表面粗糙度较小,为2.13 nm。在相同工况条件下,传统抛光材料的去除率和表面粗糙度分别为965.53 nm/min和2.27 nm。结论抛光液各组分对试验结果影响最大的为氧化铝磨粒,然后依次为氧化剂、pH值、表面活性剂。精细雾化抛光效果与传统抛光相近,但抛光液用量仅为后者的1/8。     

化学机械抛光过程抛光液作用的研究进展

化学机械抛光(CMP)已成为公认的纳米级全局平坦化精密超精密加工技术。抛光液在CMP过程中发挥着重要作用。介绍了CMP过程中抛光液的作用的研究进展,综合归纳了抛光液中各组分的作用,为抛光液的研制和优化原则的制定提供了参考依据。     

二氧化铈抛光液化学机械抛光微晶玻璃的机理及优化

以纳米CeO₂为磨料自制抛光液,研究磨料质量分数、pH值、抛光液流量、抛光盘转速、表面活性剂种类和氟化铵质量分数等因素对微晶玻璃化学机械抛光的影响,分析总结CeO₂在微晶玻璃化学机械抛光中的作用机理,利用原子力显微镜（AFM）检测微晶玻璃抛光后的表面粗糙度。结果表明:当CeO₂质量分数为3%、抛光液流量为25mL/min、抛光盘转速为100r/min、pH=8.0、十二烷基硫酸钠质量分数为0.01%,氟化铵质量分数为0.7%时,抛光后微晶玻璃表面粗糙度（R_a）最低为0.72nm,材料去除速率达到180.91nm/min。      

铜化学机械抛光材料去除机理研究

本文根据铜CMP过程中表面材料的磨损行为,建立了铜CMP时的材料去除率构成成分模型,并通过材料去除率实验,得出了各机械、化学及其交互作用所引起的材料去除率及其作用率:当np=nw=200r/min时,有最佳材料去除率,此时单纯的机械作用率为9.2%;单纯的化学作用率为仅为2.1%,抛光垫的机械与化学交互作用率为5.08%;磨粒的机械与化学交互作用率为83.6%。通过对实验结果进行分析,可得如下结论:硅片化学机械抛光中,一定的参数下有一个最优的抛光速度;在最优的速度下,机械与化学之间交互作用达到平衡,这时可获得最高的材料去除率;硅片化学机械抛光过程是一个多变的动态过程,仅仅通过增加机械作用或化学作用不能获得理想的材料去除效果。本文的研究结果可为进一步研究硅片CMP时的材料去除机理提供理论参考依据。     

化学机械抛光304不锈钢用抛光液成分研究

由于304不锈钢的优良特性,未来其将成为柔性显示器衬底的主要材料之一。为提高304不锈钢化学机械抛光的速率和质量,研究不同氧化剂在不同质量浓度或体积浓度及不同pH值下, 对材料去除率和表面粗糙度的影响。结果表明:氧化剂Fe₂O₃、H₂O₂、FeCl₃都在pH=2时抛光效果最佳,氧化剂KMnO₄在pH=10时抛光效果达到最佳。在最佳的pH值下进行抛光,H₂O₂的体积浓度为10 mL/L时,表面粗糙度R_a最好,为4 nm;在FeCl₃质量浓度为4.0 g/L时,材料去除率最高,为209 nm/min。      

钴插塞化学机械平坦化的抛光液组分优化

目的提高Co在超大规模集成电路全局化学机械抛光过程中的去除速率及Co/Ti去除选择比,并对去除机理进行详细描述。方法研究不同浓度的磨料、多羟多胺络合剂(FA/OII)、氧化剂等化学成分及不同pH值对钴去除率的影响。利用电化学实验、表面化学元素分析(XPS)揭示钴实现高去除速率的机理,通过原子力显微镜(AFM)对钴抛光前后的表面形貌进行了观察,并采用正交实验法找到抛光液最佳组分配比。结果随磨料浓度的升高,钴去除速率增大。随pH值的升高,钴去除速率降低。随氧化剂浓度的提升,钴去除速率升高,但Co/Ti去除选择比先升后降。随螯合剂浓度的增大,钴去除速率及Co/Ti去除选择比均先升后降。正交试验找到了最佳的抛光液配比及条件(3%磨料+20 mL/L多胺螯合剂(FA/OⅡ)+5 mL/L氧化剂(H_2O_2),pH=8),实现了钴的高去除(～500 nm/min)及较好的Co/Ti去除选择比(100:1)。并且,表面的平坦化效果明显提高,原子力显微镜测试结果显示Co面粗糙度由原本的3.14 nm降低到0.637 nm。结论采用弱碱性抛光液能有效提升钴的去除速率,并保证腐蚀可控。抛光液中同时含有氧化剂和螯合剂时,通过强络合作用实现了钴的抛光速率和Co/Ti去除选择比的大幅度提升。     

