Self-assembly preparation of popcorn-like colloidal silica and its application on chemical mechanical polishing of zirconia ceramic

Traditional mobile phone backplane materials are difficult to meet the requirements of the 5G era, and zirconia ceramic is one of the most promising backplane materials. However, its precision machining is difficult due to the hard and brittle nature. In this work, a novel popcorn-like colloidal silica was prepared by the self-assembly growth of nanoparticles for chemical mechanical polishing of the yttria-stabilized tetragonal zirconia ceramic sheets. The surface of the popcorn-like colloidal silica particles has a noticeably uneven shape, and the particle size distribution is uniform. The chemical mechanical polishing results show that the material removal rate of the prepared popcorn-like colloidal silica is increased by about 50% compared with the spherical colloidal silica, and the surface morphology is also obtained improvement. In the process of chemical mechanical polishing, the particles form multi-point contact with the ceramic sheet, resulting in an increase in the coefficient of friction, which is beneficial to the tribochemical reaction. In addition, multi-point contact can distribute the load, make the indentation shallower, and help reduce mechanical scratches. In general, the expected results are expected to provide experimental basis for the optimization of the structure of chemical mechanical polishing abrasive particles.     

Nano-scale surface of ZrO2 ceramics achieved efficiently by peanut-shaped and heart-shaped SiO2 abrasives through chemical mechanical polishing

Zirconia ceramics are regarded as the best development target for 5G mobile phone rear covers. However, it is necessary and urgent to improve the surface quality and processing efficiency of zirconia ceramics. Non-spherical silica abrasives were prepared by the KH550 induction method and were used in chemical mechanical polishing (CMP) of zirconia ceramics for the first time. While achieving low surface roughness of 1.9 nm, it has an efficient polishing rate of 0.31 μm/h which is superior to conventional abrasives. Silica particles are peanut-shaped and heart-shaped in the scanning electron microscopy image, and its distinctive morphology provides the possibility of its excellent polishing performance. X-ray photoelectron spectroscopy analysis shows that during the CMP process, silica abrasives and zirconia ceramic undergo a solid phase chemical reaction to form ZrSiO₄. At the same time, the contact wear model established in combination with the coefficient of friction indicates that the two-dimensional surface contact mode of non-spherical silica abrasives on the surface of zirconia ceramics greatly improves its mechanical effect.     

Surface planarization of zirconia ceramic achieved by polyacrylamide grafted nanodiamond composite abrasives through chemical mechanical polishing

Zirconia ceramics are the promising materials for cell phone backplanes in the 5G era, and smoother surfaces and higher removal efficiency are sought after for their precision machining. Although nanodiamond abrasives have high polishing rates, it is easy to bring mechanical scratches and pits on the ceramic surface because of their high hardness, resulting in degradation of the surface quality of the finished workpiece. Therefore, polyacrylamide grafted nanodiamond particles were prepared by solution polymerization method for polishing ceramic wafers. As confirmed by Fourier transform infrared spectroscopy (FTIR), the polyacrylamide has been grafted on the nanodiamond surface. According to the scanning electron microscopy (SEM) and particle size distribution, the composite abrasives have better dispersion than pure nanodiamond abrasives. The results of chemical mechanical polishing (CMP) experiments showed that the composite abrasives could reduce the average surface roughness (Sa, arithmetic mean height) of zirconia ceramic from 28.31 nm to 2.68 nm (scanning area is 500 μm × 500 μm), and the polishing rate remained high compared to pure nanodiamond abrasives, showing superior CMP performance. X-ray photoelectron spectroscopy (XPS) demonstrated that solid-phase chemical reactions occurred during the polishing process to form ZrSiO₄. Meanwhile, contact-wear model combined with contact angle testing indicates that the introduction of polyacrylamide increases the contact area of the nanodiamond on the zirconia wafer surface, thereby significantly enhanced the mechanical effect.     

