Milling Step Research Articles

Phase and microstructure formation during reactive spark plasma sintering of AlxCoCrFeNi (x=0.3 and 1) high entropy alloys

This paper is one of the first studies focusing on phase and microstructure formation mechanisms during reactive sintering of AlxCoCrFeNi (x = 0.3, 1) high entropy alloys (HEAs). The alloys have been prepared by mechanical activation followed by spark plasma sintering (SPS). Both powders are subjected to gluing to the milling vials and the phenomenon intensifies with Al content, resulting in a more important mechanical alloying delay for the equiatomic composition. The temperature influence on phase and microstructure formation was investigated by SPS from 550 to 1100 °C. Al0.3CoCrFeNi reactive sintering led to a face-centered cubic (FCC) solid solution with a grain size around hundreds of nanometers with nanometric intergranular B2 precipitates which content and size reduced with the temperature increase. Grain growth was observed at prior particle boundaries due to dynamic recrystallization, a phenomenon that can be controlled through modification of the milling and sintering steps, leading thus to tailored grain sizes. For the AlCoCrFeNi composition, temperature increase favors secondary FCC formation and leads to sigma phase precipitation. A dual homogeneous-heterogeneous microstructure is obtained due to the important gluing leading to insufficient milling. The dynamic recrystallization at prior particle boundaries promotes also body-centered cubic (BCC) to FCC phase transition. Therefore, the proposed reactive sintering route allows to obtain, for the equiatomic composition, alloys exhibiting very fine microstructures, with higher FCC fraction content than by conventional metallurgy processes.

Irreducible IrO2 Anode Co-Catalysts for PEM Fuel Cell Voltage Reversal Mitigation and Their Stability Under Start-Up/Shut-Down Conditions

IrO2 has been widely used as the anode co-catalyst for mitigating cell voltage reversal damages in proton exchange membrane fuel cells (PEMFCs). However, under the PEMFC anode operation conditions, conventionally prepared IrO2 catalysts are reduced by H2, forming metallic Ir on their surface, which is prone to dissolution during start-up/shut-down (SUSD) cycles. The dissolved Irn+ ions can permeate through the membrane to the cathode electrode, poisoning the oxygen reduction reaction (ORR) activity of the Pt/C cathode catalyst. In this study, we introduce an unprecedented approach to synthesize IrO2 catalysts (irr-IrO2) which are not reduced in the PEMFC anode environment at 80 °C over extended time. Their preparation is based on an industrially scalable procedure, consisting of a high-temperature (650 °C–1000 °C) heat treatment step, a subsequent ball milling step, and a final post-annealing step, thereby attaining catalysts with specific surface areas of ∼25 m2 g−1. The high reduction resistance of the irr-IrO2 catalysts, attributed to their highly ordered crystalline structure compared to that of typically synthesized IrO2 catalysts, is reflected by the observation that SUSD cycling of MEAs with the irr-IrO2 as anode co-catalysts does not result in iridium dissolution and the associated iridium poisoning of the Pt/C cathode catalyst.

Recycling and reuse of ceramic materials from components of waste solid oxide cells (SOCs)

As one of the main waste streams of the manufacturing process of solid oxide cells (SOCs), scrap half-cells - discarded before the deposition of the barrier layer and the air electrode - imply the loss of significant quantities of ceramic composite material containing critical and hazardous elements, namely yttria-stabilized zirconia (YSZ) and NiO. These materials represent more than 90 wt% of an entire anode-supported cell. In this contribution, scrap half-cells were fragmented and subjected to three subsequent milling and sieving (below 25 μm) steps to recover composite NiO-YSZ powders with the appropriate specifications for reuse in SOC manufacturing. The overall characterization in terms of specific surface area, particle size distribution and crystalline phase retention confirmed the suitability of the recovered powders. Half-cells were manufactured including 30 wt% of recovered NiO-YSZ composite powders in their fuel electrode support, produced via tape-casting in combination with 70 wt% of virgin materials. The obtained cells were morphologically, mechanically and electrochemically tested and compared against standard cells constituted by 100 wt% of virgin materials. The electrochemical characterization highlighted 0.68 A cm−2 for the standard and recycled cells, at 600 °C and 0.7 V, while at 650 °C and same voltage both cells measured 1.12 A cm−2. This demonstrates the feasibility of recovering scrap SOCs through the presented method.