硬质合金刀具材料化学机械抛光机理研究

目的研究硬质合金刀具材料化学机械抛光(CMP)机理,为改善硬质合金刀具表面质量提供理论支持。方法分析硬质合金刀具材料在酸性抛光液中的化学反应,研究硬质合金刀具材料CMP的化学反应机理。基于接触力学理论计算抛光垫与工件的实际接触面积和单个磨粒的实际切削面积,在运动学分析的基础上,建立硬质合金刀具材料CMP的材料去除率模型,通过实验验证材料去除率模型的有效性。结果在酸性抛光液中,硬质合金被氧化成Co_3O_4。当工件、抛光垫、磨粒类型、工件安装位置确定时,材料去除率与抛光载荷、磨粒浓度和抛光盘转速有关。常用硬质合金抛光条件下,抛光YG8刀具的修正系数Kcm为8.53,抛光后刀具的最低表面粗糙度能达到48nm,材料去除率为62.381nm/min,材料去除率的理论值和实验值的最大相对误差为13.25%,消除了表面缺陷,获得了较好的镜面效果。结论建立的材料去除率模型具有一定的有效性,对硬质合金刀具材料进行化学机械抛光能消除刀具的表面缺陷,改善表面质量。     

SiC-Al_3Ti协同增强7075铝基复合材料搅拌工艺优化研究

采用液态搅拌铸造法制备Si C-Al_3Ti协同增强7075铝基复合材料。利用OM、XRD、SEM、直读光谱仪和布氏硬度计,通过正交试验分析了搅拌温度、搅拌速度和搅拌时间等对复合材料中Si C和Al_3Ti分布、收得率及复合材料硬度的影响。结果表明,Si C-Al_3Ti协同增强7075铝基复合材料的最佳搅拌温度为800℃,搅拌速度为450 r/min,搅拌时间为20 min。     

Processing-microstructure relationships for plasma-sprayed yttrium aluminum garnet

Plasma-sprayed yttrium aluminum garnet (YAG) has been considered as a component in a thermal barrier coating system to reduce oxidation of the bond coat by impeding oxygen diffusion through the coating. For this application, a fully crystalline, dense YAG coating would be advantageous to maximize lifetime and minimize oxygen diffusion. The effects of nine processing variables on the porosity and percent crystallinity in plasma-sprayed YAG were determined. Two powder types were investigated to compare a commercial, off-the-shelf, fused-and-crushed powder to a specially-processed, spherical plasma-spray powder. The resultant models suggest that plasma torch power and spray distance had the largest effect on the responses. It was determined that the processing parameters that lead to a coating with low porosity produce a coating with low crystallinity and vice versa. A possible route to producing a dense, crystalline coating was explored where a dense, amorphous coating was subsequently heat treated to produce crystalline material that retained the microstructure of the as-sprayed YAG in the bulk of the coating. However, macrocracking in the system due to thermal mismatch and crystallization stresses would need to be addressed for a viable multilayer TBC.     

钇铝石榴石晶体的机械抛光工艺

钇铝石榴石（yttrium aluminum garnet,YAG）是性能优良的激光晶体,但其属于硬脆材料（莫氏硬度8.5）,在抛光时易产生划痕及凹坑等缺陷。为去除YAG晶体的表面缺陷,用铜盘进行粗磨,并研究载荷和抛光盘转速对晶体平面度和表面粗糙度的影响。结果显示:铜盘可改善晶体表面缺陷,在转速70 r/min、载荷15 kPa时抛光45 min可达到最佳加工效果。再使用IC1000进一步降低晶体表面粗糙度,在抛光盘转速为9 r/min,抛光压力为15 kPa的条件下抛光30 min后,平面度PV可达100 nm,表面粗糙度RMS可达0.9 nm,在体视显微镜下观察无划痕及凹坑。      