Development of Zr- and Gd-doped porous ceria (pCeO2) abrasives for achieving high-quality and high-efficiency oxide chemical mechanical polishing

Porous ceria (pCeO₂), Zr-doped pCeO₂ (pCeZrO₂), and Gd-doped pCeO₂ (pCeGdO₂) abrasives for both surface quality and removal rate improvements were developed using a facile one-pot solvothermal approach. The resulting products were characterized via XRD, SEM, TEM, HRTEM, Raman spectroscopy, UV–visible spectroscopy, and N₂ adsorption-desorption measurements. Raman spectra revealed that oxygen vacancies were the dominant defects in pCeO₂ nanospheres. Zr- and Gd-doping treatments contributed to oxygen vacancy enrichment, thus leading to an increased content of trivalent cerium (Ce³⁺) formed on the pCeO₂ surfaces. Oxide-CMP capability of pure pCeO₂, pCeZrO₂, and pCeGdO₂ abrasives were compared in terms of surface morphology/roughness/defect, topographical variation, as well as material removal rate (MRR). Atomic force microscopy and interferometric microscopy investigations showed that both pCeO₂, pCeZrO₂, and pCeGdO₂ abrasives achieved high-quality surfaces with ultra-low roughness (0.11–0.14 nm Ra, 0.13–0.17 nm RMS). As expected, the MRR was accelerated by 78.7% in alkaline slurries containing pCeGdO₂ abrasives compared to the undoped pCeO₂. The improved CMP performance might be attributed to the reduced modulus, the expend pore size, as well as the enriched Ce³⁺ and oxygen vacancy. Furthermore, the interfacial action and removal mechanism of the pCeO₂ abrasives were discussed on the basis of their structure feature and surface chemistry.     

Nanoplastic removal function and the mechanical nature of colloidal silica slurry polishing

The nanomechanical deformations on a broad range of optical material surfaces (single crystals of Al₂O₃ [sapphire], SiC, Y₃Al₅O₁₂ [YAG], CaF₂, and LiB₃O₅ [LBO]; a SiO₂–Al₂O₃–P₂O₅–Li₂O glass-ceramics [Zerodur]; and glasses of SiO₂:TiO₂ [ULE], SiO₂ [fused silica], and P₂O₅–Al₂O₃–K₂O–BaO [Phosphate]) near the elastic-plastic load boundary have been measured by nanoindentation and nanoscratching to mimic the nanoplastic removal caused by a single slurry particle during polishing. Nanoindenation in air was performed to determine the workpiece hardness at various loads using a commercial nanoindenter with a Berkovich tip. Similarly, an atomic force microscope (AFM) with a stiff diamond coated tip (150 nm radius) was used to produce nanoplastic scratches in air and aqueous environments over a range of applied loads (~20-170 μN). The resulting nanoplastic deformation of the nanoscratches were used to calculate the removal function (i.e., depth per pass) which ranged from 0.18 to 3.6 nm per pass for these materials. A linear correlation between the nanoplastic removal function and the polishing rate (using a fixed polishing process with colloidal silica slurry on a polyurethane pad) of these materials was observed implying that: (a) the polishing mechanism using colloidal silica slurry can be dominated by mechanical rather than chemical interactions; and (b) the nanoplastic removal function, as opposed to interface particle interactions, is the controlling factor for the polishing material removal rate. Furthermore, this correlation is consistent with the Ensemble Hertzian Multi-Gap (EHMG) microscopic material removal rate model described previously. The nanoplastic removal depth was also found to correlate to the measured nanoindentation hardness (H₁) of the optical material, scaling as H₁^−3.5. Two-dimensional (2D) finite element analysis simulations of nanoindentation showed a similar nonlinear dependence of plastic deformation with the workpiece material hardness. The findings of this study are used to determine an effective Preston coefficient for the material removal rate expression and enhance the predictive nature of the nanoplastic polishing rate for various materials utilizing their material properties.     

