Ion Beam Polishing Research Articles

Recent Patents for Optical Component Polishing Technology

Background: Fluid jet polishing, Airbag polishing, Magnetorheological polishing, and Ion beam polishing are all emerging polishing technologies commonly used for processing optical components, which can be used to manufacture various high-precision and high-quality optical components. Their processing mechanisms are to remove materials by high-speed jet impacting the surface of the workpiece; using a spherical flexible airbag as a polishing tool to obtain a super-smooth surface by adding polishing fluid containing fine abrasives; controlling the magnetic field to form a flexible polishing belt of Magnetorheological fluid, which undergoes relative motion to achieve material removal; using a neutral ion beam to bombard the surface of the workpiece to remove workpiece surface atoms and obtain a super-smooth surface through energy and momentum transfer between ions and workpiece atoms. The characteristics and removal mechanisms of various polishing methods are briefly described, and the advantages and key issues that need to be addressed for each polishing technology are pointed out, and suggestions and prospects for future research, application, and development are also given. Objective: In order to meet the growing demand for high-precision optical components and mass-manufactured optical components, this paper aims to study the various polishing technologies that are continuously improved and suggestions are made for future research and development directions. Method: This paper reviews the current patents related to various polishing technologies, such as Fluid jet polishing, Airbag polishing, Magnetorheological polishing and Ion beam polishing and other representative polishing technologies. Results: Various types of polishing technologies have been studied, and the main problem at the current stage is the lack of accuracy. The problem of the polishing device, such as fluid jet polishing, only considers the change of fluid velocity and pressure to construct the removal function model for analysis and summary, and suggestions for the latest research progress of various polishing technologies are given. Conclusion: The improvement and optimization of polishing technology are beneficial to improving the polishing accuracy and quality of optical components and have great help for the future development of related patents.

Microstructural BIB-SEM investigation of Upper Cretaceous Jordanian carbonate-rich oil shales bearing type II-S kerogen

AbstractIn this study, we use Broad Ion Beam polishing and Scanning Electron Microscopy (BIB-SEM) to characterize the microstructure of selected core samples of immature Upper Cretaceous carbonate-rich oil shales from Jordan and to link the observations to porosity and compositional and geochemical data. The aim of this study is to understand the distribution of pore space, primary organic matter, and organic sulfur on a sub-micron scale, particularly in carbonate- and silicate-dominated layers. The thermal maturity of these marine carbonate mudstone samples of pelagic origin was found to be influenced by the elevated sulfur contents in these Type II-S kerogen source rocks. This was confirmed through both organic geochemistry and BIB-SEM observations, which revealed high sulfur content. Porosity in the carbonate mudstone exists within foraminifera, and aggregates of microfossil fragments. Initially, these voids provided significant inter- and intra-particle porosity which were later filled by organic matter during diagenesis. This ‘mobile’ organic matter is interpreted as microscopic bitumen, which exists as a solid or highly viscous fluid at surface conditions. It is likely a residue of low-temperature (“early”) bitumen generation. By examining the samples before and after dichloromethane (DCM) extraction and subsequent BIB-SEM analyses, we observed that the specimens contained a significant amount of soluble organic matter (SOM), mostly present in the micropores associated with calcite. The microscopic solid bitumen is observed to remain stable even under various conditions, such as in vacuum oven conditions of 105 °C (24 h), or exposure to ultra-high vacuum, broad ion beam (heat > 70 °C) and an electron beam of 15 keV. This suggests that the solid bitumen acts as a solid at elevated temperatures and confining pressures (85 °C and 250 MPa), and its presence can lead to the buildup of significant fluid overpressures. Our observations indicate that the pores associated with calcite provide high storage capacity in the shales during the early stages of hydrocarbon generation. In contrast, it suggests that siliciclastic-rich samples are more prone to hydrofracturing as the (early) generated hydrocarbons cannot be expelled easily. These findings highlight the complex distribution and behavior of pore space, organic matter, and sulfur in shales, shedding light on their potential for hydrocarbon generation and storage. Graphical abstract