Plasma-Treated Cobalt-Doped Nanoporous Graphene for Advanced Electrochemical Applications

Metal–carbon nanocomposites are identified as key contenders for enhancing water splitting through the oxygen evolution reaction and boosting supercapacitor energy storage capacitances. This study utilizes plasma treatment to transform natural graphite into nanoporous few-layer graphene, followed by additional milling and plasma steps to synthesize a cobalt–graphene nanocomposite. Comprehensive structural characterization was conducted using scanning and transmission electron microscopy, X-ray diffraction, Raman spectroscopy, gas sorption analysis and X-ray photoelectron spectroscopy. Electrochemical evaluations further assessed the materials’ oxygen evolution reaction and supercapacitor performance. Although the specific surface area of the nanoporous carbon decreases from 780 to 480 m2/g in the transition to the resulting nanocomposite, it maintains its nanoporous structure and delivers a competitive electrochemical performance, as evidenced by an overpotential of 290 mV and a Tafel slope of 110 mV/dec. This demonstrates the efficacy of plasma treatment in the surface functionalization of carbon-based materials, highlighting its potential for large-scale chemical-free application due to its environmental friendliness and scalability, paving the way toward future applications.

Efficient conversion of an underutilized low-lignin lignocellulosic biomass to cellulose nanocrystals and nanofibers via mild chemical-mechanical protocols

The production of high-quality nanocellulose (NC) from an underutilized low-lignin lignocellulosic biomass source, Phalaris aquatica L., was investigated via three conversion protocols. Initially, a conventional chemical protocol (Scenario I) was optimized using statistically designed experiments, and cellulose nanocrystals (CNCs) that exhibited an adequate crystallinity index (CI) were produced under mild conditions: short processing times, reduced temperatures and decreased use of chemicals and solvents. Hydrolysis temperature was found to contribute significantly to the variation of CI. Furthermore, two additional scenarios based on a planetary ball mill were comparatively applied, namely a combined chemical-mechanical (Scenario II) and an alternative (Scenario III) protocol, in which the ball milling step followed or replaced the acid hydrolysis step, respectively. In Scenarios II and III the NC structure was modified to cellulose nanofibrils (CNFs) and microfibrillated cellulose (MFC), respectively. Accordingly, the three different NC grades (CNCs, CNFs and MFC) were correlated with the three conversion protocols.

Conjugate Multimode Heat Transfer Analysis of Cryogenic EXLO Manipulation.

In this study, a conjugate radiation/conduction multimode heat transfer analysis of cryogenic focused ion beam (FIB) milling steps necessary for producing ex situ lift out specimens under cryogenic conditions (cryo-EXLO) is performed. Using finite volume for transient heat conduction and enclosure theory for radiation heat transfer, the analysis shows that as long as the specimen is attached or touching the FIB side wall trenches, the specimen will remain vitreous indefinitely, while actively cooled at liquid nitrogen (LN2) temperatures. To simulate the time needed to perform a transfer step to move the bulk sample containing the FIB-thinned specimen from the cryo-FIB to the cryo-EXLO cryostat, the LN2 temperature active cooling is turned off after steady-state conditions are reached and the specimen is monitored over time until the critical devitrification temperature is reached. Under these conditions, the sample will remain vitreous for >3 min, which is more than enough time needed to perform the cryo-transfer step from the FIB to the cryostat, which takes only ∼10 s. Cryo-transmission electron microscopy images of a manipulated cryo-EXLO yeast specimen prepared with cryo-FIB corroborates the heat transfer analysis.

Improving the Electronic Conductivity of Alluaudite Na2.5Fe1.75(SO4)3 Cathodes for Na-Ion Batteries