CeO2抛光液对SiO2介质的抛光性能

以CeO₂为磨料配制抛光液,研究了磨料质量分数、pH及添加剂对SiO₂介质去除速率和表面粗糙度的影响。结果表明,在抛光液的磨料质量分数为1%,pH为5的条件下,SiO₂介质的去除速率为248.9 nm/min。向其中加入质量分数为1%的L-脯氨酸或0.075%的阴离子表面活性剂TSPE-PO(三苯乙烯基苯酚聚氧乙烯醚磷酸酯)后,SiO₂介质的去除速率分别提高至268.6 nm/min和302.5 nm/min,表面粗糙度(Rq)从原来的0.588 nm分别变为0.601 nm和0.522 nm。     

陶瓷砖抛光粉在混凝土中的应用研究

研究了陶瓷砖抛光粉对混凝土工作性能、力学性能和抗渗性能的影响,并分析了抛光粉对水泥净浆孔结构的影响。结果表明:陶瓷砖抛光粉替代水泥量为10%时,混凝土的工作性能最好且混凝土7d、28d强度均达到最大值;在替代量为15%时,抗渗性能最好,孔隙率达到最低;在一定的掺量范围内,陶瓷砖抛光粉有利于提高混凝土的工作性能、力学性能和抗渗性,细化浆体中的孔结构,对改善混凝土性能和结构有积极作用。     

Effect of hydroxy carboxylates as complexing agent on improving chemical mechanical polishing performance of M-plane sapphire and action mechanism analysis

As sapphire device performance continues to improve, greater challenges are posed to the chemical mechanical polishing (CMP) of sapphire, with its high degree of hardness and brittleness. M-plane sapphire substrates are not widely used because they are more difficult to process, despite having higher luminous efficiency than C-plane substrates. In this study, the effect of three hydroxyl carboxylates, namely potassium tartrate (PT), potassium citrate (Cit) and sodium gluconate (Gluc), as complexing agents on the CMP of M-plane sapphire was investigated to obtain a high material removal rate (MRR) and low root mean square surface roughness (Sq). First, the chemical reactivities of the three complexing agents were predicted with Material Studio (MS) software. The predicted results showed that the complexing ability of the three complexing agents was greatest for Gluc, followed by Cit, with PT having the least complexing ability. Experimental results confirmed that Gluc was the optimal complexing agent for the M-plane sapphire CMP. The mechanism of action during CMP was revealed by X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR). The results showed that the Al(OH)₄^? ions produced by the sapphire were complexed by Gluc to form the soluble complex Al(OH)₄^?/Gluc^?. At the same time, a solid phase reaction also occurred between the M-plane sapphire, SiO₂, and water during CMP, and Al₂Si₂O₇?2H₂O was generated. After polishing with the optimized slurry, the M-plane MRR was improved to 5.358 μm/h, a 50% improvement compared with the reference slurry, and the Sq decreased from 0.345 nm to 0.172 nm. These findings provide important guidance for the development of high-performance sapphire devices.     

ZrO2纳米颗粒的添加对ZrO2/HA复合陶瓷物相和力学性能的影响

将液相掺杂CeO2和Fe2O3的钇稳定四方ZrO2纳米粉作为着色剂添加到微米ZrO2/HA体系中,1400℃烧结制备了ZrO2/HA纳米复合陶瓷.利用X射线衍射分析了复合陶瓷的物相组成;三点弯曲法、单边切口梁法及压痕法测试了陶瓷的力学性能;讨论了纳米氧化锆的添加对复合陶瓷力学性能及物相组成的影响,分析纳米氧化锆导致复合陶瓷力学性能改变的原因.根据复合陶瓷断裂前后单斜相氧化锆的含量变化,证实氧化锆纳米粉的添加不仅有利于复合陶瓷中四方相氧化锆的稳定存在,而且可以提高基体相变四方相氧化锆的含量,相变增韧作用加强.力学性能测试结果显示:体系中适量纳米氧化锆的存在可以提高材料的抗弯强度和断裂韧性20%以上,密度和硬度少量增加,但由于没有新物相引入,对弹性模量未造成影响.     