Overview of Patents on Diamond Polishing Apparatus

Diamond, with its unparalleled combination of physical and chemical attributes, occupies a critical role in future technological domains; yet, the caliber of its surface quality is decisively linked to its performance within advanced applications. Thus, engaging in super-precision processing to elevate the surface integrity of diamond constitutes a central tenet for broadening its application potential. This paper systematically dissects patents pertaining to diamond polishing apparatus, not only revealing the distinctive strengths and pragmatic features inherent in contemporary diamond polishing technology but also identifying limitations and avenues for refinement within current polishing methodologies. With the continuous expansion and deepening of modern industrial sectors, there is a growing demand for diversified and specialized material performance. Diamond, as a pivotal raw material, exhibits immense potential in its composite applications with a variety of other materials, forming an entire industrial chain that has permeated numerous industries. Throughout the comprehensive preparation process of diamond, from rough stone to finished product, polishing techniques play a critical role, representing an indispensable step in enhancing the surface quality and functional attributes of diamond products. This study provides a comprehensive review of representative patents in the field of diamond polishing apparatus, analyzing the distinctive functional attributes and performance characteristics of various diamond polishing devices. The study classifies polishing devices according to their design characteristics and application domains into five distinct categories: polishing apparatuses specifically designed for single-crystal diamonds, systems tailored for the polishing of complex curved surface diamonds, laser-assisted diamond polishing setups, structurally-enhanced diamond polishing equipment, and functionally-specialized diamond polishing tools. The analysis underscores the unique innovative aspects and advantages demonstrated by each patent in addressing the inherent limitations of traditional polishing devices. Moreover, it elucidates the technological constraints and developmental gaps that exist within each respective area. Presently, the essence of polishing technology research revolves around the precision and efficacy in polishing single-crystal diamonds and intricate curved diamond surfaces, alongside the structural innovation and functional refinement of polishing apparatuses. Predominant among these devices are those that largely depend on mechanical polishing methods integrated with laser-assisted and chemical mechanical polishing methodologies, where patent advancements are mainly geared towards boosting efficiency, guaranteeing surface integrity, fortifying adaptability across different operating scenarios, and incorporating multiple functionalities. Concurrently, considerable attention is given to enhancing the ecological performance of these systems. There remains a significant underdevelopment and limited widespread application of diamond polishing apparatus in advanced technologies such as thermal chemical polishing and ion beam polishing. This gap presents an enormous potential for innovation breakthroughs and diversified advancements in polishing techniques. There is an urgent need for increased investment to propel the development and integration of automated control systems, intelligent monitoring, and deeper exploration of new materials within polishing technology. The aim is to realize higher-level automated and intelligent diamond polishing solutions that can achieve more efficient, precise, and environmentally friendly polishing objectives.

Anomalous hydraulic fluid absorption by carbon fiber/PEKK composites: Physical and mechanical aspects

AbstractCarbon fiber (CF)/polyetherketoneketone (PEKK) composites are exposed to Skydrol, a hydraulic fluid made of phosphate esters widely used in the aviation field. The present study investigates Skydrol absorption of CF/PEKK composite layups and the associated PEKK matrix. A significant unexpected increase of Skydrol uptake is observed for cross‐ply composites (0.50%) compared to unidirectional ones (0.06%), independently of ply number. The use of ‘model’ fluids like water and ethanol allows to identify the origin of this anomalous Skydrol absorption in the case of cross‐ply layup. We propose that the latter involves an imbibition process governed by the fluid surface tension and the presence of submicronic cavities. SEM imaging of composite cross‐section after ion beam polishing confirms fiber‐matrix submicronic debonding in the interlaminar region in the cross‐ply composite. SEM–EDX confirms the presence of Skydrol into the submicronic cavities. Despite this anomalous absorption, off‐axis tensile testing as well as ILSS testing show no significant impact of Skydrol on CF/PEKK mechanical properties with less than 10% difference compared to the initial values.Highlights Absorption by diffusion of Skydrol in neat PEKK and CF/PEKK composites Link between fluid surface tension and anomalous Skydrol absorption Evidence of submicronic cavities in CF/PEKK composites by means of SEM–EDX Low impact of Skydrol on CF/PEKK mechanical properties

Impact of Sample Preparation Approach on Transmission Electron Microscopy Investigation of Sputtered AlNi Multilayers Used for Reactive Soldering