The increasing dependency on batteries in modern technology has led to an ever-increasing demand that cannot be met by Li-ion batteries (LIBs) alone. The push towards using renewable energy and electric vehicles, coupled with the limited reserves of lithium resources is encouraging research into alternative options for electrochemical storage devices. Na-ion batteries (SIBs) are a promising alternatives due to the similarity of their chemistry to LIBs. This allows for utilisation of analogous materials and methods already in place for LIBs. Furthermore, SIBs are more economically viable and environmentally sustainable due to the abundance of the elements that can be utilised as electrode active materials. For example, SIB cathodes, such as Na2.5Fe1.75(SO4)3, can be synthesised from precursor materials that are widely available by-products of industry. The polyanionic framework of Na2.5Fe1.75(SO4)3 has three 3-dimensional vacancies within it, in which Na-ions de/intercalate.[1] However, the performance of Na-ion batteries is hindered by the low electronic conductivity of these polyanionic compounds, affecting the flow of electrons through the material and the reversible movements of the Na ions.[2] To address this issue, previous reports have shown that using a conductive additive such as carbon black and graphene oxides can increase the electronic conductivity of Na ion cathode materials and improving battery performance.[3]In this work, we investigate a non-stoichiometric alluaudite phase Na2.5Fe1.75(SO4)3 material (NFS), produced by a ball-milling-assisted solid-state synthesis. A study of the effects of variables on the ball milling process using the was carried out. A multi-step process involving a repetition of the ball milling and annealing was used to decrease particle size and eliminate impurities. The results were compared regarding particle size, impurities present, conductivity and battery performance. The obtained materials were characterised using X-ray diffraction, scanning electron microscopy and electrochemical impedance spectroscopy. The materials were tested as cathodes in sodium half-cells with 1 mol/L NaClO4 in ethylene carbonate (EC)/ propylene carbonate (PC) electrolyte. The additional ball milling and annealing steps saw a significant decrease in impurities present across all variations in methodology. All batteries show three redox peaks in their differential capacity plots, demonstrating that all three vacancies within the polyanionic framework of Na2.5Fe1.75(SO4)3 are active during charge and discharge. The best performing electrode achieved a capacity of 80 mAh/g using only C45 as a conductive additive. These are promising results that are expected to improve with further studies researching the addition of RGOs and MXenes into the ball milling process. These composite electrodes will be prepared by combining rGOs/MXenes with the NFS precursors during the synthesis process of Na2.5Fe1.75(SO4)3 to enhance battery performance further.

Dry fractionation for endosperm recovery from a barley malt waste stream

Cereal processing industry removes the fibrous tissues from kernels via abrasive milling, but this tends to remove part of the valuable endosperm components as well. Therefore, endosperm recovery from such abraded barley malt material (53% endosperm and 47% husk) was evaluated for three dry separation technologies. Electrostatic separation recovered 25% of the endosperm at 85% purity and this recovery increased to 39% in a second run, which indicated potential to further improve the setup. Increasingly finer sieves removed up to 40% of the husk with little endosperm loss, but further husk removal up to 95% by the finest sieve reduced the endosperm yield to 54% due to decreasing differences in smallest diameter between the endosperm and husk particles. Air classification outperformed sieving by yielding 71% of the endosperm while removing 95% of the husk, and further, less selective air classification steps could yield up to 94% of the endosperm while still removing 59% of the husk. Moreover, such additional air classification steps currently recovered residual endosperm particles more selectively than electrostatic separation after an initial air classification. Overall, air classification after abrasive milling increased the removal of insoluble matter from malted barley kernels. The loss of soluble endosperm components remained similar to the loss as observed in a single abrasive milling step.

Comparison of hydration water properties of common and durum wheat brans upon grinding with different loading modes

Wheat bran brings healthy properties in food products. However, its incorporation requires a first milling step during which it is subject to various loading modes which have an influence on its properties. This study investigated the influence of the loading modes (high shear or impact) generated by grinders during the milling on the hydration properties of common and durum wheat brans. An original study at molecular scale to target the distribution and intensity of hydration water bonds was carried out by gravimetric and spectroscopic methods. Results were analyzed in regards to the particle size distribution and shape factors as well as biochemical composition to highlight the process-structure-function relationships at macro and microscales. Impact grinder has a stronger effect on water vapor sorption capacity and FTIR multimer water at 3600 cm−1 of durum wheat bran as well as a red shift in the band at 1030 cm−1 related to a high decrease in residual starch crystallinity degree (about 17%). High shear grinder tends to increase the proportion of water strongly bound. Low field NMR analysis revealed differences in the high mobility water peak and a significant lower relaxation time T2 for native and ground durum wheat bran (up to 1.7 fold less).