Preparation of transparent yttrium aluminum garnet ceramics by relatively low temperature solid-state reaction

1　INTRODUCTIONYttriumaluminum garnet(YAG )isakindofcomplexoxideresultedfromthereactionofY2 O3andAl2 O3.ItschemicalformulaisY3Al5O12 .Ithasagarnetcrystalstructureandbelongstohexagonalsys tem .YAGceramicsholdpromiseforcertainopticalapplicationssuchashightemperaturewindowsusedtodetectinfraredwavesordevicesusedtorecordnu clearradiation .Becauseofitsthermalstability ,highhardness,physicalandchemicalstability ,andexcel lenttransparencyinawidewavelengthregionfromvisiblelighttoinfraredlight…     

2219铝合金化学铣切溶液配方优化

通过正交试验以及多指标分析法对2219铝合金的NaOH+ Na2S+TEA+ Al3化学铣切溶液配方进行了最优化研究.实验结果表明,当将化铣后试样表面粗糙度作为分析时着重考虑的指标时,化铣溶液的最优配比为160 ～ 180 g·L-1NaOH,5g·L-1Na2S,60 g·L-1 TEA,25 g·L-1 Al3+.当优先考虑化铣速率的影响时,溶液的最有配比为200 g·L-1NaOH,14 g·L-1Na2S,10～60 g·L-1 TEA,5g·L-1Al3+.而若同时考虑表面粗糙度和化铣速率两个指标,适用于2219铝合金化学铣切的最优溶液配方则应为200 g·L-1 NaOH,5 g·L-1Na2S,60 g·L-1 TEA,5g·L-1Al3+,当使用此配比溶液对2219铝合金进行化铣后得到的试样表面粗糙度与化铣速率分别为0.6055μm以及0.1638 mm·min-1.     

Improving corrosion properties of high-velocity oxy-fuel sprayed inconel 625 by using a high-power continuous wave neodymium-doped yttrium aluminum garnet laser

Thermal spray processes are widely used to protect materials and components against wear, corrosion and oxidation. Despite the use of the latest developments of thermal spraying, such as high-velocity oxy-fuel (HVOF) and plasma spraying, these coatings may in certain service conditions show inadequate performance,e.g., due to insufficient bond strength and/or mechanical properties and corrosion resistance inferior to those of corresponding bulk materials. The main cause for a low bond strength in thermalsprayed coatings is the low process temperature, which results only in mechanical bonding. Mechanical and corrosion properties typically inferior to wrought materials are caused by the chemical and structural inhomogeneity of the thermal-sprayed coating material. To overcome the drawbacks of sprayed structures and to markedly improve the coating properties, laser remelting of sprayed coatings was studied in the present work. The coating material was nickel-based superalloy Inconel 625, which contains chromium and molybdenum as the main alloying agents. The coating was prepared by HVOF spraying onto mild steel substrates. High-power continuous wave Nd:YAG laser equipped with large beam optics was used to remelt the HVOF sprayed coating using different levels of power and scanning speed. The coatings as-sprayed and after laser remelting were characterized by optical microscopy and scanning electron microscopy (SEM). Laser remelting resulted in homogenization of the sprayed structure. This strongly improved the performance of the laser-remelted coatings in adhesion, wet corrosion, and high-temperature oxidation testing. The properties of the laser-remelted coatings were compared directly with the properties of as-sprayed HVOF coatings and with plasma-transferred arc (PTA) overlay coatings and wrought Inconel 625 alloy.     

Effect of pre-aging pH on the formation of yttrium aluminum garnet powder (YAG) via the solid state reaction method

Yttrium aluminum garnet (YAG) powder was successfully synthesized by a novel solid state reaction method. The starting materials including: yttrium oxide (Y₂O₃), boehmite (AlOOH) and cerium chloride (CeCl₃·7H₂O) are pre-aged at pH 1, 2 and 3, respectively, before calcining. According to the experimental results, the case of pre-aging at pH 1 is the best condition for the formation of YAG powder. The particle size of Y₂O₃ and AlOOH are reduced by the pre-aging at pH 1. It induces to shorten the diffusion distance of the solid state reaction. The pre-aging at pH 1 process leads the formation of YAG powder via solid state reaction more easily. The emission intensity of the product was increased by the decrease of the pre-aging pH, the increase of the calcination temperature and the increase of the heating time.     