This work presents studies of sputtered Al/Ni reactive multilayers by transmission electron microscopy. They are prepared for these analyses by three methods (both Ga‐ and Xe‐based focused ion beam, FIB, and tripod polishing plus Ar+ ion milling in precision ion polishing system, PIPS) to check their impact on these materials. Every sample shows polycrystalline and mostly chemically pure Al/Ni layers. They also hint existence of intermetallic compounds, especially the tripod‐prepared sample. These intermetallics first originate from the sputtering process. The layers are increasingly rough along the growth direction. Other remarkable findings can be highlighted. First, the heating operations applied during the tripod polishing preparation lead to recrystallization and blurred Al/Ni interfaces due to increased metals reactions, although additional contributions by roughness and preparation thickness to the current compositional uncertainties must be distinguished by optimizing future sample fabrications and preparations. Second, Xe‐based FIB leads to lamellae with seemingly low contamination, although Ga‐FIB is a potentially good alternative. Finally, FIB is better to study cross‐section preparations of pristine Al/Ni multilayers, whereas the present tripod polishing procedures are unsuitable for this purpose but allow to observe the beginning of Al/Ni transformations upon heating, which is interesting for the technological optimization of these materials.

Preparation of multilayer samples for scanning thermal microscopy examination

Thin film multilayer materials are very important for a variety of key technologies such as hard drive storage. However, their multilayered nature means it can be difficult to examine them after production and determining properties of individual layers is harder still. Here, methods of preparing multilayer samples for examination using scanning thermal microscopy are compared, showing that both a combination of mechanical and ion beam polishing, and ion beam milling to form a crater produce suitable surfaces for scanning thermal microscopy examination. However, the larger exposed surfaces of the ion beam milled crater are the most promising for distinguishing between the layers and comparison of their thermal transport properties.

Multipurpose Additives Toward Improving the Polymer Cold Spray Process

Polymers have proven to be challenging to cold spray, particularly with high efficiency and quality when using inexpensive nitrogen (N2) and air propellants. Helium (He), when used as a process propellant, can improve spray deposit properties but is often undesirable due to its limited availability and high cost. In this study, additives of multiple particle sizes and materials were mixed with polymer powder in an effort to improve the performance of polymer sprays using mainly N2 as a process propellant. The effects of hard-phase additives on deposit microstructure were investigated by precise ion beam polishing of deposit cross sections and subsequent electron microscope imaging. Additional metrics including the density and post-spray composition of deposits were investigated to quantify the peening effect and the amount of embedded additive. Additives, regardless of size, were observed to embed in the spray deposits. Additionally, hard-phase additives demonstrated nozzle cleaning properties that continually remove polymer fouling on the nozzle walls. Inversely, sprays with polymer powder and no additives tended to clog the nozzle throat and diverging section because of continual fouling.

Interface smoothing in short-period W/B4C multilayers using neon ion beam polishing

Short-period 2.5 nm W/B4C multilayers are useful as dispersive Bragg reflectors in wavelength-dispersive x-ray fluorescence. However, high roughness at the W–B4C interfaces deteriorates optical performance. To improve this, low-energy neon ion beam polishing (IBP) has been applied in sputter-deposited 2.5 nm W/B4C multilayers. Two energies, 200 and 50 eV, were investigated to study the effects of polishing by sputter removal (200 eV) and polishing by the mobilization of weakly bound surface atoms (50 eV). Atomic force microscopy and x-ray scattering showed reduced interface roughness for both IBP energies. However, the optical constant profile of 200 eV IBP showed strong W–B4C intermixing and interface asymmetry, leading to significant reflectance loss. In contrast, 50 eV IBP resulted in sharp, symmetric interfaces and increased optical contrast. A 43% peak reflectance at θ = ⁓9.7° grazing for W/B4C with 50 eV IBP was measured at λ = 0.834 nm—a 6.4% increase relative to non-polished W/B4C, corresponding to a 25% increase in integrated reflectance. These results highlight the necessity of using low-energy ion polishing by the mobilization of weakly bound surface atoms in short-period multilayers—rather than polishing by sputter removal.

