单晶SiC化学机械抛光液的固相催化剂研究

针对单晶SiC化学机械抛光使用的抛光液,研究了产生芬顿反应Fe、FeO、Fe₂O₃、Fe₃O₄等4种铁系固相催化剂的效果。结果发现当Fe₃O₄作为催化剂时,SiC表面能够产生明显的化学反应,生成较软易去除的SiO₂氧化层,化学机械抛光时材料去除率最高达到17.2 mg/h、表面粗糙度最低达到R_a2.5 nm。相比Fe、FeO、Fe₂O₃等固相催化剂,Fe₃O₄更适宜用作SiC的化学机械抛光。抛光液中Fe²⁺离子浓度和稳定性是决定芬顿反应速率和稳定性的重要因素,固相催化剂电离自由Fe²⁺能力的差异直接影响了化学抛光液中的Fe²⁺浓度,固相催化剂电离Fe²⁺的能力越强,抛光液中Fe²⁺浓度就越高,芬顿反应速率越快,与SiC进行化学反应速度越快,材料去除率越高,抛光质量越好。     

络合剂对蓝宝石晶片化学机械抛光的影响

利用自制的抛光液对蓝宝石晶片进行化学机械抛光,研究化学机械抛光过程中抛光压力、抛光液pH值、SiO2浓度、络合剂种类及其浓度等参数对抛光速率的影响,采用MicroNano D-5A扫描探针显微镜观察抛光前后蓝宝石晶片的表面形貌。结果表明:在抛光条件为压力7psi、转速为50 r/min、抛光液流量为60 mL/min,抛光液组成为pH值12、SiO2浓度5%、络合剂Ⅰ及其浓度为1.25%时,得到最大抛光速率为35.30 nm/min,蓝宝石晶片表面质量较好,表面粗糙度Ra达到0.1 nm。     

单晶SiC的电助光催化抛光及去除机理

为满足电子半导体等领域对SiC超光滑、无损伤和材料高效去除的要求，提出了电助光催化抛光SiC的新方法。研究了光催化剂种类及其pH值对抛光液氧化性和抛光效果的影响，讨论了材料的去除机理。结果表明：以p25型TiO2为光催化剂配制抛光液所获得的最大氧化还原电位为633.11 mV，材料去除率为1.18 μm/h，表面粗糙度Ra=0.218 nm；抛光后SiC表面氧化产物中，Si-C-O、Si-O和Si4C4O4的含量明显增加，SiC表面被氧化并被机械去除是主要的材料去除方式。     

用于光学玻璃CMP的高效稀土抛光液研究

以纳米二氧化铈(CeO₂)为磨料,使用球磨与不同化学试剂(如pH值调节剂乙酸、丙酸、植酸和分散剂离子型表面活性剂、非离子型表面活性剂)的协同分散方法制备纳米CeO₂抛光液,研究酸性体系下不同抛光液的分散性能与抛光性能。研究表明,球磨时以乙酸为pH值调节剂,调节溶液pH值为3,料球比为1∶4,球磨时间为6 h,球磨后纳米CeO₂悬浮液分散效果较好。采用制备的纳米CeO₂抛光液对石英玻璃进行抛光实验。结果表明：在磨料质量分数为1%、pH为4的条件下,石英玻璃的材料去除速率最高为409 nm/min,粗糙度仅为0.03 nm;阳离子、非离子型表面活性剂均有助于提升酸性体系下CeO₂悬浮液的分散稳定性,而加入非离子表面活性剂AEO-9(脂肪醇聚氧乙烯醚)效果最佳,其能够在提高分散稳定性的基础上改善石英玻璃的表面质量。     

静电层层自组装复合磨粒及抛光液的抛光性能研究

利用静电层层自组装原理,通过PDADMAC在聚合物粒子表面改性和吸附不同层数的SiO2磨粒,制备n-SiO2/BGF复合磨粒及其抛光液。分析了交替吸附PDADMAC和SiO2磨粒的BGF微球表面Zeta电位的变化,利用TEM表征了不同层数的n-SiO2/BGF复合磨粒SiO2磨粒的吸附情况。分析了聚合物表面磨粒的吸附层数、游离磨粒浓度、聚合物粒径对复合磨粒抛光液抛光的影响。抛光实验表明:3-SiO2/BGF复合磨粒抛光液的材料去除率最高,为368.8nm/min;复合磨粒抛光液中的聚合物粒子为1～2μm、游离磨料SiO2的质量分数为5%时,材料去除率取得较大值。经3-SiO2/BGF复合磨粒抛光液抛光后的硅表面,在10μm×10μm范围内,表面粗糙度从0.3μm降至0.9nm,峰谷值小于10nm,表明复合磨粒抛光液对硅片具有良好的抛光效果。     