化学机械抛光中Co/Ti电偶腐蚀与去除速率选择性研究

通过电化学测试研究了pH、配位剂(柠檬酸钾)和缓蚀剂[包括1,2,4-三氮唑(TAZ)和3-氨基-5-巯基-1,2,4-三氮唑(AMTA)]对Co/Ti电偶腐蚀的影响.结果表明,溶液pH升高会增大Co与Ti之间的腐蚀电位差.当pH=8时,加入0.5％(质量分数)柠檬酸钾会加剧Co和Ti之间的电偶腐蚀,而再加入缓蚀剂TA...     

Study of the effect of the concentration,size and surface chemistry of zirconia and silica nanoparticle fillers within an epoxy resin on the bulk properties of the resulting nanocomposites

Epoxy resin nanocomposites were prepared by curing bisphenol‐F with an aliphatic amine in the presence of SiO₂ and ZrO₂ nanoparticles as inorganic fillers. Both types of particles were prepared with diameters of around 10 nm and 70 nm to study size effects in the nanocomposites. The nanoparticles showed a different constitution: while silica was amorphous and spherical in nature, zirconia was crystalline and non‐spherical. Both nanoparticles were surface‐functionalized with novel diethylene‐glycol‐based capping agents to increase the compatibility with the epoxy matrix. The organic functionalities were attached to the nanoparticle surface via phosphonic acid (zirconia) and trialkoxysilane (silica) anchor groups. The homogeneity of the distribution of surface‐modified inorganic nano‐sized fillers in the matrix up to 5.8 vol% in case of silica and 2.34 vol% in case of zirconia was determined by small‐angle X‐ray scattering and transmission electron microscopy. Mechanical properties such as hardness and storage modulus were increased with increasing filler content while thermal stability of the obtained materials was nearly unaffected after incorporation of nanoparticles. Copyright © 2011 Society of Chemical Industry     

锆硅包膜金红石型钛白粉工艺优化及性能

采用溶胶–凝胶法制备了锆硅包膜金红石型钛白粉。通过正交实验研究了浆液浓度、分散剂用量和Zr O2、Si O2两种包膜剂含量对锆硅包膜金红石型钛白粉的影响,得到了制备锆硅包膜金红石型钛白粉的优化工艺条件。采用Nano-ZS型粒度仪、扫描电子显微镜、透射电子显微镜和能谱仪、Fourier红外光谱仪等测试手段,考察锆硅包膜金红石型钛白粉的效果和包膜机理。结果表明:金红石型钛白粉表面包覆了两层均匀而致密的Zr O2膜和Si O2膜。包膜后金红石型钛白粉的失光率、吸油量和遮盖力都有所下降,白度值增加。同时,证实了这两层膜是以化学键Zr-O-Ti和Si-O-Zr的形式结合在金红石型钛白粉颗粒表面。     

Effect of mixed-shaped silica sol abrasives on surface roughness and material removal rate of zirconia ceramic cover

Zirconia ceramic, as mobile phone body-materials, will become increasingly important with the coming of 5G communication technology. Surface quality and material removal rate of zirconia ceramic cover are vital factors to determine its wide application. Therefore, mixed-shaped silica sol abrasives were prepared by ion connecting-inducting method and applied to achieve a good surface quality and a high material removal rate on zirconia ceramic cover by using chemical mechanical polishing (CMP). Mixed-shaped silica sol abrasives contained spherical and beaded shapes were measured by scanning electron microscopy (SEM). Si–O–Al bonds were formed in the mixed-shaped silica sol abrasives and were proved by X-ray photoelectron spectroscopy (XPS). Results of CMP tests showed that zirconia ceramic cover obtained a low surface roughness of 1.824 nm and an efficient material removal rate of 0.33 μm/h. Compared with traditional spherical silica sol abrasives, the polishing rate of mixed-shaped silica sol abrasives increased by 242%. Additionally, solid-phase chemical reactions happened to formed ZrSiO₄, ZrAl₂Si₂O₉ in the CMP process. Moreover, friction coefficient was tested and polishing mechanism had been explored by a contact-friction model in this work.     