Growth and optical performance of short-period W/Al and polished W/Si/Al/Si multilayers

Short-period multilayer mirrors are used in wavelength-dispersive x-ray fluorescence to reflect and disperse elements in the O-Kα– Al-Kα range. In this work, we investigated sputter-deposited 2.5 nm W/Al with 20 periods. Our results show that W/Al is a poor reflector due to a combination of high interfacial roughness and strong W–Al intermixing. To address this, we introduced 0.5 nm Si seed layers at the W-on-Al and Al-on-W interfaces each consecutive period, while reducing the Al thickness from ∼2.0 to ∼1.0 nm. The Si seed layers significantly reduced interfacial roughness and W–Al intermixing, which led to an increase in the reflectance of the first Bragg peak at λ = 0.154 nm. To further reduce interfacial roughness, ion beam polishing of the top Si layer was applied at each period. The resulting structure of W/Si/Al/Si with ion beam polishing showed that the reflection coefficient of the first Bragg peak at λ = 0.154 nm was comparable to that of standard W/Si. These findings demonstrate the effectiveness of seed layers combined with polishing techniques in synthesizing smooth, high-reflectance multilayers containing two materials that are otherwise challenging to synthesize.

Advanced Analyses of Heating Elements Manufactured by an Optimized Arc Spraying Process

Heating elements in the automotive industry are currently produced by several thermal spray processes and materials. However, simpler spraying technologies such as arc spraying are investigated regarding technological suitability as a cost-effective alternative to plasma spraying in the production process of these components. Thus, several mixtures and combinations of alternative pressurizing gases and further modifications of an arc spray process were examined in this study. Consequently, coatings based on NiCr were produced, since this alloy is typical for heating elements. Coating properties were investigated by SEM, EDS, and resistivity measurements. The results demonstrate reduced oxygen content and improved morphology compared with the industrially used plasma-sprayed coatings. Additionally, the improved microstructure affects the surface quality and specific resistivity of the coatings positively. This allowed for laser texturing the arc-sprayed coatings successfully. It must be considered a drawback, though, that cracks partially appeared in the underlying coatings. In contrast, the temperature coefficients of resistance and the resistivities of the heating elements were superior to the conventional coatings, which can lay the foundation for a future industrial application. To further investigate this and to minimize the influence of potential sample preparation issues on the analysis results, different methods of cross-sectioning, i.e., in detail hot mounting, cold mounting, and ion beam polishing, were evaluated.

Preparation of Cross-Sectional Membrane Samples for Scanning Electron Microscopy Characterizations Using a New Frozen Section Technique.

Characterization of the cross-sectional morphologies of polymeric membranes are critical in understanding the relationship of structure and membrane separation performances. However, preparation of cross-sectional samples with flat surfaces for scanning electron microscopy (SEM) characterizations is challenging due to the toughness of the non-woven fabric support. In this work, a new frozen section technique was developed to prepare the cross-sectional membrane samples. A special mold was self-designed to embed membranes orientationally. The frozen section parameters, including the embedding medium, cryostat working temperature, and sectioning thickness were optimized. The SEM characterizations demonstrated that the frozen section technique, using ultrapure water as the embedding medium at a working temperature of -30 °C and a sectioning thickness of 0.5 µm, was efficient for the preparation of the membrane samples. Three methods of preparation for the cross-sectional polymeric membranes, including the conventional liquid nitrogen cryogenic fracture, the broad ion beam (BIB) polishing, and the frozen section technique were compared, which showed that the modified frozen section method was efficient and low cost. This developed method could not only accelerate the development of membrane technology but also has great potential for applications in preparation of other solid samples.

EBSD evaluation of damage in micro-tribology experiments on WC/Co hardmetals

WC/Co hardmetals are used in many applications where resistance to abrasive wear is important. To provide further information on the mechanisms of damage that can occur in abrasion, a series of micro-tribology experiments were carried out on a number of WC/Co hardmetal samples. Samples were traversed under a diamond indenter with a sequence of controlled applied loads. The resultant damage was examined by scanning electron microscopy (SEM). Electron back scattered diffraction (EBSD) analysis of the damage was also carried out, both of the test surface, and also at some distance below the surface. To ensure that no damage was introduced to the structure of the materials, broad ion beam polishing was used to polish the original test surfaces and form the sub-surface section.It was found that plastic deformation of the WC grains and the Co binder phase occurred at all test loads. The visibility of slip increased with increasing test load, with fracture to the WC grains starting to occur at higher loads. EBSD analysis confirmed the trend for increasing plastic deformation with increasing load, but also showed that the degree of deformation had a strong relationship with orientation of the WC grains. Some transformation of the normal fcc Co phase to hcp was also detected close to the scratch path.