Fabrication and characterization of Bi-substituted yttrium iron garnet films by pulsed laser deposition

We have systematically investigated the effects of processing parameters, including various oxygen pressures (Po₂) ranging from 200 to 1000 m Torr and substrate temperatures (T_s) ranging from 500 to 750°C, on the characteristics of Bi-substituted yttrium iron garnet (Bi:YIG) films grown on (111) gadolinium gallium gamet (GGG) substrates. Bi: YIG films were grown using a pulsed laser deposition method with an ArF excimer laser (λ=193 nm). Although the compositions of all the Bi:YIG films grown at the constant T_s of 600°C were close to the target composition irrespective of Po₂, the Bi contents were slightly increased with increasing Po₂, which was consistent with the variation in Faraday rotation angles (θ_F). In addition, the crystallinity of the Bi:YIG films was deteriorated with increasing Po₂, and their grains became irregular. At T_s above 700°C, Bi-deficient yttrium iron garnet films were grown. Consequently, high quality epitaxial Bi:YIG films exhibiting Faraday rotation angles of −1.0≈−1.5 degree/μm were successfully grown at the substrate temperatures in the range of 500–650°C when the Po₂ of 200 mTorr was used.     

基于响应面法的单晶硅CMP抛光工艺参数优化

为提高单晶硅化学机械抛光(chemical mechanical polishing,CMP)的表面质量和抛光速度,通过响应面法优化CMP抛光压力、抛光盘转速和抛光液流量3个工艺参数,结果表明抛光压力、抛光盘转速、抛光液流量对材料去除率和抛光后表面粗糙度的影响依次减小。通过数学模型和试验验证获得最优的工艺参数为:抛光压力,48.3 kPa;抛光盘转速,70 r/min;抛光液流量,65 mL/min。在此工艺下,单晶硅CMP的材料去除率为1 058.2 nm/min,表面粗糙度为0.771 nm,其抛光速度和表面质量得到显著提高。      

Yttrium aluminum garnet powders by nitrate decomposition and nitrate–urea solution combustion reactions—a comparative study

Precursors for yttrium aluminum garnet (Y₃Al₅O₁₂—YAG) were synthesized by simple decomposition of concentrated aqueous solution of nitrates and combustion of concentrated aqueous solution of nitrates with urea on a heater. The precursor formed by the former reaction was granules of agglomerated powder while that from the latter reaction was a voluminous and porous sponge-like mass. Both precursors were ground to powders and subjected to detailed thermogravimetric–differential thermal analysis and X-ray diffraction studies. The precursor from the simple decomposition of nitrates exhibited a total loss in weight of about 18% in stages (25 to 300 °C and 300 to 600 °C) accompanied by endotherms—characterized as processes of dehydration of absorbed moisture and decomposition of residual nitrates, respectively. The as formed precursor and that heated to 820 °C were amorphous. Crystallization to YAG phase occurred from an amorphous oxide characterized by an exotherm above 820 °C with no loss of weight. The precursor from nitrate–urea combustion reaction was found to exhibit a weight loss of 2.5% accompanied by a shallow endotherm in the range of 25 to 300 °C—characterized as the process of dehydration of absorbed moisture. No further weight loss or heat effect was noticed, confirming it to be chemically pure YAG. This as formed precursor was found to be crystalline YAG. The difference in chemical composition of the precursors formed by these two reactions is attributed to the difference in the actual reaction temperatures during their formation—lower reaction temperature for the endothermic decomposition of nitrates and higher reaction temperature for the exothermic combustion associated with the formation of a bright flame. The morphology of the precursor powder formed by the former reaction exhibited only cracks while that of the precursor from the latter reaction exhibited pores and voids. The precursor from the former reaction was calcined at 1100 °C to form into chemically pure YAG. Zeta potential variation with pH for the aqueous suspensions of the crystalline YAG powders from both the reactions exhibited a maximum value in the range of 40 to 50 mV around a pH of 4, indicating stability of these dispersions towards coagulation at this pH. Particle size distribution of wet ground powders (slurries with 20%, v/v, solid at a pH of 4) showed that the powder from combustion reaction could be formed into a finer size than that from simple nitrate decomposition, indicating the agglomerates of combustion reaction were softer.