Process optimization of broad ion beam milling for preparation of coating cross-sections

The application of Argon ion based broad ion beam milling in the preparation of coating cross-sections is systematically evaluated in this work. In order to reduce and eliminate defects and artefacts from the prepared sectional surface, the substrate side of the sample is found to be best facing the ion beams, and the milling time needs to be optimized to be not too long to introduce scratching of the obtained surface, while not too short to result in particle deposition. Further, the energy of the ion beams is found to have great effect on the etch rate of the sample, thus having a large impact on the process time and quality depending on the materials nature of the samples. It is found that by introducing a second low-energy polishing step after the high-energy milling step, the quality of the cross-section is greatly improved with the measured surface roughness down to the nanometer scale. The capability of broad ion beam milling method to provide smooth cross-sections for the subsequent microscopic investigations by e.g. scanning electron microscopy or atomic force microscopy is important to reveal morphological information of the coating systems with high level of details without distortions due to sample preparation.

Influence of particle contact on flash sintering of ZnO and 8YSZ: Microstructure and electrical conductivity

The flash phenomenon in flash sintering of ceramic materials is closely related to electrical conductivity of the material. However, our understanding of how particle-to-particle contact of ceramic powders affects this phenomenon and, consequently, the microstructure and electrical properties of flash-sintered materials remains limited. To address this, we utilized “pseudo-in-situ” impedance spectroscopy to investigate the effect of particle-to-particle contact in nanometric powders of ZnO and 8YSZ, both before and after flash sintering. The powders were prepared using two different procedures, either grinding with a binder or employing multiple milling and calcining steps. After compacting into pellets, the samples were characterized before and after flash sintering, either with current-to-voltage control or with the application of current density ramps until the flash event occurred. Pseudo-in-situ impedance was employed to demonstrate that preparing powders using multiple milling and calcining steps improved charge-carrier mobility paths, facilitated homogeneous passage of electric current, reduced thermal gradients, and consequently resulted in better microstructural homogeneity and electrical conductivity. In addition, the use of the electric-current ramp control retained microstructural homogeneity to a greater degree.

Yerba Mate (Ilex paraguariensis) Processing and Extraction: Retention of Bioactive Compounds.

Ilex paraguariensis is a native tree from South America known for the presence of bioactive compounds, and its processed leaves are consumed as hot and cold infusions. After harvest (step 1), the leaves are subjected to flame blanching to inactive the enzymes (step 2), followed by drying and milling (step 3). The impacts of I. paraguariensis processing on leaf composition were investigated by extracting the major compounds (chlorogenic and isochlorogenic acids (3-CQA, 4-CQA, 5-CQA, 3,4-DQA, 3,5-DQA and 4,5-DQA), p-coumaric acid, caffeine and rutin) using different ratios of ethanol and water as extraction solvent (EW 25:75, 50:50, and 75:25 (w/w)). The solvent ratio of EW 50:50 was more effective in extracting the chlorogenic acids isomers, with retention of chlorogenic acids of 3463, 9485, and 9516µg mL- 1 for steps 1, 2, and 3, respectively. Rutin and p-coumaric acid exhibited similar behavior with the increment of processing steps; however, p-coumaric acid was only detected in steps 2 and 3 for the solvent ratios EW 50:50 and 25:50. The caffeine extraction from I. paraguariensis varied from 936 to 1170µg mL- 1 for all processing steps, with emphasis on its concentration extracted in step 1. The evolution of processing steps led to a higher retention of phenolic compounds from I. paraguariensis, which was not observed when using different solvent ratios, and the solvent ratio EW 50:50 was more effective for the extraction of chlorogenic acids. The successful extraction of chlorogenic acids from I. paraguariensis in this study proved to be a promising alternative for the use of yerba mate beyond the cuia cup.

Natural occurrence of ustiloxins in rice from five provinces in China and the removal efficiencies of different milling steps.

The widespread incidence of "false smut" disease in rice has caused extensive ustiloxin contamination around the world. Until now there has been a lack of knowledge regarding the natural occurrence of ustiloxins in paddy. The development of efficient removal methods is also still a challenge that remains unexplored. In the current study, three main ustiloxins - ustiloxin A (UA), ustiloxin B (UB), and ustiloxin G (UG) - were determined simultaneously by ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) in 206 paddy samples collected in 2021 from five rice-producing provinces in China. The predominant ustiloxin was UA with an occurrence of 46.1% and an average concentration of 49.71 μg kg-1 . This was followed by UB (31.1%, 13.31 μg kg-1 ) and UG (18.4%, 9.19 μg kg-1 ). No targeted ustiloxins were detected in white rice samples randomly collected from supermarkets in Shanghai. To reveal the causes, two approaches were tested for the removal of the ustiloxins: most of the targeted ustiloxins (>93%) were removed in brown rice by husking and, subsequently, all targeted ustiloxins (100%) were removed by whitening. A wide distribution of ustiloxins was discovered in paddy samples in this study. The UA contaminations were significantly different depending on their origin, with the highest occurrence in paddy from Shanghai and Jiangsu, southeast coast provinces in China. Contamination by UG was also found in paddy for the first time and was strongly correlated with those of UA and UB. A combination of husking and whitening has been verified to be a practicable and promising way to ensure efficient removal and food safety. © 2023 Society of Chemical Industry.