Surface morphologies, chemical compositions and luminescent properties of ZnO thin films flattened by ion milling procedure

The luminescent properties of ZnO thin films have been developed to form a nanometric light source for an electron beam-excitation assisted optical microscope. Spatial uniformity of the electron-induced luminescence is important when using this luminescent ZnO film-based light source. In this work, ZnO thin film surfaces have been flattened using broad ion beam polishing with Ar+ ions at a grazing angle of incidence. Atomic force microscopy and electron microscopy confirmed transformation of needle-like ZnO surface structures into scale-like morphologies during ion irradiation. The root-square-mean roughness, corresponding to the height distribution decreased dramatically from 32 to 8 nm after 5 keV Ar+ ion irradiation for 60 min. X-ray photoelectron spectroscopy and Monte Carlo simulations revealed changes in the chemical state and lattice defects during ion irradiation. Positive shifts in the binding energies of the Zn 2p and O 1s spectra suggested preferential Zn atom sputtering and chemical composition change from oxygen-deficient to stoichiometric ZnO. The ultraviolet region luminescent intensity improved after ion irradiation for 60 min. Valence band electron redistribution was considered to influence the ZnO thin film’s luminescent properties. We propose that homogeneous luminescence over a specified area with flat surfaces can be accomplished by repeated short-duration ion irradiation.

Evaluation of the surface topography quality of large-area diamonds by image processing and mathematical modeling

Diamond with ultra-smooth and flat surface plays a crucial role in the various fields of nonlinear optics, NV center, waveguide, and so on, due to its remarkable physical properties. Consequently, the fast and efficient polishing and evaluating of diamond surfaces are indispensable to obtain high-quality smooth and flat diamond surfaces. As one of the most widespread techniques, atomic force microscope (AFM) and optical profilometry (OP) are enslaved to their small measurement regions and high time consuming, especially in the case of high-resolution measurement of large area diamond surfaces. Therefore, a novel approach to evaluate the polished diamond surface with high-efficiency and accuracy is desperately required. In this works, we propose a novel approach, surface topography quality (STQ) mathematical model, to achieve fast and large area evaluation to the polished diamond surface. Specifically, by combining currently popular image processing with mathematical statistics, STQ mathematical model generates a concept called surface topography quality rate (STQR) to quantitatively evaluate the surface quality of diamond. The results from large-area scanning electron microscope images before and after ion beam polishing demonstrates its reliability and preponderant advantage in dealing with large area surface compared to that of the conventional use of atomic force microscope. The mathematical model provides a unique and reliable approach to comprehensively and objectively evaluate diamond surface, which may promote the advancement of high-performance diamond-based devices.

Broad Ion Beam–Scanning Electron Microscopy Characterization of Organic Porosity Evolution During Thermal Treatment of Bazhenov Shale Sample

Summary Organic matter-hosted pores are considered as the main type of porosity in organic-rich shales. At the same time, literature indicates the formation of pore space during pyrolysis of oil shales. However, controls, evolution, and types of organic porosity remain controversial. This study aims to experimentally investigate the evolution of organic pores in an organic-rich shale sample during thermal treatment. This paper reports the organic porosity evolution during an artificial maturation experiment of the Bazhenov Formation (BF) shale sample (West Siberian Petroleum Basin). The siliceous-argillaceous organic-rich shale immature nonporous rock sample was treated in an open system in the temperature range of 350–450°C with the step of 10°C. Organic porosity was characterized by the combination of broad ion beam (BIB) polishing and scanning electron microscopy (SEM). After each episode of treatment, the area of 1000×1000 μm was scanned with a resolution of 25 nm. The acquired mosaic SEM images were segmented by the neural network algorithm and quantitatively analyzed. We demonstrate direct experimental evidence that thermal maturation/thermal treatment influence on organic porosity development. Organic porosity evolution is shown within the individual organic matter (OM) particles throughout the experiment. Thermal treatment leads to the formation of two types of organic pores, which are shrinkage and spongy pores. The first shrinkage pores start to form after the evacuation of existing hydrocarbons; they are relatively large and might reach 7 µm. This type of pore dominates at the initial stages of treatment (350–390°C). Porosity at this stage does not exceed 1.4%. The second type is spongy pores, which are up to 3–5 μm in size and are potentially formed due to hydrocarbon generation from the kerogen. This type of porosity becomes major after 400°C. This is confirmed by the pore size distribution analysis. The porosity spikes up to 2.3% after 400°C and rises up to 2.9% after 450°C. Revealing of artificial organic porosity development during thermal treatment experiment shows the crucial importance of the thermal maturity level. The formation of pore space during the treatment is critical during the implementation of thermal enhanced oil recovery (EOR) technologies in shales for fluid flow, and a mandatory aspect that should be accounted during thermal EOR simulations.