光催化氧化对GaN材料腐蚀电化学及化学机械抛光的影响

考察了氮化镓(GaN)晶片在不同质量分数和pH的溴酸钾(KBrO3)溶液中的腐蚀电化学行为.结果显示,GaN在溴酸钾质量分数为1％时腐蚀电位最低.在此基础上使用光催化氧化法能够显著降低腐蚀电位,使GaN材料的腐蚀速率进一步提高.CMP实验结果显示:紫外光(UV)的加入使GaN在1％KBrO3溶液(pH=4)中的抛光速率...     

Effects of particle size in silica sol on the mechanical and thermal properties of SiO2f/SiO2 composites

In this paper, quartz fiber-reinforced silica matrix SiO_2f/SiO₂ composites were prepared by the precursor impregnation-heat treatment method using quartz fiber needle felt as the reinforcement and silica sol as the precursor. The effects of particle size in silica sol (10, 50, and 100 nm) on the density, apparent porosity, mechanical properties, and thermal properties of SiO_2f/SiO₂ composites were investigated. The phase composition and microstructure of the composites were characterized by X-ray diffraction and scanning electron microscopy, respectively. The thermal expansion coefficient and thermal conductivity of composites were measured by a push rod method and the laser method. The results show that the density, apparent porosity, and mechanical strength of the specimens firstly increase and then decrease with the increase in the particle size in silica sol. The sample using silica sol with particle size 50 nm has the optimum overall performances (i.e., the flexural strength of 13.7 MPa and the compressive strength of 59.8 MPa), and shows a ductile fracture behavior. At 300°C–700°C, the average thermal expansion coefficient of the optimal sample is .783 × 10⁻⁶/°C. And the thermal conductivity of the samples increases with the increase in temperature, and it reached the highest value of .810 W/(m·K) at 700°C. The SiO_2f/SiO₂ composites show obvious advantages in the application of load-bearing and thermal insulation integration, and they are expected to meet the demanding requirements of hot-pressing sintering and non-ferrous metallurgy industries.     

Effect of zirconia content and particle size on the properties of 3D-printed alumina-based ceramic cores

Alumina-based ceramic cores are used to manufacture the internal structures of hollow alloy blades, requiring both high precision and moderate properties. In this work, zirconia is regarded as a promoter to improve the mechanical properties of sintered ceramic. The effect of zirconia content and particle size on the microstructure and mechanical properties of ceramics was evaluated. The results indicate that the flexural strength of sintered ceramics reached the maximum of 14.5 ± 0.5 MPa when 20 wt% micron-sized (10 μm) zirconia (agglomerate size, consistent with the alumina particle size) was added, and 26.5±2.5 MPa when 15 wt% 0.3 μm zirconia was added. Zirconia with submicron-sized (0.3 μm) particles effectively filled the pores between alumina particles, thus leading to the maximum flexural strength with a relatively low content. The corresponding sintered ceramics had a bulk density of 2.0 g/cm³ and open porosity of 59.6%.     

Structural characteristics and properties of silica/poly(2-hydroxyethyl methacrylate) (PHEMA) nanocomposites prepared by mixing colloidal silica or tetraethyloxysilane (TEOS) with PHEMA

Two methods were used to prepare the silica/poly(2-hydroxyethyl methacrylate) (PHEMA) nanocomposites: one was the direct mixing of colloidal silica with PHEMA using methanol as a co-solvent (colloidal silica/PHEMA) and the other was the adding of the inorganic precursor, tetraethyloxysilane (TEOS), to the PHEMA/methanol solution, followed by the sol-gel process with an acid-catalyst (TEOS/PHEMA). The structure of the colloidal silica/PHEMA hybrid consisted of nano-silica uniformly dispersed in the PHEMA phase with slight inter-molecular hydrogen bonding. The structure of TEOS/PHEMA hybrid was similar to a semi-interpenetrated network with PHEMA chains tethered into the nano-silica network by inter- and intra-molecular hydrogen bonding. Consequently, the TEOS/PHEMA hybrid gels exhibited a smoother surface, higher transparency, and better thermal stability than the colloidal silica/PHEMA hybrid gels.     