152 Top-down Preparation and Characterization of Crystalline Nanosilica for Toxicological Investigations

Abstract Crystalline silica (CS) is a well-known human carcinogen and freshly fractured CS is strongly held to be more toxic than aged dust. Mechanical fracturing indeed generates on CS surface a specific family of Nearly-Free Silanols (NFS), a moiety that was proved to destabilize cell membranes and initiate inflammation in vivo. During milling, silica nanoparticles are also generated, however their contribution to the overall toxicity of quartz is still largely unexplored. Nanoquartz can be synthetized via bottom-up methods, but the surface chemistry of those crystals strongly differs from nanoparticles resulting from fracturing. We report here a top-down milling procedure to obtain a nanometric quartz that shares with fractured quartz the key surface properties relevant to toxicity. Fracturing procedure was optimized by coupling dry and wet milling steps, using water as a dispersing agent, and varying milling times and rotational speeds. We obtained a set of samples that would be classified as nanomaterials under EU CLP regulation (>50% of particles in number are < 100 nm) and exhibited a strong tendency to form submicrometric agglomerates. Deagglomeration with surfactants or simulated body fluids was negligible. Partial lattice amorphization and bimodal crystallite domain size were observed, as confirmed by the presence of two distinct domains of scattering with nanometric (< 50 nm) and submicrometric (0.8-1 µm) crystallite size. A moderate membranolytic activity, which nicely correlated with the amount of surface NFS, signalled that our nanoquartz may induce inflammation in vivo. Overall, a membranolytic nanoquartz for investigating the toxic activity of nanometric silica was obtained.

CryoFIB milling large tissue samples for cryo-electron tomography

Cryo-electron tomography (cryoET) is a powerful tool for exploring the molecular structure of large organisms. However, technical challenges still limit cryoET applications on large samples. In particular, localization and cutting out objects of interest from a large tissue sample are still difficult steps. In this study, we report a sample thinning strategy and workflow for tissue samples based on cryo-focused ion beam (cryoFIB) milling. This workflow provides a full solution for isolating objects of interest by starting from a millimeter-sized tissue sample and ending with hundred-nanometer-thin lamellae. The workflow involves sample fixation, pre-sectioning, a two-step milling strategy, and localization of the object of interest using cellular secondary electron imaging (CSEI). The milling strategy consists of two steps, a coarse milling step to improve the milling efficiency, followed by a fine milling step. The two-step milling creates a furrow–ridge structure with an additional conductive Pt layer to reduce the beam-induced charging issue. CSEI is highlighted in the workflow, which provides on-the-fly localization during cryoFIB milling. Tests of the complete workflow were conducted to demonstrate the high efficiency and high feasibility of the proposed method.

Twice-milled magnetic biochar: A recyclable material for efficient removal of methylene blue from wastewater

Although magnetic modification has potential for preparing recyclable biochar, the traditional preparation methods of loading magnetic materials on biochar will probably lead to pore blockage and consequently remarkable adsorption recession. Herein, a preparation method was developed in which ball milled biochar was loaded with ultrafine magnetite and then milled for a second time, thus generating a magnetic, recyclable biochar with minimal pore blockage. The deposits of magnetite did not significantly wrap the biochar, although a decreased sorption performance was still detectable. Benefitting from the extra milling step, surface functional groups and specific surface areas of the adsorbents were largely restored, thus leading to a 93.8 % recovery adsorption of 84.6 ± 2.5 mg/L on methylene blue. Meanwhile, the recyclability of the material was not affected. The adsorption was driven by multiple interactions. These twice-milled magnetic biochar is quite outstanding for sustainable removal of aqueous contaminants with its recyclability and high sorption efficiency.

Okapi-EM: A napari plugin for processing and analyzing cryogenic serial focused ion beam/scanning electron microscopy images.