精细雾化抛光TC4钛合金抛光液优化研究*

配制适用于TC4钛合金雾化施液抛光的特种抛光液,通过抛光实验获得纳米级的光滑钛合金表面。研究不同磨料、氧化剂和络合剂含量对钛合金材料去除率和表面粗糙度的影响,通过正交试验优化抛光液组成及配比。优化后的抛光液由质量分数20%的SiO2磨料、0.1%的柠檬酸、1%的聚乙二醇-400、2%的H2O2组成,pH值为4。抛光试验结果表明,优化后抛光液的抛光效果较好,材料去除率及试件表面质量均有所提升,其中材料去除率为549.87nm/min,表面粗糙度为0.678 nm。XPS分析表明,抛光过程中钛合金表层在酸性环境下与H2O2和柠檬酸反应,生成了易于通过机械作用去除的氧化层。     

超声波精细雾化抛光石英玻璃的抛光液研制*

为了配制适用于JGS1光学石英玻璃超声波精细雾化抛光的特种抛光液,以材料去除率和表面粗糙度为评价指标,设计正交试验探究抛光液中各组分含量对雾化抛光效果的影响,并对材料去除机制进行简要分析。结果表明：各因素对材料去除率的影响程度由大到小分别为SiO2、pH值、络合剂、助溶剂和表面活性剂,对表面粗糙度影响程度的顺序为SiO2、表面活性剂、pH值、助溶剂和络合剂;当磨料SiO2质量分数为19%,络合剂柠檬酸质量分数为1.4%,助溶剂碳酸胍质量分数为0.2%,表面活性剂聚乙烯吡咯烷酮质量分数为0.9%,pH值为11时,雾化抛光效果最好,材料去除率为169.5 nm/min,表面粗糙度为0.73 nm;去除过程中石英玻璃在碱性环境下与抛光液发生化学反应,生成低于本体硬度的软质层,易于通过磨粒机械作用去除。使用该抛光液进行传统化学机械抛光和雾化化学机械抛光,比较两者的抛光效果。结果表明：两者抛光效果接近,但超声雾化方式抛光液用量少,仅为传统抛光方式的1/7。     

颗粒等抛光液组分对硬盘盘基片抛光的影响

硬盘盘基片粗抛光必须在较高材料去除率的基础上获得高表面质量。分别用合成法和粉碎法制得的α-A l2O3颗粒做了抛光实验,并分析了抛光液中氧化剂、络合剂含量和抛光液pH值对材料去除率的影响机制。结果表明:用合成法制得的颗粒抛光后基片表面凹坑严重,降低抛光液配方中氧化剂的含量,虽可使表面粗糙度(Ra)和表面波纹度(Wa)大幅降低,但材料去除率也大幅下降,该颗粒不适合基片粗抛光;用粉碎法制得的颗粒抛光后基片表面划痕密集,加入一定量的减阻剂后基片Ra和Wa大幅降低,材料去除率有所降低但仍维持在较高的水平,因此减阻剂可平衡该颗粒的材料去除率和抛光表面质量;粉碎法制得的颗粒抛光液中,随氧化剂和络合剂的增加,材料去除率均呈先升后降趋势;pH值的升高会使材料去除率下降,但酸性太强会引起过腐蚀,适宜的pH在2.0~3.0之间。     

新型环保抛光液的制备及其对软脆碲锌镉晶片的化学机械抛光

针对软脆碲锌镉晶片的传统加工工艺“游离磨料-抛光-化学机械抛光”存在的缺点,提出“固结磨料研磨-新型绿色环保抛光液化学机械抛光”新方法。固结磨料研磨工艺为：采用3000号刚玉防水砂纸,压力为17kPa,抛光盘与抛光垫转速均为80r/min,研磨时间为5min。新型绿色环保抛光液含有双氧水和硅溶胶,采用天然桔子汁作为pH值调节剂。化学机械抛光工艺为:采用自行研制的化学机械抛光液,绒毛抛光垫,抛光压力为28kPa,抛光盘与抛光垫转速均为60r/min,抛光时间为30min。试验结果表明,经过上述加工可获得超光滑的表面,表面粗糙度算术平均值、均方根值、峰谷值分别可以达到0.568nm、0.724nm、6.061nm。     