Optimizing broad ion beam polishing of zircaloy-4 for electron backscatter diffraction analysis

To provide useful materials characterization, we must prepare samples well so that we can avoid studying artefacts induced during sample preparation. This motivates us to systematically study our preparation methods. In this work, we focus on improving “broad ion beam” (BIB) polishing through a combination of consideration of the ion-sample interactions and a systematic study of options provided by commonly available broad ion beam milling machines. Our study specifically aims to optimise the preparation of zircaloy-4, which is an alloy of zirconium used in nuclear fuel cladding, and we note that this alloy is difficult to prepare with other sample preparations routes. We optimise BIB polishing to study the microstructure of the zircaloy-4 with electron microscopy based electron backscatter diffraction (EBSD). To conclude our study, we provide recommendations for new users of BIB based polishing methods.

Chemical – crystallographic characterisation of cement clinkers by EBSD-EDS analysis in the SEM

Characterisation of cement clinkers is a prerequisite to optimise properties of cements and concretes. Therefore, the protocol to prepare and characterise cement clinkers using electron backscatter diffraction (EBSD) in combination with energy dispersive X-ray spectrometry (EDS) is described.It is shown that argon broad ion beam polishing delivers surfaces with high contrast electron backscatter diffraction patterns (EBSP). EBSD data quality in high and low vacuum SEM reveals that high vacuum conditions and state-of-the-art EBSD cameras deliver EBSPs of cement clinker at improved quality.Furthermore, exemplary EBSD-EDS analysis is discussed for two Portland cement clinkers. Results clearly show that differentiation between major phases can reliably be achieved. In addition, it is revealed that crystal distortion in belite is high. Analysis of C3A phases show that differentiation of orthorhombic and cubic polymorph is possible, and that Mg incorporation leads to amorphization.Results demonstrate that EBSD-EDS analysis allows reliable phase characterisation of cement clinkers.

Study on Continuation Correction of Ion Beam Polishing to Remove Border Effect

Study on Continuation Correction of Ion Beam Polishing to Remove Border Effect

Ion Beam Polishing Process of Off-Axis Parabolic Mirror

Ion Beam Polishing Process of Off-Axis Parabolic Mirror

Pore Connectivity Characterization Using Coupled Wood’s Metal Intrusion and High-Resolution Imaging: A Case of the Silurian Longmaxi Shales From the Sichuan Basin, China

Pore connectivity is crucial for shale gas production. However, the three-dimensional (3D) characteristics and distribution of pore networks and, more fundamentally, the underlying role of different pore types on pore connectivity in shales are inadequately understood. By comparing the 3D pore connectivity derived from direct microstructural imaging of pores filled with Wood’s metal at a pressure corresponding to the finest accessible pore throat in the resolution ranges that may be achieved by X-ray micro-CT and SEM, it is possible to evaluate pore connectivity of different types of shales. The pore connectivity of three shales including a mixed mudstone, siliceous shale, and argillaceous shale from the Silurian Longmaxi Formations is investigated via combined broad ion beam (BIB) polishing, and SEM and X-ray micro-CT imaging after Wood’s metal injection at a pressure up to 380 MPa. The three shales show significant differences in pore connectivity. The mixed mudstone shows excellent pore connectivity in the matrix; the siliceous shale shows an overall poor connectivity with only a small amount of OM (organic matter) pores immediately adjacent to microfractures displaying interconnectivity, while the pores in the argillaceous shale, dominated by plate-like clay pores, are largely not interconnected.