An emergent volume electron microscopy technique called cryogenic serial plasma focused ion beam milling scanning electron microscopy (pFIB/SEM) can decipher complex biological structures by building a three-dimensional picture of biological samples at mesoscale resolution. This is achieved by collecting consecutive SEM images after successive rounds of FIB milling that expose a new surface after each milling step. Due to instrumental limitations, some image processing is necessary before 3D visualization and analysis of the data is possible. SEM images are affected by noise, drift, and charging effects, that can make precise 3D reconstruction of biological features difficult. This article presents Okapi-EM, an open-source napari plugin developed to process and analyze cryogenic serial pFIB/SEM images. Okapi-EM enables automated image registration of slices, evaluation of image quality metrics specific to pFIB-SEM imaging, and mitigation of charging artifacts. Implementation of Okapi-EM within the napari framework ensures that the tools are both user- and developer-friendly, through provision of a graphical user interface and access to Python programming.

The effect of boron-doped cobalt additions on mechanical properties of a recycled WC-Co powder

Cobalt and tungsten have been listed since 2008 as “critical raw materials” by the European Commission. Recycling used cemented carbide tools is a solution to reduce the criticality of those materials. However, recycled tungsten carbide powder, made from the Coldstream process, shows low sinterability properties at conventional sintering temperatures. To enhance mechanical properties, boron-doped cobalt powder is added during the ball milling step. Due to the formation of a eutectic between boron and cobalt, the sinterability of the powders is greatly improved, and the sintering temperature could be decreased by 100 °C compared to conventional processes.The as-received recycled powder contains 7.5 wt% cobalt. That powder has been milled with the addition of boron-doped cobalt powder. Three powders have thus been prepared: WC-7.5(CoB), WC-10(CoB), and WC-15(CoB). The sintered parts have been characterized in terms of physical, and mechanical properties, and grain size distributions. The boron-doped parts showed superior mechanical properties for a lower sintering temperature than boron-free samples.

Top-Down Preparation of Nanoquartz for Toxicological Investigations.

Occupational exposure to quartz dust is associated with fatal diseases. Quartz dusts generated by mechanical fracturing are characterized by a broad range of micrometric to nanometric particles. The contribution of this nanometric fraction to the overall toxicity of quartz is still largely unexplored, primarily because of the strong electrostatic adhesion forces that prevent isolation of the nanofraction. Furthermore, fractured silica dust exhibits special surface features, namely nearly free silanols (NFS), which impart a membranolytic activity to quartz. Nanoquartz can be synthetized via bottom-up methods, but the surface chemistry of such crystals strongly differs from that of nanoparticles resulting from fracturing. Here, we report a top-down milling procedure to obtain a nanometric quartz that shares the key surface properties relevant to toxicity with fractured quartz. The ball milling was optimized by coupling the dry and wet milling steps, using water as a dispersing agent, and varying the milling times and rotational speeds. Nanoquartz with a strong tendency to form submicrometric agglomerates was obtained. The deagglomeration with surfactants or simulated body fluids was negligible. Partial lattice amorphization and a bimodal crystallite domain size were observed. A moderate membranolytic activity, which correlated with the number of NFS, signaled coherence with the previous toxicological data. A membranolytic nanoquartz for toxicological investigations was obtained.

Fabrication of high aspect ratio atomic force microscope probes using focused ion beam milled etch mask

The shape and dimension of atomic force microscope (AFM) probes are essential considerations to acquire high resolution images at the nanoscale. In the cases of nanostructures with high aspect ratio (HAR) features, including dot and line arrays, commercially available standard silicon AFM probes fail to provide satisfactory results. This is due to the low aspect ratio pyramidal tip profile which cannot adequately follow the sample surface. Here a simple method is introduced to convert commercially available pyramidal probes to HAR probes by combining focused ion beam (FIB) and plasma etching techniques. A bilayer metal is deposited on standard AFM probes using e-beam evaporation, followed by a quick FIB milling process to pattern the very thin top metal layer. The FIB milled metal layer is used as the hard mask to transfer the pattern to the underlying metal layer and an HAR pillar on top of the tip apex was achieved via plasma etching. Compared to the traditional HAR tip fabrication, where the tips are individually manufactured at high cost and in a time-consuming fashion, our method significantly reduces the usage of FIB milling. Additionally, this method is suitable for batch fabrication via plasma etching once the simple FIB milling step is performed.