酸碱度对磁流变抛光去除作用的调节机制

随着磁流变抛光技术在超精密加工领域的应用需求不断增长,提高该技术的抛光效率成为一种必然趋势。本文从研究磁流变抛光液料浆的性质出发,建立了以pH值调节为手段改善抛光液性能的实验方法。采用透射电镜、粒度分析,黏度测试和Zeta电位测试等实验分析表征了抛光颗粒的分散行为及料浆的流变特性,并对抛光料浆特性进行了研究和优化。结果表明:当pH值为12时,抛光料浆具有绝对值最大的Zeta电位(33.28 mV)和最小的颗粒粒径(260nm),获得了抛光颗粒分散均匀、悬浮性能稳定的料浆。使用该料浆抛光液与初始抛光液在相同工艺条件下对熔石英进行抛光。实验结果表明,在未明显恶化表面粗糙度的前提下,该抛光液的峰去除效率和体去除效率分别提升87%和66%,获得了良好、高效的去除效果。     

The effects of iron particles on the friction and wear mechanisms of ceramics in ethanol

For the combinations of an Si₃N₄ pin and five kinds of ceramic disk (SiC, Si₃N₄, Al₂O₃, ZrO₂, TiC), a friction and wear test was carried out in ethanol and in ethanol containing iron particles (1 wt.%, average diameter d = 200 nm, D = 12 μm under cohered condition) under a load in the range 5.88–11.50 N, at a sliding velocity of 0.138–0.196 m s⁻¹. A topographical analysis was also performed on the microasperities of the wear surfaces to estimate the behavior of the iron particles, and the degree of surface damage. As a result, the following facts were found. (1) The addition of iron particles in ethanol decreased both the wear rates of SiC and TiC disks and the mating pins, and also decreased the wear rate of the Al₂O₃ disk but increased that of the mating pin. The addition increased the wear rates of both ZrO₂ and Si₃N₄ disks and the mating pins. (2) The average coefficients of friction with the addition of iron particles were greater than those without iron particles. (3) The wear rates of pin and disk depended on the topographies of wear surfaces and the wear index Γ.     

TWO STEPS CHEMICAL-MECHANICAL POLISHING OF RIGID DISK SUBSTRATE TO GET ATOM-SCALE PLANARIZATION SURFACE

In order to get atomic smooth rigid disk substrate surface, ultra-fined alumina slurry and nanometer silica slurry are prepared, and two steps chemical-mechanical polishing (CMP) of rigid disk substrate in the two slurries are studied. The results show that, during the first step CMP in the alumina slurry, a high material removal rate is reached, and the average roughness (Ra) and the average waviness (Wa) of the polished surfaces can be decreased from previous 1.4 nm and 1.6 nm to about 0.6 nm and 0.7 nm, respectively. By using the nanometer silica slurry and optimized polishing process parameters in the second step CMP, the Ra and the Wa of the polished surfaces can be further reduced to 0.038 nm and 0.06 nm, respectively. Atom force microscopy (APM) analysis shows that the final polished surfaces are ultra-smooth without micro-defects.     

数字光盘玻璃基片的三步抛光技术

为得到超光滑的数字光盘母盘玻璃基片表面,研究玻璃基片的亚纳米级抛光技术。分别采用2 m、0.3 m超细氧化铈抛光液以及纳米氧化硅抛光液进行三步化学机械抛光(Chemical mechanical polishing, CMP),抛光后最终表面粗糙度Ra达到0.44 nm,为目前报道的数字光盘母盘玻璃基片抛光的最低值。原子力显微镜分析表明,抛光后的表面超光滑且无微观缺陷。通过对玻璃基片CMP中机械作用及化学作用进行分析,对抛光机理进行了探讨。     

Investigation of Chemical/Mechanical Polishing of Niobium

A chemical/mechanical method for polishing flat niobium sheets to a mirror finish was developed. Various polishing slurries with different open circuit potentials and pH values were considered. All slurries fell within the niobate region of the Pourbaix diagrams, indicating that slurries are in a thermodynamically stable region. Oxidation characteristics of the niobium in the various slurries were determined by XPS and confirmed previously published work that niobium forms various layers of stable niobium oxides roughly 4.5–4.7 nm in thickness on the surface. A multi-step polishing method that relies on mechanical abrasion of the surface proved to be effective, and particles of different hardness and size were explored. Niobium wafers with initial peak-to-valley (PV) surface roughness of 3 to 7 μm were polished. The multi-step process utilized a slurry containing 1 μm diameter alumina particles to polish this initial roughness down to a submicrometer level. The final polish was provided by a slurry containing smaller particles. The oxide slurry with 70 to 100 nm silica particles gave the best mirror finished surface, with PV = 235 nm, Ra = 32 nm, and RMS = 39 nm. While polishing caused some disorder in the niobium metal, using the oxide slurry gave results closer to those obtained by buffered chemical polish (BCP), which exhibits the highest degree of atomic order based on XPS studies. A polishing process starting with mechanical abrasion, followed by a two-step mechanical polish, is successful for obtaining smooth niobium surfaces on flat wafers.     