焦磷酸钾和双氧水对化学机械抛光中铜/钴电偶腐蚀及去除速率的影响

通过电化学测试和化学机械抛光(CMP)试验研究了pH=10的抛光液中焦磷酸钾和双氧水的质量分数对Cu/Co电偶腐蚀的影响。结果表明,适量K₄P₂O₇和H₂O₂的存在能够有效减小Cu与Co之间的腐蚀电位差,最小可降至11 mV。采用由0.3%H₂O₂、0.1%K₄P₂O₇和2%硅溶胶组成的抛光液进行化学机械抛光时,Cu、Co的去除速率分别为312.0?/min和475.6?/min。     

Evaluating the chemical stability of metal oxides in SO3 and applications of SiO2-based membranes to O2/SO3 separation

The decomposition of sulfur trioxide to produce sulfur dioxide and oxygen using a catalytic membrane reactor is technology that promises to improve the economic viability of the thermochemical water-splitting Iodine-Sulfur (IS) process for large-scale CO₂-free hydrogen production. The chemical stability of membrane materials under SO₃, however, is a significant challenge for this strategy. In this study, microporous membranes with a layered structure that consisted of a membrane support prepared from α-Al₂O₃, an intermediate layer prepared from silica-zirconia, and a top layer prepared from bis (triethoxysilyl)ethane-derived organosilica sols, were examined for stability under SO₃ and for use in SO₃/O₂ separation. An α-Al₂O₃ support that features SiO₂–ZrO₂ intermediate layers with large pore sizes and a high Si/Zr molar ratio showed excellent resistance to SO₃, which was confirmed by N₂ adsorption, Energy Dispersive X-ray Spectroscopy (EDS), and Scanning Electron Microscopy (SEM). These membranes also demonstrated a negligible change in gas permeance before and after SO₃ exposure. Subsequently, in binary-component gas separation at 550°C, microporous organosilica-derived membranes achieved an O₂/SO₃ selectivity of 10 (much higher than the Knudsen selectivity of 1.6) while maintaining a high O₂ permeance of 2.5 × 10⁻⁸ mol m^–2 s^–1 Pa^–1.     

Effects of sintering on the mechanical and ionic properties of ceria-doped scandia stabilized zirconia ceramic

The effect of conventional sintering from 1300 to 1550 °C on the properties of 1 mol% ceria-doped scandia stabilized zirconia was investigated. In addition, the influence of rapid sintering via microwave technique at low temperature regimes of 1300 °C and 1350 °C for 15 min on the properties of this zirconia was evaluated. It was found that both sintering methods yielded highly dense samples with minimum relative density of 97.5%. Phase analysis by X-ray diffraction revealed the presences of only cubic phase in all sintered samples. All sintered pellets possessed high Vickers hardness (13–14.6 GPa) and fracture toughness (~3 MPam^1/2). Microstructural examination by using the scanning electron microscope revealed that the grain size varied from 2.9 to 9.8 µm for the conventional-sintered samples. In comparison, the grain size of the microwave-sintered zirconia was maintained below 2 µm. Electrochemical Impedance Spectroscopy study showed that both the bulk and grain boundary resistivity of the zirconia decreases with increasing test temperature regardless of sintering methods. However, the grain boundary resistivity of the microwave-sintered samples was higher than the conventional-sintered ceramic at 600 °C and reduced significantly at 800 °C thus resulting in the enhancement of electrical conduction.