剪切增稠抛光磨料液的制备及其抛光特性

为了实现对工件的剪切增稠抛光(STP),采用机械混合与超声波分散法制备了一种Al2O3基STP磨料液,并研究了它们的抛光特性。利用应力控制流变仪考察其流变性能,通过扫描电镜和光学轮廓仪研究了单晶硅加工后表面显微组织的变化,并测量其表面粗糙度。结果表明:STP磨料液具有剪切变稀和可逆的剪切增稠特性,达到临界剪切速率后,会形成Al2O3"粒子簇";当剪切速率增大至1000s-1,储能模量,耗能模量和耗散因子都增至最大值,此时主要表现为类似固体的弹性行为,有利于形成类似"柔性固着磨具"。在STP加工单晶硅过程中,采用塑性去除的材料去除方式。随着抛光时间的延长,硅片去除速率先增大后减小;表面粗糙度不断减小并趋于稳定。实验显示,磨粒浓度不宜过高,否则会因剪切增稠效应造成黏度过大,导致流动性差而影响抛光质量。当Al2O3质量分数为23%时,抛光25min后,硅片表面粗糙度Ra由422.62nm降至2.46nm,去除速率达0.88μm/min,表明其能实现单晶硅片的高效精密抛光。     

Y2O3改性石墨/CaF2/TiC/镍基合金复合涂层微观组织与摩擦学性能研究

为提高石墨/CaF₂/TiC/镍基合金（GCTN）复合涂层的力学性能和摩擦学性能,运用等离子喷涂技术在45钢表面制备了Y₂O₃改性GCTN复合涂层,研究了Y₂O₃对复合涂层的微观组织、显微硬度、断裂韧性和摩擦磨损性能的影响。结果表明：Y₂O₃改性GCTN复合涂层主要由γ-Ni、CrB、Cr7C₃、TiC、CaF₂和石墨等物相组成。Y₂O₃在等离子火焰加热作用下与C元素反应生成活性元素Y,Y净化了复合涂层的微观组织,并细化了CrB、Cr₃C7等硬质相晶粒,提高了其致密性。当Y₂O₃质量分数为0.5%时,复合涂层的显微硬度和断裂韧性分别为593.3MPa和6.82MPa·m^1/2,比不含Y₂O₃的复合涂层分别增大了8%和22%,其机理主要是Y₂O₃细化了CrB、Cr₃C₇等硬质相晶粒,起到了细化强化作用。由于GCTN-0.5Y₂O₃复合涂层的显微硬度和断裂韧性显著提高,减少了其黏着磨损和微观断裂磨损,因而GCTN-0.5Y₂O₃复合涂层的摩擦因数和磨损率最小,分别为0.085和0.39×10-3mm3/m。     

Friction and wear of self-mated SiC and Si3N4 sliding in water

The friction and wear of self-mated SiC and Si₃N₄ with different initial roughness sliding in water were investigated with pin-on-disk apparatus at normal load of 5 N and sliding speed of 120 mm/s in ambient condition. It was found that, for self-mated Si₃N₄, the wear mechanism for surface smoothening to obtain low friction was tribochemical wear, but for self-mated SiC, it changed from mechanical wear into tribochemical wear with increasing sliding cycles. After running-in in water, self-mated Si₃N₄ exhibited lower steady-state friction coefficient than self-mated SiC did. For these two ceramics, initial and steady-state friction coefficients were hardly dependent on initial roughness. Initial roughness mainly affected the running-in period. The larger the initial roughness, the longer the running-in period, but the running-in period was much shorter for self-mated Si₃N₄ at each initial roughness than that for self-mated SiC.     

Study on tribological and electrochemistry properties of metal materials in H2O2 solutions

Hydrogen peroxide (H₂O₂) is a kind of ideal green propellant. It is crucial to study the wear behavior and failure modes of the metal materials under the strong oxidizing environment of H₂O₂. This study aims to investigate the wear of rubbing pairs of 2Cr13 stainless steel against 1045 metal in H₂O₂ solutions, which has a great effect on wear, the decomposition and damage mechanism of materials. The comparison analysis of the friction coefficients, wear mass loss, worn surface topographies and current densities was conducted under different concentrations of H₂O₂ solutions. There were significant differences in the tribological and electrochemistry properties of the rubbing pairs in different H₂O₂ solutions.